Author: ecogrow

Accordingly, the order anaerolineae of the phylum chloroflexi has been identified as an obligate anaerobe, and the order flavobacteriales of the phylum bacteroidota are aerobic chemoorganotrophs . The sequence reads of anaerolineae after dry down events are highest for the CF treatment, followed by LS. In contrast, flavobacteriales follow the opposite trend, increasing in sequence reads after the dry down event for HS and MS treatments. Given that the identified aerobic and anaerobic orders in our rhizosphere soil samples correlate with the oxic and anoxic conditions introduced by dry down treatments and follow an expected trend with regards to the severity of the treatments, we can infer that II treatments of a single dry down event have the potential to shift the microbial communities of the rhizosphere in rice paddies. As we aim to understand how changes in the abundance of microbial communities under II treatments throughout a rice growing season affect the chemistry and cycling of elements in the rhizosphere, we recall that in Chapter 2 and in Seyfferth et al., 2017, a positive correlation between As and Fe precipitated in rice root plaque was found. Now we must determine if bacterial communities are contributing to the interactions between these elements in the rhizosphere of rice. Bacteria of the family geobacteraceae of the phylum desulfobacterota, anaeromyxobacteraceae of the phylum myxococcota , as well as the genus ferribacterium of the class gammaproteobacteria ,vertical vegetable tower have been found as iron reducing bacteria in paddy soils. In our study, geobacteraceae was found in a lowest amount in the HStreatment, and anaeromyxobacteraceae in the MS and HS treatments.

Both taxa increased in sequence reads between 60-90 days after sowing. Reads of the genus ferribacterium were present in all treatments before dry down events and decreased progressively to zero following dry down treatments for HS, MS, and LS. Additionally, some commonly reported Fe oxidizing bacteria, which may also oxidize As, include genera acidovorax and thiobacillus of the class gammaproteobacteria , and the genus nitrospira of the phylum nitrospirota . The sequence reads of thiobacillus were higher for the HS treatment, followed by MS throughout the growing season. Similarly, acidovorax expressed higher reads for the HS treatment after a dry down event and decreased after reflooding; it was not identified in the CF treatment. Unexpectedly, nitrospira, despite being aerobic, did not follow this trend; higher sequence reads were identified for the LS and CF treatments after dry down treatments. This genus has been related to different processes involved in Fe, N, and S cycling in the rhizosphere of rice, which could explain a contrasting trend given that it may be impacted by proton exchange processes in these elemental cycles . Our results show changes in aerobic and anerobic, as well as iron oxidizing and reducing, taxa related to II treatments, confirming that oxic and anoxic fluctuations in soil due to a single dry down event impact the community structure of rice rhizosphere soil bacteria. Alpha diversity results revealed 20 to 25% more diversity in features within a CF soil sample compared to dry soil before sowing. In contrast, we learned from our PCoA results that the changes in microbial community composition expressed in variability between samples is higher for II treatments than CF throughout the growing season.

These changes in the diversity of the II samples are explained by the variability factors such as taxonomic differences and abundance. Our pot experiment was conducted as a replication of the 2017 2018 rice growing field trials at Biggs, CA explained in Chapter 1. Although water management treatments, as well as plant care were carefully planned, it is necessary to consider that this experiment cannot fully imitate field conditions in terms of scale, hydrology, and other environmental factors. In fact, it may be considered as a closed system given that each replicate consists of 1 gallon of soil, thus the movement of dissolved constituents of the soil solution is limited, as well as the space for root growth and the balance of air and water in soil . In addition, dry down treatments were not performed in the precise way as field trials, given that our system cannot imitate the evapotranspiration and percolation rates of a paddy field. Instead, bins were drained for 1, 3.5, and 5.5 days for LS, MS, and HS, respectively. Despite having reached the water potential of the II treatments at the field trial, the period of drainage was shorter. Given these differences, we cannot expect that the observed changes in microbial communities from pot trials will necessarily be the same at the field scale. Additionally, As concentrations in the soil used for this experiment represented northern California conditions and are low in comparison to paddy soils in Southeast Asia and other rice growing regions. Consequently, As levels were too low to be the main factor shaping the bacterial communities in this study . It is important to consider that higher concentrations of As may significantly affect the microbial community diversity in paddy soils . Seasonally dry tropical forests are dominated by deciduous species coexisting with a small number of evergreen species . Trees withstand the dry season through two mechanisms of drought resistance: desiccation delay and desiccation tolerance . Two important traits related to desiccation delay are leaf shedding which reduces water loss, and depth of rooting , which determines the sources of water and nutrients used by vegetation . Although previous reports suggested that evergreen species access relatively deeper water sources than deciduous species ,more recent reports suggest that access to water is more related to tree size than phenology .

However, there is relatively little information regarding differences among deciduous species having different timing or leaf shedding behavior, even though it is well known that leaf senescence behavior varies greatly among tropical dry forest tree species. Flushing and leaf abscission result from complex interactions between plants and their environment; in many species, the main abiotic factors driving these processes are solar radiation, air relative humidity, vapor pressure deficit,vertical farming equipments precipitation and soil water content . Four main categories of leaf shedding phenology have been proposed by Williams et al. : evergreen species, which retain a full canopy throughout the year; partially deciduous species, which lose up to 50 % of their canopy during the dry season; semi deciduous species, which lose more than 50 % of their canopy during the dry season; and deciduous species, in which all leaves are lost during the dry season as they remain leafless for at least 1 month. Most tropical dry forest species are thought to deploy the majority of their root systems relatively deep in the soil profile where moisture tends to be greater and of longer duration . However, in northern Yucatan the hard upper limestone layer, beginning immediately below the shallow soil, impedes root growth, limiting downward growth to crevices and rhizoliths, and the occasional cavities filled with soil material .Thus, in the seasonally dry tropical forests of northern Yucatan, the ability of tree species to grow deep roots and access additional sources of water beyond topsoil could be a crucial characteristic related to variation in phenology and the relative abundance of contrasting tree species. Sources of water used by trees can often be identified by comparing the isotopic composition of water from stems with potential water sources, because there is usually no isotopic fractionation of either hydrogen or oxygen isotopes during water uptake . When trees take water from more than one source, the proportion of water absorbed from each source can be calculated using isotope mixing models . Such models were developed to cope with multiple sources and allow the input of ancillary data that are known about the system to constrain model outputs, thereby providing results that are restricted to real possibilities. Sources of water used by native trees in northern Yucatan have been studied using these approaches, and large variation in the depth of water uptake among deciduous and evergreen species has been observed . Furthermore, using these same isotopic approaches along a forest age chronosequence in northeastern Yucatan, evergreen trees were found to access deeper water sources than deciduous species in early succession . Thus, integrating rooting depth as a component of tropical dry forest tree strategies appears especially promising in complex karstic Yucatecan soils. Water use efficiency , the ratio of carbon gained in photosynthesis relative to water loss during transpiration , is another key factor when considering the costs and benefits of a deep rooting system.

Leaf carbon isotopic composition can be used to assess WUE in certain circumstances, and is often positively related to WUE because a high photosynthetic rate per unit stomatal conductance is usually associated with relatively low internal CO2 concentration and reduces discrimination against 13CO2 by rubisco . Although d13C has been used alone to infer WUE, its combination with analysis of isotopic composition leaf organic oxygen improves interpretation of leaf d13C values by allowing analysis of whether variation in d13C is due to changes on the photosynthetic activity or stomatal activity . When humidity increases, the isotopic enrichment of leaf water decreases, causing a reduction in d18O . Theory and empirical data also demonstrate that d18O correlated negatively with stomatal conductance . In shallow soils of northern Yucatan, Querejeta et al. showed that individuals of the same tree species differing in age had different WUE, with younger trees having greater WUE than older ones, indicating that these techniques hold promise for integrating potential differences in water sources with leaf physiological activity. This study focuses on phenological variation between two dominant tropical dry forest species in relation to the depth of water uptake. We hypothesize that the late deciduous habit in P. piscipula and the early deciduous habit in G. floribundum may be determined by their ability to take water from different sources. P. piscipula may have access to deeper sources than G. floribundum. However, due to the restrictions for root growth imposed by the hard bedrock, both species will likely extract most of their water from shallow sources. We also hypothesize that differential use of water sources is linked to key ecophysiological measures of plant performance, including the timing of leaf fall, leaf size, leaf water potential and the balance of carbon gain and water loss as interpreted by leaf stable isotopic composition.Our results show that the greatest variation in stem water d18O and plant water sources occurred during the frontal season and initiation of the dry season in February, whenG. floribundum was shedding old leaves and growing new leaves, but P. piscipula maintained its leaves from the previous wet season . Contrary to what was expected, P. piscipula took water primarily from shallow sources regardless of the month, although some contribution from deeper sources has the potential to occur. Rain also appeared to be an important source for this species. This implies that P. piscipula could have a very well developed shallow root system that allows rapid water uptake after a precipitation event. On the other hand, G. floribundum took water from topsoil and bedrock, the latter being a more important source in the dry season. This suggests a deeper root system than G. floribundum. Overall, our results indicate that the contrasting early and late dry season leaf loss phenology of these two species is not simply determined by rooting depth, but rather a more complicated suite of species based characteristics based on opportunistic use of dynamic water sources, the balance between carbon gain and water loss, and maintenance of water potential at the end of the dry season. These results are consistent with other studies demonstrating a broad array of coordinated strategies for dealing with seasonal drought in tropical forests . A primary factor determining differences in leaf loss phenology between the two studied species appears to be the maintenance of water potential. G. floribundum consistently exhibited more positive water potential values than P. piscipula, suggesting that G. floribundum has a limited capacity to tolerate negative water potential and moderates water use in a manner that maintains bulk leaf water potential at relatively more positive values compared to P. piscipula . This could provide an advantage of maximizing carbon gain during the dry season when light availability is high .

Traditionally, measuring soil quality parameters requires destructive sampling and laboratory analyses that are laborious, slow, or expensive. Similarly, root phenotyping requires time and labor intensive processing and scanning of root tissue to collect data such as root length density and root architecture . Advances in imaging have been able to offset some of these hands on analyses: high resolution RGB imaging can differentiate between soil types facilitating soil type detection, which can improve mapping and hence conservation efforts . New approaches that overcome the limitations of laboratory tests include thermal infrared imaging, which can be used to assess soil moisture distribution and hydraulic properties and inform land surface models . Near infrared spectroscopy has been used for rapid and accurate identification of soil total nitrogen , organic matter , and pH levels in soil that can replace laboratory techniques . Similarly, hyperspectral imaging can be used to accurately provide TN, OM, and organic content information in various soils as well as fungal viability based on pixel spectra specific to browned, damaged, and undamaged tissue types . Because image processing of HSI is more challenging than that of RGB imaging, the two technologies can be used in tandem; for example, to optimize comprehensive analyses of soil and root systems in rhizoboxes . The accuracy of both IR and HSI can be improved by applying extreme learning machine models, which were previously used to increase the accuracy of soil moisture and surface temperature measurements . Because UAVs are scalable and programmable,vertical plant rack we expect that drone usage in phytobiome research will move toward autonomous UAV fleets that can monitor extensive fields with an array of cheaper and more accurate sensors.

We also expect aerial monitoring to be more closely coupled to robotics on the ground that could aid in conducting soil and plant analysis and deployment and maintenance of local sensor networks among various other tasks. Thus far, the development of robotics to measure soil characteristics has primarily focused on applications in environments that are difficult or unsafe to access. For instance, a robot was developed for measuring soil strength over depth, which is normally manually measured using a penetrometer, in unsafe zones . The Mars Phoenix Lander returned in situ measurements of Mars soil temperature, generated a topography map using imaging, and excavated soil samples for downstream testing .Plant microbiome signaling and metabolism rely on exchange of a large diversity of metabolites derived from microorganisms, plants, and the soil environment. Metabolomic methods enable direct characterization of these small molecules from soils and the various biological components. Given the large diversity of compounds that reside intra and extracellularly in these systems, mass spectrometry coupled to chromatography such as liquid chromatography MS and gas chromatography MS have become primary methods for chemical analysis. Both techniques are well suited for identification and quantification of a wide range of molecules found in biological and environmental samples by coupling the physical separation of the compounds using LC with the separation and analysis of ions using MS mass.GC MS typically has higher resolving power and produces richer fragmentation spectra, which makes it particularly well suited for identifying molecules such as small glycans that are often difficult to characterize by LC MS. It is also well suited for volatile molecules and poorly ionizing molecules that are often lost or not detected by LC MS.

LC MS, on the other hand, is better suited for thermally labile compounds and is a technique of choice for analysis of novel compounds. Typically, these approaches are suitable for identification of several hundreds of metabolites based on spectral databases and authentic standards . However, they are currently far from comprehensive, and improving metabolite identification is an important goal of metabolomics research. A number of studies have used MS based metabolomics to examine the chemical exchanges within phytobiomes; for example, the signaling molecules that direct the establishment of bacterial and mycorrhizal pathogens or symbionts with host plants. A number of metabolites have been identified, including sugars, amino acids, organic acids, phenolic compounds, and plant hormones, that are associated with beneficial interactions and are also implicated by single strain and whole community approaches . Exometabolite profiling methods have been used to examine root exudates and their function in recruiting soil bacteria . O’Banion et al. have reviewed the function of the main chemical constituents of plant microbe signaling. Similarly, chemical imaging of solutes in soils has been reviewed . Although MS imaging is a powerful and promising technique , it is extremely difficult to identify organic components from complex environmental samples due to chemical complexity of these samples and the lack of physical separation of compounds prior to ionization. New developments in using ion mobility to separate ions within mass spectrometers have tremendous potential to overcome these limitations and enable direct analysis of metabolites from tissues and environmental samples .It is well known that phytobiomes are affected by plant growth form and life history , plant community composition and habitat of origin, and even host plant species . In fact, there is growing evidence of that intraspecific variability of plant hosts produces variability in phytobiomes . Genetic differences within host species can affect microbe recruitment, community assembly, and, ultimately, the composition of phytobiomes.

As such, the phytobiome can be considered an extended phenotype of the plant that is determined by host genetics, the environment, and their complex interaction. Here, the standard tools of quantitative genetics can be used to study the phytobiome. For example, family experimental designs or kinship based mixed models can be used to partition variation in microbial abundance or composition into genetic and environmental components of variance for an entire assemblage of microbes associated with a particular plant compartment. This approach can provide insight into the host genetic architecture of the plant microbiome and, potentially, help to identify classes of microbes with close affinities for specific genotypes within a population. A number of recent publications have documented genetic variation within plant species for aspects of the microbiome, including providing estimates of heritability for overall microbial community diversity and richness and for the abundance of specific microbial taxa based on counts derived from amplicon sequencing,growing strawberries vertical system for example The majority of such studies have focused on crop plants in agronomic settings and little is known about the heritability of microbes from more natural populations; one exception to this is the outdoor study of Bergelson et al. . We imagine that some of these host genetic effects are related to available habitat for microbial establishment , to resources shared with microbes as root exudates, or from more complex immune responses in the plant. Incorporating host genetics in plant microbiome studies is promising because it will point to mechanisms leading to beneficial or deleterious plant–microbe interactions, as well as leverage the growing resources available in plant genomics. In order to more efficiently develop and deploy improved plant varieties, it is valuable to identify the causal genes or genetic markers underlying agronomic traits and disease resistance . In addition, there is a need to understand the plant genes that influence the composition and function of the microbiome to improve our understanding and in order to maximize plant productivity. Two methods are commonly used to identify genes or markers associated with quantitative traits: quantitative trait locus mapping and genome wide association studies . Both approaches rely on genome wide scans for statistical association between polymorphic genetic markers and quantitative variation in a measured phenotype. In the case of phytobiomes, the phenotype of interest could be a feature of the aggregate microbial community or an estimate of the relative abundance of a specific taxon . A key distinction between these methods is that QTL mapping populations are derived from lines crosses and, therefore, represent experimentally structured populations, whereas GWAS focus on naturally occurring individuals. QTL mapping tends to have more power to detect true associations but reduced ability to localize effects in the genome because of limited recombination in a breeding population. In contrast, GWAS are frequently under powered, given limited sample sizes, but can yield remarkably fine scaled localization due to extensive historical recombination.

It can also be much faster to establish a GWAS population than a QTL population because there is no need to create recombinant progeny through complex breeding designs across multiple generations. However, GWAS requires dense markers and reliable controls for population structure and, at best, yields correlative results rather than causal inference as achieved with QTLs. Because, in QTL studies, fewer alleles and markers are analyzed using a randomized genetic background, statistical analysis can yield causal relationships between alleles and traits . Although both GWAS and QTL analyses establishing relationships between plant genetics and phenotypic traits are common, links between plant genetics and microbiome composition and function have been rare. The earliest studies utilizing this approach focused on plant related microbial diseases , including fungal, oomycete, and bacterial pathogens. More recently, studies utilizing the model plant Arabidopsis thaliana have been published that explore complete microbial communities based on 16S rRNA gene amplicon sequencing. For example, Horton et al. identified host loci that influence fungal and bacterial colonization density on leaves across an A. thaliana population in the field and found that loci encoding defense and cell wall integrity affect bacterial and fungal community variation, whereas loci that influence the reproduction of viruses, trichome branching, and morphogenesis affect bacterial species richness. Similarly, Wallace et al. looked at the leaf microbial communities across maize lines and found that functions related to short chain carbon metabolism, secretion, and nitrotoluene degradation primarily encoded by Methylobacteria spp. are heritable metabolic traits, and that few plant loci were found to be significantly associated. These studies provide an exciting glimpse of the potential importance of host genetic variation in the phytobiome and give a clear path to the identification of candidate genes. Future studies will help to define the groups of microbes with strong host impacts, as well as identify new genetic and metabolic pathways important in plant– microbe interactions. Although aggregate community metrics may be relatively straightforward to generate, they may be difficult to interpret and less meaningful than studies focused on individual microbial species. However, it is also unclear how to best define microbial taxa for counting—what inference can be made from amplicon sequence variants, traditionally defined operational taxonomic units, or gene content abundance derived from enrichment or metagenomic analyses? Finally, genome wide studies carry a heavy multiple testing burden due to dense testing both across genomes and also across multiple taxa or phenotypes. Care will need to be taken to limit false positives and misleading inferences—methods developed for other “omics” based quantitative genetic systems such as expression or metabolic QTL analyses may provide helpful directions as the field matures.In an effort to conduct plant microbiome research across biologically meaningful spatiotemporal scales and with increased control, a range of fabricated ecosystems are being developed. Experimental control and complexity are inversely related in plant microbiome research. At the most extreme, controlled laboratory experiments are often binary , whereas field experiments feature real world complexity that is difficult to replicate year by year. A new generation of experimental platforms of increasing complexity now allows for multi factorial insight, reproducibility, and increased statistical power. The concept of controlled environments for exploring plant ecophysiology dates back to the late 1940s, when Firits Went developed a Phytotron at Caltech , a “Climatron” in St. Louis, MO , and an ecophysiology lab at the Desert Research Institute, University of Nevada, Reno, which is now home to the recently developed EcoCELLs . Went’s work inspired the development of the EcoTron program at Centre National de la Recherche Scientifique, Montpellier, France , and the EcoTron at Imperial College London, United Kingdom . EcoTrons are large, fabricated ecosystems that consist of an above ground dome of approximately 40 m3 and a below ground chamber that contains a lysimeter that can hold 2 to 12 tons of soil . The canopy area is up to 2 m tall and allows work under natural light as well as under controlled or artificial light conditions. Both above and below ground compartments are equipped with arrays of sensors and instrumentation for environmental control. Using the EcoTron, simulations of a wide range of environmental scenarios under realistic conditions can be performed, while measurements important for ecosystem processes such as atmospheric and soil gas composition, temperature, and pH, among others, can be conducted.

Sugars constitute a significant fraction of exudates, and are a main carbon source for microbes. Interestingly, many more sugar uptake than release systems have been described. Sugar Transport Proteins utilize high extracellular proton levels to import sugars, and mutation of STPs leads to higher external sugar levels. Sugars Will Eventually Be Exported Transporters are sugar uniporters, and all root expressed members localize to the vacuole. Due to an alteration of root sugar homeostasis, SWEET mutant plants exhibited higher sugar export from roots compared with wild type plants, and were more susceptible to disease. Intriguingly, no transporters directly exporting sugars into the rhizosphere have been characterized so far, and it is debated whether sugar exudation is a transport driven process at all. Potential evidence for passive sugar efflux was supported by the observation of higher sucrose concentrations around young, permeable root tissue than around older, less permeable root tissue. However, because sugars are synthesized in leaves, they still need to be unloaded either from phloem or from root cells to be exuded into the rhizosphere, a process likely depending on transporters due to the hydrophilic nature of sugars. A further indication of the presence of elusive transporters is the differential sugar exudation in various environments, as shown, for example, for maize grown in potassium , phosphate , or iron deficient conditions.Sugar alcohols are imported by secondary active proteins with broad substrate specificity , whereas the modes of export are enigmatic. Sugar phosphates are involved in intracellular carbohydrate metabolism,hydroponic vertical farming and plastid localized sugar–phosphate co transporters have been reported in several species.

Although sugar phosphates are detected in exudates, neither import nor export mechanisms are currently characterized.Amino acids are recognized by microbial chemoreceptors crucial for the early steps of root colonization, making amino acids an important fraction of exudates. Modulation of amino acid transport could be either a means of communication with microbes, or a response to microbial presence. Amino acid uptake is mediated by several transporter families with broad substrate specificity. Amino acid exudation is affected by several transporters expressed in vascular tissue: mutation of phloem localized UmamiTs resulted in lower amino acid exudation, whereas mutation of xylem localized Glutamine Dumpers caused increased exudation. Although no plasma membrane localized amino acid exporters have been characterized so far, several lines of evidence suggest their presence. First, higher tryptophan exudation from older root zones than younger parts suggests the involvement of transport proteins in exudation, due to the fully formed Casparian strips and thick cell walls in mature root parts interfering with diffusion. Second, concentration differences between amino acids in root exudates and root extracts are not the same for all the amino acids, suggesting the selective transport of at least some amino acids. Third, various transporter families exhibit bidirectional amino acid transport characteristics in heterologous systems , and could be involved in amino acid exudation.Organic acids constitute a large fraction of exudates, and are microbial nutrients. No importers have been characterized so far, but the release of malate and citrate by Aluminium Activated Malate Transporters and Multi drug and Toxic Compound Extrusion families are among the few well understood examples of transporters involved in exudation .

Activity of members of both families is often modulated by metal ions and microbes . Uncharacterized ALMT and MATE family members are primary candidates for exporters of other organic acids due to their similarity to already characterized members, their plasma membrane localization, and their function as proton antiporters.Nucleotides are imported by secondary active transporters, but their exudation remains elusive. It is well established that extracellular ATP has a signaling function, and ABC transporters were proposed to mediate cellular export. Peptide uptake is transporter mediated in heterologous systems, and a role of ABC transporters in peptide exudation has been suggested .Fatty acid transport is necessary for mycorrhizal symbiosis: mycorrhizal fungi depended on their hosts for the synthesis of certain fatty acids, and the current model includes transport of lipids by ABCG proteins in the symbiotic membrane. One ABCG member, STR, was previously shown to be required for mycorrhization. Interestingly, arabidopsis ABCG transporters were similarly shown to export fatty acids for cutin synthesis in above ground tissues . Lipid transport was required not only for symbiotic interactions, but also for pathogen colonization. Fatty acids are detected in root exudates , but the mode of lipid exudation into the rhizosphere has yet to be discovered. A role in lipid exudation could be envisioned for root expressed ABCG members .Secondary metabolites are ubiquitous in root exudates, and ABC transporters are likely candidates for specialized metabolite transport into the rhizosphere. A distinct exudation profile was described for seven ABC mutants, and one mutant line displayed an altered microbial community. Although the causal metabolites could not be identified, the authors noted transport of the same compound by various proteins, and possible broad substrate specificity for some transporters. In a later study, exudates of arabidopsis ABCG37/PDR9 mutant lines were found to be deficient in several phenylpropanoids.

Arabidopsis PDR9 was previously characterized as auxin precursor transporter, which suggests a broad substrate specificity for PDR9. Interestingly, a PDR9 homolog was highly expressed in cluster roots of white lupin devoid of phosphate, illustrating PDR9 involvement in response to various abiotic stresses. These studies illustrate the potential for the discovery of novel transporter functions in the ABC family, an excellent target for future studies investigating root exudation. In addition, MATE proteins transport secondary metabolites into the vacuole,vertical hydroponic garden and plasma membrane localized members could also be involved in secondary metabolite exudation. In summary, more transport proteins involved in metabolite import into roots than in export from roots have been reported so far . The characterization of additional transport families involved in exudation will enable the generation of mutant lines that are devoid of the exudation of specific metabolites. Such lines could be used to investigate the correlation of exudation profiles and microbial communities.Plant derived transporters and exometabolites are intrinsic to plant–mycorrhizal and rhizobial symbioses . We speculate that, although there is paucity of evidence, plants analogously select for a beneficial rhizobiome. Given that plants evolved in the presence of microbes, a subset of which benefits plant growth, we hypothesize that, over millennia, plant exudation via active transport processes evolved with the substrate specificity of plant associated bacteria. In Box 2, we discuss exudates and other steps involved in root microbiome assembly, analogously to the establishment of plant–mycorrhizal and rhizobial symbioses. However, intense future research is needed to reveal the precise mechanisms governing plant microbiome assembly, and the possible beneficial functions of the microbial community. The major mechanisms by which plants are thought to modulate microbial interactions currently include: modulation of their exudate profiles ; root morphology ; and regulation of immune system activities . In turn, mechanisms for successful rhizosphere colonization by soil microbes require that they: are metabolically active ; sense the plant ; move towards the root and successfully compete with other microbes for root niches . In addition, for successful colonization of the rhizoplane or root tissue, microbes must be able to attach to the surface or enter root tissue . Despite apparent parallels between plant microbiomes and the aforementioned symbioses, plant microbiomes have some specific characteristics. First, microbiomes are detected in all environmental conditions, whereas mycorrhizal and rhizobial symbioses are induced in specific circumstances. Second, microbiomes occur on various tissues, whereas rhizobia and mycorrhiza interface with roots only. Third, microbiomes comprise many members, whereas the aforementioned symbioses persist between two predominant partners. Fourth, although most members of the microbiome originate from the environment similar to rhizobia and mycorrhiza, there is evidence that some endophytes may be vertically transmitted via seeds.

Future research should focus on the factors involved in microbiome assembly, the relative contribution of epi and endophytes to microbiomes, and the signaling crosstalk between plants and microbial communities.Rhizobiome assembly and the involvement of the plant in this process are currently enigmatic. Here, we have discussed multiple factors shaping the rhizobiome, including host genotype and development, root morphology, border cells and mucilage, and root exudates. Root exudation is a dynamic process, likely dependent on a plethora or transporters that are mostly uncharacterized. Spatially defined exudation likely results in distinct microbial communities that are observed to be associated with specific root parts. The success of microbial colonization of the rhizosphere depends on several aspects, such as chemotaxis, substrate specificity, competitiveness, and cooperativeness. Furthermore, endophytes likely form biofilms on the root surface, and encounter the plant immune system. Although some factors shaping root microbiomes emerge, many open questions remain .Due to the chemical complexity of soil, exudation is traditionally analyzed in hydroponic culture, an environment distant from the more natural settings of plant microbiome studies. Furthermore, novel technologies enabling high throughput screening of putative transporters against possible substrates are needed to reveal the impact of the respective substrates on the rhizobiome and, in turn, on plant health. An increased understanding of root morphology, exudation, and involved transporters will likely enable the engineering or breeding of plants with altered abilities to interact with specific beneficial microbes or pathogens. This needs to be complemented with an improved understanding of the substrate preferences of plant associated microbes, their interactions, and the mechanisms through which they benefit the plant. A holistic understanding of the functions of a healthy plant rhizobiome would enable the directed design of customized microbial communities. With this, specific plants in a given environment could be tailored to a specific purpose, such as phytoremediation, stress resistance, altered plant development, or increased yield.Interactions between plants and microbes are an integral part of our terrestrial ecosystem. There are several types of plant microbe interactions: competition, commensalism, mutualism, and parasitism. The more common interactions are commensalism or mutualism, where either one or both species benefit from the relationship, respectively . There are several excellent reviews reporting current research on lifestyles and molecular interactions of plant associated bacteria , rhizosphere interactions , plant responses to bacterial quorum sensing signals , endophyte applications , and rhizosphere bacteria responses to transgenic plants . Examination of these interactions helps us to understand natural phenomena that affect our daily lives and could lead to applications resulting in sustainable resources, less impact on the environment, cleanup of pollution and influence on atmospheric gases on a global scale. Advantages of using these interactions for biotechnological applications are many fold. The use of naturally existing plant microbe symbiosis for plant growth and bio control reduces synthetic fertilizer and pesticide treatments leading to cost effectiveness and less impact by nutrients and pesticides on surrounding fauna and flora. The production of useful compounds with pharmaceutical and industrial relevance using plant bacteria symbiosis is energy efficient and diminishes the need to add expensive precursors and catalysts. Remediation through conventional method, such as excavate and treat, is expensive and labor intensive. Conversely, plantmicrobial remediation strategies can be less intrusive and much more economical .Carbon sequestration through plant rhizosphere processes is a potentially sustainable method to lowering atmospheric carbon . This review focuses on recent progress in the fields of plant growth promotion, plant disease control, production of bio active compounds and bio materials, remediation of contaminated sites, and carbon sequestration. The potential of applying these new developments are discussed. Figure 1 summarizes applications resulting from microbe shoot and microbe root interactions and techniques used. Table 1 is a glossary of the techniques mentioned in this review. Plant microbe interactions have been utilized to improve plant growth for the production of food, fiber, bio fuels and key metabolites. The mutualistic interaction can be beneficial in directly providing nutrients to the plant or increasing the availability of compounds such as iron or phosphate. Free living plant growth promoting bacteria also produce compounds that directly affect plant metabolism or modulate phytohormone production or degradation. The phytohormones: auxins, cytokinins, gibberellic acid , abscisic acid and ethylene are signaling molecules essential for growth which mediate a range of developmental processes in plants. Recent studies on each of these areas are presented in the following section. As chemical fertilizers are costly both to the agricultural businesses and the environment, development of biofertilizers is an important and exciting area.

This strategy considers several domains represented by specific tools ranging from relatively simple in the lower tiers to more complex and specific in the higher tiers. The framework aim is to structure information collection and generation for cost efficient risk assessment, compliant with 3R animal use testing principles , which should also be pursued by means of grouping ENMs. A strategy for grouping ENMs based on releases, uses, physicochemical properties, bio accumulation, bio availability, and effects for both human and ecological risk assessment is currently in development across a number of EU research projects such as MARINA, NANoREG, SUN, and GUIDEnano. These efforts have been challenged by the complexity of ENM identity and interactions, but this approach is necessary, as the costs for safety assessment on a case by case basis would be exorbitant.Therefore, a vision on ENM grouping is needed, which should apply in a regulatory context.Applying grouping in regulatory risk assessments should enable read across, that is, filling a data gap by using information on one ENM, or a nonENM, for another substance in the same group.This strategy should be flexible enough to address different assessment goals depending on the user’s needs, considering all data already available as a starting point, contingent upon data quality evaluation and selecting the most appropriate tools to fill existing data gaps. Such a strategy should ideally be exposure driven, starting with identifying the most relevant exposure scenarios in the ENM life cycle, and evaluating completeness and quality of the available data from a risk assessment perspective. This facilitates careful prioritization of ENMs to optimize testing efforts and can inform more realistic ecotoxicological investigations.

Doing so can allow one to screen out irrelevant exposure routes, eliminate unnecessary testing,danish trolley and support prioritization of exposure scenarios. Exposure assessment should begin with an analysis of plausible exposure scenarios; where none is expected, further testing may be precluded for the applicable use patterns and volumes.Researchers and regulators need to understand actual exposures at biological receptors. This exposure driven approach can also provide important information on realistic environmental conditions to affect test designs for improved interpretation of laboratory toxicology studies. Such practices can ensue in the interim, while research continues to discover best hazard assessment practices. Experimental ENM toxicity assessments, using ecologically relevant receptors and across linked biological levels of organization, should inform developing and parametrizing dynamic process based models. Such models should respond to future scenarios and predict impacts. ENM characteristics, exposure conditions, and ENM transformation, dose, and body burden should be used in interpreting biological and computational findings for assessing ENM risks. ENM test results should be bench marked to results for appropriate controls to establish relative hazard . This applies to pinnacle concerns in ecological fate assessment of bio accumulation, bio magnification, and bio persistence.How to develop, interpret, and use pertinent information in ENM environmental risk assessment is a larger issue that should become part of an extended dialogue among regulators, industry, civil society organizations, researchers, and other societal members so that the fundamental research will inform decision making. Collaborative decisions are recommended for focusing ENM ecotoxicology toward relevant scenarios, including testing the most relevant materials throughout ENM life cycles and employing appropriate hazard assessment approaches, toward meaningful ecological risk assessment.

The overarching question motivating this critical review was: how can we ensure that hazard assessment in ENM ecotoxicology is as environmentally relevant as possible? The answer requires considering how ecotoxicity tests are performed, what constitutes pertinent concentration and test conditions for ENMs , the main biotic and abiotic attributes of the environment, how ecologically oriented hazard assessment is undertaken , and how the resulting information should be interpreted. Answering this question yielded three primary insights. First, environmental relevance is informed by a logical consideration of what exposures might occur, to which receptors, and to what outcomes. The consideration should begin with a plausible release and exposure scenario , and use best available knowledge and technologies to develop the full assessment approach. Concerns regarding ENM concentrations used in hazard assessments are paramount, but are not the only concerns. ENM concentrations should be selected to assess potential effects, but overly high concentrations that fundamentally change media conditions should be avoided. Still, concentrations ranging above and below predicted ENM average concentrations must be assessed for understanding potential organismal effects, underlying mechanisms and their concentration dependencies, and for informing process based dynamic biological effects models. In addition to the nanomaterial, the conventional material should be tested. ENM distributions and fates in broad environmental compartments do not equate to concentrations and forms near, or effective at, actual biological receptors.Therefore, research results on ENM effects should not be disregarded on the limited basis of environmentally relevant exposure concentrations when the study conditions were predicated on a broader hypothesis.

In addition to tethering ENM ecotoxicology to exposure initiation scenarios , the concept of employing tiered approaches in hazard and risk assessment resonated . Multistage approaches to ENM hazard assessment are advocated.A highly developed tiered approach for health and safety testing of nanotechnologies has been published and strategies for tiered risk assessment and grouping are underway.Staging ENM ecotoxicology efforts, such that potential interactive impacts at all levels of biological organization are evaluated, could simultaneously inform risk assessment and predictive process based effects model development. As some ENMs can cause biological impacts from ENM properties or characteristics,ENM ecotoxicology should be oriented to logical exposure initiation scenarios based on ENM life cycles, via testing tiers . Finally,vertical aeroponic tower garden coordination is recommended among multiple disciplines in ENM environmental analysis, fate and transport modeling, and hazard assessment, toward rapidly advancing research using tiered approaches around realistic exposure scenarios.Scholars have published extensively on the multifunctional benefits of urban agriculture including: promoting urban sustainability, reducing air and water pollution, building social cohesion, promoting community health and nutrition, teaching food literacy, and creating radical economic spaces for resistance to the capitalist political economy and structural inequities embedded in the “neoliberal city” . Despite growing evidence of these diverse health, education, and environmental benefits of urban agriculture, these vibrant spaces of civic engagement remain undervalued by city policy makers and planners in the United States. Thriving urban farms and gardens are under constant threat of conversion to housing or other competing, higher value land uses due to rising land values, and other city priorities. This land use challenge and threat to urban farm land tenure is especially characteristic of U.S. cities like San Francisco, one of the most expensive land and housing markets in the country. Under the current urban agriculture paradigm in the U.S., food justice scholars and advocates either try to quantify and highlight the multiple benefits of UA or pursue a critical theoretical approach, arguing that urban agriculture can yield unfavorable results if pursued without an equity lens, especially in cities with intense development pressures and gentrification concerns . A productivist focus is problematic, because, while urban agriculture can be an important component of community food security, its other social and ecological benefits are just as, and sometimes more, significant . In this article, we suggest that the current debates around “urban agriculture” in the U.S. often lead to an unhelpful comparison with rural farms regarding yield, productivity, economic viability, and ability to feed urban populations, most notably in the policy arena.

Defined in these ways, the radical, transformative potential of urban food production spaces and their preservation often gets lost or pushed to the side in city planning decisions in metropolitan regions such as the San Francisco Bay Area, where the threat of displacement is ubiquitous given high levels of economic inequality and extreme lack of affordable land. In order to facilitate what scholars such as Anderson et al. 2018a refers to as the “agroecological transition,” already underway in many urban food ecosystems around the globe , we argue that applying an agroecological approach to inquiry and research into the diversity of sites, goals, and ways in which food is produced in cities can help enumerate the synergistic effects of urban food producers. This in turn encourages the realization of the transformative potential of urban farming, and an articulation of its value meriting protected space in urban regions. Urban agroecology is an evolving concept that includes the social ecological and political dimensions as well as the science of ecologically sustainable food production . UAE provides a more holistic framework than urban agriculture to assess how well urban food initiatives produce food and promote environmental literacy, community engagement, and ecosystem services. This paper presents a case study of 35 urban farms in San Francisco’s East Bay in which we investigated key questions related to mission, production , labor, financing, land tenure, and educational programming. Our results reveal a rich and diverse East Bay agroecosystem engaged in varying capacities to fundamentally transform the use of urban space and the regional food system by engaging the public in efforts to stabilize, improve, and sustainably scale urban food production and distribution. Yet, as in other cities across the country, urban farms face numerous threats to their existence, including land tenure, labor costs, development pressure, and other factors that threaten wider adoption of agroecological principles. We begin by comparing the concepts of UA and UAE in scholarship and practice, bringing in relevant literature and intellectual histories of each term and clarifying how we apply the term “agroecology” to our analysis. We pay particular attention to the important nonecological factors that the literature has identified as vital to agroecology, but seldomly documents . We then present findings from a survey of 35 diverse urban farm operations in the East Bay. We discuss the results, showing how an agroecological method of inquiry amplifies important aspects of urban food production spaces and identifies gaps in national urban agriculture policy circles. We conclude by positing unique characteristics of urban agroecology in need of further studies and action to create equitable, resilient and protected urban food systems.Agricultural policy in the United States is primarily concerned with yield, markets, monetary exchange, and rural development. The United States Department of Agriculture defines agricultural activities as those taking place on farms. Farms are defined as “any place from which $1,000 or more of agricultural products were produced and sold, or normally would have been sold, during the year” . Urban agriculture has been proliferating across the country in the last decade on both public and private lands, as both for profit and nonprofit entities, with diverse goals, missions and practices largely centered on food justice priorities and re localizing the food system. Yet U.S. agriculture policy has been struggling to keep up. In 2016, the USDA published an Urban Agriculture Toolkit, which aims to provide aspiring farmers with the resources to start an urban farm including an overview of the startup costs, strategies for accessing land and capital, assessing soil quality and water availability, production and marketing, and safety and security . The 2018 U.S. Farm Bill provides a definition of urban agriculture to include the practices of aquaponics, hydroponics, vertical farming, and other indoor or controlled environment agriculture systems primarily geared towards commercial sales. In both the Toolkit and Farm Bill, non profit, subsistence, and educational urban farming enterprises are not well integrated or included in the conceptualization of UA. While there are many definitions of urban agriculture in the literature from the simplest definition of “producing food in cities” to longer descriptions of UA such as that of the American Planning Association that incorporate school, rooftop and community gardens “with a purpose extending beyond home consumption and education,” the focus of many UA definitions used in policy arenas continues to center around the production and sale of urban produced foods. Accordingly, food systems scholars have recognized that “Urban agriculture, [as defined], is like agriculture in general”, devoid of the many political, educational, and food justice dimensions that are prioritized by many U.S. urban farming efforts. Thus the social political nature of farming, food production, and food sovereignty are not invoked by formal UA policy in the U.S. Many goals and activities common in urban food production, including education, nonmonetary forms of exchange, and gardening for subsistence are obscured by the productivist definitions and can be thus neglected in policy discussions.

The people I spoke with were not ignorant or easily molded, and were justifiably proud of all the learning and hard intellectual work they had put in to becoming eligible olim. As I discussed in the first chapter, however, the materials used in Iquitos’ conversion and migration-preparation courses come from a very limited number of sources, including the Jewish Agency for Israel and a number of self-avowedly Zionist rabbis from Argentina and New York. It does not seem outside the realm of possibility that information about daily life for Jews in Israel, about Palestinians generally, and about Jewish-Palestinian relations specifically, is heavily biased against Palestinians. Much as I found that the educational materials available in Iquitos strongly encouraged adopting love for, belief in, and loyalty to the modern state of Israel as an integral part of being a Jew, these same resources, which contain implicit information about racial hierarchies in Israel, emphasize Jewish-Palestinian strife and the importance of believing in Jewish difference as a core part of Jewish identity. Iquiteño Jews are necessarily being purposefully manipulated by the Israeli government to form Jewish-supremacist ideas before entering Israel. However, many parts of the conversion and migration process encourage a kind of racialized nationalism. In particular, the community focus on the modern state of Israel as central to a contemporary Jewish identity and the need to perform dedication to Israel and a particular form of Jewishness in order to be permitted conversion encourage this. These small nationalisms compile, and the result is that people learn to discriminate without it being a necessity planned by any individual or agency.

Given my observations,flower pots for sale the entire process of Jewish education, conversion, and migration, with all its particularities, contingencies, and administrative requirements, seems to encourage anti-Arabracism as a side-effect. And, as that side-effect is beneficial to the state, it seems evident that it is at the least allowed to continue, even if it was not a premeditated plan. It is important to note that a perspective that puts the burden of creating this internalized hierarchy ignores Peruvian influences. I also suggest that, as most Iquiteño Jews belong to a relatively privileged ethnic group within Peru, most are not accustomed to thinking of themselves as racially marginalized. Rather, the Peruvian field of racial positions in which Iquiteño Jews locate themselves position Afro-Peruvians and indigenous Peruvians as the other points of the triangle, against whom the mestizo Iquiteños define themselves as relatively valorized. Although nobody I interviewed specifically compared Palestinians to any other groups, I noted similarities in the ways in which some Iquiteños referred to their indigenous neighbors. They used racist epithets like “indio” in the way that my young interviewee referred to Palestinians as rats. One might assume, therefore, that Iquiteño Jews find it easy to imagine themselves fitting into a similarly elevated place in Israel, and difficult to imagine changes to their current position of privilege. Historically, futhermore, due to Peru’s large indigenous population, racial censuses and other state documents struggled to clearly demarcate “indigenous” and “not-indigenous” categories based on descent alone; rather, the assumption of European cultural markers became key to classification 24.

Thus Iquiteño Jews might also draw on Peruvian historical dynamics around cultural assimilation as a means of racial advancement as a way of reading their options in an Israeli context. In combining both perspectives, then, a proposed method of transmission for knowledge of the Jewish-Israeli/Palestinian divide begins to appear. The other half of the equation is still missing, however. It is intriguing to consider that, at least in a relatively isolated place such as Iquitos, Israeli racial hierarchies reveal their fundamental dichotomy but not the complexity of intra-Jewish triangulation. Latin American Jews who migrate to Israel might expect to enter the country in a position of privilege, only to find that the truth is more complicated. Thus, it seems apparent that processes that train diasporic Jews to become potential Israeli citizens end up educating these future olim on their likely place within an Israeli field of racial positions — to an extent. Regardless of whether most Iquiteño Jews who wish to migrate to Israel expect to fit into a given field of racial positions in which they gain one enormous privilege, of Jewishness, but might yet face a very difficult battle against many forms of racialized prejudice, and whether their education on these matters is intentional or not, they are involved in an explicit attempt by the Israeli state to maintain and deepen that fundamental Jewish/Palestinian divide. To describe this instrumentalization of Latin American, specifically Peruvian, Jewish migrants, I will use Nadera Shalhoub-Kevorkian’s concept of demographic warfare. Shalhoub-Kevorkian names the strategies the Israeli government uses to surveil and control Palestinian lives via restrictions on settlement, movement, and living spaces “demographic warfare.”

She highlights the ways in which population control is central to Zionist Israeli political projects. Preventing family reunification, return to homes and land owned before the Nakba,tower garden and zoning laws are only some of the ways in which Palestinians are demographically controlled. The goal of this control is to eliminate Palestinians, or at the very least make sure they are outnumbered by an order of magnitude by Jews. I argue that the aggressive advertising and subsidizing of aliyah on part of the Israeli state also represents an act of demographic warfare. Shalhoub-Kevorkian only passingly refers to the Citizenship and Entry into Israel Law , which governs immigration, but controls on immigration directly shape the makeup of a country’s population. Although Iquiteño Jews are construed as racially undesirable, unideal Jews, they are nonetheless Jews. As such, they receive support and encouragement from the Israeli state as they journey towards becoming acceptable Israeli citizens. Thanks to the global reach of Jewish educators and educational material that position Israel as central to Jewish identity, far-flung diaspora communities can both be shaped and shape themselves into better-conforming citizens. After all, an ideal Jew is not needed to be superior to a Palestinian. It is no coincidence that so many Iquiteños have ended up in Ramla: in a city with a large Muslim minority, even undesirable Jews can serve the state’s demographic purpose. How does the Israeli citizenship and immigration regime navigate this complex set of desires? The key is in its power to enforce a specific set of standards for deciding who is a Jew, and therefore who is eligible to come to Israel as a potential Jewish citizen. The split between levels of citizenship and the impossibility of creating a neat and widely acceptable definition of Jewishness reveals how weak and divided the Israeli political consensus is on issues of immigration, race, and Jewish identity. The basis for this incorporation regime is the Law of Return of 1950. Together with the Citizenship Law of 1942, these two pieces of legislation form the basis of Israel as a state; they are arguably more important than any other law in Israel, including the constitutional Basic Laws. Put together, they define Israeli citizenship, and thus who is granted free movement into Israel, in a seemingly very simple way: if a person is a Jew, then they are a citizen. If they are a citizen, wherever they may be in the world, wherever they were born, they may enter Israel to live legally and with full government support. It is, of course, not so simple. Citizenship is always subject to citizenship discourses, or the different “schools of thought” that govern what access to rights citizenship grants to its holders, how people think about citizenship, and who gets to be a citizen. In Israel, these citizenship discourses present a tug-of-war between ethno-nationalist and ultra-religious priorities.

While some scholars add the demands of a liberal democratic regime , this seems like an increasingly over-optimistic characterization as Israel entrenches itself increasingly firmly in the category of illiberal democracy in which the appearance of being reasonably democratic excuses highly undemocratic social and civil rights violations. Iquiteño Jews face two particular and linked difficulties in integrating into this discourse: navigating Israel’s tiered citizenship regime and being recognized as appropriately and fully Jewish.Since the time of the second incorporation regime at the state’s founding, Israel has effectively created tiers of dejure citizenship. On the highest tier are those recognized to be Jews by the state, as well as some minority groups such as Armenian Christians, with a fairly full complement of social, civil and political rights. On the next tier down are those reliant on the increasingly frail liberal framework of Israel’s non-ethnic citizenship. The largest proportion of this group is “1948” Palestinians, those who remained within Israel’s armistice boundaries, who are technically citizens but enjoy many fewer rights, which have historically been suspended at the state’s whim. However, Jewish Israelis also fall into this category if their Judaism is somehow in question. For example, Israeli-born Jewish people who are not strictly halakhically Jewish are denied the civil right of marriage despite being citizens , and the very large demographic of ex-Soviet Jews whose halakhic bona fides are insufficient to merit full inclusion is a perennial source of anxiety to the state. Shifting between these tiers is the non-citizen legal resident, who enjoys a scattershot basket of rights and yet has more security and standing than undocumented or non-citizen Israelis. The situation an Iquiteño Jew wishes to avoid is that of becoming an ambiguous Jew, prevented from accessing full rights despite their citizenship. The fact of this strange bifurcation highlights a cleft between secular nationalists and ethnocentric religious communities apparent in the Law of Return itself: that of the perennially impossible problem of deciding who is a Jew. This is a loaded question regardless of who is asking it. Identity and belonging are fraught with emotional, historical, and familial weight that becomes all the heavier and more complex when an identity is, like Jewishness, a shifting blend of culture, religion, and ethnicity. It becomes truly urgent when the allocation of basic rights depends on fitting this deeply personal and subjective identification into a bureaucratic box and proving it to the satisfaction of an immigration judge. When this is the case, deciding who is Jewish “is not an autonomous problem waiting to be politically and legally resolved but rather a social language that serves the political purposes of social engineering”. According to Jewish religious law, halakha, a Jewish person is someone with a Jewish mother or someone who has converted through an extended community process under the guidance of a rabbi. These rulings postdate the Biblical period and so derive entirely from rabbinical debate. As may be predictable by this point, this seemingly simple pair of criteria are in fact very complex. What if the Jewish mother is herself a convert? What if a child is adopted? What about those whose fathers are Jewish, or those born of Jewish parents who do not practice, or those born to a Jewish mother who have converted to a different religion? What if the conversion is not Orthodox? And whatever the case is, how do you prove it? The Law of Return attempts to avoid these complications for immigration purposes by making the requirements for entry relatively loose. Today, those with Jewish parents or at least one Jewish grandparent and their spouses and children may enter Israel and achieve some level of citizenship. This more permissive approach fits badly with other stricter state applications of halakha, however. They are Jewish enough to enter Israel, Jewish enough to be subjected to the draft, and Jewish enough, in many cases, to consider their Jewishness an indelible part of their identity. However, they are not Jewish enough to fully access the benefits of Israeli citizenship. This divide is exemplary of the clumsy compromises Israel has had to make between secular nationalists and the ultra-religious, compromises visible in the history of the Law of Return. Before 1970, the Law of Return granted entry to those with Jewish ancestry up to three generations back; the major amendment of the Law of Return in that year to its present, more restricted form was the culmination of two decades of court and legislative fights that progressively tightened the criteria for entry across many potential defining aspects of Jewishness. 

The community’s rebirth began with the 1990 revival of the Sociedad de Beneficencia Israelita de Iquitos by community member Víctor Edery in response to his own personal desire to rekindle Jewish community life in Iquitos among the remaining practicing families. Without a Torah or other sacred texts, a solvent community fund, much collective knowledge of Jewish ritual outside the home, or a synagogue, the new community officers and the thirty-three members they represented felt outside help was needed to make a group of individual families of varying levels of independent practice into a cohesive community. They wrote letters to the Lima community asking for such help, and reached two important figures: the Argentinian-born Conservative/Masorti rabbi Guillermo Bronstein and Federación Sionista del Perú member Debora Frank. While current members of the community remember little of Debora Frank, Guillermo Bronstein continues to be active in the community, despite recent illness. It is already notable that Edery and the community sent these letters to a non-Peruvian rabbi and an Israel-focused organization as well as to Lima. The Iquitos community, which, despite its isolation,hydroponic net pots has always been diasporic by virtue of being Jewish, realized that a transnational action was needed to get the support they desired, and did so through intra diasporic networks.

Although Lima’s community of 1,900-2,000 Jews is by far the largest and closest Spanish-speaking Jewish community in Peru , internal dynamics, such as colorism and citified prejudice against far-flung Loretanos, made Lima’s Jewish community a less viable option for aid, which explains why the letter moved from the Limiñosynagogue to Bronstein and the Federación Sionista. Meanwhile, transnational forces in the Jewish diaspora ensured that international institutions like the Conservative/Masorti movement and pro-Israel organizations like the Federación were most likely to respond. A jump from Lima to Argentina is also unsurprising; Argentina boasts South America’s largest Jewish community, at 180,300 individuals , with attendant resources. Rabbi Bronstein’s connection to the Conservative/Masorti movement is significant, as it is linked to member synagogues throughout the world, including Israel, and has strong relations with the Jewish Agency for Israel , an organization relevant to the post-2011 Iquiteño experience. When the Iquitos community broke its long isolation, it reconnected itself to the webs of organizations that crisscross the Jewish world. The organizations that were most eager and financially ready to engage with the Iquiteño community, therefore, were institutions that centered Ashkenazi practices and the modern state of Israel as foundational to Jewish identity writ large, which thought of diaspora as requiring transnational integration. At this point, it was practically certain that the influence of Israel-focused groups, who make up a significant percentage of Jewish philanthropic organizations working internationally, and Ashkenazi groups, where there is the most money and influence, would have an out sized impact on the future of Iquitos. Bronstein especially responded with alacrity, encouraging the Iquitos community to draw up congregational statutes and begin to observe various major holidays.

He also reached out to his contacts in Buenos Aires, Miami, and New York. Among them was Ariel Segal, then a PhD student at the University of Miami, who visited Iquitos in 1995 and involved himself intimately in projects to convert Iquiteños and help them make aliyah. Meanwhile, Debora Frank made the Iquitos community familiar to the Federación Sionista, which boasted many connections to Israeli officials and other Zionist groups across South America. The stage was set. The impact of this is immediately visible in the circumstances of the two first mass conversions in August 2002 and December 2004. Rabbi Bronstein, in a 1993 letter reproduced in full in the fifth appendix of Ariel Segal’s book, argues that conversion should be granted only to “those who pledge to make aliyah” and who will undergo a second, Orthodox, conversion once in Israel.10 From the very beginning, then, not only was emigration to Israel dependent on conversion, but conversion was dependent on emigration to Israel. To be as clear as possible: in order to make a spiritual commitment, a practical action was seen as necessary. In order to make a practical move, a spiritual commitment was necessary. Regardless of whether these migrants continued to practice as they were taught in Israel, a question that is beyond the scope of this thesis but which deserves attention, it is clear that mixing together transitional actions with religious and diasporic identity was useful to actors invested in a particular transnational outcome. The conflation of Jewish identity and Israeli citizenship in Iquitos begins to show itself most clearly here, with no thought to standards of living, improved education, or other practical concerns. The practical and the religious converge here, and they do so because transnational activity was used as proof of diasporic conviction.

Segal speculates that the emigration stipulation was meant to weed out those who were not sufficiently devoted to Judaism, a concern that appeared again and again in my interviews, ironically twisted to a fear that some individuals would “fake” a conversion in order to emigrate. The state/institutional level, therefore, allows us to understand that,blueberry grow pot for the first several years of the Iquitos community’s revitalized existence, Jewish education, community support, and conversion depended on external institutions which happened to strongly support connections between Jewishness and Israel. Before examining the individual/community-level through data from the interviews Iquiteño Jews and I conducted in 2016 and 2019, I wish to remind readers of the timeline of this community. While states and major international organizations were instrumental in setting up the initial conditions for conversion and migration, they no longer play as important a role in influencing the individual decisions Iquiteños make in response to global or personal factors. Between the second conversion, in December 2004, and the third, in August 2011, there was a great shift. The presidency transferred to the Abramowitzes and the synagogue moved into its current location in 2009, and leadership attitudes towards conversion and migration have practically reversed — a notable change and one that proves, in case there was any doubt, that despite strong interference from non-Iquiteños, a great deal of the changes happening there come from within the community. “I do not want people to see us as a travel agency,” Señora Francisca Abramovitz told me sharply over lunch one afternoon. The de facto female leader for the community, Sra. Abramovitz is also the primary bookkeeper, synagogue caretaker, programming coordinator, outreach specialist, Internet publicist, and general macher of the Iquitos community. She makes the arrangements with the rabbis, solicits donations for, selects, and distributes prayer books and Hebrew primers, sets up the synagogue for services and cleans it up afterwards, conducts the entrance interviews for people interested in joining the synagogue, organizes outings and children’s classes at the synagogue in everything from liturgy to karate, collects and records dues and donations received, and reaches out to Jewish youth groups in Argentina to come visit. Although she and Sr. Abramovitz are technically two of the five-member Directiva , they do almost all the work of maintaining the community’s organized behaviors themselves. Congregants often refer to them as a unit simply as “la Directiva” or “los presidentes.” Sra. and Sr. Abramovitz are also the intermediaries between individual congregants and the rabbis of the Batei Din and the Jewish Agency for Israel, which currently handles the emigration paperwork for Iquiteño olim.

The process is not easy, and Sra. Abramovitz’s travel agency remark came at the end of a long demonstration of the mountains of complex paperwork involved in journeying from non-affiliated Iquiteño to new Israeli citizen. If one does not know the community’s history with Israeli immigration, the option seems no better than emigrating to, say, the United States or Argentina if gain is the primary motivation. Nonetheless, the fear that people might be taking advantage of Sra. Abramovitz’s hospitality —the synagogue, after all, is literally inside her home— and fierce Jewish faith to simply pursue a selfish financial end permeated many of our conversations.They must find it, first of all, and then make it past Sra. Abramovitz’s entrance interview. Then, there is an application to become a “Miembro Activo de la Asociación Judía de Beneficencia y Culto de Iquitos”. The new members must then take classes in Hebrew, liturgy, and “Jewish life,” and regularly attend Friday night and holiday services, as well as other community events, for at least two years. This educational programming is done in conjunction with Rabbi Bronstein and Rabbi Rubén Saferstein of Buenos Aires, who began his involvement with the Iquitos community in 2004. These two rabbis, and a rotating cast of others, eventually conduct a formal conversion in the Masorti tradition, complete with a brit for the men, and present the new converts with a stamped and signed certificate of conversion, a shtargeirut. Those who wish to make aliyah must provide three copies of that document, their birth certificates, passports, and National Identity Cards and those of their spouses and children, certificates of completion for all the classes they have passed complete with syllabi, their marriage records, proof of circumcision for the men, and a letter from the presidents affirming that they have been “good and active participants” in the community. That enormous packet of documentation passes from the Abramovitzes to the Jewish Agency for Israel, and then, through some alchemy that the Abramovitzes themselves do not fully understand, to the Israeli Bureau of Immigration, where applications are tentatively approved or denied. Potential olim must then travel to Lima, a matter of either an expensive plane flight or a days-long journey by boat and bus, to be followed by an also-expensive stay of multiple days in the capital, for an entrance interview. Only then may they officially be granted Israeli citizenship and have their travel and resettlement expenses taken on by the state. Those with family already in Israel may choose to live near them; those without are settled according to the dictates of the state. Most in the latter category are sent to the mixed Jewish-Arab city of Ramla. All this, and even then, theolim and their children will need to undergo a further, Orthodox conversion to access the full rights of an Israeli citizen11 and may also be required to serve in the Israel Defense Forces. At the time of writing, this process is for people who very likely have practiced a form of Judaism for much or all their lives, identify as Jews, have Jewish parents , and frequently have relatives already living in Israel. If this is a travel agency, it seems like one of the most redundant, possibly insulting, and certainly difficult tours I have ever heard of. Why do this? In 2002 and 2004, aliyah was a prerequisite to conversion. That is no longer the case; converts in 2011 and 2018 made no such commitment. Sra. Abramowitz ensured that this would no longer be the case, hoping that it would prevent more Iquiteño Jews from leaving Perú. On the one hand, if migration is undertaken for practical personal gain, why undergo a long, difficult, expensive, and, frankly, annoying process to go to a country where one does not speak the language and may not be able to control even where one lives? On the other, if aliyah is undertaken out of a deep spiritual desire to connect with a particular facet of perceived Jewish identity, why submit to the indignity of being told your Jewish practice is insufficient, inauthentic, and invalid? Although not in as many words, these were the questions I posed to my interviewees in 2016 and 2019. It is in the content of Iquiteños’ responses and the eagerness with which they gifted them to me that I have found something approaching an answer. I argue that, despite changes in leadership conversion method over a long period of time, Iquitos’ Jewish education has always conflated Jewish authenticity with Israeli citizenship because of its early influence by the Federación Sionista, Rabbi Bronstein, and Ariel Segal, creating an environment that suggests the endpoint of a successful conversion is aliyah. Furthermore, there is now a self-sustaining transnational dynamic between immigrants from the 2002 and 2004 conversions now living in Israel and friends and relatives in Iquitos. Lastly, when deciding whether to migrate or not, Iquiteños do not draw clear distinctions between practical and spiritual reasons for migration, because those pro-Israel individuals and institutions framed Israel as central to a valid diasporic Jewish identity.

Yellow leaves resemble green ones in that, in contrast with brown leaves, they have an intact cuticle, and their cells are essentially still alive. California bay leaves infected by P. ramorum have been shown to senesce and abscise from trees more frequently than uninfected leaves. In infested forests, a great portion of senescent leaves probably enters the stream already colonized by P. ramorum. As leaves that fall into the water do not dry out, their cells likely remain alive for an extended period, allowing further colonization by P. ramorum. However, stream resident clade 6 Phytophthora species also compete for this substrate and may limit the extent to which P. ramorum can grow on, persist, and reproduce from them. As dry, brown, senesced California bay leaves begin to make up a greater proportion of leaf litter in late summer and fall, the ability of clade 6 Phytophthora species to exploit these, while P. ramorum cannot, may be one explanation for why the latter is recovered less regularly and with lower frequency from these and other California streams in the fall and early winter. Moreover, as the summer progresses, green and yellow leaves will be more decomposed and less suitable for P. ramorum. The warming of streams late in the summer may additionally favor clade 6 Phytophthora species that are known to have generally higher optimal growth temperatures than most other species. We maintained temperatures constant for experimental purposes, but the persistence and sporulation of these Phytophthora species, and P. ramorum in particular,dutch buckets may be significantly affected by temperature fluctuations and extremes.

We have isolated P. ramorum and clade 6 Phytophthora from leaf litter of other tree species in naturally infested streams, including leaves of coast redwood, madrone, white alder, big leaf maple, and coast live oak. Occasionally, we have found portions of other submerged riparian plants, such as chain fern or elk clover , to be colonized. It is well-established that California bay leaves are an optimal substrate for P. ramorum, and though clade 6 Phytophthora species are known from a great variety of vegetative litter, it is uncertain how conducive other vegetative litter would be to survival and sporulation of either species. Stamler et al. recovered primarily clade 6 and 9 Phytophthora species from rivers in the southwestern USA using leaves of Salix and Populus species, common asriparian trees, as bait. It would be expected that natural leaf litter in such ecosystems would also harbor these organisms. Themann et al. recovered primarily P. gonapodyides but also P. cinnamomi from vegetative litter in sediments in an irrigation reservoir. Therefore, leaf and other vegetative litter should be considered as potential sources of Phytophthora, including pathogenic species, whether they are found in natural streams or other surface waters. Alternatively, the suitability of local vegetation may be a determinant of what Phytophthora species become established or prominent in streams.Current farming and food systems confront and are implicated in multiple challenges and unsustainable changes, including biophysical dimensions such as climate change , environmental pollution, escalating losses of biodiversity, and deteriorating ecosystem services. 

Social forces and structures as well as unsustainable socioeconomic processes also strain present capacities to manage growing population pres sure, unplanned urbanization, food and nutrition insecurity, dietary shifts, and health disparities associated with poverty, and growing inequality among multiple stakeholders, including women, youth, migratory workers, and indigenous peoples. Both urban and rural actors are impacted in relation to land ownership and land use change issues and drivers underpinning global industrial agriculture and connected food systems. Human activity has approached critical limits over an increasing number of the so-called Planetary Boundaries , beyond which the functioning of ecosystem ser vices may be substantially altered, increasing the risk of destabilizing life on our planet. Agriculture and food systems are both a villain and a victim in approaching or breaching PBs, and this is already impacting the ability to farm and produce food. How can humanity sustainably grow nutritious food and return to a safe operating space within the PBs? As an alternative to this scenario, a growing number of studies and reports indicate significant potential gains from transitioning toward agroecological agriculture as a way of nourishing current populations sustainably while allowing for future generations to support their livelihoods. One core quality of transitioning to agroecological farming systems is the regenerative trend of increased “outputs” per unit “input” for a more efficient agriculture for using and conserving diversity on a long-term basis, through the use and combination of different agricultural techniques in ways which restore and nourish the soil and enhance the local environment, instead of continuously degrading it.

In addition, the diversification strategy makes food producing systems resilient to external shocks and influences, such as floods or droughts, using, for example, approaches built on the principles and science of agroecology. There is growing evidence that such production systems allow for lower cost and more diverse fruit and vegetable supply. Furthermore, conventional thinking about food is increasingly being challenged, shifting from being regarded only as a commodity toward becoming acknowledged for its nourishment, social and cultural values, the links it creates between people, and its deep connectedness with ecosystems, ecosystem services, and natural resources. The current globalized industrial food system exhibits the same drivers which impact and shape farming industries and food production, and underscores the importance of focusing on how food flows into food systems, and which structures and related policies are shaped to support and reinforce current farming as well as food systems. It is not only conventional and industrial production of animal feed, genetic material, or major commodities such as wheat, rice, coffee, sugar, maize, and chicken which are controlled and shipped across continents by large trans-national corporations. Our globalized industrial food systems sometimes also include food which originates from farming systems based on organic farming regulations and principles like the IFOAM principles, calling for more coherent, equitable and holistic food systems,grow bucket and applying agroecological farming methods. In other words, the intentions behind such farming systems and their contributions to agricultural and environmental sustainability are not always extended to food systems, which generally contribute to out-competing local produce, distorting prices and producing huge amounts of food waste and other waste. This can be seen as a contradiction and emphasizes the importance of thinking of not only organic and agroecological production, but also has consequences for thinking the principles into the entire food systems. At the same time, there are many examples of organic farming and food as well as agroecology presenting alternatives to the industrial farming and food systems , and by increasing and emphasizing this, we can move toward a food system that falls within the PBs. This calls for profound analyses of how agroeco logical food systems function, and how they can contribute to coherent, resilient and equitable production and exchange of food, while human and social capitals are built up throughout the food systems, and resources are cycled rather than transported through, from or to disconnected parts of the systems. How can such food systems meet challenges such as losses of complex and system-oriented, context-relevant knowledge about farming and food, and how can they contribute to re-connect consumers and the food that they eat across urban-rural settings in city-region food systems? An increasing number of papers and reports link agroecology and food systems , referring to the fact that agriculture and food systems are intricately linked, and to a large extent driven by the same global structures.

Given the intricate and mutually-reinforcing relations between agriculture, food, and socioeconomic systems, the present article aims to characterize and explore how the concept of agroecology stimulates the conceptualization of agroeco logical food systems, or perhaps even a more inclusive term like “socio-agroecological food systems.” Food systems following the principles of agroe cology calling for resilience, multi-functionality , equity, and recycling of resources face particular challenges and have significant options for impacting sustainable development in city regions. This needs to be seen in a light where an increasing amount of the global population lives in urban areas, from smaller towns with a few thousand inhabitants, to mega-cities of millions of people. Urbanization has changed diets and nutrition, while food consumption has become detached from food production worldwide. Taking a systems approach to reconnecting these gaps requires major changes in consumption patterns, resource management and social responsibility, if everybody is to be nourished in agroecological food systems. We aim to explore the connections and linkages between the concepts of agroecology and food systems, and focus particularly on how the food system framework can locate and ground the concept of agroecology within a rural– urban landscape setting. This exercise requires us to critically examine the reciprocal flows and the multiple environmental, social, and governance related connections needed for an agroecological food system transformation.A food system is a system that involves activities, social and institutional structures, and processes related to the production, distribution, exchange, and consumption of food. Agricultural systems are part of food systems, integrated in ecosystems, and constituted socioecological systems. Over the past few decades, the understanding of food systems has clearly developed as result of the development of a more and more globalized food system. Ericksen compared some features of “traditional” versus “modern” food systems, and addressed the governance of different food systems, with or without support for local production, and Foran and co-authors point to the existence of different concepts of how food systems are constructed, with examples from so-called developing countries. The structure and governance of the food system clearly influences consumption patterns by providing both producers and non-food-producing consumers with options of availability. The range of social and environmental welfare outcomes stemming from food system activities were also discussed and visualized in Ericksen , and Jennings and co-authors analyzed how planned and well gov erned city-region food systems could contribute to different aspects of food security for different groups of citizens, stable incomes, circular economies, and resilience at various levels. Characterizing a food system can follow through its different social aspects and arrangements, like the type and degree of contact between those who grow and produce food and those who receive and eat the food without participating in the production of it, or who and how many people are involved in the cycle between the soil and the plate. Where local food systems with short supply chains have potential for involving resource feedback loops, raising collective awareness among different actors within the food system, and give possibilities for mutual learning , a larger and decoupled food system lacks the direct interaction and feedback, reduces exchange of experiences and knowledge, or the embedded ness inherent in a localized food system. A decade of research on New York’s Chinatown produce economy gives an example of the importance of this con nectedness: the studies revealed that 80-plus produce markets offered an incredibly diverse assortment of lower-cost produce because they are connected to a web of nearby, independently-run small farms and wholesalers.In a food chain , a product flows through different steps, where various forms of transformation may occur, and connection and feedback loops between these different steps may not necessarily exist. In such systems, farmers or industrial food producers can risk becoming producers of “food from nowhere,” as expressed by Bové and Dufour , and later unfolded by Campbell , and “consumers” can become reduced to a non-informed and non-responsible person, only “consuming food no matter of origin,” as a contrast to so-called “food citizens” defined as a consumer who makes decisions that support a democratic, economically just and environmentally sustainable food system, with a possibility of being actively involved in the food system at different levels. The call and practice of re-localizing of food systems is similarly seen as a harbinger of rural– urban reciprocity as consumers and producers are re-embedded physically and socially in the food system while raising awareness of their respective impacts on one another.Agroecology is widely acknowledged equally as a science, a practice and a movement. Its academic roots go back nearly 100 years, drawing on the fields of agronomy, horticulture, and ecology.

Sediment and plant samples were also collected at the PCW inlet, midpoint, and outlet. Sediment samples were collected as described above.All samples were transported on ice prior to laboratory storage at 4 °C. Sediment samples were dried and ground with a mortar and pestle before extraction. Plant samples were thoroughly washed with DI water to remove any attached sediment particles and biofilms. The cleaned plant samples were dried before pulverizing the tissue in the presence of liquid nitrogen using a mortar and pestle. The TSS, sediment, and plant samples were extracted by pressurized fluid extraction on a Dionex ASE 350 using a method similar to Brennan et al. and Maul et al.. Briefly, sample cells were filled with 1:1 dichloromethane:acetone , heated to 100 °C, and extracted at 1500 psi for two 5 min cycles before being flushed with 60% solvent for 1 min. For the TSS samples, the entirety of the solids from each water sample was extracted. Aliquots of the prepared sediment and whole plant samples were extracted and subjected to in-cell cleanup with Cu powder packed between cellulose filters. All extracts were evaporated to approximately 2 mL under a gentle nitrogen stream. Each sample then underwent clean-up on a Florisil cartridge preconditioned with hexane and was eluted with 9:1 hexane:acetone. Cleaned extracts were again evaporated under a gentle stream of nitrogen to approximately 0.5 mL and reconstituted in 1.0 mL hexane for final analysis. Samples were analyzed using an Agilent 6890N/5973N GC/MSD equipped with a 30 m x 0.25 mm x 0.25 µm DB-5MS column.

Additional analytical information is provided in the SI. Following sample quantification,ebb flow tray statistical analyses were performed using SAS® 9.4. Numerous steps were taken to ensure the accuracy and quality of analysis. Instrumental controls during analysis included running a calibration standard every 10 samples, adding 13C4- 15N2-fipronil and d5-bifenthrin as internal standards to each extract, and determining method detection limits using EPA Method 40 CFR Part 136, Appendix B. Calculated MDLs were 2 μg L-1 for all analytes except for fipronil desulfinyl, which had an MDL of 1 μg L-1. In addition, several procedural controls were utilized. Reagent blanks were analyzed with every set of 7 liquid-liquid extraction samples and 10 pressurized fluid extraction samples. Reagent blanks revealed no presence of the target analytes. Matrix spike samples were analyzed to measure extraction efficiencies, which are listed in the SI. In addition, ethiprole and decachlorobiphenyl were added to all samples prior to extraction to assess surrogate recoveries, which were 105 ± 23% and 121 ± 18% for liquid-liquid extraction, respectively, and 108 ± 21% and 116 ± 18% for pressurized fluid extraction, respectively. Additional quality control measures are described in the SI. The concentrations of fiproles and pyrethroids in water samples collected from the PCW are depicted in Figure 3.1. In general, mean whole water concentrations progressively decreased on a spatial level when moving from the inlet to midpoint to outlet for all compounds of interest. In addition, mean outlet concentrations were always lower than mean inlet concentrations. Furthermore, statistically significant differences existed for the majority of inlet and outlet concentration comparisons. When the differences between inlet and outlet concentrations were not statistically significant, inlet concentrations were found at low levels and with relatively high variability.

Since water and the associated TSS is all that enters and leaves the PCW, these findings provide evidence indicating that statistically significant removal of fiproles and pyrethroids occurred as a result of treatment in the PCW. Previous research by agricultural and WWTP effluent-polishing CWs has similarly shown removal of fiproles and pyrethroids. The mean whole water concentrations of fiproles and pyrethroids also exhibited distinct temporal trends during the sampling period. Mean fipronil concentrations peaked in June 2018, gradually decreased until October 2018, and then increased until January 2019. Mean whole water concentrations of fipronil desulfinyl, fipronil sulfide, and fipronil sulfone incrementally increased from June-August 2018, decreased, and then increased until January 2019. The peak mean whole water concentrations for fipronil desulfinyl and fipronil sulfone occurred in January 2019 while the peak for fipronil sulfide occurred in August 2018. Taken together, these trends correspond to high fipronil application rates in the summer months, gradual decrease via degradation of the parent compound and delayed formation of degradates, and increased transport of applied and degraded residues due to rainfall events in the winter months of 2018-2019. The mean whole water concentrations of bifenthrin and cyfluthrin, on the other hand, steadily increased from June-August 2018, gradually decreased until November 2018, and then increased in December 2018 and January 2019. The mean bifenthrin concentrations peaked in August 2018 while mean cyfluthrin concentrations peaked in January 2019. These trends indicate high use of pyrethroids in the summer months, followed by a period of reduced use and transport, and finally an increase due to runoff from the rain events in the winter that could have transported additional residues through the CW and/or caused resuspension of residues from the sediment bed. Fipronil and cyfluthrin were detected at the highest levels in whole water PCW samples, with mean concentrations ranging from 13.5-369 and 13.8-455 ng L-1 , respectively. 

Fipronil sulfone and bifenthrin were detected at moderate mean concentrations of ND-32.5 and ND-63.9 ng L-1, respectively. The compounds detected at the lowest levels, fipronil desulfinyl and fipronil sulfide, had mean whole water concentrations of ND-2.48 and ND-4.09 ng L-1, respectively. The water concentrations of fiproles and pyrethroids measured in this study were similar to previous measurements in California in urban runoff. Figure 3.2 shows the sediment concentrations of fiproles and pyrethroids in the PCW. As was the case with mean levels in whole water samples,flood and drain tray mean sediment concentrations for all compounds followed a decreasing spatial trend from the inlet to midpoint to outlet. Since the same spatial pattern was observed for mean water concentrations, this suggests that sediment binding was partially responsible for the dissipation of fiproles and pyrethroids from the water. This finding was to be expected due to the hydrophobicity and strong affinity of these two insecticide classes, particularly for pyrethroids. This was in agreement with previous studies where sediment binding was shown to be an important removal mechanism for pyrethroids in flow-through wetlands receiving agricultural drainage. However, based on this spatial trend alone, it was unclear whether the contaminants were temporarily retained by the sediment and available for partition back into the passing water or if they were subsequently degraded in the sediment. The mean sediment concentrations of fipronil desulfinyl, fipronil sulfide, and bifenthrin followed a similar trend over time. These contaminants generally increased in concentration from June-August 2018, when they reached a peak for the entire study, followed by a decreasing trend until November 2018 before gradually increasing until January 2019. Fipronil in the sediment increased from June-July 2018 when it reached its peak level, decreased until November 2018, and then increased until January 2019. Fipronil sulfone and cyfluthrin peaked in January 2019 and June 2018, respectively, but they followed the same trend as the other compounds. An inspection of Figure 3.1 and Figure 3.2 reveals similar seasonal temporal trends for fiproles and pyrethroids in both whole water and sediment samples. In other words, when analytes were present at high levels in whole water samples, they tended to also be present at high levels in the sediment. This finding, combined with the fact that sediment concentrations did not continuously increase over the duration of the study, indicates that fiproles and pyrethroids were likely actively degraded once partitioned into the sediment phase. Another possibility is that the contaminated sediment particles underwent resuspension and were carried out of the PCW; however, the generally lower whole water concentrations at the outlet relative to the inlet suggested that the contribution of this process was likely negligible. Among the six compounds, fipronil and cyfluthrin were detected at the highest mean sediment concentrations during the study period. Fipronil sulfone and bifenthrin were present at moderate levels ranging from 0.166-4.42 and ND-5.40 ng g-1, respectively.

The lowest mean levels were found for fipronil desulfinyl and fipronil sulfide, at ND-0.740 and ND-0.718 ng g-1, respectively. This pattern was also reflected in the whole water concentrations. These results again suggest that fiprole and pyrethroid residues in PCW water partitioned into the sediment and underwent degradation on site, rather than accumulated over time. Fiprole and pyrethroid concentrations in whole plant samples are shown in Figure 3.3. Mean plant concentrations follow the same spatial trend as whole water or sediment concentrations, with levels generally decreasing from inlet to midpoint to outlet for all compounds. Since the spatial trends of fiproles and pyrethroids are the same in whole water and plant samples, it appears that plant uptake played a role in the removal of these insecticides in the PCW. Fipronil is a systemic insecticide, so some degree of plant uptake of fiproles was to be expected. Detection of pyrethroid residues in whole plant samples was an unexpected finding due to the hydrophobicity of these insecticides and their consequent affinity for sediment. However, there are studies that have documented detection of pyrethroids in plant samples, either by uptake or by apparent irreversible sorption to plant tissues. Different temporal trends were observed for fipronil, fipronil degradation products, and the pyrethroids in plant tissues. Fipronil mean plant concentrations initially decreased from June-July 2018, increased to peak levels in August 2018, gradually decreased until November 2018, and progressively increased until January 2019. This trend of fipronil concentrations over time coincided with the temporal trends of fipronil in whole water and sediment samples, providing more evidence that plant uptake contributed to the removal of fipronil in the PCW. Moreover, it is likely that fipronil initially adsorbed to wetland sediment and was then absorbed into macrophyte roots. The mean plant concentrations of fipronil desulfinyl, fipronil sulfide, and fipronil sulfone all gradually increased from June 2018-January 2019, indicating some degree of accumulation in plant tissues over time. However, since fipronil did not follow this temporal trend of accumulation in wetland macrophytes, it is likely that some of the parent compound was metabolized into these derivatives upon uptake. Fipronil sulfone was present at higher concentrations in plant samples than the other degradation products, which was in agreement with previous studies showing that in vivo plant oxidation is a major metabolic pathway for absorbed fipronil. Bifenthrin and cyfluthrin displayed no temporal trend in plant tissues since they were both only detected in inlet samples at one time point. This suggests that plant adsorption or absorption did not play a major role in the removal of pyrethroids by the PCW. Fipronil was detected at the highest levels in PCW plants, with mean concentrations of 4.70-194 ng g-1. Moderate mean concentrations of ND- 17.7 ng g-1 were observed for fipronil sulfone. The lowest mean plant concentrations were measured for fipronil desulfinyl , fipronil sulfide , bifenthrin , and cyfluthrin. The results of plant tissue analysis reveal that plant uptake played an important role for the removal, degradation, and storage of fipronil, but did not contribute substantially to the removal of fipronil degradation products or pyrethroids. However, it must be noted that the dense vegetation was essentially slowing down the flow and filtering off suspended solids, contributing greatly to the removal through sedimentation. In addition, microbial activity in the rhizosphere of plant roots likely facilitated the degradation of these chemicals in the sediment, further contributing to the overall pesticide removal. The concentration-based removal values of fiproles and pyrethroids from water flowing through the PCW are given in Table 3.1. Over the entire course of the study, removal values for fipronil desulfinyl, fipronil sulfide, fipronil, fipronil sulfone, bifenthrin, and cyfluthrin were 100%, 99.7-100%, 57.8-88.1%, 75.6-100%, 74.7-100%, and 36.6-82.2%, respectively. The compounds with the highest removal values were fipronil desulfinyl, fipronil sulfide, fipronil sulfone, and bifenthrin, while fipronil and cyfluthrin showed the lowest removal. It is important to note that only fipronil, bifenthrin, and cyfluthrin were detected every month, and fipronil and cyfluthrin were detected at higher levels than all the other compounds. Previous studies have similarly shown that the average CW removal rates of fipronil and pyrethroids were 44% and 52-94%, respectively, for other CW systems. 

Observations of the regulation of production of this surfactant in various culture conditions suggest a role for this surfactant primarily in fully hydrated environments. Its coordinated expression with flagella suggests an intimate role between surfactant production and flagellar motility, but the identification of many other regulatory elements reveals a complicated mechanism of regulation. Examinations of the interaction of this surfactant with the bacterial cell, its flagella, and with the surfaces that this bacterium colonizes should illuminate its role in the epiphytic lifestyle of P. syringae. Biosurfactants, or biologically-produced surface active agents, are a broad group of natural amphiphilic compounds that are capable of lowering the interfacial tension between two phases. Although many different types of natural products have been identified to function as biosurfactants, one of the most intriguing classes of these compounds is the lipopeptides. Lipopeptides have a peptide head group attached to a lipid tail, and the peptide moiety is unique in that it is synthesized non-ribosomally; ie, it is not translated from an mRNA. Rather, lipopeptides are generally synthesized by non-ribosomal peptide synthetases , large enzyme complexes that catalyze the sequential assembly of a small peptide, as well as direct the addition of a carbon tail. Additionally, these assembly units can specify the incorporation of unusual amino acids,ebb and flow bench modifications, and/or cyclization. Because of this flexibility and ability to create unique peptides, NRPSs have found widespread use in bacteria and fungi for the synthesis of a variety of compounds including antibiotics, siderophores, pigments and many others. 

NRPSs specific for lipopeptide synthesis contain an initial condensation domain that catalyzes tail addition to the first amino acid of the peptide, and thus can be readily identified bioinformatically in genomes. The most familiar example of a lipopeptide is that of surfactin produced by Bacillus subtilis. This cyclic lipopeptide is composed of seven amino acids linked to a 12- to 16-carbon tail; the seven amino acids being somewhat variable in composition due to the low fidelity of many NRPSs. Although generally linked to biofilm formation and motility, surfactin has recently been revealed to act as an autoinducer signal, wherein surfactin production is sensed by non-surfactin producing cells, inducing them to produce an extracellular matrix. Other Bacillus lipopeptide families include the iturins and fengycins, while Pseudomonads have been found to produce an even broader range of lipopeptides. Two of the most extensively studied Pseudomonas lipopeptides are syringomycin and syringopeptin produced by Pseudomonas syringae, which have been noted for their membrane-disrupting and resultant phytotoxic properties. These cyclic lipopeptides contain 9 and 22 to 25 amino acids, respectively, and contribute to the virulence of this microorganism. Recently, production of syringafactin, an 8-amino acid linear lipopeptide, was also described in P. syringae DC3000 and B728a. With the continued identification of new lipopeptides and the sequencing of their genetic loci, an interesting pattern has emerged; many of the NRPSs for lipopeptide production in Pseudomonads possess divergently transcribed LuxR-type regulators both upstream and often also immediately downstream, of the biosynthetic cluster. When they have been characterized, disruptions in the upstream and sometimes downstream regulator results in blockage of lipopeptide production. These LuxR-type regulators have a characteristic C-terminal helix-turn-helix DNA-binding region, but form a distinct family separate from other characterized LuxR-type regulators. 

Classic LuxR homologs have an autoinducer-binding domain, while other LuxR-type response regulators have receiver domains typical of two-component systems.However, the NRPS-associated LuxR-type regulators have neither domain, and thus form their own group of regulators. SalA and SyrF are the best characterized of these LuxR-type NRPS regulators; they control and are located in close proximity to the NRPS loci for syringomycin and syringopeptin in P. syringae B301D. They have been shown to dimerize, and that a dimerized SalA binds the promoter region upstream of syrF, while dimerized SyrF binds to the promoter region of syringomycin. Thus, similar to V. fischeri LuxR, they become active after forming a multimeric complex. However, while LuxR must first bind an autoinducer to dimerize and become an activate transcription factor , it is unclear what if any factors contribute to the activation of the NRPS associated LuxR-type regulators. In addition to SalA and SyrF, a third LuxR-type regulator, SyrG, also exhibits partial control over syringomycin synthesis in P. syringae, although it operates independent of SalA and SyrF. Furthermore, P. syringae B728a possesses two additional regulators of this type , which flank the syringafactin biosynthetic cluster on both sides. SyfR, the regulator physically upstream of the cluster, was previously demonstrated to be required for syringafactin production in P. syringae DC3000. However, the LuxR homolog downstream of the syringafactin biosynthetis cluster had no effect on syringafactin production when deleted, and remains unnamed. No further characterization of SyfR has appeared. Although it is clear that these LuxR-type regulators often control lipopeptide synthesis in Pseudomonads, there has been little investigation of how environmental signals feed into this regulation. Some plant signals have been shown to induce lipopeptide production in plant associated Pseudomonads, supporting their proposed roles in virulence. Additionally, lipopeptides are regulated in a manner dependent on quorum sensing and cell density in a few Bacillus and Pseudomonas species. 

We recently found that expression of syringafactin in P. syringae is dependent on contact of cells with surfaces. The current study was undertaken to investigate the role of SyfR in such contact-dependent syringafactin production in strain B728a. We will show that SyfR controls more than syringafactin production,4x8ft rolling benches and is involved in a complex web of cross regulation between other LuxR-type regulators and other lipopeptides in P. syringae. Neither of the truncated SyfR constructs restored syringafactin production in a syfR– mutant. Either SyfR164-257 apparently did not include the correct regions of the DNA-binding domain, or SyfR has a different structural organization than LuxR. We also introduced these truncated SyfR variants into the wild-type strain to test for dominant negative interference which would indicate that SyfR forms multimers similar to SalA and SyrF. While the wild type strain expressing SyfR164-257 retained full syringfactin production, the wild-type strain constitutively expressing SyfR1-198 produced only the same size small surfactant halo as a syfR– mutant strain. Additionally, when we introduced the pPsyfA-gfp reporter fusion into these strains, we observed a similar pattern of GFP fluorescence as production of syringafactin in these strains; overexpression of the SyfR binding domain has a repressive effect on syfA transcription. This supports the hypothesis that this regulator forms a multimeric complex in order to induce syringafactin transcription. We tested the hypothesis that SyfR might be involved in conveying the preferential production of the surfactant syringafactin when cells were cultured on agar plates compared to broth cultures. Initially, we determined if constitutive expression of SyfR is sufficient to induce high levels of syringafactin production in broth culture. We grew the wild-type strain, a syfR– mutant, and a wild-type strain that over-produced SyfR by expressing syfR constitutively on the plasmid p519n–syfR, in both plate and broth conditions, and tested for surfactant production by the drop collapse method. Similar to the oil spray assay depicted in Figure 1, the water drop collapse assay indicated that relatively large quantities of syringafactin were produced in both the wild type and wild-type harboring plasmid p519n-syfR strains on agar plates, while a syfR– mutant was deficient in surfactant production. In contrast, while syringafactin production was low in a wild-type strain when these strains were grown in shaken broth cultures, constitutive expression of SyfR induced sufficient syringafactin production to enable drop collapse under these culture conditions. This suggested that low levels of SyfR might be responsible for the low levels of syringafactin production seen in broth cultures. We thus hypothesized that the surface regulation of syringafactin is at least in part mediated by SyfR.We determined if the apparently low levels of SyfR in broth culture stemmed from low levels of syfR transcription. To test this model we constructed a bioreporter in which a gfp reporter gene was expressed under the control of the promoter of syfR in plasmid pPsyfR-gfp. When a wild type strain carrying pPsyfR-gfp was grown in broth media, apparent syfR transcription was about 3-fold lower than when grown on agar plates. 

As a control, similar levels of GFP fluorescence were observed in a strain constitutively expressing the gfp reporter gene in these two culture conditions. It should be noted that rates of syfA transcription itself were more than 10-fold higher in cells cultured on agar plates compared to broth. We attribute the larger effect of broth culture on syfA expression than on expression of its regulator syfR as a consequence of the strong concentration dependence of oligomerization of SyfR that would be expected to contribute to its activation. We investigated the possibility that syfR is subject to autoregulation in P. syringae since LuxR induces its own expression at least 2- to 3-fold compared to that in luxR– mutant strains. Similarly, constitutive SalA expression results in a 2- to 3-fold upregulation of salA. It is noteworthy that this range of autoregulation is of the same magnitude as the differences in syfR transcription observed between broth and plate cultures. Therefore, we investigated the transcription of syfR in the absence of functional SyfR protein. Surprisingly, we observed equally low GFP fluorescence of a syfR– mutant strain harboring pPsyfR-gfp cultured on both agar plates and in broth media. This finding suggested two important points. First, it suggests that SyfR is autoregulated, and is necessary for the induction of its own transcription above a low baseline level. Second, it suggests that the surface regulation of both syringafactin production and SyfR abundance are conferred by a post-transcriptional process that affects SyfR levels or activity. Thus, we hypothesize that broth culture conditions reduce the magnitude of SyfR autoregulation, either through degradation of the syfR transcript or SyfR itself, or by alteration of SyfR. Further biochemical experimentation will be necessary to determine the mode of this control. If broth conditions foster the hypothesized destruction or modification of SyfR, then we might expect that constitutive production of SyfR would nonetheless result in lower promoter induction of syfR and syfA in broth cultures compared to growth on agar plates. We earlier observed that constitutive expression of SyfR enabled syringafactin production even in broth culture, but we did not examine syfA expression per se. Apparent syfA expression in broth culture, as estimated with the plasmid pPsyfA-gfp introduced into a strain constitutively expressing SyfR, was slightly below that observed on agar plates , which might lend support to our hypothesis. However, the promoter activity of syfR in a strain with constitutive expression of SyfR wasslightly higher in broth cultures than in cells recovered from agar plates. We have no explanation for why syfA expression was lower in broth cultures than on agar plates while syfR was higher. Further biochemical work might help elucidate any additional factors that contribute to syfA regulation. Nonetheless, the observation that constitutive expression of SyfR results in a further up-regulation of syfR further supports our claim that SyfR is autoregulated. A test of the self-sufficiency of the autoinduction process of syfR would be to demonstrate that SyfR is sufficient for syfA induction in another bacterial taxa that might lack ancillary components found only in P. syringae. Introduction of luxR from V. fischeri along with its regulated bioluminescence-encoding operon resulted in expression of of bioluminescence in E. coli. We sequentially transformed E. coli strain DH5α with both p519n-syfR and pPsyfA-gfp.This indicates either that additional transcription factors are necessary for syfA transcription, that processing or some unknown activation of SyfR cannot occur in E. coli, that these components were not efficiency transcribed in this E. coli host, or that SyfR does not directly regulate syfA. Additional investigation to distinguish these possibilities is warranted. We investigated the possibility that SyfR functions downstream from other global regulators in P. syringae. There have been multiple reports that the GacA/GacS two-component regulatory system controls lipopeptide production. In P. syringae, it has been further demonstrated that GacA/S controls lipopeptide production through its regulation of SalA. We hypothesized that Gac might also control syringafactin production, and thus tested surfactant production in a ∆gacS deletion mutant using the atomized oil assay as well as determining the expression of various genes involved in syringafactin production using transcription reporters.

Private industry interviewees were the most keen in believing that price increases promote technology adaption. Interviewees working for environmental organizations were most supportive of pricing increases for conservation. One academic interviewee, however, was cautious about promoting water conservation projects purely on a price basis, believing that the financial argument will always be less effective than a moral argument centered on values. All agreed that the recent introduction of tiered pricing regimes, where water is cheap initially but rises rapidly as usage increases, are a positive development that will lead to increased efficiency and conservation. The 1973 initial completion of the State Water Project largely signified the end of the State’s major north-south surface infrastructure projects. The 1982, voter rejection of the peripheral canal served to hammer the point home. The state has been forced to innovate in order to create “new” water sources for the growing southern coast. The most recent California Water Plan projects that new sources will make up over 20% of regional water supply by 2030 . The state has five major “new resource” initiatives: water markets, groundwater banking, urban conservation, desalination, and recycled wastewater. The first two do not actually create a new source, but rather more effectively manage existing sources. Water markets would encourage trade between users, for example cities and farmers might trade water so that each uses only what is necessary. Today California’s water market now accounts for roughly three percent of the state’s water use,hydroponic channel with the majority of trading occurring in the Central Valley, much of it a result of the Central Valley Project Improvement Act that required the restoration of the bay delta and introduced some water market mechanisms .

Trading markets are perhaps the simplest idea to implement technologically, as they often do not require much in the way of new infrastructure or technologies, however markets would likely require major changes to the way our institutions are run. For example, the aforementioned San Diego County Water Authority water purchase from farmers in the Imperial Valley is an example of this already occurring.The region’s institutional framework was designed to deliver water, not to allocate it efficiently . SDCWA has taken to the airwaves in its bitter legal dispute with MWD over both the price it is charged to use MWD’s infrastructure for transferring it’s purchased water and the price increase for MWD in general, which the significant hurdles that water markets face . The fact that MWD and its member agencies have resorted to producing academic studies that show MWD has subsidized San Diego’s consumption for decades further muddies the waters .Economists have advocated numerous institutional reforms to promote water markets . However, the State legislature has shown little enthusiasm for action. To an objective observer, unfamiliar with the various legal complexities, groundwater banking is clearly the most logical idea. In wet years when water is plentiful, it should go back into the ground to save for dry years. The exact opposite of a rainy day fund. Furthermore, aquifer depletion is a major concern for the regions, with estimates as high as 60% of the groundwater already being depleted, this despite being nearly a third of the regions water supply—up to 40% in dry years . But, as evidenced by the numerous conflicts and lawsuits over groundwater rights and appropriation, groundwater replenishment faces significant legal hurdles. Furthermore, it is estimated that potentially up to one third of regional urban ground water may be polluted and cleaning costs are uncertain . Additionally, as San Diego’s lawsuit shows water pricing concerns and rights to use existing infrastructure for transferring water must be sorted out before groundwater banking can become a widespread reality.

Organizational and institutional reform will likely be necessary for widespread adoption of ground banking. Currently California does not monitor groundwater, nor does it have the legal authority to, despite its critical importance to the water supply . Utilizing ground banking most effectively would require changes to our management structures to align incentives with rights. Better functioning water markets with the right to use transfer infrastructure would also help by ensuring that the water will make it to the appropriate regional aquifers and then harvested as needed for appropriate end use markets. Arguably, conservation has been the most effective “new source” as evidenced by the fact that the region uses roughly the same amount of water today as it did in the early 1990’s . However, much of the low hanging fruit in conservation has already occurred. Water wasteful toilets have been replaced. Wasteful water users have been identified and behaviors corrected. Tiered pricing regimes that punish wasteful users have been implemented. Numerous conservation programs have spread the message about good water practices. Furthermore, the state continues to pass progressive legislation. Significantly the 2007 20X2020 reduction has called for utilities to reduce their water consumption by 20% by 2020 . Many utilities have already met the goal partially through implementing additional conservation and efficiency measures, but also due to the prolonged economic downturn . Further reduction, however, will require technological investments and changes to systems. Today, the state’s attention is turning to landscaping, which accounts for over half of residential water use in Southern California. Programs such as “Cash for Grass” a program which pays residents to remove lawns and install water efficient landscaping .

Desalination, which creates freshwater by removing saline from ocean water is the only real “new source” of the five being pursued. There are approximately 20 desalination plants at various stages of planning in the region, with the Carlsbad plant the furthest in development . Desalination, however, is inherently controversial. Desalination is very energy intensive, and therefore an additional strain to an already burdened electricity grid. An estimated 19.2% of all electricity statewide is already used for moving, treating, or heating of water . Desalination also has major environmental impacts on the coastal areas where it is located. Both the drawing of ocean water,hydroponic dutch buckets and the discharging of huge volumes of brackish wastewater that results from the process, dramatically affect the surrounding sea life and can even impact the local currents . California has several nonprofit organizations actively working against desalination plants, most notably the group Desal Response, who is solely dedicated to preventing desalination plants . It is notable that San Diego is currently considering purchasing water supplies from a desalination plant under consideration in neighboring Tijuana, Mexico—which is outside the jurisdiction of U.S. environmental laws . Much of the innovation that has occurred in the last 30 years has been spurred by a combination of natural and legally-generated water shortages: a prolonged drought, from 1988 to 1994, and a series of environmental rulings requiring water use cutbacks . Among the successes have been dramatic improvements in agricultural and urban water conservation. These have been driven by new metering and monitoring requirements, new plumbing codes, pricing incentives, water markets, and regulatory cutbacks—all of which which have spurred technological and managerial innovation . This trend appears set to continue. Recent court decisions protecting the smelt in the Sacramento/San Joaquin Delta mean that if the region suffers another drought, then water for human use will be curtailed to ensure the smelt’s survival . In the near future, there are several additional pressures that will likely spur investment in the creation of “new water” sources. California suffers from a rapidly aging infrastructure, much of which was built 50 to 100 years ago . In a 2005 national study, the EPA estimated that over $39 billion in investment is needed statewide by 2020 simply to maintain current infrastructure . Additionally, state agencies increasingly recognized that an earthquake in the Central Valley would disrupt the State Water Project and devastate Southern California’s water supply. A disruption would effectively remove one quarter of the region’s water supply—not to mention the harm it would do to Central Valley’s powerful agriculture industry . Finally, there is the wildcard promised by climate change. Many current models predict a drying out of the Sierra Nevada snow pack . If this forecast is even remotely true, then an ever increasing share of water will have to come from “new sources.” All of these existing conditions and possible future scenarios point towards increased water innovation. When one further considers that the legal complications that exist in water markets and groundwater management are unlikely to be changed soon, and that the electricity, environmental, and fiscal constraints that exist on desalination, then it seems most likely that innovation will likely come fastest in the development of efficiency, conservation, and water reuse.

Turning to reuse technologies, innovation will likely come in two principle forms. There will be small scale distributed—non centralized—technologies such as residential grey water systems or small localized water cleaning systems like UCLA Water Center’s smart water systems . The second form will be major new infrastructural projects such as Orange County’s GWRS or West Basin’s Edward C. Little complex . Culturally our water agency institutions are predisposed more towards centralized engineering solutions rather than advocating a cultural shift to conservation or multiple distributed reuse solutions. Public health concerns further promote centralized infrastructure solutions over small scale local solutions where there is more risk of potential problems . California’s legislative priorities, institutional incentives, and water agencies are all slowly moving in the direction of additional water reuse. A question that this thesis presents is: Are these developments occurring fast enough for the local industry to maintain its global lead in these fields? Or will Southern California find itself purchasing goods and services from other regions whose water technology innovation systems are functioning more efficiently.“Water reuse,” “water recycling,” and “water reclamation” are terms that often used interchangeably and all refer to water that has been subjected to advanced treatment in order to use again. In 1995, the California legislature chose to embrace the term water recycling and amended regulations and statutes that read ‘reclaimed water’ and ‘water reclamation’ to read ‘recycled water’ and ‘water recycling’ . It was thought that the public would be more receptive to water recycling. Water reuse in California dates back to at least the eighteenth century when it was common for farmers to use wastewater for crop irrigation due to lack of steady water sources . At the turn of the century, San Francisco’s Golden Gate park used city sewage water for irrigation . As early as 1967, the state legislature directed the state to encourage the development of water reclamation plants . In 1974, the legislature passed the Water Reuse Law which stated: “The primary interest of the people of the state in the conservation of all available water resources requires the maximum reuse of reclaimed water in the satisfaction of requirements for beneficial uses of water” . Only one year later, the Orange County Water District’s water recycling plant Factory 21 became operational and water recycling became a truly viable solution to the states drinking water problem. The Fountain Valley facility, the precursor to the GWRS, treated wastewater and injected it into 23 wells along the coast, creating a seawater intrusion barrier. Factory 21 became the world’s preeminent prototype water reuse treatment facility,and arguably ignited the global industry . As the OCWD likes to say, since its founding in 1975, Factory 21 has consistently met all State and Federal drinking water standards . In 1991, the state further committed its dedication to water reuse through the passage of the Water Recycling Act. There, the Legislature set statewide water recycling goals that a total of 700,000 acre-feet would be reused per year by 2000 and 1,000,000 acre-feet per year by 2010 . Today there are nearly 200 water reuse facilities throughout the state . Over 70% of reused water is used outdoors, with nearly half used for agriculture, and another 20% for landscaping. Despite the success of the Orange County GWRS, groundwater replenishment only makes up 14% of water reuse . Industry makes up another 7%, although both of these are poised to expand in coming years as new projects and planned expansions at The Edward C. Little Water Recycling Facility are completed.