Tag: greenhouse vertical farming

The respiration rate of shade grown segments that were shifted to high light became significantly more negative four days after transplant . The shade grown segments exposed continuously to low light showed small changes in Afull sun and Rd relative to the SH-SU segments. Rd acclimation in SU-SH segments took about 13 days, with an initial rapid change followed by a more gradual change .The intercellular CO2 concentration remained constant among the treatments , and the changes in Afull sun were attributable to shifts in photosynthetic capacity rather than CO2 supply. Stomatal conductance paralleled the changes in Afull sun . We did not find evidence of changing patterns of stomatal control, and the simplest explanation is that conductance simply responded to Afull sun acclimation. Leaf acclimation was highly localized; individual leaf segments acclimated to local light autonomously from the rest of the leaf. Previous studies of leaf acclimation have focused on entire leaves, and acclimation by segments of mature leaves has received less attention . The ability for mature leaf acclimation varies among species, and has been reported in several herbaceous and a few woody species . Our findings of segmented acclimation are most closely related to those of Prioul et al. , who found that Afull sun, chlorophyll content,fodder growing system and Rubisco activity changed markedly from the base to tip of Lolium multiflorum leaves. Likewise, reciprocal transplants to contrasting light conditions inL. multiflorum showed the capability for rapid photosynthetic reacclimation to high and low light along the leaf, even in fully expanded leaves .

Detailed investigations of leaf anatomy and biochemistry are beyond the scope of this study, but our observations provide evidence of the mechanisms responsible for acclimation. Photosynthetic acclimation in Typha appears to result from biochemical or cellular changes, and a general up or down regulation of metabolic activity within individual leaf segments.Acclimation did not involve a significant change in nitrogen content on either a mass or area basis. We did not find evidence that a morphological change in leaf thickness, or a net movement of nitrogen into or out of a leaf segment, were required for photosynthetic acclimation.Our results confirm previous reports that species from highly variable light environments have a strong capacity for photosynthetic acclimation. In the case of T. latifolia, light heterogeneity is created by the combination of a basal meristem and a dense canopy of live leaves and litter . Typha leaves are exposed to markedly different light environments as they grow and individual segments are pushed upward . The upper segments of leaves in the field, which occurred in a brighter environment, had higher rates of CO2 uptake . Previous field studies on T. latifolia have also reported large CO2 assimilation and gs gradients along leaves . We hypothesize that the patterns of leaf photosynthesis and conductance in Typha reflect four properties. Mature Typha leaf segments are morphologically preformed to function in high light and allow high rates of Afull sun, regardless of the current or growth environment. Mature Typha leaf segments contain sufficient amounts of nitrogen to support high rates of Afull sun, regardless of the current or growth environment. Mature Typha leaf segments rapidly reallocate nitrogen between active and inactive pools in response to local light availability; acclimation occurs at a local level and does not require nitrogen translocation into or out of a leaf segment.

The controls on stomatal conductance remain constant over time; the patterns of conductance can be explained based on simple, short-term adjustments that act to maintain a nearly constant Ci concentration despite the changes in Afull sun and the physical environment. We interpret these patterns as a highly plastic strategy that maximizes carbon gain by a monocot growing in a vertically heterogeneous light environment. The construction of leaves that are morphologically capable of high rates of Afull sun is a simple consequence of the spatial decoupling of the growth environment fromdegradation of cellular components, such as Rubisco, cytochrome f, and chloroplast ATPase . The amount of nitrogen in leaf segments remained nearly constant over time, leading us to hypothesize a fraction of the nitrogen in shaded segments is stored in inactive pools and is rapidly activated following transfer to high light. These changes may include adjustments in partitioning among carboxylation, electron transport and light harvesting, chloroplast ultrastructure, volume, and orientation . The high N content of shaded segments should not be viewed as wasteful. These nutrients can be reabsorbed and reallocated to the rhizome during senescence; a high reabsorption efficiency of P and N has been reported for Typha dominguensis . Moreover, this strategy allows a leaf segment to rapidly and autonomously respond to a change in light availability, without importing or exporting nitrogen to or from other leaf segments or organs.Polycyclic aromatic hydrocarbons are a group of persistent organic pollutants that are composed of two or more fused aromatic rings in linear, angular, or cluster arrangements . Depending upon the structure of the rings, PAHs are classified as either alternant or non-alternant.

Alternant PAHs contain only fused six membered rings , while non-alternant PAHs contain four- or five-membered rings in addition to the six-membered rings . The aromatic structure of PAHs results in increased thermodynamic and chemical stability due to electron delocalization in the π orbitals, which plays a critical role in the environmental fate and toxicity of these contaminants . There are 16 PAHs designated as priority pollutants by the United States Environmental Protection Agency due to their occurrence in the environment and toxicity. The physicochemical properties of the 16 priority PAHs are detailed in Table 1.1 . These compounds are all hydrophobic, as demonstrated by their relatively high octanol-water partition coefficients and low solubility in water . The impact of the PAH structure on its chemical behavior is primarily dependent upon molecular size and angularity. Typically, an increase in the number of rings and angularity results in increased electrochemical stability and hydrophobicity . For example, low-molecular-weight PAHs are considerably more water soluble and volatile than high-molecular-weight PAHs . In addition to increases in hydrophobicity and environmental persistence with increasing PAH molecular size, PAH genotoxicity generally increases and toxicological concern shifts towards chronic toxicity, primarily carcinogenesis . Numerous studies have indicated that LMW PAHs exhibit acute toxicity to humans, whereas HMW PAHs exhibit chronic effects such as genotoxicity . The acute effects of PAHs on human health such as nausea, vomiting, and respiratory and skin irritation depend primarily on the extent of exposure, the route of exposure , and the concentration and toxicity of the individual PAHs . Polycyclic aromatic hydrocarbons can be widely distributed throughout the human body and have been detected in almost all internal organs, especially adipose tissues due to their lipophilicity . Once they enter the body, PAHs undergo metabolism primarily through the cytochrome P450 mixed-function oxidase system. This metabolic pathway transforms PAHs into polar epoxide intermediates that are further converted to dihydrodiol derivatives and phenols, which then form glucuronide and sulfate conjugates that are finally excreted in the bile and urine . However, this metabolic transformation can also result in the formation of electrophiles that elicit deleterious human health effects . Because of this, PAHs are considered procarcinogens because they do not directly induce DNA damage, but require metabolic activation to exert their genotoxic, mutagenic, or carcinogenic effects . There are three major pathways for PAH carcinogenic activation: the bay region dihydrodiol epoxide pathway, the radical cation pathway, and the o-quinone pathway,which result in the formation of radical cations, diol epoxides, and electrophilic and redox-active o-quinones, respectively, all of which may react with DNA to produce DNA adducts . Following extensive and systemic studies on the toxic effects of individual PAH metabolites in animals, it has been determined that the vicinal or bay-region diol epoxides are considered the ultimate mutagenic and carcinogenic species of PAHs .The International Agency for Research on Cancer classifies numerous PAHs as known, probably,chicken fodder system or possibly carcinogenic to humans . The IARC has determined that benzo[a]pyrene is one of the most potent carcinogenic PAHs, benzo[a,h]anthracene is a probable human carcinogen, and naphthalene, benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, and indeno[1,2,3-c,d]pyrene are possible human carcinogens . Altogether, PAHs rank as #9 on the Agency for Toxic Substances and Disease Registry’s Substance Priority List , which ranks contaminants based on a combination of their toxicity, frequency, and potential for human exposure at National Priority List sites . Of the approximately 1,400 NPL sites that are targeted for remediation by the U.S. EPA, more than 700 sites are contaminated with PAHs.

Polycyclic aromatic hydrocarbons are formed primarily during the incomplete thermal decomposition of organic substances and their subsequent recombination . Thus, the composition of the PAHs formed is dependent upon the temperature and the starting organic material . Polycyclic aromatic hydrocarbons occur as complex mixtures in the environment instead of single compounds due to their differing physicochemical properties during the incomplete combustion process . There are three primary sources of PAHs in the environment: pyrogenic, petrogenic, and diagenetic/biogenic. Pyrogenic PAHs areproduced from the rapid oxygen-depleted, high-temperature incomplete combustion of fossil fuels and organic materials . These pyrogenic PAHs are formed from the breakdown of organic matter to LMW radicals during pyrolysis, which is then followed by rapid reassembly into PAH structures . Pyrogenic PAHs are typically found at greater concentrations in urban areas because the major sources of pyrogenic PAHs are the incomplete combustion of gasoline and diesel in vehicles, the production and use of coal tar and asphalt, heat and power generation, and discharges from aluminum smelters and manufactured gas plants . The most abundant pyrogenic PAHs are typically fluoranthene and pyrene . Petrogenic PAHs originate from diagenetic processes at relatively low temperatures over a long duration, leading to the formation of petroleum and other fossil fuels containing PAHs . Petrogenic PAHs are introduced into the environment through accidental oil spills, discharge from tanker operations, and underground and aboveground storage tank leakage . Diagenetic/biogenic PAHs are produced from biogenic precursors by plants, algae/phytoplankton, and microorganisms . For example, concentrations of perylene, naphthalene, and phenanthrene concentrations have been found in hydromorphic soils, Magnolia flowers, and Coptotermes formosanus termite nests . While diagenetic/biogenic PAHs are often found at background levels in recent sediments, they are frequently the primary PAHs in older sediments deposited before increased industrial activity . The environmental ubiquity of PAHs is due to their chemical stability and numerous natural and anthropogenic sources. Natural sources of PAHs include volcanic eruptions, forest and prairie fires, and seeps of crude oil deposits . Anthropogenic sources, which contribute the vast majority of PAH contamination in the environment, include the production and use of fossil fuels such as coal, oil, and natural gas, refinement of crude oil, heat and power generation, wood treatment preservation processes, landfills, residential wood burning, and improper industrial waste disposal or spillage . Over the past century, there has been a substantial increase in environmental concentrations of PAHs following increased anthropogenic sources from industrialization, which can be demonstrated by PAH levels being the greatest in urban areas followed by agricultural and rural environments . Even the lowest PAH concentrations in temperate soils are approximately 10 times greater than PAH concentrations assumed to have been present before global industrialization . Once PAHs are emitted to the environment primarily through the combustion of fossil fuels, they are distributed atmospherically and deposited onto terrestrial, lacustrine, and marine surfaces . However, unlike most persistent organic pollutants like polychlorinated biphenyls that follow the global distillation transportation effect, PAH concentrations generally decrease as the distance from the initial source increases . Atmospheric PAHs are generally more abundant at night than daytime, and during the winter months compared to the summer months due to greater deposition at lower temperatures and increased coal combustion for heating . Polycyclic aromatic hydrocarbons are semi-volatile organic compounds; therefore, PAHs can be found in both vapor and particle phases depending on the vapor pressure of the PAH, temperature, and size and surface area of suspended particles . However, given the physicochemical properties of PAHs, they tend to more readily sorb to atmospheric particulates than be present in the gas phase . Because PAHs are commonly adsorbed onto atmospheric particulates, PAH transformation and degradation by thermal or photodecomposition and reactions with O3, SO2, NOx, or OH radicals are reduced and can even be completely inhibited .

Up or down changes in carbohydrate and lipid metabolism and protein handling pathways are also evident, although these are more difficult to interpret. Aquaporins, which affect membrane water permeability, were found to be upregulated in two studies . When drought-stressed seedlings are re-watered, most gene expression quickly returns to normal. In Pinus taeda, only 76 of the 2445 genes with altered expression during drought were still different after 48 h of recovery . Lorenz et al. found 11 genes upregulated in ‘recovered’ P. taeda seedlings relative to either drought-stressed or well-watered seedlings, including probable cell wall proteins, an aquaporin and a gene involved in vacuole function. These may reflect recovery or repair processes that occur once drought stress is removed.Pinus pinaster has at least eight dehydrin genes, based on expressed sequence tag analyses . Three of five were downregulated during drought, whereas the other two were upregulated . Most dehydrin induction occurred after 20 d of drought , which may be why a similar but shorter study did not reveal the upregulation of dehydrins. Expression can also vary by tissue. Of seven dehydrins examined in P. abies, drought stress upregulated four in needles, but only two in bark, with one being down regulated in bark . To investigate the link between drought and defense gene expression, Fossdal et al. exposed P. abies seedlings to a pathogen , drought stress or both,grow strawberry in containers and examined the transcription of 14 candidate defense genes. Genes were upregulated more slowly in drought-stressed seedlings than in pathogeninoculated seedlings.

The combined treatment led to more rapid and/or higher expression of many defense genes than either alone, which may be related to the synergistic mortality risks posed by biotic and abiotic stressors. Pleiotropic effects for some drought/ defense-related genes are also possible, but none have been identified to date.Multiple provenance studies have identified patterns consistent with local adaptation to drought. Trees from drier climates often exhibit conservative growth strategies , such as slower height or needle growth , less above ground biomass or a shorter growing season . Seedlings from dry environments often also exhibit more root growth and higher drought survival . Provenance trials of Pinus halepensis have shown mixed responses, with low growth and high water use efficiency in dry-sourced populations , but high growth in populations from intermediate-aridity areas , which may be related to growth plasticity. Because of the importance of carbon resources for plants, WUE – the ratio of carbon fixed to water lost – has long been considered to be closely tied to drought tolerance . Measures that integrate over longer time periods, such as the carbon isotope ratio d13C , are most frequently used to represent changes in WUE in trees. However, although different measures of WUE are often correlated , they are not interchangeable. For example, carbon discrimination is sensitive to chloroplast carbon concentrations and mesophyll conductance, whereas WUE itself is heavily influenced by evaporative demand, which does not directly affect D . In addition, nitrogen fertilization can increase WUE and decrease D, but does not affect gs or transpiration . Thus, WUE and D do not always co-vary, and caution is needed in the interpretation of d13C as a measure of WUE. Additional caution is warranted when using WUE as an indication of drought tolerance. High WUE may not be adaptive in some dry environments if the use of less water per unit carbon fixed does not result in slower depletion of soil water , or if plants with higher WUE grow faster and thus use more total water. Although a few studies have shown higher d13C for populations from dry sites , others have shown the opposite .

There was no difference between three populations of Pinus ponderosa seedlings from varying climates in d13C or instantaneousWUE; the drought adapted populations exhibited greater plasticity in water use . In P. halepensis, however, individuals from more mesic sources showed higher plasticity of WUE than those from drier sources , but dry sources may show higher average WUE . Highly plastic growth and water usage reduce apparent WUE over the whole season compared with consistently moderate to low water usage . Instantaneous measures of WUE can change over a day, whereas integrated measures can differ significantly for a source population grown under different conditions or for the same tree across years . Changes in WUE may thus be a useful indication of drought stress, but, in conifers, radial growth and WUE are often weakly or negatively correlated . In pines, higher WUE usually results from reduced gs and/or reduced leaf area , which can limit photosynthesis and growth . Low gs can also result in higher tissue temperatures, which can be damaging, particularly in seedlings . Drought length and severity can influence measures of relative drought tolerance between populations. In P. ponderosa seedlings,the relative growth rate under moist conditions was positively correlated with previously measured tolerance to severe drought, whereas, under 4-wk drought, the intermediate-drought-tolerant population grew faster . When Silim et al. examined Picea sitchensis, P. glauca and their hybrids, they found that P. sitchensis and the hybrids had the highest WUE and growth in well-watered conditions, but P. glauca and the hybrids had higher WUE and growth in drought conditions. Similarly, the relative transpiration and photosynthetic rates, WUE and growth of P. halepensis tree provenances differed between near-desert and Mediterranean planting sites . Such shifts in ranking are often a result of plasticity differences between populations. Provenances of P. pinaster from across the species’ range did not vary in cavitation resistance, suggesting uniform selection or lack of genetic variation . In P. halepensis, however, the percentage loss of conductivity differed significantly between provenances, but not between environments .

Although plasticity has been observed in xylem wall thickening, time to thickening and number of cells in Picea mariana in drought experiments , cell anatomy studies often focus on only one population, so that the extent of local adaptation is unknown.Genome scans have identified loci in conifers that may be under differential selection across environments . Of 13 candidate genes for drought response in P. pinaster, two showed signs of divergent selection, although only one exhibited a pattern correlated with a climatic gradient; three, including two dehydrins, showed evidence of balancing selection . Prunier et al. examined SNPs from 313 candidate genes in P. mariana and found 16 that exhibited differentiation correlated with precipitation, including a LEA protein and genes in the ubiquitin protein handling pathway. However, differentiation between populations can be driven by processes unrelated to climatic gradients. Conifer populations are likely to violate the assumptions of such tests because they rarely form discrete isolated populations and are often far from demographic equilibrium; mis-specification of population hierarchical structure can lead to high false positive rates . However, newer methods are being developed that avoid frequently violated assumptions and reduce false positives . The approach preferred by recent studies is to directly assess the association of loci with environmental gradients ,hydroponic nft channel whilst controlling for population structure . JaramilloCorrea et al. examined the correlation of P. pinaster candidate gene SNP allele frequencies with climate principal component axes, using transcriptome-wide SNPs to control for population structure and demographic history. They identified 18 environmentally associated SNPs, many of which were in genes relating to carbohydrate transport, cell wall construction and photosynthesis. Two surveys of P. taeda examined associations between candidate gene SNPs and environmental gradients. One examined the association of these loci with five climatic PC axes , whereas the other used an aridity index for each county . There was some overlap in function between the loci identified. However, the studies disagreed on whether SNPs associated with climate also tended to be Fst outliers. G2E associations have been detected even over short geographical distances, suggesting that selection can drive local adaptation in the presence of high gene flow. Eckert et al. examined Pinus lambertiana populations around Lake Tahoe, an area of c. 35 9 65 km2 , and found 11 genes associated with environmental PCs reflecting differences in water availability. These included genes involved in carbohydrate metabolism and transport and response to biotic stress . A cross-species comparison of environmental associations suggests some similarities in the genetic mechanisms involved in climatic tolerances across conifer genera. For each of four European conifer species in the Italian Alps, 6–18 SNPs were associated with precipitation/temperature PC axes . There was some overlap between species in the genes represented, including heat shock proteins, and cell wall construction and carbohydrate metabolism genes .Gene expression studies have identified a range of genes that may be involved in drought responses, but these results are not easily connected to the results of physiological or provenance response studies.

First, RNA transcripts reflect the genes being expressed at a particular instant, whereas morphological or physiological traits are the result of processes acting over a longer time. Second, most gene expression studies do not examine differences between populations. Although some evidence suggests that stronger gene expression changes during stress are associated with greater growth or survival, different genotypes and demographic stages can show significant differences in gene expression changes . A few studies have begun to address this. Provenances of P. pinaster differed in the expression response of two dehydrin genes, as well as in physiology and mortality rates . Similarly, three genotypes of P. taeda differed in their gene expression responses to drought and re-watering . More such studies are needed, but care must be taken to distinguish between drivers of expression differences. For instance, a more drought-sensitive tree might express higher levels of dehydrins at a given drought stage because the leaf water potential has dropped faster than in a drought-resistant tree, whereas the resistant tree might express higher levels of dehydrins than the sensitive tree at a given leaf water potential. Genome scan and G2E association studies can be useful tools in the search for genes responsible for local adaptation. Although such studies can identify loci at which allele frequencies differ between environments, it is not always clear how these differences are connected to phenotypic differences, and thus what traits are under selection in a given environment. This is where QTL and G2P association studies are useful.Most conifer QTL studies have focused on wood traits, growth or yield. Of the two that have examined drought tolerance, the first identified four significant and four suggestive QTLs for d13C in P. pinaster, none of which co-located with QTLs for ring width . The second examined a wider range of traits – photosynthesis , chlorophyll fluorescence, gs, d13C, intrinsic WUE and specific leaf area – in F1 cross seedlings of P. pinaster when well watered or after 1 or 2 wk without water, and identified 28 significant and 27 suggestive QTLs . Locations of the QTLs for each trait varied by time point. Candidate genes within the QTLs were identified : those for gs and WUEi included stomatal regulation, ABA signaling and cell wall construction genes; those for d13C included an aquaporin; and those for chlorophyll fluorescence included transcription factors and a histone chaperone. G2P studies focusing on quantitative traits have generally been successful in identifying associated loci . However, only a few studies have investigated drought tolerance in conifers , with less success. All such studies used d13C as the focal trait. As we argue in Section VI, other traits would probably yield results that are more helpful for the understanding of drought responses. Gonzalez-Martinez et al. examined 41 candidate stress response genes of P. taeda, using 61 tree families planted at two sites. However, drought stress was probably mild, and they only identified one strongly associated gene and one weakly associated gene at each site. A later study on the same species examining 3938 SNPs identified seven new associations with d13C . Four of the associations were with unknown proteins, with only a transcription factor probably involved in the ABA-mediated stress response having an obvious connection to drought responses. G2P and G2E association studies complement one another, with the first identifying loci linked to targeted traits, but not whether these loci are under selection in nature, and the second doing the opposite.

A better understanding of the transmission of HLB between the psyllids and citrus hosts in natural landscape is crucial to formulating effective control strategies. A spatially-explicit agent-based model, which simulates the actions and interactions of autonomous agents within the epidemiological system, has been developed to investigate how ACP and HLB spread in the Central Valley of California, an intermixed landscape of residential and commercial citrus. This study is a practical extension of the mathematical model with purposes to quantify the influence of input epidemiologic parameters on disease progress under sensitivity analysis, and investigate the efficiency of ACP/HLB management strategies by running scenario-based simulations. Although there are numerous hypothetical management strategies for testing, we focus more on survey design , and biological and chemical control strategies . In addition, we incorporated these management strategies into disease modelling with consideration of the social-economic perspective of citrus growers. Growers’ awareness of ACP/HLB and their attitude toward control strategies will change along with disease development, and we evaluate the set-points that yield optimal operation cost and sustainable control using a cost-benefit analysis. Our results indicate that climate change can have a large effect on the performance and spatiotemporal distribution of ACP and biological control agent populations in central California. ACP spread occurs more frequently and faster within commercial citrus clusters, but comparatively slower for low density or well separated residential areas. For different spray strategy scenarios,vertical rack system a comparison between simulation outputs confirms that the synchronize rate for coordinated spray plays an important role in slowing ACP epidemic development.

The Asian citrus psyllid vectors causal pathogens of huanglongbing or citrus greening disease. Its control is critical in all habitats including organic citrus grown in the United States and other regions of the world. Three separate organic programs, organic insecticides applied alone or with horticultural mineral oil and insecticidal soap were compared with one conventional program for impact on ACP and beneficial insects including release of nymphal parasitoid Tamarixia radiata in bearing citrus in southwest Florida. During the dormant winter season, Pyganic applied alone or with 435 oil or M-pede applied in November, December and January and Danitol applied in November and January all provided significant reduction in ACP with residual lasting longer for Danitol.Organic programs 2 and 3 rotated organic insecticides with 435 oil or M-pede resulting in 50% reduction in use of insecticides while providing better ACP control than program 1 with organic insecticides only. However, ACP was reduced more in the conventional program. Tamarixia radiata, ectoparasitoid of ACP nymphs was released in all programs but recovered more from ACP nymphs in the organic program compared to the conventional program. Lacewings, spiders, ants and ladybeetles were observed in all programs that also may have contributed to ACP reduction. Best yields were obtained in programs using organic insecticides with 435 oil or conventional insecticides. Monthly applications of Pyganic with 435 oil during dormant winter period and rotation of organic insecticides with oil during growing season appear to be reasonable options for ACP management in organic citrus. Organic insecticides will also be suitable for conventional citrus growers as selective options to avoid excessive use of non-selective insecticides, to limit pesticide resistance and harm to beneficial insects.

Candidatus Liberibacter asiaticus colonizes the citrus phloem and causes the most destructive citrus disease. Understanding how the bacterium interacts with citrus is important to improve or devise new methods of disease control. The objective of this work was to assess Las movement in citrus plants, from the initial infection site to the root, which is the part of the tree that apparently first suffers after pathogen infection. Experiments were carried out using 208 three-year-old, 60-cm high, potted Valencia/Volkamer lemon. The plants were grafted at the stem 60 cm above the substrate surface with 3- to 4-cm-long buds from Las-positive branches, and assessed over time at different distances from the inoculation site to determine the presence of the bacterium. Two evaluation procedures were used in three experiments carried out in two time periods. In the first, the stem of the inoculated plants were pruned sequentially at 10, 20, 30, and 40 cm below the inoculation site at 14, 21, 28, 35, and 42 DPI. The new leaves that developed at the top of the remaining stems were assessed regularly for HLB symptoms and through qPCR at six months post inoculation. This procedure was used in two experiments carried out from August 2015 to January 2016 and from March to August 2016 . In the second procedure, fibrous roots and one-centimeter long bark rings were removed just below the inoculation site and, at 10-cm intervals from it, up to near the soil level. The evaluations were made at 7, 14, 21, 28, 35, 42, and 49 days post inoculation , with the samples processed and analyzed through qPCR. This procedure was used in just one experiment carried out from March to April 2016. The fastest Las speed were 1.14, 1.43, and 2.02 cm per day for E1, E2, and E3, respectively. The frequencies of the evaluated sites positive for Las, at all evaluation dates, were then subjected to regression analysis. The logistic model better described Las distribution in the plants over time.

The probability of detecting Las at any portion of the plant was a function of time and distance from the inoculum. The longer the time between the inoculation and sampling dates and the shorter the distance from the inoculum, at any given time, the higher the probability of testing positive. Extrapolations made using the regression model allowed estimations of minimum 51 and 131 days for Las to reach the root of 2- and 7-m high citrus trees from a single inoculation site at the top of the tree. This fast movement explains the difficulties of curing an HLB affected tree and reinforces the importance of the implementation of areawide preventive actions to control the disease in citrus orchards. One of the long-term solutions for cultivation of citrus in presence of HLB may be development of disease resistant cultivars. In the genus Citrus, resistance to HLB is not known although some tolerant varieties have been reported. We have identified resistance and significant field tolerance in many citrus relative genera native to Australia. Field and greenhouse studies indicated that many naturally occurring hybrids of citrus and Eremocitrus/Microcitrus are resistant to HLB. Since the HLB resistance in the Australian types appears to be heritable, we have generated hundreds of citrus hybrids by crossing Citrus and Poncirus with disease resistant/tolerant, sexually compatible Australian citrus relatives. The hybrid plants are challenged by exposure to psyllids carrying HLB-associated Liberibacter pathogen. Preliminary evaluations of the hybrids in green house experiments conducted in Fort Pierce, FL indicate that a significant number of the novel hybrids appear to be disease resistant. Further testing to confirm HLB resistance is in progress. The promising hybrids will be useful in understanding the basis of HLB resistance and in developing methods to impart resistance to commercial citrus cultivars. The Asian citrus psyllid is the insect vector responsible for the worldwide spread of ‘Candidatus Liberibacter asiaticus’ , the bacterial pathogen associated with citrus greening disease. Developmental changes in the insect vector impact pathogen transmission,mobile grow rack such that D. citri transmission of CLas is more efficient when bacteria are acquired by nymphs as compared to adults. We hypothesize that expression changes in the D. citri immune system, including the insect’s commensal microbiota, occur during development and regulate vector competency. In support of this hypothesis, more proteins, with greater fold changes, were differentially expressed in response to CLas in adults as compared to nymphs, including insect proteins involved in bacterial adhesion and immunity. Discovery of protein interaction networks has broad applicability in the study of hostmicrobe relationships. Using Protein Interaction Reporter technology, we show how protein interaction networks in D. citri are regulated during development and in response to CLas-infected citrus trees. Notably, a hemocyanin protein highly upregulated in response to CLas was found to physically interact with the CLas coenzyme A biosynthesis enzyme phosphopantothenoylcysteine synthetase/decarboxylase. In addition, hemocyanin was found to physically interact with several other D. citri signaling and stress response proteins.

Co-evolved protein interaction networks at the host-microbe interface are highly specific targets for controlling the insect vector responsible for the spread of citrus greening.Huanglongbing , also known as citrus greening, is one of the most destructive citrus diseases worldwide and is seen as a major threat to the multimillion dollar citrus industry in California. The vector of two of the bacterial species associated with this disease, Candidatus Liberibacter asiaticus and Ca. L. americanus , is the Asian citrus psyllid , Diaphorina citri. In August 2008, the first ACP in California was found in a trap located in San Diego County. The detection triggered an ongoing state wide risk-based survey and HLB testing program for ACP and HLB host plants in California. Since 2008, a total of 135,000 citrus trees and 252,000 ACP samples have been tested so far by the California Department of Food and Agriculture using the United States Department of Agriculture HLB Work Instruction which utilizes a TaqMan real-time PCR assay based on 16S rDNA primers and probe developed by Li et al. . After eight years of challenging Li’s 16S HLB primers with hundreds of thousands of environmental samples, we have found that Li’s primers are highly specific but on rare occasions will cross amplify other closely related bacteria such as Ca. L. crescens . Lcr has never been reported in citrus before, and has only been reported in Babaco papaya during a survey for Papaya Bunchytop Disease in Puerto Rico. Currently there are six recognized species of Candidatus Liberibacter, four of which are pathogenic and two that have not been shown to cause symptoms in plants. Lcr falls in the latter category and is also the only member of this group that has successfully been cultured in artificial media. To date, Lcr has been confirmed in six citrus samples collected in three different counties in California and one from Hawaii. The detections were made during routine HLB testing in which the samples produced Fam Ct values between 33-36. A 1,149 bp fragment of the 16S ribosomal RNA gene was amplified from the DNA extracts using conventional PCR with primers Ol1 and OI2c. The sequence showed 99% identity with the corresponding regions of Ca. L. crescens strain BT-1. All samples had the same two single nucleotide polymorphisms differing with positions characteristic to Lcr. This is the first report of Lcr in citrus. Follow up sampling and testing of the CA trees confirmed all were negative for the HLB associated bacterium. Only one tree was retested for Lcr and was confirmed positive. Plans to retest the other trees for Lcr are underway. We evaluated the percentage of psyllid population with Las and its correlation with insect population captured in sticky cards and the HLB management in the property over a year. Assessment was carried out in four citrus regions in São Paulo state according to the Fundecitrus Phytosanitary Alert System. Cards were installed, read and replaced every two weeks on the period of February 2014 to February 2015 in the regions of Avaré, Santa Cruz do Rio Pardo , Araraquara and Bebedouro . In each reading, up to 50 psyllids per regions were collected and detection of insects Las+ was made by qPCR. Bi-monthly averages of the percentage of psyllids Las+ were compared. Santa Cruz do Rio Pardo region had 71% of Las+ samples and differed from Bebedouro region that had 56%. Avaré and Araraquara regions had 68 and 66%, respectively. The number of psyllids increased gradually between July and August in Avaré and Santa Cruz regions, from September to October in Araraquara region and intermittently from October in Bebedouro region. Potentially infective psyllid was higher in early spring in Avaré and Santa Cruz, with the largest population; Araraquara were higher starting in October, peaked in December ; Bebedouro region reaches the highest values in January and February . Percentage of Las+ psyllids collected in properties without HLB management were higher and statistically different from the averages on the properties that adopted psyllid control. The relationship between the percentage of psyllids Las+ and the number of captured psyllids in the region in a given time denotes the most critical time of year that psyllids Las+ intake in the orchards can occur.

We have used genome sequence data to identify epitopes on the surface of CaLas. Genes that encode these epitopes have been cloned in E. coli, and the proteins expressed, purified and used to immunize rabbits. The major outer membrane protein A has been used as the basis of a immune tissue print assay for CaLas. A problem for assays of CaLas isthe well known erratic distribution of the pathogen in infected citrus trees. DNA based detection methods require extraction and purification of the DNA prior to the assay. The immune tissue print assays are done directly on plant material and preserve and record the distribution of the pathogen with resolution of single infected phloem cells. Using this method, the pathogen has been readily detected in all tissues of infected sweet orange and lemon trees, a portion of the leaf midrib has been identified as ideal site for sampling. The tissue print assay also scales well to many samples. The rabbit polyclonal antibody has also been used to purify CaLas cells from plant extracts prior to PCR. Immune tissue prints and standard qPCR assays have been carried out on the same samples and are complementary. When both immune tissue prints and qPCR assays are used, the combined data show instances where each assay records a false negative, but together nearly all infected samples are detected.Huanglongbing is a devastating bacterial disease of citrus which causes yield loss, tree decline and reduces fruit and juice quality. HLB is caused by Candidatus Liberibacter asiaticus and transmitted by the Asian citrus psyllid.Many horticultural management practices have evolved to manage HLB infection such as pest management practices,nft growing system the establishment of Citrus Health Management Areas and addition of bactericides. There has been much investment by many funding agencies in many research topics to find solutions to HLB, including plant breeding and biotechnology.

Plant improvement to develop HLB resistant or tolerant root stocks and scions through conventional or biotechnology is the most likely to provide sustainable solutions to HLB. The goal of Citrus Research Development Foundation is to support research and to deliver HLB solutions to growers as quickly as possible. There are several plant improvement research programs in the US using conventional and biotech methods. In Florida, there are researchers at the University of Florida and USDA-ARS research departments comprised of several programs and many researchers. Due to the diversity of programs, program objectives, approaches to research and evaluation, it is difficult to understand the scope and progress of post HLB research and the current status of projects. CRDF is investing in efforts to work with researchers to develop a common development, evaluation, and deployment platform to accelerate commercial release of economically viable HLB resistant or tolerant root stocks and scions.The Asian citrus psyllid Diaphorina citri Kuwayama is the insect vector of the fastidious plant pathogen bacterium Candidatus Liberibacter asiaticus , the causal agent of citrus greening disease, also known as Huanglongbing which is the most significant and widespread threat to the citrus industry. To investigate gene expression profiles that associate with ACP- CLas interactions and identify genes in response to CLas infection, we constructed RNA-seq libraries from CLas-infected and CLas-free ACP samples of three different developmental stages . With 150 bp paired-end sequencing on the Illumina Hiseq2500, we generated 152 Gb of sequence data from 56 million reads per library/replicate, which was assembled into 34,122 contigs with 18,827 being annotated, which were then further analyzed for potential functional classification and potential roles in infection. The results suggested that gene expression in different developmental stages did not respond in the same manner to CLas infection. With more contigs being up or down- regulated, nymphal instars 4-5 showed a more sensitive response to CLas infection than nymphal instars 1-3 and adults. A comprehensive analysis of the transcriptomes revealed vector life stage differences and differential gene expression in response to CLas infection, and identified specific genes with roles in nutrition, development, immune response and transmission pathways.

In Florida approval was granted for field application to citrus trees of formulations of streptomycin and oxytetracycline to control infections by ‘Ca. Liberibacter asiaticus’ and the subsequent development of the associated disease, huanglongbing . We developed a procedure for infecting individual trees by grafting a single symptomatic leaf to the tree. We wanted to determine if this procedure could serve as a small scale assay system for testing conventional antibiotics and other compounds for antimicrobial activity effective against ‘Ca. L. asiaticus’. The working hypothesis behind the assay was that the application of the candidate compound to the inoculum leaf before or after grafting would impede or prevent bacteria in the inoculum leaf from infecting the receptor tree. Aqueous solutions of oxytetracycline or streptomycin, containing either glycerol or the commercial compound Pentra-Bark to aid penetration were applied under 20 psi of pressure to both the adaxial and abaxial surfaces of individual symptomatic leaves before or after grafting the leaf to a receptor tree. Receptor trees were inspected periodically for symptoms and after five to seven months leaf samples were evaluated for infection using real time PCR to detect pathogen DNA. The cumulative results from six trials found 44/60 , 46/75 and 53/80 of trees infected by grafted leaves treated with oxytetracycline, streptomycin or no treatment, respectively. The data suggest that under the conditions of this study, these two compounds failed to impede infection of the receptor trees relative to non-treated controls. The reasons for the lack of success in preventing infection are unknown but could be related to either the effectiveness of the compounds or the method of application, or both. The Asian citrus psyllid is the insect vector of the bacterium Candidatus Liberibacter asiaticus , the causal agent for the citrus greening or Huanglongbing disease which threatens citrus species worldwide. This vector is the primary target of approaches to stop the spread of the pathogen. Accurate structural and functional annotation of the psyllid’s gene models and understanding its interactions with the pathogenic bacterium, CLas, is required for precise targeting using molecular methods. The draft genome was annotated with automated pipelines.

Knowledge transfer from well-curated reference genomes like Drosophila to a newly sequenced insect is challenging due to the diversity and complexity among all insect genomes. We opted for manual curation of gene families that have key functional roles in D. citri biology and pathology. The community effort produced more than 450 manually curated gene models across developmental, RNAi regulatory, and immune-related pathways. Curators included undergraduate and graduate students from multiple institutions as well as experienced expert annotators from the i5k community. Here we report the official gene set for the Asian citrus psyllid genome that includes manually curated genes involved in pathways of experimental interest for vector control strategies. The Asian citrus psyllid, Diaphorina citri is the insect vector of ‘Candidatus Liberibacter asiaticus’ ,nft hydroponic system the causal agent of HLB. Proteomic characterization of D. citri identified hemocyanin as central to the insect’s response to CLas-infected trees. Hemocyanin expression is highly induced psyllids reared on CLas-infected Citrus medica Linn. and has been found to physically interact with a CLas vitamin A biosynthetic enzyme. Hemocyanins function as respiratory proteins of mollusks and arthropods with conserved histidine residues forming a coordination complex with copper ions binding oxygen for transport in the hemolymph. Hemocyanins have evolved from oxygen-binding tyrosinase enzymes, which participate in melanin biosynthesis and have documented roles in insect defense, including parasite encapsulation. This study evaluated the role that hemocyanin plays in the insect response to CLas infection. Specific dsRNA to hemocyanin in D. citri were designed and delivered via artificial diet feeding. Effects of hemocyanin suppression on CLas transmission were evaluated using detached leaf transmission assays. The levels of hemocyanin mRNA expression were highly correlated with the different D. citri color morphs and thus, we hypothesized that the blue abdominal color commonly observed in D. citri may be attributed to the oxygen coordinating copper associated with hemocyanin in the insect. Insight into the function of D. citri hemocyanin may reveal novel strategies to specifically disrupt CLas transmission by the insect vector. The commonly employed technique for monitoring the Asian citrus psyllid utilizes yellow cards covered with glue. These have several disadvantages: the sticky surface is messy and indiscriminate for other insects or debris trapped, it is difficult to remove intact specimens for complete identification, and insects are not well preserved for tissue analysis. An alternative design that can preferentially attract ACP while avoiding the sticky substance, while also preserving the specimens for complete analysis, is therefore desirable. This project enhances the mitigation of citrus greening through early detection of huanglongbing through improved trapping technologies.

Trapping of ACP, with “smart” traps that make it possible to accurately test for the presence and spread of the HLB pathogen, Candidatus liberibacter spp., facilitates the rapid site management response to enable delimitation and potential containment of citrus greening in regions where the disease is not widespread. The first attempt at psyllid trap design was a simple, color-attractive, yellow cylinder that eliminated the sticky glue, but the catch yield was consistently lower than that of the sticky trap, even when tested inside a psyllid rearing facility where the target population was high. Since making manual tweaks to our design quickly became both labor and time intensive, we decided to make the various physical modifications to our prototype by utilizing computer modeling software coupled to a 3D printer. This approach allows us to virtually model the design before testing, and then we can print viable traps within a single day, without the time needed to purchase and assemble the components derived from various sources; this removes a major impediment to rapid innovation. The modeling software can be used to make iterative tweaks to successive designs or to immediately create entirely new models, and the designs are limited only by the capabilities of the 3D printer. The printers deposit heated plastic into intricate designs, a method that is not possible using injection molding techniques, so the shapes of our traps can include projections and voids in strategic places to exploit the natural behaviors of citrus psyllids. Trap designs can easily be developed within a single day, allowing modifications and adjustments to be made in real time as new field data is acquired. Our improved “SmartTrap” designs can favor the capture of certain insects only, such that >50% of the insects collected would be psyllids. The trap base also contains a preservative liquid that allows those captured psyllids to be analyzed by standard molecular techniques. This enables researchers to better study the vector of citrus greening, therefore leading to improvements in control and prevention methods that may be more effective than the expensive, broad-spectrum pesticide sprays. The yellow trap color may be an adequate psyllid attractant for sticky traps, but our group is experimenting with slight color variations of different types of plastics and LED lights, incorporating the UV wavelengths that have been identified as psyllid-specific attractants. The concept of our latest design is to attract ACP to colored plastics and LEDs, where they will land on the primary cylindrical body of the trap. As they naturally crawl upward on rubberized plastic projections, designed to resemble the tender new growth of citrus stems, they will pass under the shade of an opaque overhang, where they will then crawl toward a view of sunlight that appears to be coming through the holes in the trap body, protected from the elements by a clear umbrella dome. Once inside the trap they will remain inside, preferring not to reenter the holes which appear dark from the interior perspective. They then fall down a slippery, fluon-lined funnel and into a preservative-filled test tube, which can be removed for inspection without dismantling the trap itself. Other researchers have identified potential chemical and auditory attractants for psyllids, and these features can easily be incorporated into a single trap design, made possible by 3D print technology.This presentation will show our latest designs and provide commentary on our observations.

HLB-affected Valencia fruit together with healthy fruit, were harvested in the middle of the harvest season, and peel oil extracted from flavedo tissues using methylene chloride/pentane solvents. Volatile compounds were analyzed by GC-MS. All HLB-affected fruit produced a lower volume of peel oil compared to healthy fruit, however, only green fruit showed substantially different volatile profiles from healthy fruit. The green fruit contained low concentrations of most of sesquiterpene hydrocarbons and derivatives, such as, nootkatone, valencene, α-selinene, 7-epi-α-selinene and caryophyllene oxide, some monoterpene hydrocarbons and derivatives with orange/citrus characteristics, such as, limonene, myrcene, α-pinene, neral, geranial, and α-terpineol, and straight-chain aldehydes, such as, octanal, nonanal and decanal. Eight compounds were determined in the green fruit peel which were not present, or present in very minor quantities, in the healthy fruit. Their retention indices on a DB-5 column were RI 1137, 1144, 1149, 1189, 1320, 1334, 1346 and 1387. The preliminary identifications based on MS and the NIST database RI comparisons were -p-mentha-2,8-dien-1-ol, 1,8-p-menthadien-2-ol, 3-[-3- methyl-1-butenyl]-cyclohexene, 6-methyl-bicyclo[3.3.0]oct-2-en-7-one, p-mentha-2,8-diene-1-hydroperoxide, an unknown, p-menth-8-en-2-ol and p-mentha-[1,8]-diene 2-hydroperoxide, respectively. Other compounds in HLB-affected green fruit were cis-3-hexenol, cispinocarveol, carvone, and α-cubebene. The large scale surveys for detecting Asian citrus psyllids and HLB in Texas and California are on-going. We continue to analyze the spatial pattern of the diagnostic Ct-values from psyllid samples and our goal is to help focus the survey effort for HLB infected citrus trees. The realtime polymerase chain reaction diagnostic methods used to detect HLB are set to run for 40 cycles. The reaction must surpass a threshold of ≤ 32 prior to the completion of the run to be considered positive for HLB. Currently,growing hydroponically reactions that surpass the threshold at 33 or more cycles have proven impossible to acquire a confirmatory PCR bands and DNA sequence data and are considered inconclusive.

The question we are trying to answer is whether there is additional information in the spatial pattern of inconclusive psyllid samples for predicting locations with HLB infected trees. Based on analysis of the spatial pattern of psyllid Ct-values proximate to HLB positive tree detections in both Texas and California, there appears to be a biological process underlying indeterminate Ct-values in the range of 32 – 38. Analyses indicate significant clustering of indeterminate Ct-values of psyllid samples, and some clusters in both Texas and California were around known positive HLB trees. The San Gabriel area infections in California were found after more intensive survey around an inconclusive psyllid sample. Analyses have also revealed significant space-time scales of pattern in the California psyllid data, such that inconclusive samples tend to cluster within 1.5 miles and 15 months of each other. A secondary cluster was found for inconclusive samples > 4.5 miles and > 3 years from the first detection in Hacienda Heights. These analyses may serve as early warning indicators for HLB positive trees, as well as informing dynamic spread models in development. A long period of data about the occurrence of HLB in commercial citrus farms located in São Paulo state, Brazil, was used to evaluate the disease progress and its management. Approximately 260 Sweet orange plots from five farms , naturally affected by HLB and under strict disease management , were evaluated considering the proportion of HLB-affected trees, occurrence of Diaphorina citri, plot location, and presence of neighboring commercial and non-commercial citrus plants. The logistic model better explained, than Gompertz, the yearly proportion of HLB-affected trees. The cumulative disease incidence varied from <4.0% to 80% and highly correlated with area under disease progress curve, independently of plant age, but not with the disease rate of progress . Adults of D. citri were poorly detected by shoot evaluation conducted 2 to 5 times/month in 1% of trees in each plot. In contrast, higher frequency of D. citri identified in yellow stick cards occurred in the most HLB-affected plots.

However, the majority of yellow cards presented no adults for most of the time. Spatial heterogeneity was observed for both HLB-tree incidence and D. citri detection . In all farms, a strong concentration of HLB-affected trees occurred in some plots located in their borders.In the majority of plots, especially those presenting higher disease incidences, >95% of HLB-trees occurred up to 200 meters from their borders. The disease incidence in each farm varied from 7.1% to 25.9%, though the similar disease management adopted for HLB . Recently, surveys around those farms have been started to identify neighboring citrus and Murraya sp. plants that could may act as HLB-sources of inoculum. Their location, represented by commercial and non-commercial citrus plants, strongly suggests that non-commercial trees are very effective sources of HLB, even when represented by a few plants. The Asian citrus psyllid Diaphorina citri Kuwayama is the insect vector of Candidatus Liberibacter asiaticus , the causative agent of the citrus greening disease. Understanding the interactions between the insect vector and the bacterial pathogen is essential for the development of efficient strategies aimed at limiting the spread of the infection and inhibition of bacterial growth. Furthermore, better knowledge of insect-pathogen interaction at the metabolite level will help develop in vitro culture of CLas, a much needed tool for studying its metabolism and designing means to combat it. In this study, we compared the primary metabolite and lipid profiles between CLasinfected and healthy psyllids using GC-TOF-MS and LC-TOF-MS, respectively. We found that both feeding on infected trees and the actual infection with CLas cause dramatic changes in monitored compounds’ accumulation. The results of metabolomic analyses and the possible implications for the pathogen-vector interactions will be presented and discussed. Huanglongbing is a devastating disease of citrus caused by the Candidatus Liberibacter asiaticus . The inability to sustainably culture and reinoculate Las into any host has prevented functional genomics and impeded research and development of disease control methods.

Phosphatidylcholine has recently been established as an important membrane component of those few bacterial species that associate with eukaryotic membranes, such as Legionella pneumophila, Agrobacterium tumefaciens and Rhizobium leguminosarum. For many of these species, PC is required for virulence. Las colonizes living citrus phloem cells, and infects psyllid hosts systemically, moving both intraand inter-cellularly, crossing through multiple membrane layers. We hypothesize that Las PC is similarly required for colonization of psyllids. Liberibacter crescens , the only cultured Liberibacter to date, is a useful and genetically tractable proxy for functional genomics of Las. It carries two predicted pathways for synthesis of PC: 1) import of exogenous choline and subsequent conversion of choline to PC utilizing phosphatidylcholine synthase , and 2) de novo synthesis of PC utilizing phospholipid N-methyltransferase . Notably, Las is missing the de novo pathway, and must import choline,flood and drain table which is abundantly present in psyllid hemolymph and phloem sap, to make PC. We created individual marker interruption mutations of both Pcs and Pmt in Lcr. Rescue of the Pmt mutant in Lcr required 0.1% choline supplementation in the medium. The standard culture medium for Lcr is BM7 which contains 6X10-6 % choline, an amount that appears to be insufficient for culturing Las. Other genes found in Lcr but not found in Las and that should significantly limit Las culturability are: glyoxylase I and the ATP/ADP translocase. Phage lytic cycle genes found in Las but missing from Lcr also likely significantly limit Las culturability. Despite the availability of multiple complete genomic DNA sequences of Candidatus Liberibacter asiaticus , inability to sustainably culture, manipulate or re-inoculate Las has seriously impeded the identification of virulence factors and subsequent development of disease control methods. Liberibacter crescens , is a culturable proxy for Las, but is not pathogenic. Given that the Las genome is even more reduced than Lcr and several Lcr genes are suspected of contributing to its culturability, one long term goal of our lab is to sequentially delete multiple Lcr genes not found in Las and to make its morphology and metabolism more comparable to Las, and make informed incremental adjustments in the growth medium to help compensate for the loss of the Lcr functions. To date, the best growth of Lcr has been obtained in the complex growth medium BM7, containing fetal bovine serum , ACES, α-ketoglutarate, and TNM-FH insect medium. We have found that replacing FBS with 1 mg/mL of methyl-β- cyclodextrin reduced growth, even though such replacement has been reported to improve culture of the fastidious pathogenicmicrobes Coxiella burnetii. In addition, both BSA and glucose, major components of FBS, inhibited growth of Lcr. Both MβCD and BSA are hypothesized to inhibit Lcr growth by sequestering fatty acids and other small hydrophobic molecules that are important to Lcr growth. Lcr growth was unaffected by the presence of cholesterol in the medium.

Replacing TNM-FH with Schneider’s insect medium resulted in removal of sucrose and marginally improved growth of Lcr. Eliminating sucrose from the culture medium allows use of conditionally lethal DNA cloning vectors such as pUFR080 carrying sacB that can be forcibly and reliably evicted by adding sucrose to growth media. Such a system is important to make sequential mutations. We report here that Lcr is able to import isotopic sucrose in a time- and dose-dependent manner, enabling use of the sacB eviction system. We have successfully created 2 marker interruption mutations in Lcr that make Lcr more Las-like and that will likely inform culture media components. Other genes found in Lcr but not found in Las and that should significantly limit Las culturability are: glyoxylase I; ATP/ADP translocase and the sucrose transporter. We are currently attempting a series of conditional knockout mutations involving a sacB vector with genes suspected of enabling Lcr growth in media, each time evaluating different rescue strategies to keep the resulting mutant strains alive. Fruit from trees with severe symptoms of Huanglongbing produce juice that is described as less sweet, more sour with some bitterness and harshness together with typical off-flavor in comparison with juice made with fruit from healthy trees. Commercial juice processing includes separation and recovery of peel oil from the fruit, which is then used in flavor manufacturing including add-back to orange juice to standardize flavor. To this date, there is no published data on the aroma quality of peel oil from fruit affected by HLB. Hamlin and Valencia fruit from healthy and HLB-infected trees were harvested in December 2013 and April 2014, respectively. Fruit were washed and juiced using a JBT industrial extractor. Peel was separated and the oil was expressed using several cycles of manual cold pressing followed with centrifugation. Peel oil was then analyzed by gas chromatography mass spectrometry and olfactometry , as well as presented to a trained taste panel for aroma differences. Juice from the same fruit were also presented to the trained taste panel for sensory descriptive analysis. For peel oil from Hamlin, 14 compounds had higher peaks by GC-MS in healthy samples, including 1-octanol which was perceived by GC-O. Further, three unidentified peaks with mint , citrus and pungent odors were perceived only in the oil from healthy fruit by GC-O. For Valencia oil, differences by GC-O were for peaks with odors of -cadinene and metallic which were only perceived in HLB samples. Other differences were for RI=955 , α-phellandrene , and terpinolene , which had higher intensities in Valencia healthy samples. Overall, those differences detected by GC-O were not translated to aroma differences between oil samples by a trained panel. The same trained panel found differences when tasting the juice of Hamlin, with HLB juice having more ‘typical HLB flavor’, ’bitter’, ‘metallic’, ‘tingling’ and ‘astringent’, likely due to differences in nonvolatile compounds. There were no difference between HLB and healthy samples for Valencia juice. Some new hybrid root stocks grafted with commercial citrus scion cultivars produce trees with reduced huanglongbing symptoms and higher fruit production over a period of many years, following infection by Candidatus Liberibacter asiaticus , as compared with trees on other common commercial root stocks in the same trials. In one replicated trial with ‘Valencia’ scion severely affected by HLB, highest yields over five consecutive harvests were with ‘US-942’ and ‘US-1516’ root stocks. Other components of tree health, including fruit quality, tree growth, and tree survival, differed greatly among the root stocks, and provided additional evidence of improved field tolerance to HLB for some root stocks.

Previous research had found that “supermarket flight” in fact traced back to the 1950s and 1960s, when retail suburbanized with housing and the grocery industry began a gradual process of consolidation to remain competitive . By the 1980s, Reagan-era deregulation relaxed previous corporate antitrust policies. This would encourage the trend towards larger, fewer supermarkets, each of which gained larger shares of grocery sales over time—an benefit to stockholders but not necessarily consumers . Between 1979 and 1989, 16 of the nation’s top 20 grocery retailers experienced mergers and leveraged buyouts, resulting in a complete reorganization of the grocery industry . Furthermore, between 1970 and 1990, half of the supermarkets in the three largest U.S. cities closed . The U.S. Mayor’s Conference report reinforced this findings emphasizing the implications for these industry wide changes on local communities and vouching for the creation of new policies to ‘end the redlining of urban America by the supermarket industry’ . As a result, the report drew a strong response from the national media, trade associations, grocery retailers, and the federal government. The news media featured the findings of the report as well as the beginnings of coordinated local responses by local entrepreneurs. Despite disputing the rhetoric of the report, the Food Marketing Institute created an Urban Initiatives Task Force designed to revitalize communities through the development of grocery stores and job creation.Regional retailers Lucky’s, Von’s,hydroponic growing system and Path mark Supermarket made new commitments to open stores in underserved areas mostly in the Pacific West and Northeast respectively .

The hearing featured statements from urban grocery experts, Ronald Cotterill and Mark Winne, residents of grocery-deficient communities, and notably, the work of the Monsignor William Lindor, executive director/founder of Newark’s New Community Corporation . A faith based CDC operating in Newark’s poor urban areas since 1968, NCC garnered widespread acclaim for its comprehensive scope of work including retail, housing, health centers, and social service programs initiatives for poor urban residents. Amongst its most notable achievements was its joint venture partnership with Path mark supermarket, among the first of larger supermarket chains to reenter urban areas by way of CDC partnerships. Together, these speakers highlighted several key trends among urban grocery stores that were beginning to be explored but had not yet been widely publicized. This included new evidence showing that poorer urban residents pay between 8 to 30% more for food each year than more affluent residents and spend an extra $400-$1000 per year to commute to supermarkets outside of their own communities due to limited vehicle ownership . Several ways forward were identified including: 1) more stringent corporate anti-trust policies that promote more competition within the grocery industry and Electronic Benefits Transfer systems ; 2) grocery shuttles for resident of low income communities ; 3) regulatory and tax incentives for urban grocery development ; 4) public private partnerships among entrepreneurs and community organizations ; and 5) municipal and federal policies to support the financing, development, and operations of new grocery stores, new funding streams to support inner city economic development . The hearing did not lead to immediate federal policy actions per se, but it generated political awareness of the visceral nature of disinvestment in poorer urban communities as exemplified by access to grocery stores. Additionally, it reinforced the critical role of CDCs as key drivers of economic development, even in spite of dwindling federal funding channels and limited organizational capacities for retail-oriented initiatives. Finally, while the hearing did not result in immediate federal policy actions around grocery stores, it would pave the way for a new era of federal revitalization policies advantageous to urban grocery development.

As such, the “urban grocery gap” was situated within broader discussions on how best to leverage the private sector, the burgeoning “community development industry” , and government to systemically address urban poverty and disinvestment. In line with the scope and intent of Clinton-era federal urban revitalization policies, scholars of business, economic development, and community planning looked to these CDC experiments as further confirmation of the need for modes of “inner city revitalization.” For example, Bendick and Egan argued for mutual integration of community development and business development to more systemically address the symptoms of urban poverty. Namely, community development activities can become a boon to business by expanding the pool of potential employees, improving service delivery, rehabilitating real estate. And yet, business alone may not impart the trickle down social impacts, which may be best provided in the form of community development activities including social services, housing rehabilitation, and workforce development. Ultimately, business that serves community goals and vice versa, may be more effective in revitalizing poor communities than one singular approach. Bendick and Egan’s view reflects a longstanding divide between social and economic goals in community development practice, despite integrated efforts through the Economic Opportunity Act of 1964 and subsequent practices by CDCs. And yet the gradual diminishing of funding for business-oriented activities by CDCs reflected the continued challenge to truly marry these largely disparate approaches to neighborhood revitalization. Bendick and Egan begin to suggest the business benefits brought on by community development, however pre-eminent business scholar, Michael Porter, perhaps made the most influential argument for business development in the “inner city.” In his seminal article, “The Competitive Advantage of the Inner City,” Porter argued that entitlements and social investments alone may not mitigate urban poverty. Rather, inner cities must create wealth in order to redistribute wealth through “private, for profit-initiatives and investments based on economic self-interest and competitive advantage” . Furthermore, contrary to perceptions, inner cities are poised for successful economic development given their locational benefits, untapped market demands, an available workforce, and potential for regional economic development.

In a follow-up piece, Porter highlighted CDC-supermarket partnerships as models of how “the private sector is already waking up to the potential of inner cities” and how “entrepreneurs are creating businesses that cater to the distinct needs of inner city consumers” . Critics have argued that Porter’s model oversimplifies the solution to urban poverty , understates the role of minority-owned and locally-owned businesses in economic revitalization , and discounts the role of government and community development corporations in encouraging private investment .Yet Porter has been credited for widening ongoing discussions about inner city revitalization to encompass the question of retail. Porter put forth his proposal amidst growing research on the magnitude of urban grocery and retail gaps and continued suburban retail expansion due to available land, lower development costs, looser zoning laws, and higher purchasing power . Still Porter elicited a strong response from grocery retailers in particular,mobile vertical grow tables who began reentering poorer under served communities in the early 1990s in part due to new federal incentive programs . Although federal programs specifically focused on grocery stores would emerge in the 2010s, the Clinton Administration initiated a string of federal urban revitalization programs that would provide preliminary solutions to the urban grocery gap. The first of these programs was Empowerment Zone program, which aimed to combine the economic incentive structure of the statewide Enterprise Zones with workforce development and social services. Administered by U.S. Department of Housing and Urban Development since 1993, the program provides competitive block grants to local governments for collaborative economic and workforce development activities. Food security was part of a national policy concern since 1930s and 1940s with the instatement of the first Food Stamp program and the National School Lunch Act of 1946 . Although the initial goals of the Food Stamp program was primarily focused on hunger alleviation, some argue that it was focused more on assisting farmers by purchasing food surpluses and feed the poor . The School Lunch Act was premised in improving childhood health, when almost half of potential draftees were rejected due to physical ailments traceable to malnutrition. Essentially, access to nutritious and healthy food was part of national security agendas—whether keeping the U.S. self-sufficient in terms of its food needs or as a way to ensure the health of future citizens. And yet by the 1960s, hunger became a central national policy issue with growing medical research and journalistic accounts of childhood hunger in poor urban communities.The Kennedy administration reinstated the Food Stamp Program, which was later expanded to include a School Breakfast Program and what is now known as Women, Infants, and Children . In cities across the U.S., anti-hunger movements proliferated against the backdrop of the civil rights, free speech, and anti-war movements. Between 1969 and 1970, the Office of Economic Opportunity funded the first anti-hunger voluntary associations, including the Food Research and Action Center, based in Washington D.C. . Amidst continued local advocacy around childhood malnutrition and hunger, in December 1969, Nixon initiated his own “war on hunger” at a White House conference on Food, Nutrition, and Health noting, “the moment is at hand to put an end to hunger in America itself. For all time” . For the decade that followed, federal food programs expanded its focus on cash subsidies and vouchers—all premised in a “medical model” of hunger and malnutrition . However, the anti-hunger movement would shift more broadly towards “food security,” with growing research and evidence of the connections between socioeconomic status and hunger. During the early years of Reagan administration, social assistance programs experienced significant reductions amidst an economic recession . As a result, existing emergency food providers reported an abrupt rise in the use of their services by ‘the new poor,’ suddenly under-resourced children, youth, and families . Evaluations of food assistance recipients at the time further confirmed that the risk of hunger multiplied with increasing poverty and reduced food assistance benefits .

Amidst this crisis, the Reagan administration looked to private sector food banks, food pantries, and soup kitchens to meet increasing food demands. These circumstances elicited a strong response from anti-hunger, anti-poverty, and social justice activists who began promoting “community food security” policies in the late 1980s and 1990s. The culmination of these early efforts was the Community Food Security Coalition, a national network of activists promoting new provisions in the 1995 U.S. Farm Bill ensuring community food security: that ‘all persons obtaining at all times a cultural acceptable, nutritionally adequate diet through local non-emergency sources.” The proposed 1995 Community Food Security Empowerment Act called for reductions in traditional food assistance programs and instead the creation of a new competitive grants program for community food projects35 in low income, under served communities. Already prior to the Community Food Security Act, the U.S. had a long history of community-based and local government community garden programs , counterculture food movements involving food buying clubs and cooperatives , and community-driven food assistance programs . However, the Act was distinct in its focus integrating social equity, economic justice, environmental sustainability through community-based means . As of 1996, the Act was included in the Farm Bill, authorizing the USDA Community Food Projects Competitive Grants Program, which allocates $16 million over the course of seven years with guidance from the Community Food Security Coalition. Through a competitive application process, the USDA administers one to three-year matching grants ranging from $10,000-300,000. The community food security movement distinguished itself from the anti-hunger movement by focusing on community food needs through community food planning, direct marketing, community gardening, food assistance, farmland protection, food retail strategies, and associated community and economic development . Domestically, this initial scholarship inspired hundreds of ‘food desert’ studies since 2000, ranging from academic studies, government-sponsored assessments, health assessments, and GIS analyses . These studies tend to use different definitions of what food deserts are and entail- some tend to define food deserts in terms of the number of grocery stores or lack thereof, while others focus on the type of quality of foods . The most widely cited early study on food deserts emphasized the connections between food access, wealth, and racial make-up of neighborhoods, noting that supermarkets abound in higher income areas while convenience and fast food stores dominate in low-income areas . Subsequent studies found similar trends regarding the distribution of stores and their impacts: poorer residents tend to pay 3-37% more for food items at small stores compared to residents shopping at suburban supermarkets and available food is often processed and of poor quality . Residents living in areas without a grocery store or supermarket tend to be of ethnic minority groups and with higher rates of obesity, diabetes, and diet-related diseases . In light of these findings, researchers continued to suggest that increase access to supermarkets might lower prevalence of obesity, improved fruit and vegetable consumption, and better diet quality among African Americans, low income households, and pregnant women .

The availability of BC as a secondary product of bio-energy production and/or waste stream management , as well as lower transportation costs made possible by regional or on-site BC production, could further leverage economic advantages over peat and peat alternatives . Recent studies support the unique ability of BC to mediate biological interactions with benefits for greenhouse production such as enhanced pathogen and pest suppression. For example, 1–5% additions of citrus wood BC to peat-based substrates increased expression of pathogen defense genes in strawberry and as a result suppressed fungal disease ; for tomato and pepper , such additions delayed and reduced disease from fungal pathogens and mites . However, lower susceptibility of plants to pathogens in soil-free substrates with a BC component may be muted by fertilization , and therefore may not be possible under intensive greenhouse production. On the other hand, substrates with a high proportion of BC such as in this study could have detrimental effects on biological processes that support plant productivity , largely due to interference of chemical signals between beneficial microorganisms and host plants . As a result, BC could lessen establishment of rhizobial and mychorrizal associations and reduce nodulation in leguminous species . Strong sorption by BC could afford horticultural advantages, however. For example, bulbet organogenesis of grape hyacinth was enhanced with the use of BC-like material in substrates due to its sorption of inhibitory compounds . Potential plant health benefits of BC-based substrates are relatively under-investigated in evaluations of peat alternatives, despite one of the main uses of soil-free substrates being the avoidance of plant exposure to pathogens . Finally, the ability to replace peat with BC offers potential economic and environmental benefits. The expense of peat is expected to increase in the coming decades due to production costs, competing uses for peat, and its perception as being unsustainable . Such a perception in part stems from the negative impacts on wetland ecosystems of some peat mining operations , though the sustainability of peat harvesting is a subject of debate . Peat mining operations and the eventual decomposition of peat after its use in substrates represents a transformation of a terrestrial C sink of global importance into a net C source, with climate change forcing effects . Assuming a conservative aerobic decomposition rate for peat in substrates of 5% per annum ,vertical hydroponics within one century of mining and use in soil-free substrates 95% of mined peat would be expected to revert from a C sink to source .

In contrast, high-temperature BCs are thought to generally exhibit lower decomposition rates than undecomposed or humified biomass such as compost and peat and exhibit centennial to millennial residence times . The molar O:C = 0.36 for the BC in this study corresponds to a half-life of 100–1000 years , suggesting that one century after production and use in soil-free substrates, at least 50% of C in the softwood BC in this study would be converted to CO2. The use of non-peat biomass or even waste in the form of BC in soil-free substrates is an additional strategy for ‘sustainable bio-char to mitigate global climate change’ due to its greater stability and ability to preserve a key global C sink.In landscape, we form meaning through placefulness; ‘‘place’ places man in that dimension which reveals the revealing meaning of being’. Gardens imply a more accelerated and amplified rendition of this process, while the gardens that we personally make and dwell in further magnify this condition. The garden is in effect the most permanent communion we can make with a piece of the world, whether that patch is on traditional earth or elevated in an artificially constructed environment. Those who have been faced with moving from somewhere they have resided for a long time may confer that vacating the house is one issue, but leaving the associated garden is an altogether more fraught separation. The most fundamental biological fact that plants are rooted and sedentary—while we are not—is laid bare during this process. Accordingly, John Brinkerh off Jackson defines the landscape of place as ‘a space on the surface of the earth … with a degree of permanence’.Nonetheless, we are also remarkably adept and manufacturing meaning on the run. There are countless accounts of how travelers, explorers and refugees have rearranged their immediate surroundings to assemble meaning from the background void. Furthermore, this phenomenon is not restricted to those who move long distances by choice of profession or byproduct of circumstance, since modern urban dwellers also possess this capacity. As Ian Nairn notes, ‘people need to put down roots in a terribly short time’, himself taking ‘about forty-eight hours’. Nairn concludes that movement paradoxically amplifies the sense of place, observing that ports—while being highly fluid—are nevertheless very well defined places. The gardens in a garden show can be considered within this context. Such exhibits are not gardens with which the visitor grows and coinhabits with its meaning, but rather passes through en mass in a matter of minutes.

And not long after they are experienced, the gardens are either wholly deleted or at the very least downgraded to mere residual features in the landscape-park that typically inherits the site once the spectacle of the expo has concluded. Under these circumstances meaning is absorbed and place manufactured on the run. To apply a vegetal analogy, this is less a process of terrestrial rootedness than the ‘continuous-flow solution culture’ associated with hydroponics. This interplay between rootedness and mobility in the place making and meaning-construction of the individual in the garden prefigures a society-scale condition found within Modernity as a whole. That is, the tension between the rapidity of globalism and the romantic yeaning to resist-and-return as Paul Ricoeur describes: ‘how to become modern and return to the sources, how to revive an old dormant civilization and take part in a universal civilization’. While visible in the landscape generally, the tension of this ‘paradox of place’ is manifest most acutely in the garden. The ‘sense’ or ‘spirit of place’ is both a manifestation of this paradox and an attempt to resist or realign it.In the midst of a fast-tracked industrial-to-consumption revolution, this tension is patently visible in the rapidly urbanizing cultural landscape of China. Framed by these dialectics of transience versus groundedness and tradition versus modernity, I focus in this essay on a particular example of a phenomenon that has persevered throughout the West’s Modernity and has found new vigor in China’s; that of the garden show or horticultural exposition. Both an expression of the yearning for otherness within the totalizing fabric of Modernity and a product of the very global reach of Modernity, international garden shows are increasingly commandeered into the mega-events that are used to influence the fortunes of cities. Typically, in the vein of the World’s Fairs and indeed Olympic Games , installments of the World Horticultural Exposition have fulfilled this transformative role, involving themed extravaganzas underpinned by massive quantities of construction far beyond that which is required for the simple promulgation of horticulture. Positioned at the northeastern periphery of the ancient capital, the 2011 Xi’an International Horticultural Exposition continues this bootstrapping city-building logic by leveraging the adjacent development of alluvial farmland and traditional villages into a regional financial centre.

The site preparation for the Expo involved remodeling a clay quarry into a simulacrum of the ancient Guangyun Lake, which was once an important port on the Chan-Ba River. Reinterpreted as a constellation of lined lakes interconnected with weirs,hydroponic vertical farming systems the shorelines inform the necklace structure of the exhibits . While most displays represented other provinces and countries, two areas moved beyond kitsch regional simulacra; the first being the collection of gardens by selected ‘Masters’ of landscape architecture, and the second a collection of University gardens by invited international academic teams. To investigate the state-of-the-art of current garden expo design, I explore these two collections of gardens with several objectives: to position the gardens in relation to contemporary landscape architecture design paradigms; to examine the role of the frame in the contained context of the expo garden with the implicit hypothesis that these tactics have agency in the wider contemporary metropolis; to understand why one set of gardens appeared to function as intended within the Expo, while the other appeared to be dysfunctional; and to create a record of Expo Gardens themselves, since despite pretences of being ‘permanent’ installations, it is highly unlikely that any of the gardens will survive physically or semiotically intact beyond the short extravagance of the Expo event.In the first part of the essay I describe, interpret and theoretically and poetically position a number of exhibits from both the Masters and University collections. In the second part of the essay I explore the issue of framing that so vividly distinguishes the Masters’ from the University Gardens. I develop the argument that dissolving the frame—while relevant in contemporary landscape praxis—does not necessarily translate into the context of individual gardens; rather it is the boundary between the Expo and the city that is the most potent threshold. Extending this argument to the city itself, I conclude the essay with discussion regarding the fate of the horticultural expo and its devolution into the urban fabric. In terms of methodology, I draw on my involvement with the Expo from several perspectives; participation in the design workshop for the University Gardens; observations on site during the construction process; and my experiences at the opened Expo as a member of the public.In regards the latter, when on site I was sensitive to Bernard St-Denis’s critique of the tendency for contemporary garden scholarship to place semantic interpretation over ‘the gratification of spending time in a garden’.To be sure, whereas St-Denis was undoubtedly referring primarily to established gardens, the transient nature of the Horticultural Expo gardens tested this challenge to its practical limits. I made repeat visits to the gardens and loitered insofar as was practical, but never attained a contemplative communion with any one garden. However, the impracticality of experiencing ‘time in a garden’ in the Expo context was offset by the heightened experience of the ‘first encounter-reality’ of the perception that results from the initial visit to each garden. Far from being superficial, first impressions are a potent mechanism in our ongoing formation of a sense of place. They are also rarely isolated as purely experiential events; as Donald Apple yard notes, ‘prior indirect information supplied through social contacts or media are also influential’. Like over-the-horizon radar that allows us to cognitively image un-experienced places, these preconceptions are legitimate component of the construction of an environmental image.In addition to my own experiences—keenly honed but biased as a gardenphile and designer of gardens—I also observed the behavioral tendencies of Chinese visitors in each garden. When visiting other more thematic representative gardens of local provinces, it was clear that on the whole the Chinese knew how to act in each garden, and seemed to be far more in tune with the living cultural narrative of garden history than Westerners in equivalent situations in the West, who as Robert Riley intimated, have lost connectivity with and hence knowledge of what to do in a garden.That said, although the gardens in question are located in China, an apparent deficiency of this essay may appear as a lack of attention to traditional Chinese garden landscape themes and narratives. This is perhaps partially a consequence of my limited command of this material, but most importantly it is a product of the Expo being very much a condition of modern China. Indeed, the modern history of the botanic garden / horticultural expo in China is transplanted from the West rather than emerging from Daoism or Confucianism.That Westerners designed all but one of the Masters Gardens and the majority of University Gardens, but that virtually all Expo visitors were domestic in origin, illuminates this complex condition.In raw form, the 10 000 sq ft plots allocated to each designer are typically flat in profile and trapezial in plan, buffered by thick stands of bamboo with controlled access on two sides. These manufactured site circumstances present a strong case for utilizing the timeless phenomenology of the walled garden as an other world decisively withdrawn from the surrounding landscape.

Geochemical characteristics have an important influence on HM plant uptake. Future investigations can focus on the interactions between trace elements or other factors that may demonstrate an influence on HM plant uptake. Forage and water intake are important considerations in livestock, and soil ingestion must also be considered. In the current examination, the soil samples showed greater HM concentration than sheep tissue and forage samples. It has been demonstrated that sheep, a ground feeding animal, eat one to two percent of soil when good forage is available and about 18% when low quality forage is available. It has been shown that sheep intake and digestibility of more mature plant material decreases with advancing maturity due to greater effort and time in chewing by the animal; sheep selectively graze in high-quality forage areas when they are available. The forage environment of the sheep in the current study area exhibited high stocking rates, sparse vegetation, and mature forage samples, which may have contributed to higher HM concentrations in forage. Dung analysis can evaluate the amount of inorganic material in sheep diets and may be useful in future studies in the current study area. Previous studies have reported the concentrations of HMs in sheep tissues, plants, and soil in the target study area . In most categories, our study results were comparable to or less than what was previously found. The current study tissue measurements were below the exposure and control concentrations reported by Millard et al. and Ruttenber et al. in the 1980s. No excess cancer risk was calculated to be attributed to eating sheep meat, liver, kidney, and soup bone by humans; researchers recommended continued monitoring at that time. The highest HM metal concentration in the diet was used for each animal to calculate and compare to the maximum tolerable concentrations, and the lowest concentration for each HM was used to compare to the requirements for Mo and Se. The calculations are based only on the forage samples collected and are not representative of the complete sheep intake. Maximum tolerable concentrations are established for sheep intake for As Cd, Pb, Mo, and Se. All study animals did not exceed the calculated maximum tolerable concentrations for As, Cd, Mo, and Pb.

All study sheep met the Mo and Se dietary requirements. Liver is the organ of choice to diagnose Se deficiency,vertical garden indoor and concentrations less than 0.21 mg/kg in sheep liver are considered deficient. All study sheep liver concentrations did not indicate deficiency. In sheep, Se toxicity was reported at 0.25 mg/kg of body weight chronically. However, the National Research Council set the maximum tolerable concentrations for Se at 5.0 mg/kg of DM. Of the donated sheep, the shepherds did not report indicators of acute or chronic Se poisoning . Other supplementary sources of forage were not reported at the time of sampling; sheep harvesters reported relying on alternative fodder sources for their sheep in the late winter months only . New Mexico is one state that was reported to have high Se concentrations in soils and those in areas with low annual rainfall or alkaline soil. The mean study soil pH was 7.31 ± 0.51. Primarily, most of the Se is absorbed in the small intestines of ruminants and less absorption is seen in forage based diets versus diets based on concentrate. Plants that accumulate Se may be unpalatable to grazing animals, but if there is lack of more palatable forage, animals may develop signs of toxicity from ingestion. According to one study calculation, selenosis can occur in lambs ingesting 0.2% BW of Se accumulating plants. Soil ingestion during foraging, seasonal soil forage adhesion , pulling up of roots while foraging, and licking snouts by livestock may also contribute to higher HM concentrations. The forage plants that we sampled were not known Se obligate or secondary accumulator plants. Aside from Se, whether study plants accumulate Mo and Cd needs further evaluation. Selenosis diagnosis is primarily based on Se measurements , anemia and the presence of physical examination findings identifying toxic levels. Selenium concentrations in the liver and kidneys were not elevated on a DM basis. One source reported that plant forage containing >3–5 mg/kg induced toxicity in sheep. In our study, several plant roots exceeded 3 mg/kg, which is a concern with the pulling up of roots when sheep forage. The amount of root consumption in relation to the total sheep forage intake is important to determine. Further work examining these factors is an area of future research. Based on drinking water standards for livestock, none of the heavy metal concentrations were above maximum tolerable concentrations. Heavy metal water measurements collected by the DiNEH study from two of the water sources identified for Sheep 3 contained lower concentrations of Pb in comparison to our data ; the remaining HM data were less than what the DiNEH researchers found.

Most of the shepherds obtained public water for sheep consumption, which was reflected in the concentration levels found in sheep water. Harvesters in the study reported a history of consuming unregulated water intended for livestock. However, the As, Cd, Pb, Se, and U concentrations did not exceed the maximum contaminant levels set for human consumption. The implementation of water use maps may have contributed to the use of safer alternative water sources for these shepherds. Continued emphasis on the use of safe alternatives for water use in sheep and human consumption put forth by deLemos et al. is essential. Harvested food selling and sharing was common among the participants in the study. Emphasis should be placed on determining the incidence and frequency of food selling and sharing when assessing food chain contamination. Harvesting locations and activities can overlap in mining impacted areas. A few important factors to consider include the availability of harvest items based on seasonal variation and peak consumption periods . It is important to consider the consumption of contaminated food not only by individuals and their families but potentially the whole community and beyond. Studies identified mutton as a core food staple, comprising 6% of the total energy and 10% of the total protein consumed in the Diné diet. The current study participants reported that 35% of their total protein meat intake is comprised by local O. aries. The mean intake of local sheep protein was reported to be one day per week. In the study community, the typical serving size per foodstuff is reported to be 76.54 g of sheep muscle protein, roasted or boiled whole liver 377.5 g, roasted one whole kidney 76 g, and roasted or boiled lung 111.5 g. Using the typical serving size for each food stuff, we used the maximum HM concentration for each food item to calculate the weekly intake of HM from the current diet of the study population. The calculations for Mo and Se are based on the information provided by harvesters and are reflective of the sheep meat average consumption of one day per week. The Recommended Dietary Allowance for Mo was exceeded by more than a factor of 2 but, but the tolerable upper intake limit was not exceeded. The liver alone exceeded the Mo RDA by a factor of 1.8. By our estimates, an individual would have to consume half of the typical serving size to meet the RDA. The Mo levels in all sheep food products consumed comprised of 4.6% of the UL. The Se Reference Dietary Intake for adult males and females is 55 µg per day, and the Tolerable Upper Intake level is set at 400 µg/day. For all sheep products,vertical garden indoor system the harvesters exceeded the Se RDI by more than a factor of seven and were slightly below the tolerable upper intake level of 400 µg/day.

The liver protein intake alone comprised 80% of the tolerable upper limit of Se. Hypothetically, if one consumes liver protein more than once a week in the current scenario, the Se UL will be exceeded. The reported values only take into account the levels representative of sheep protein intake evaluated in this study and exclude non-subsistence and other dietary sources. In summary, in this U mining impacted area, our calculations indicate that the Se levels found in locally harvested sheep exceeded the RDI significantly but were marginally below the established daily tolerable upper intake level. Similarly, the RDA for Mo was exceeded, while the Mo UL was not exceeded. Consuming liver once a week has exhibited exceedances in Se RDI and Mo RDA, and it is anticipated that eating more than one serving size of liver per week would cause one to exceed the Se UL. Diversification of the overall dietary intake or minimizing the intake of high HM content foods are recommended until further research can be done. Our study was comprised of adults only; therefore, our calculations are based exclusively on adult food intake. Recommendations based on tailored research are needed for those that are more sensitive to HM exposure such as children, the elderly, pregnant women, or those with at risk health conditions. There is no dietary intake guideline for the remaining HM examined in this study.The results of this study need to be generalized with caution as the sheep sample sizes were small. Further, the sheep samples were collected from two communities that were near in distance. Still, geographical dissimilarities were apparent between the two communities. Plant heavy metal contamination levels evaluated both surface contamination and plant uptake. As this was a food chain study, we strived to examine the HM concentrations available to the primary meat staple. Comparable differences in HM levels were found in controlled and field studies utilizing unwashed plant samples. Over 30 years ago branched β-1→3-glucans and the EP – AA and EPA – were characterized as potent oomycete elicitors of innate immune responses in plants. These and the Phytophthora elicitin proteins with activities in a somewhat narrower host range figured prominently in the literature in subsequent years, and were used to examine physiological, biochemical and molecular events associated with the HR and induced resistance. Intriguing is that β-glucans and EP are important in modulating innate immunity and inflammation in animals, although these cross-kingdom parallels are likely not fully appreciated by the plant and animal research communities. Oomycetes are among the most important plant pathogens, responsible for devastating plant diseases worldwide.

New Phytophthora species, in particular, are continually being discovered, with the number of species identified nearly double that of only a decade ago . Downy mildew pathogens and the diseases they cause are also current threats to U.S. and world agriculture, with two listed as Select Agents as serious threats to U.S. agriculture . The Phytophthora research community is attuned to the need and urgency to develop novel control strategies that are broadly applicable yet sustainable, with vigorous research programs studying population genetics, genomics, effector biology, host resistance, and disease epidemiology and management. Within this research portfolio, determining how β-glucans and EP are perceived and act in plants could be useful for enhancing disease resistance against oomycetes and possibly other attackers. In this review, we highlight early studies of β-1→3- glucans and EP, discuss their roles as evolutionarily conserved signals, and consider their action in relation to current models of MAMP1-triggered immunity.Arachidonic acid and eicosapentaenoic acid are 20-carbon, all-cis PUFAs containing four and five double bonds, respectively . In mammals, AA and EPA undergo enzymatic oxidation to oxylipins, referred to as eicosanoids, which serve crucial signaling functions in stress responses . Examples of these eicosanoids include prostaglandins and thromboxanes, formed via the action of cyclooxygenases, and leukotrienes, formed via the action of LOXs. Eicosanoid-mediated stress responses include pain, inflammation and fever , platelet aggregation and vasoconstriction , and allergic responses and asthma . Although higher plants do not contain AA and EPA, AA and EPA are found in oomycete pathogens and plants are exposed to these fatty acids during infection . Many molecules of microbial pathogens identified as elicitors in earlier studies have been reclassified as MAMPS to conform to terminology used in animal immunity. MAMPs are motifs in essential molecules such as proteins, lipids, and polysaccharides that are present in entire classes of microbes . These molecular motifs are generally absent from hosts and can be recognized by plants and animals, such as in response to attempted infection or colonization.

Evergreen is premised on harnessing procurement flows from anchor institutions, but this approach relies on the enlightened leadership of the anchors – most of which are private institutions and not subject to any public procurement policy, were it to be instated. Fortunately anchor leaders in Cleveland support the plan to direct procurement flows towards community economic development: as well as their contract with Evergreen, they participate in a Community Benefits Agreement recently spearheaded by the City to promote local and diverse hiring in Cleveland construction projects . Civic and anchor leaders are committed to community wealth building, but nurturing this support has been an ongoing process for representatives from the Cleveland Foundation and the Democracy Collaborative. In spite of these alliances,capturing procurement flows has been a significant challenge for Evergreen. For example, until recently, Evergreen Laundry did not have a single contract with an anchor in Greater University Circle.The anchor institutions are generally locked into long-term million dollar contracts with their laundry services. Evergreen plans to forward bids when contracts end, as was done with University Hospitals, but in the meantime has focused its efforts on nursing homes and hotels. “We still have a long way to go in terms of really capturing anchor supply chains,” said Howard during our interview . The City of Cleveland has been supportive of Evergreen but has not yet directed procurement flows its way. The City’s charter requires competitive bidding for its contracts, with economic performance as the primary determinant for a successful bid. Recent efforts, however, have sought to heighten purchasing flexibility to support broader policy goals. For example, a 2010 ordinance gives a slight bidding advantage to local firms and to companies certified for their use of green business practices, such as reducing waste and energy consumption .

Bidding advantages also exist for firms certified as a small business or as a female-owned or minority-owned enterprise. Rules to facilitate competitive bidding are meant to forestall cronyism,vertical rack but they can also be a barrier to social impact procurement efforts. Policy innovations that enable public bodies to responsibly direct purchasing power towards community wealth building would accelerate co-operative growth. Experiments by the City of Cleveland are promising in this regard, and may become important policy supports for Evergreen’s growth.Evergreen has benefitted from ad-hoc and private versions of co-op recognition, financing, infrastructure support, and preferential procurement. More regularized public support in all six policy areas would have made Evergreen’s founding less dependent on contingencies and heroism and would smooth the way for replications in other regions. Co-operative policy in the US is underdeveloped, especially compared to the co-op dense regions. The US Department of Agriculture does offer grants to rural cooperatives for technical assistance and product development . A similar program focused on urban co-operatives would have been a helpful funding source for Evergreen. The Cleveland Model was enabled by robust foundation support and champions in local government. There is evidence suggesting that in this period of contested neoliberalism similar alliances might be possible elsewhere. In 2014, local governments in New York City and Madison, Wisconsin approved initiatives aimed at financing the development of worker co-ops .These local measures offer co-operative recognition, financing, and technical assistance. At the state level, California has passed a bill that establishes a legal form for worker co-operatives . The bill offers official recognition by explaining the purpose and benefits of worker co-operatives, and allows worker co-operatives to create voluntary indivisible reserve accounts . According to Sushil Jacob of the Tuttle Law Group, who helped craft the legislation, the long-term goal is to get tax credits for monies invested in indivisible reserve funds, as is done in Italy . Finally, the legislation allows worker co-operatives to raise capital from “community investors,” a new legal category of investor; worker cooperatives can raise up to $1,000 per investor, without registering these investments with the state securities regulator . Federally, the National Co-operative Business Association is spearheading an effort to pass legislation that would create a program within the US Department of Housing and Urban Development to provide capital and technical assistance to cooperatives. This program would be a much-expanded version of the USDA’s rural cooperative development program; it would help with financing, not just technical support, and urban co-operatives would be eligible.

The bill has been introduced twice but has not yet made it out of the House of Representatives . This would be a breakthrough piece of legislation; it would greatly facilitate co-operative growth in the United States. Mondragon, and the robust co-op sectors in Quebec and Emilia Romagna, have all benefitted from supportive policy. But a crucial point that became apparent during our literature review is that strong co-op sectors in these regions all preceded the policy breakthroughs that enabled further sectoral growth. Adeler writes: “In the Spanish, Italian, and Quebec examples, co-operative development was pursued by federations of cooperatives, and co-operative groups or alliances, initially with little or no state support, yet proved highly successful in producing an enabling environment for co-operative development” . Policy change played an important role in facilitating sectoral growth, but a robust sector was needed to win and keep these legislative victories in the first place. This finding is aligned with the social movement approach to co-operative development. According to Diamantopoulos , “Co-operative development may benefit from supportive public policy and sound management but it necessarily depends on concerted movement action to transform the field, periodically realigning movement frames and resources to effectively focus on new opportunities and drive new campaigns.” The political muscle needed to pass co-op-supporting legislation first requires a more robust national sector. Local policy change can precede vibrant co-op movements, but movement building will be needed to win the state and national legislation required to scale-up the co-operative economy. The Next System Project is hopeful in this regard. While still a young initiative, it is beginning to assemble the popular power required to push legislative and systemic changes that can facilitate the scaling up of the worker-cooperative alternative that Evergreen represents.Populations of a species are frequently distributed across climatic gradients, where natural selection can lead to adaptation to local conditions. The environmental conditions that cause local adaptation have been well documented through reciprocal transplants and studies of clines. These experiments show that divergent patterns of selection cause shifts in the mean values of many traits leading to a multivariate response. Such a response to selection improves fitness and promotes successful adaptation to local conditions. Despite a large body of research, it remains a challenge to determine the specific genetic loci that respond to selection and confer local adaptation. Long-term breeding programmes and quantitative genetic studies have demonstrated variation in nearly all traits, and thus a simple lack of additive genetic variation is not expected to constrain adaptation. Instead, a limited amount of genetic variation along vectors of selection has been shown to limit adaptive evolution. Theoretically, independence of all loci and phenotypes will improve the potential for adaptation by optimizing evolvability and the response to selection.

However, certain genetic correlations can disrupt the optimal genetic architecture by reducing the amount of genetic variation which is available to selection and causing correlated responses ofnon-adaptive traits. Although this maladaptive role for genetic correlations is not universal, genetic correlations may affect R by limiting the dimensionality of the genetic variance matrix or restricting genetic variation to vectors which are not aligned with selection. The combined effects of the pleiotropic loci,vertical farming hydroponic which cause genetic correlations, may have a profound impact on patterns of local adaptation. As pleiotropy can constrain multivariate adaptation and cause correlated evolution of adaptive and deleterious phenotypic values, these loci are typically considered ‘antagonistic’. Adaptation is especially constrained when pleiotropic gene action limits phenotypic correlations along a vector orthogonal to that of selection and reduces R. Antagonistic pleiotropy is well documented and has led to the belief that all pleiotropy is maladaptive. However, recent theoretical work has countered this viewpoint by demonstrating that intermediate levels of pleiotropy may actually improve the conditions for adaptation and evolution of complexity. To study the adaptive value of pleiotropic loci, it is necessary to assess the effects of genetic variation on the structure of many phenotypes which are subject to correlational selection in nature. Adaptation to drought in plants provides an ideal system to achieve this goal. In natural and agricultural systems, annual plants can be adapted to local drought conditions by either growing and reproducing before the onset of drought or by delaying reproduction, increasing water use efficiency and conserving resources. For example, accessions which exhibit early-flowering time and low WUE were selected for in consistently wet soil and late-season drought conditions, whereas direct selection on increased WUE favoured a dehydration avoidance strategy in environments with early season drought. Therefore, adaptation to different local soil moisture conditions and seasonal rainfall patterns contributes to the observed strong correlations between FT, growth rate and WUE within and among species. Several studies have suggested that pleiotropy may also affect this correlation. Here, we provide empirical evidence for an adaptive role of pleiotropy. Using genome-wide approaches, allelic variants and transgenic manipulation, we demonstrate that the ‘FT’ gene, FRIGIDA pleiotropically affects phenotypic variation in growth rate, WUE and FT. Derived, null FRI alleles produce a drought escape phenotype relative to the ancestral adaptive strategy. This phenomenon, which we term ‘adaptive pleiotropy’, enhances the likelihood of adaptation by increasing adaptive responses to selection.Population genetic models are at odds about the role of pleiotropy in maintaining variation within and among populations. Pleiotropic gene action may cause non-adaptive and adaptive phenotypes to covary, thus reducing the efficacy of correlational selection and permitting the persistence of multiple allelic states within populations. However, where the effects of pleiotropy are more aligned with the direction of selection, within-population variation can be purged by strong directional selection. Therefore, we predicted low levels of within-population variation at FRI, because multivariate selection would favour either a functional or non-functional allele . In addition, if variation at FRI can lead to local adaptation, then we predicted increased population structure between functional and non-functional FRI classes. A population genetic test for adaptive pleiotropy is complicated in our study as FRI may cause population structure through both adaptive pleiotropy and allochrony: FRI-NILs and tr-FRI lines flowered at least 28 and 32 days later than Col-0, respectively. All main-raceme Col-0 flowers had been pollinated and produced fruits before any FRI-NIL or tr-FRI lines produced open flowers. In the greenhouse environment, single mutations at FRI can produce a reproductive isolation index near 1.0. However, assortative mating owing to variation at FRI may be tempered in nature as the environment has a profound effect on phenology.To test for evidence of reproductive isolation between accessions and populations that differ at FRI, we first imputed FRI functionality of 1188 accessions, then compared the group of individuals with derived, weak alleles to the group of individuals with functional, ancestral-type FRI. We then calculated FST between FRI allele functional classes in PLINK. FST values averaged across 216 130 SNPs are significantly greater between the FRI functionality classes than is expected from genomewide sub-sampling . To control for geographical population structure, we divided the global sample into 11 geographical regions according to Horton et al.. Ten of 11 geographical regions showed elevated FST at FRI compared with a genome-wide sample of sites with the same allele frequencies as the FRI functional variants . These results show that elevated global FST when sorting by FRI is due to a lack of within-population variation in FRI. Less than 2 per cent of 574 local populations harboured functional variants at FRI. While extremely low within-population variation is present at FRI, functionally divergent alleles have gone to fixation in geographically proximate populations. Several authors have shown that an abundance of derived null FRI alleles are present in nature, far more than would be expected by chance. Here, we demonstrate that these mutations cause a phenotypic leap between drought adaptation strategies which may promote adaptation to novel ecological conditions. Combined, the strong signature of selection, high levels of population structure and lack of within-population variation observed at FRI suggests an adaptive role of this pleiotropy.Previous studies have found that the early flowering, low WUE phenotypes associated with drought escape are adaptive in sites without consistent low soil moisture.

This study will focus on Settler Colonial Theory , a newly delineated branch of Postcolonial studies. SCT is at its core aligned with the basic tenets of postcolonial theory, and takes as its point of departure the fact that, as famously stated by Patrick Wolfe, “settler colonization [is] a structure rather than event” . A settler colony entails the permanent settlement of a group of people, who appropriate land and have at least some degree of local governance based on a shared ideology, often informed by religion and/or ethnic or national identity. Land ownership is of paramount concern. In contrast, a franchise colony is one centered around resource extraction, where government administrators generally are not permanent residents; usually, they establish an administrative class of Indigenous peoples, such as the colony the British imposed in India. These aspects sometimes overlap, but the key factor is that settler colonialism rarely ends, that is, the United Kingdom , the United States, Israel, and Australia, were and still are settler colonizer countries. SCT is further defined by foundational theorist Patrick Wolfe as having the following essential characteristics: it is premised on the idea that the land to be settled is empty, or “terra nullius,” and ready for colonization, despite the fact that this perceived “natural” land was actually developed by Indigenous peoples . The logic of elimination of the Native is crucial in the settler colony as opposed to franchise colonies, and it is to be achieved through a variety of means, including by enslavement, removal from land, and assimilation. Further, Wolfe shows through a comparative study of settler colonies, including the US and Australia, that processes of racialization of non Europeans are paramount in settler colonization, and vary based on the needs of those Europeans who administer a particular area. Also important to this study is the way that European settler colonizers espoused “manifest destiny,” or the idea that God meant them to expand Westward from Europe, not only to the Americas but beyond, and to dominate “inferior races.” We can see manifest destiny and the idea that Europeans are superior as an underlying ideology behind globalization. But for Wolfe,vertical gardening in greenhouse manifest destiny is not the end of racialization but accounts for the continuing unequal distribution of global power: he demonstrates that post-frontier and post-emancipation societies intensify racialization because settlers must rationalize inequality when slavery and the “outside” of the frontier no longer delineate racial boundaries.

Racialization is thus a colonial and a postcolonial process. Wolfe also highlights the ways that all “modalities of settler colonialism … come back to the issue of land” . That is, the settler deploys various ways of elimination and assimilation — forced labor, forced removals, homicide, parceling community land into family holdings, miscegenation, religious conversion, boarding schools, and so forth — to take land from Indigenous peoples. Land is a central issue for colonizer and colonized alike. To the settler colonizer, land is viewed primarily as a resource for profit and expansion/perpetuation of European society. By contrast, for Indigenous peoples, especially in North America, land is of paramount importance as the spiritual home of peoples. Cajete explains the “spirit of place,” defined as the “ecological relationship borne of intimate familiarity with the homeland, and the homeland became an extension of the ‘great holy’ in perceptions, heart, mind, and soul of the people.” Cajete goes on to cement this relationship in terms of loss of land during colonization: “It is easy to understand why Indigenous people around the world lamented the loss of their land for it was a loss of part of themselves” . For Cajete and others, land is part of the way Indigenous peoples perceive the world, a central aspect of their epistemologies; because this importance is reflected in decolonized conceptualizations of utopia, land and land use is also a central aspect of this project, in particular in Chapters 2 and 3. I focus on SCT in part because “utopia” as a blueprint society has strong settler colonial implications that I draw on for this study: both historically and contemporarily in countries like Israel, the colonizer comes to build utopia on Indigenous land, through violent dispossession. Western utopian imaginings tend toward the homogenous, privileging Whiteness and European culture, and erasing cultural difference by great hope for both preventing climate change, and for surviving in an already changing climate. Indeed, Little Bear, in his forward to Cajete’s Native Science, espouses the powerful potential of uniting Western and Indigenous sciences to combat the urgent problem climate change, and offers a ray of hope in such uncertain times that is nothing if not utopian at the level of global collectivity.Speculative fiction imagines our world differently in order to grasp the complexities of the human condition. Darko Suvin, in discussing science fiction specifically, famously calls this “cognitive estrangement:” sf it is not so much about technology itself, or aliens or time travel, but rather uses these tropes to think about culture, politics, the nature of humans as tool users, etc. — this definition generally extends to speculative fiction, a term more suited to encompassing future-oriented works that may not focus on science and technology. Sf author Samuel R. Delany argues that sf is not even about the future, but that it is usually set there to ponder the future implications of society’s present problems.

Utopias are by definition speculative in nature, and utopian fiction can be considered a subgenre of speculative fiction. Utopian Studies revolves around the central question: What do we mean by “utopia?” It is a term much maligned across the Western political spectrum, though it is still a fundamentally Western concept, and the field of Utopian Studies is dominated by Western theorists. In Utopia as Method: The Imaginary Reconstitution of Society, Ruth Levites summarizes contemporary utopian scholarship of the last half-century or so, which has generally been critical of capitalism in a Marxist tradition. She rejects the idea, commonly touted by detractors, that “utopia” is a static, totalitarian society, or a “blueprint.” Instead, she argues that utopia is a method, a way to “develop alternative possible scenarios for the future and open these up to public debate and democratic decision—insisting always on the provisionally, reflexivity and contingency of what we are able to imagine” . Utopia in other words is fluid, emergent. Levitas argues that we have an imperative to first refuse that this capitalist, globalized world is the best of all possible worlds; to then imagine a better world ; and finally to actively work toward implementing that imagination, through, to begin with, a number of socialist programs. As Jameson argues forcefully in “Progress versus Utopia, or, Can We Imagine the Future?”, utopia cannot be imagined from within Western culture; it is so totalizing on a global scale, so limits our thinking that it is impossible. Still, as utopian scholars like Robert Tally argue, building from Jameson’s work,greenhouse vertical farming the postmodern era is the most important time to imagine utopia, even if it is also the most impossible, because we must imagine radical alternatives to the capitalist world system. Further, Tally argues that if utopia is a literary process of mapping the world around us and a guide for operating within it, rather than simply an “ideal society” of another place or time — we then find that “[u]topia is everywhere today” . We find utopia where communities — especially communities of color, as Imarisha highlights — self-organize in ways that resist power. And it follows, I would argue, that if Western thought is so totalizing that we can’t imagine utopia, then people outside Western hegemonic power structures would likely be well-placed to transform the utopian imagination, to decolonize it, in ways that Jameson does not account for. This “utopia from below” is indeed everywhere today. Utopian Studies defines “utopian fiction” loosely as well, though its historical connotations are distinctly colonial.

While the term “utopia” predates Western thought, it was popularized in the West through what is arguably the first science fiction book of the Western world, Thomas More’s Utopia . More inaugurated the “blueprint utopia” format; he took advantage of the excitement Europeans felt over early explorations of the New World to imagine an explorer discovering a society that, while in some ways better than our own, is not perfect . However, rather than define utopian fiction stringently as a blueprint society, as most early utopias were, utopian fiction can be more broadly considered any work that posits a world that is better than our own. Expanding on what counts as utopian fiction still further, we can identify “utopian traces,” or hints at the possibility of creating a better world , in most fiction and art, not just science fiction. Phillip Wegner argues that it is the job of sf texts to represent a moment of “dramatic break in the status quo,” in contrast to other fiction that represents and interrogates a given social and cultural moment. This means that utopian ideas are inherent in the sf genre. Wegner argues that “the most concrete manifestation of any sf narrative’s Utopianism is to be located in those moments wherein the closure of the conventional realist work is displaced by an openness to the unfinished potential of historical becoming” . The argument advanced by much of the fiction I study — that Indigenous philosophies and sciences are integral to imagining a better world — represents such a break in the status quo, a challenge to the primacy of Western philosophy and science, even though few of the works I study actually depict better, utopian societies. Dystopias can be defined as societies that are meant to be utopian, but are so only for a select few, while the majority of people remain oppressed; often these societies are totalitarian in nature. The texts I study here would primarily be described as “critical dystopias,” a term coined by Tom Moylan. For Moylan, “critical utopias” describe sf from the late 20th century that rejects the idea of utopia as blueprint, and tries to imagine a better world in the context of Marxist principles of freedom and justice. Meanwhile, “critical dystopias” respond to capitalist market ideologies such as neoliberalism, which are alternately “pseudo-utopian” and “anti-utopian,” because they hold that “a viable market-driven society” can only be achieved by dismantling welfare and other social support systems and destroying the environment . Critical dystopias first “linger in the terrors of the present” bringing a feminist and antiracist perspective to the anti-utopia of capitalist ideology. But then they explore “ways to change the present system so that such culturally and economically marginalized peoples not only survive but also try to move toward creating a social reality that is shaped by an impulse to human self-determination and ecological health” , and in their open endings offer a utopian hope. I enhance Moylan’s analysis by looking specifically at Indigenous-authored dystopian fiction and dystopian fiction with Indigenous themes, focusing my analysis on how neoliberalism and the destruction it has wrought specifically impacts Indigenous peoples, and how they respond to it. There is a growing body of postcolonial studies of sf, including those that engage with utopian/dystopian works, such that postcolonial science fiction studies could be considered a new sub-field of SFS—and this study would fall into it. The most important example is John Rieder’s Colonialism and the Emergence of Science Fiction, on which this study draws heavily. Rieder looks at early American sf, which is coterminous with colonialism, and persuasively argues that colonialism is “woven into the texture” of the genre. Another antecedent to this study is Eric Smith’s Globalization, Utopia and Postcolonial Science Fiction: New Maps of Hope. Smith focuses on the emergence of science fiction in the so-called third world and how it challenges the institutional limits of postcolonial readings of “first world” sf. Smith’s work is very closely aligned with my project, though I intend to conduct a more systematic engagement within the context of settler colonialism, and with more attention to Indigenous science and philosophy.