Author: ecogrow

SA treatment and SA deficiency conferred by NahG did not significantly impact ABA levels

The results suggest that SA responses in tomato play a less important role in defense against Phytophthora capsici than to Pst. The impact of SA and plant activators on ABA accumulation was measured in tomato roots and shoots.However, ABA accumulation in non-stressed TDL and BTH treatments trended higher than those observed in salt-stressed plants that did not receive a plant activator treatment . Protection by TDL against Pst is likely the result of a triggered SAR response and not the result of an antagonistic effect on ABA levels. The efficacy of plant activators depends on the specific diseases targeted and the environmental context, which may present additional stressors to confound defense network signaling in the plant. A challenge for successful deployment of plant activators in the field is to manage the allocation, ecological and fitness costs that are associated with induced defenses . These costs can be manifested by reduced growth and reproduction, vulnerability to other forms of attack, and potential interference with beneficial associations . It would seem that the severity of these costs is conditioned in part by the milieu of abiotic stressors operative at any given time. Reactive oxygen species contribute to the initiation of SAR , are induced by SA and BTH , and are essential co-substrates for induced defense responses such as lignin synthesis . ROS also are important in modulating abiotic stress networks, for example in ABA signaling and response . The potential compounding effect of ROS generated from multiple stressors presents a dilemma in that the plant must reconcile these to adapt or else suffer the negative consequences of oxidative damage for failure to do so . Paradoxically, SA and BTH also are reported to protect plants against paraquat toxicity, blueberry grow pot which involves ROS generation for its herbicidal action . How plants balance ROS’s signaling roles and destructive effects within multiple stress contexts is unresolved and a critically important area of plant biology with relevance for optimizing induced resistance strategies in crop protection .

Although our experiments were conducted under highly controlled conditions, the results with TDL are encouraging and show that chemically induced resistance to bacterial speck disease occurs in both salt-stressed and non-stressed plants and in plants severely compromised in SA accumulation. Future research with plant activators should consider their use within different abiotic stress contexts to fully assess outcomes in disease and pest protection.These syntenies of wheat and rye chromosomes permit the formation of compensating translocations of wheat and rye chromosomes. A compensating translocation is genetically equivalent to either of the two parental chromosomes; that is, it carries all relevant genes, but not necessarily in the same order. On the other hand, homoeology between wheat group 1S and rye 1S arms permitted induction of homoeologous genetic recombination, thus the development of recombinants of much smaller segments of rye 1RS to wheat than the entire arm. Many of the present wheat cultivars developed by breeding for disease resistance carry a spontaneous centric rye-wheat translocation 1RS.1BL that has been very popular in wheat breeding programs . This translocation contains a short arm of rye chromosome 1, and the long arm of wheat chromosome 1BL . It must have occurred by misdivision of centromeres of the two group 1 chromosomes, and fusion of released arms and first appeared in two cultivars from the former Soviet Union, Aurora and Kavkaz. Rye chromosome arm 1RS in the translocation contains genes for resistance to insect pest and fungal disease but as it spread throughout wheat breeding programs it became apparent that the translocation was also responsible for a yield boost in the absence of pests and disease . Besides the presence of genes for resistance and yield advantage on 1RS, there is a disadvantage of 1RS in wheat due to the presence of the rye seed storage protein secalin, controlled by the Sec-1 locus on 1RS, and the absence of the wheat loci, Gli-B1 and Glu-B3, on the 1RS arm. Lukaszewski modified the 1RS.1BL translocation by removing the Sec-1 locus and adding Gli-B1 and Glu-B3 on the 1RS arm. Lukaszewski developed a set of wheat−rye translocations, derived from ‘Kavkaz’ winter wheat that added 1RS to wheat arms 1AL, 1BL, and 1DL in spring bread wheat ‘Pavon 76’, a high yielding spring wheat from CIMMYT.

Studies showed that the chromosomal position of 1RS in the wheat genome affected agronomic performance as well as bread-making quality . Using the 1RS translocation, Lukaszewski developed a total of 183 wheatrye short arm recombinant lines for group 1 chromosomes in a near-isogenic background of cv. Pavon 76 bread wheat. Out of 183 recombinant chromosomes, 110 were from 1RS- 1BS combinations, 26 from 1RS-1AS and 47 from1RS-1DS combinations. Mago et al. used some of these lines to link molecular markers with rust resistance genes on 1RS. These recombinant brea kpoint populations provide a powerful platform to locate region specific genes. Wheat roots have two main classes, seminal roots and nodal roots . Seminal roots originate from the scutellar and epiblast nodes of the germinating embryonic hypocotyls, and nodal roots, emerge from the coleoptiler nodes at the base of the apical culm . The subsequent tillers produce their own nodal roots, two to four per node and thus contribute towards correlation of root and shoot development . The seminal roots constitute from 1-14% of the entire root system and the nodal roots constitute the rest . Genetic variation for root characteristics was reported in wheat and other crop species . Genetic variability for seedling root number was studied among different Triticum species at diploid, tetraploid, and hexaploid level and it was found to be positively correlated with seed weight . In a hydroponic culture study in winter wheat, Mian et al. found significant genotypic differences in root and shoot fresh weights, number of roots longer than 40 cm, longest root length and total root length. Wheat genotypes with larger root systems in hydroponic culture were higher yielding in field conditions than those with smaller root systems . Also, wheat yield stability across variable moisture regimes was associated with greater root biomass production under drought stress . Studies in other cereal crops associated quantitative trait loci for root traits with the QTL for grain yield under field conditions. Champoux et al. provided the first report of specific chromosomal regions in any cereal likely to contain genes affecting root morphology. They reported that QTL associated with root traits such as root thickness, root dry weight per tiller, root dry weight per tiller below 30 cm,hydroponic bucket and root to shoot ratio shared common chromosomal regions with putative QTL associated with field drought avoidance/tolerance in rice. Price and Tomos also mapped QTL for root growth using a different population than that used by Champoux et al. in rice.

In a field study of maize recombinant lines, QTL for root architecture and above ground biomass production shared the same location . Tuberosa et al. reported the overlap of QTL for root characteristics in maize grown in hydroponic culture with QTL for grain yield in the field under well-watered and droughted regimes occurred in 8 different regions. They observed that QTL for weight of nodal and seminal roots were most frequently and consistently overlapped with QTL for grain yield in drought and well watered field conditions. Also, at four QTL regions, increase in weight of the nodal and seminal roots was positively associated with grain yield under both irrigation regimes in the field. There are a few reports on QTL studies for root traits in durum wheat but none has been reported in bread wheat. Kubo et al. studied root penetration ability in durum wheat. They used discs of paraffin and Vaseline mixtures as substitute for compact soil. Later, a QTL analysis was done for the number of roots penetrating the poly vinyl disc, total number of seminal and crown roots, root penetration index and root dry weight . The QTL for number of roots penetrating the poly vinyl disc and root penetration index was located on chromosome 6A and a QTL for root dry weight was located on 1B. Wang et al. demonstrated significant positive heterosis for root traits among wheat F1 hybrids. They showed that 27% of the genes were differentially expressed between hybrids and their parents. They suggested the possible role of differential gene expression in root heterosis of wheat, and possible other cereal crops. In a recent molecular study of heterosis, Yao et al. speculated that up-regulation of TaARF, an open reading frame encoding a putative wheat ARF protein, might contribute to heterosis observed in wheat root and leaf growth. Rye, wheat and barley develop 4-6 seminal roots which show a high degree of vascular segmentation . Feldman traced files of metaxylem to their levels of origin in maize root apex and showed their differentiation behind the root apex in three-dimensional model. In drier environments, Richards and Passioura demonstrated that genotypes, when selected for narrow root xylem vessels as against unselected controls, yielded up to 3%-11% more than the unselected controls depending upon their genetic background. This yield increase in the selections with narrow root vessel was correlated with a significantly higher harvest index, also higher biomass at maturity and kernel number. Huang et al. indicated the decrease in diameter of metaxylem vessel and stele with increase in temperature which resulted in decreased axial water flow in wheat roots. The decrease in axial water flow is very critical in conserving water during vegetative growth and making it available during reproductive phase of the plant. In a recent study on root anatomy, QTL for metaxylem were identified on the distal end of the long arm of chromosome 10 of rice . In another comparative study of rye DNA sequences with rice genome, the distal end of the long arm of chromosome 10 of rice showed synteny to the 1RS chromosome arm . The 1RS.1BL chromosome is now being used in many wheat breeding programs. Rye has the most highly developed root system among the temperate cereals and it is more tolerant to abiotic stresses such as drought, heat, and cold than bread wheat .

Introgression of rye chromatin into wheat may enlarge the wheat root system. Manske and Vlek reported thinner roots and higher relative root density for 1RS.1BL translocations compared with their non-translocated bread wheat checks in an acid soil, but not under better soil conditions. Repeated studies with the 1RS translocation lines of Pavon 76 have demonstrated a consistent and reproducible association between root biomass and the presence and position, of the rye 1RS arm . The increased grain yield of 1RS translocations under field conditions observed and reported earlier may be due to the consistent tendency of 1RS to produce more root biomass and also to the higher transpiration rate measured .Those authors have shown a significant increase of root biomass in wheat lines with 1RS translocations, and a positive correlation between root biomass and grain yield. All translocations of 1RS: with 1A, 1B, and 1D chromosomes have shown increased root biomass and branching as compared to Pavon 76 and there was differential expression for root biomass among these translocation lines with ranking 1RS.1AL > 1RS.1DL > 1RS.1BL > Pavon 76. In Colorado, the 1RS.1AL translocation with 1RS from Amigo showed 23% yield increase under field conditions over its winter wheat check, Karl 92 . Many present day bread wheat cultivars carry a centric rye-wheat translocation 1RS.1BL in place of chromosome 1B . Originally the translocation was thought to have been fixed because the 1RS arm of rye carries genes for resistance to various leaf and stem fungal diseases and insects . However, the translocation increased grain yield even in the absence of pathogens . It has been shown recently that this yield increase may be a direct consequence of a substantially increased root biomass . Studies by Ehdaie et al. 2003 showed a significant increase of root biomass in wheat lines with 1RS translocations and a positive correlation between root biomass and grain yield. In sand cultures, all three 1RS translocations on 1AL, 1BL, and 1DL in ‘Pavon 76’ genetic background showed clear position effects with more root biomass and root branching over Pavon 76 .

The transcript level of ALS3 target gene increased in AlT treatment

A previous study about the response of different Andean and Mesoamerican common-bean cultivars to AlT showed that Andean genotypes are more tolerant to this abiotic stress, as compared to Mesoamerican genotypes . Our phylogenetic analysis revealed that all the Andean genotypes present a deleted version of the MIR1511 that would result in the absence of functional mature miR1511 . Previous work from our group showed that common-bean miR1511 expression responds to AlT stress . Here we analyzed the regulation of miR1511 and ALS3, as well as the early effects of AlT in roots of common-bean plants from the Mesoamerican BAT93 genotype vs. Andean G19833 genotype, with a deleted MIR1511 . Common-bean plantlets from BAT93 and G19833 genotypes were grown in hydroponic conditions either in control or AlT treatments, for up to 48 hrs. First, we performed the expression analysis of miR1511 and ALS3 target gene, using qRT-PCR . In AlT-stressed BAT93 plants, the transcript accumulation level of mature miR1511 gradually decreased, reaching more than half at 24 hours post-treatment , while at 48 hpt it returned to values close to those of time 0 . As expected, G19833 plants did not express mature miR1511 .The ALS3 transcript accumulation was significantly higher in G19833 roots, which lack miR1511, compared to BAT93 roots . At 6 hpt, ALS3 expression in G19833 roots almost doubled and remained unchanged up to 48 hpt, when transcript accumulation in BAT93 and G1988 roots reached similar levels . To further study the role of miR1511/ALS3 in the physiological reaction of common-bean plants to high Al levels, nft hydroponic system we aimed to over express the miR1511 precursor in transgenic roots.

As long as stable transformation of Phaseolus vulgaris plants is, to date, nearly impossible, we chose to use BAT93 and G19833 composite plants -with untransformed aerial organs and transgenic roots . As long as common bean is recalcitrant to stable transformation, this method is an alternative to demonstrate miRNA functionality . The miR1511-overexpressing composite plants as well as control plants, transformed with empty vector , were grown in AlT and control treatments. The expression level of miR1511 and ALS3 were determined by qRT-PCR in roots from composite plants harvested at 48 hpt . A two-fold accumulation of miR1511 transcript was observed in BAT93 OE1511 roots from plants grown in either treatment, compared to EV . In G19833 EV roots, the absence of miR1511 was confirmed, however a significant accumulation of miR1511 mature transcript was observed in OE1511 roots, albeit at lower levels than the level from BAT93 OEmiR1511 roots . In control treatment, both genotypes showed lower expression level of ALS3 in OEmiR1511 vs. EV roots. In addition, increased ALS3 transcript levels were observed in AlT stressed roots from both genotypes, as compared to control treatment . The primary and earliest symptoms of plants subjected to AlT stress is an inhibition of lateral root formation and root growth due to the alteration of root cell expansion and elongation, inhibiting cell division . On this basis, we analyzed the root architecture phenotype of BAT93 and G19833 OEmiR1511 and EV plants, grown under AlT or control treatments for 48 h . The growth rate of root length, width and area as well as the number of lateral roots, was calculated from the difference of each value at 48 hpt vs. time 0. The BAT93 EV plants under AlT showed decreased rates of each root parameter , thus indicating the drastic effect of high Al on root development. In contrast, G19833 EV plants showed higher tolerance to AlT evidenced by similar rate of the root length, area, width and lateral root number in stress vs control treatments .

These results are in agreement with those previously reported indicating a higher tolerance to AlT of Andean common-bean genotypes compared to Mesoamerican genotypes . Surprisingly, in G19833 plants genetically engineered for the expression of mature miR1511, the effect of root phenotype was evident. The rate of root length, area, width and lateral root number of G19833 OEmiR1511 AlT-stressed plants significantly decreased ascompared to EV plants, showing reduced levels similar to those from BAT93 stressed plants . In A. thaliana, primary root growth inhibition under phosphate limitation or AlT is mediated by ALS3 and LPR1, a ferroxidase . LPR1 acts downstream of ALS3 and its expression is epistatic to ALS3 expression . To determine if LPR1 could be involved in the different response to AlT of BAT93 vs. G19833 plants, we measured the accumulation of LPR1 transcripts in similar AlT conditions as those from Figure 4. The transcript level of LPR1 gene decreased in AlT treatment. In AlT BAT93 roots, the transcript level of LPR1 gradually decreased reaching half of the initial expression at 48 hpt. In AlT G19833 roots, the LPR1 expression was significantly lower compared to BAT93 roots from 6 hpt to 24 hpt . At 48 hpt, LPR1 transcript reached similar levels in roots from both genotypes . The LPR1 expression pattern was opposite to the ALS3 expression profile in AlT-stressed roots , indicating an epistatic relation between these two genes and the possible participation of LPR1 together with ALS3 in the control of common-bean root growth under AlT. In order to determine if miR1511 indirectly controls LPR1 expression via the regulation of ALS3 transcript, we evaluated the LPR1 transcripts accumulation in transgenic roots from OEmiR1511 and EV composite plants, growing in Alt vs control conditions. In both BAT93 and G19833 roots, a significant increase of LPR1 transcript accumulation was observed in OEmiR1511 roots from plants grown in either treatment, compared to EV roots . In AlT treatment, roots from both genotypes showed significant lower LPR1 transcript level compared to roots from control condition.

Again, LPR1 expression pattern was the opposite compared to that of ALS3 in the same transgenic root samples , thus indicating the probable epistatic relationship between these two genes and the indirect regulation of miR1511 on LPR1 expression. In plants, microRNA genes have a higher birth and death rates than protein-coding genes . For various authors, the miRNAs’ evolution rate generates a reservoir of adaptability for gene regulation . Due to this high evolutionary turnover rate, new miRNA families and members emerge, while others lose their regulatory role and disappear from genomes of phenotypically close species or genotypes. In soybean, MIR1511 is subjected to this mechanism. Htwe et al.,reported two altered versions of MIR1511 alleles in some annual wild soybean genotypes,hydroponic nft system whereas no deletion was found in G. max and perennial wild soybean MIR1511. Here, we report a similar phenomenon for P. vulgaris MIR1511 genotypic variations. Only part of the MW1 subgroup of P. vulgaris Mesoamerican genotypes and all the Andean genotypes analyzed displayed a 58 bp-deletion in the miR1511 precursor gene compared to the corresponding sequence of P. dumosus, P. coccineus, the PhI gene pool and the rest of P. vulgaris Mesoamerican genotypes . As MIR1511 is present in non-legume species, the most parsimonious hypothesis to explain the evolution process associated with this event is to consider a deletion of part of miR1511 precursor sequence. In contrast to soybean, where probably two deletion events were required for the generation of two alternative MIR1511 alleles, our results suggest a single deletion event in the common ancestor of a part of MW1 Mesoamerican subgroup and the Andean genotypes for the generation of a different allele of miR1511 precursor gene. This single MIR1511 deletion event hypothesis supports the Mesoamerican model proposed by Ariani and colleagues where the Mesoamerican gene pool is the ancestral population from which the other gene pools have derived. The fact that the PhI gene pool contains an untruncated version, as do the other closely-related Phaseolus species included in this analysis, further confirms the sister-species status of the PhI gene pool, now known as P. debouckii . P. debouckii also contains ancestral, i.e., non-derived, sequences for phaseolin seed protein and chloroplast DNA . Based on the MIR1511 phylogenetic history presented here , we propose an addendum to this model where AW gene pool genotypes derived from one, or more, member of the MW1 Mesoamerican subgroup. A clear distinct geographical distribution pattern was observed among the P. vulgaris genotypes featuring the MIR1511 deletion and the ones with an unaltered allele . MIR1511 deletion occurred in genotypes originating from the northern and southern extreme limits of the common-bean distribution in Latin American area. Such distribution pattern correlates with the annual precipitation pattern reported for the American continent , indicating that genotypes with MIR1511 deletion originated from areas with significantly less precipitation as compared to areas where genotypes with unaltered MIR1511 originated . Drought makes soil not suitable for agriculture; it tends to increase soil concentration of different compounds that would result in plant toxicity, including aluminum toxicity, which is an important plant growth-limiting factor . The harsh soil conditions of areas where P. vulgaris genotypes lacking of MIR1511 originated probably forced these common-bean populations to adapt and favored selection of genotypes with higher AlT tolerance. In this work, we showed the experimental validation of a target gene for P. vulgaris miR1511. We validated the miR1511-induce cleavage of ALS3 transcript, an ABC transporter participating in Al detoxification in plants . However, additional action of miR1511 by translation repression of ALS3 cannot be excluded. Other proposed target genes for P. vulgaris miR1511 are not related to plants AlT response and show high binding-site penalty score, thus improbable to be considered as functional in the AlT response. Here we provided evidence of the role of the miR1511/ALS3 node in the common-bean response to AlT .

We interpret that the MIR1511 deletion resulting in lack of mature miR1511 allowed common-bean adaptation to high Al in the soils by eliminating the negative regulation of ALS3 transcript and the accumulation of LPR1, in the first 48 hpt, thus increasing its tolerance to AlT and favoring plant growth. Interestingly, similar characteristics hold for the soybean MIR1511-deletion case where the origin of soybean genotypes featuring a MIR1511-altered allele is geographically correlated with areas susceptible to high Al concentration in soil due to presence of drought in these regions .High aluminum levels in soil mainly affect plant roots; aluminum can be allocated to different subcellular structures thus altering the growth of the principal root and the number of lateral roots . In this sense, it has been observed that AlT-stressed plants favor the transport of chelated Al to vacuoles and from roots, through the vasculature, to aerial tissues that are less sensitive to Al accumulation . In Arabidopsis and other plants, ALS1 and ALS3, from the ATP-binding cassette transporter family, are involved in Al detoxification and enhance tolerance to AlT . ALS3 is located in the tonoplast, the plasma membrane of root cortex epidermal cells, and in phloem cells throughout the plant . It has been shown that Arabidopsis als3 mutants are more sensitive to AlT exhibiting extreme root growth inhibition, compared to wild type plants . Recent studies on the role of Arabidopsis ALS3 in root growth inhibition revealed its regulation via the inhibition of the STOP1-ALMT1 and LPR1 pathways, which indirectly control ROS accumulation in roots via the modulation of Fe accumulation . Furthermore, Arabidopsis ALS3 expression is induced by excess Al , a phenomenon we observed in common-bean plants as well . Common-bean ALS3 expression doubled after 6 hours under AlT in roots from G19833 plants, while in stressed roots from BAT93 plants a similar level was reached only after 48 h of treatment . The opposite expression profile was found for the ALS3-epistatic gene LPR1, in the same samples . Our data on the different ALS3 and LPR1 expression level from both genotypes indicate that the absence of the negative regulator miR1511 in G19833 plants allows a faster response to AlT. Although the level of mature miR1511 decreased in BAT93 roots up to 24 h of after exposure to high Al, this level seems sufficient to induce degradation of ALS3 transcript, which showed reduced levels compared to G19833 roots, and an increase of LPR1 expression . Our analysis of root architecture in common-bean plants showed that G19833 Andean genotype plants are more tolerant to AlT as compared to Mesoamerican BAT93 plants . These data agree with those reported by Blair et al. .

Nucleotide sugar transporters regulate the flow of donor substrates into the Golgi for use by GTs

Since hpGGLT1 plants grown in the presence of 1 mM boric acid or no added boric acid had different phenotypes,we were curious to know if altering the structure and dimerization of RG-II in hpGGLT1 led to changes in other cell wall components. Therefore we determined the monosaccharide composition of destarched leaf AIR from plants grown under different borate concentrations . No significant visible differences were discernible in hpGGLT1 and EV plants grown with 1 mM borate . However, we saw increases in the abundance of several neutral monosaccharides, in particular glucose , in the walls of plants grown with no added borate. No differences in aniline blue staining of the walls of EV and hpGGLT1 lines were observed, suggesting that the increase in non-cellulosic glucose in plants which appear severely stressed is not due to callose deposition . Finally, we performed Saeman hydrolysis of the TFA-resistant AIR to determine the amount of glucose derived from crystalline cellulose. A substantial increase in cellulose-derived glucose was detected in the hpGGLT1 lines grown with no added borate but not in plants grown under high-borate conditions . To further investigate the altered cell wall in the hpGGLT1 plants grown with no added borate, we performed a saccharification assay on the destarched AIR to measure the quantity of enzymatically accessible sugars in this material. Following pre-treatment with hot water,macetas de 5 litros the samples were treated with a commercial saccharification cocktail of GHs, and the amount of reducing sugar released after 72 h was measured.

As expected, given the increase in cell wall glucose , low-borate-grown hpGGLT1 plants had a significant increase in the amount of sugar released compared with EV , a difference that was not seen in high-borate growth conditions .Wall structure is also important for growth under environmental stress Salinity stress weakens the wall, probably by disrupting pectin cross-linking . The FERONIA receptor directly binds pectin, and prevents uncontrolled cell expansion caused by salt stress . Similar to the fer mutant, the root cells of mur1 burst during growth in the presence of salt,suggesting a role for RG-II cross-linking in allowing roots to recover growth. Since hpGGLT1 plants have disrupted RG-II, we predicted that if the FERRONIA model is correct the roots should show a similar loss of wall integrity as mur1 when grown in the presence of salt. Indeed, compared with the wild type, root cells of hpGGLT1 plants burst after salt treatment during the growth recovery phase . However, it is challenging to predict the NDP-sugar transported by these enzymes from amino acid sequences alone. Here, we have provided evidence that GGLT is a GDP-L-galactose transporter, and show that it is required for the production of structurally normal RG-II. Reducing GGLT1 expression led to a decrease in the L-galactose content of RG-II and a reduction in RG-II dimerization and dimer stability. Growth of the silenced plants is rescued by adding additional borate to the growth medium. Thus, suppressing GGLT provides a unique opportunity to investigate the effects of structural changes of RG-II on boron requirements for plant growth.Despite multiple reported failures to heterologously express the GGLT1 protein , we were able to transiently express GGLT1 as a YFP fusion in onion epidermal cells and confirm its predicted localization to the Golgi apparatus. Unfortunately, as others have also reported, we were unable to express GGLT1 in yeast to perform biochemical analysis of in vitro activity. Therefore, we took an in planta approach to determine the function of GGLT1. GDP-L-galactose lacked a reported NST, and in wild-type Arabidopsis L-galactose is present only in the pectic polysaccharide RG-II.

Analysis of RG-II from hpGGLT1 plants showed that there was a reduction in RGII dimer formation, which was correlated with a specific loss of the terminal L-galactose present on side-chain A. We did not detect changes to other biopolymers known to use GDP-mannose, GDP-glucose or GDP-fucose.We propose that GGLT1, and the L-galactose decoration on RG-II, is essential for plant development and reproduction. This is consistent with previous studies showing that L-galactose is present on side-chain A of all RG-IIs analyzed to date , with studies suggesting that RG-II is critical for pollen development, pollen germination and seed development, and that plants with abnormal RGII exhibit major growth defects . When the plants were grown in the presence of boric acid, their reduced growth phenotype was partially rescued. This was also reported for GME-silenced tomato plants . While a reduction in GME expression affects the biosynthesis of all GDP-linked sugars, as well as ascorbate, the authors suggested that it was the loss of RG-II dimerization that was critical , and our study supports this conclusion. It should be noted that the rosette morphology of hpGGLT1 plants is different from that described for mur1 or hpGFT1, which has been suggested to arise from the replacement of RG-II L-fucose with L-galactose, leading to the incomplete formation of side-chain A . Since plants lacking fucose on xyloglucan or arabinogalactan proteins grow normally, the phenotype had been ascribed to reduced RG-II dimerization because of the altered RG-II structure in mur1 and hpGFT1. Our results suggest that either the phenotype is dependent on the exact nature of the RG-II side-chain modification, or that the ‘cabbage-like’ growth habit of mur1 and hpGFT1 results from the loss of fucosylation of another molecule. For example, it has been proposed that fucose is necessary for epidermal growth factor domainactivation of receptor-like kinases , and for promoting the interaction of DELLA with the brassinosteroid pathway .

Boron is an essential micronutrient that is required for normal plant growth and development, and its availability is important for maintaining plant productivity. Too little results in poor plant growth, but too much is toxic. To date, the major described role for boron is to cross-link RG-II . This has been shown to affect the tensile strength and porosity of cell walls. In some species, borate deficiency results in cell wall thickening . In our hands, boron-deficient plants did show an increase in cellulose-derived glucose, as well as some hemicellulose derived sugars, including mannose. A cell wall integrity-sensing pathway responsive to salinity stress, and acting via the receptor kinase FER, has recently been described and is thought to act via interaction with pectin . Here we show that hpGGLT1 plants display a similar salt-specific loss of cell wall integrity as fer and mur1. These data suggest that RG-II cross-linking is directly disrupted by salinity,macetas cultivo or part of a compensatory feedback loop that is necessary to recover wall strength during acclimation. Such a feedback loop has also been reported in other primary cell wall mutants . Transcriptomic data from plants grown under boron deficiency show altered transcript accumulation for polygalacturonases, pectin methylesterases and pectate lyases, all enzymes involved in cell wall remodeling, as well as stress response genes . The hpGGLT1 plants will be a useful tool for investigating this process further. Boron has also been shown to affect the catalytic activities of plasma membrane proteins , control the transcription of specific gene targets  and to affect the homeostasis of oxidative compounds that may alter lipid properties . More recently, it was proposed that boron may serve as a potential link between RG-II and GIPCs. These are a heavily glycosylated class of sphingolipids and are major components of the plant plasma membrane. Interestingly, this proposed linkage would provide a physical interaction between the plasma membrane and the cell wall , and is promising avenue for future investigation.Human space travel depends upon the operation of life support systems. In deep space missions, such as the mission to Mars, life support cannot depend upon storage alone, it requires a fully regenerative system as well, i.e. waste must be reclaimed for reuse. A number of solid waste reclamation technologies are under investigation for space applications .

Technologies such as incineration, supercritical water oxidation, steam reformation, and electrochemical oxidation are at various stages of development for use in space. Incineration is perhaps the most promising technology because it rapidly and completely converts the waste to carbon dioxide, water, and minerals. Incineration also lends itself to experiment more affordably than most of the other technologies, and it is already the most thoroughly developed technology for use in a terrestrial environment. The major difficulty with the use of incineration, particularly in a closed environment, is the emission of pollutants that can build up, thus necessitating a flue gas cleanup system. Incineration of the inedible portion of crops and wastes, such as human feces, produces mostly carbon dioxide, water, and ash. However the incineration also produces NOx and SO2; pollutants that need to be removed from flue gas and recovered for reuse. NOx is produced from nitrogen in the waste or fuel and from the nitrogen in the air. Similarly, the sulfur in the waste is converted to SO2 during incineration. To conserve the nutrients for life support, NOx should be converted to N2, NH3, and/or nitrates. The N2 can be used to replace cabin N2 leakage and/or the loss of N2 during combustion, while NH3 and nitrates can be recycled as part of the plant hydroponics nutrient solution. The SO2 can be converted to either elemental sulfur or sulfate because elemental sulfur can be safely stored or converted to sulfate, where sulfate can be recycled as part of the plant hydroponics nutrient solution as well. Many flue-gas clean up technologies have been developed to remove NOx and SO2 from terrestrial incineration . Most of the technologies require expendables, making them unsuitable for a space application. Processes that use catalyst may have problems because catalyst poisoning is an issue that limits the life-span of a catalyst. The poisoning of the catalyst by soot, alkali metals, and chlorides in the flue gases can occur, and wet processes that handle liquids, like using spray absorbers, pose difficulty because of the micro-gravity situation. What also need to be addressed are the issue of safety and energy requirements of the technology. Using potential hazardous high-pressure systems and/or systems that require an excessive amount of electric energy is unwarranted for space missions. In view of the aforementioned constraints and requirements, we are investigating an approach involving the use of rice hulls, an inedible biomass that can be continuously produced in a space vehicle, to clean up flue gas pollutants generated during incineration. We have found that flue gas from the incineration of biomass contains an insignificant amount of SO2, and that most of the sulfur in the biomass has ended up as sulfate in flyash. Presumably, SO2 has reacted with the alkali metal in the biomass, thus, this study focuses on the control of NOx emissions. The approach involves the carbonization of the rice hulls to produce activated carbon for the adsorption of NOx and a subsequent reduction of the adsorbed NOx by carbon to N2. The optimal conditions for the production of activated carbon from rice hulls for the adsorption of NOx has been determined. Parametric studies on the adsorption of NOx by the carbon have been performed. The effectiveness of this approach to control NOx emissions in deep space missions has also been assessed. The activated carbons were characterized by the measurement of their average pore size and surface area. There are three types of pores which developed in the solid: micropores , mesopores , and macropores . The average pore size has an effect on the total surface area that is available for adsorption. The BET surface area and BJH average pore size of activated carbon prepared from rice hulls under different conditions were measured. Temperature and hold time used for activation was varied. As the temperatures varied from 350°C to 800°C and the activation time from 0.5 hr to 5 hrs, the BET and BJH of activated carbon from rice hulls ranged from 76.5 m2 /g to 172.9 m2 /g and from 25.1 to 67.1 Α, respectively. In general, the BET increases with the increase of temperature until about 700°C. Further increases of temperature results in decreases of BET surface area. The BET of rice hulls activated carbon was 76.5 m2 /g, 167.1 m2 /g, 172.9 m2 /g, and 147.9 m 2 /g with an activation temperature of 350°C, 600°C, 700°C, and 800°C, respectively. The time used for activation did not affect the BET surface area substantially under the conditions employed.

Nft Hydroponics Pvc Channel For Hydroponic Growing System

The results from this study showed that it may be valuable to evaluate the BCF or BAF of CECs in earthworms over time, as there may bean increased potential for biomagnification at a given time point. However, more research is needed to determine if these differences persist for a longer time scale and if they occur in different soils or for other CECs. Out of four major metabolites examined in this study only N4- acetylsulfamethoxazole was quantifiable in the earthworm tissues. N4- acetylsulfamethoxazole was seen to increase to a peak concentration of 4.39 ± 0.4 ng g-1 at 3 d and then decreased to 2.62 ± 0.01 ng g-1 by the end of the 21 d incubation . Further, N4-acetylsulfamethoxazole was also detected in the earthworm soil with the highest concentration observed at 7 d , indicating that earthworms was capable of metabolizing these CECs and excreting the transformation product into its surrounding environment. N4-acetylsulfamethoxazole is the primary metabolite of sulfamethoxazole in humans and has been previously detected in wastewater effluent, environmental samples and plant tissue . However this was, to the best of our knowledge, the first time that N4-acetylsulfamethoxazole has been observed to form in earthworms. The continued observation of the formation of N4-acetylsulfamethoxazole, an acetyl conjugate, in the environment is of considerable interest because conjugates have the potential to maintain the biological activity of the parent compound . Further, because researchers traditionally only quantify parent compounds during environmental assessments,macetas de 10 litros the formation and accumulation of conjugates implies that there may be an underestimation of environmental exposure to CECs such as pharmaceuticals and further incomplete environmental risk assessment of CECs .

This is of particular concern for antibiotics, because of the rise of antimicrobial resistance . The major metabolite of methyl paraben, p-hydroxybenzoic acid, was observed in all soil samples, including the non-treated controls . This was likely due to the endogenous p-hydroxybenzoic acid in sphagnum peat . However, the concentration of p-hydroxybenzoic acid was higher in the spiked earthworm treatments than in the blank controls or non-earthworms chemical controls indicating that E. fetida was also capable of taking up and metabolizing methyl paraben and excreting of p-hydroxybenzoic acid into the soil. This was consistent with previous contact tests in which 70% of the initial methyl paraben was found to be metabolized to p-hydroxybenzoic acid and phenol within 48 h in E. fetida . The transformation products o-desmethylnaproxen and nordiazepam were not detected in earthworm tissues, but o-desmethylnaproxen was quantifiable in earthworm-CEC treated soils during the 21 d incubation , indicating active uptake, metabolism, and excretion. The quantification of the major metabolites for naproxen, sulfamethoxazole and methyl paraben, o-desmethylnaproxen, N4- acetylsulfamethoxazole, and p-hydroxybenzoic acid suggested a trend in the capabilities of E. fetida to take up, metabolize and excrete then transformation products of some CECs in the soil environment. Activities of several vital antioxidant enzymes were determined after exposure to CECs. A significant increase in the activity of glutathione-S-transferase in the treatment samples over the controls was observed starting after 3 d into the incubation , and the GST activity continued to increase until the end of the 21 d incubation . This observation suggested that increased exposure time resulted in increased oxidative stress because glutathione is considered a critical antioxidant that acts to maintain redox homeostasis and signaling in cells . Further, GST is a crucial enzyme family for the detoxification of xenobiotics during Phase II metabolism . Thus, the observed increase in GST activity may indicate that there was a formation of additional Phase II metabolites.

However, the detection of these potential metabolites was not attempted due to a lack of authentic standards. High GST activity was also observed at 0 h for both the controls and treated samples. However, this increase in activity is likely due to the initial stress of the earthworm being transferred into the test media, and the effect dissipated within the first day of exposure. No significant difference in catalase activity was observed between the treatment and controls until the end of the exposure period . At the 21 d time point a significant increase was seen in the treatment samples , indicating that extended exposure to CECs likely resulted in increased production of hydrogen peroxide in earthworm tissue . However, an increase in the CAT activity was also found in the control at 0 h. The increase in CAT activity was, again, likely due to the initial stress of the earthworms being transferred to different environmental conditions and the difference dissipated within 24 h. A significant increase in superoxide dismutase was observed at 1 d and 3 d . However, no significant differences were observed between the treatment and controls after 3 d . This trend was in accordance with SOD has the first line of defense against reactive oxygen species . SOD acts to catalyze the superoxide radical into oxygen molecules or hydrogen peroxide . As an increase in CAT was observed at the later time point it was likely that SOD activity increased initially, resulting in an increased production of hydrogen peroxide, which was then detoxified by CAT. Previous studies examining the biochemical effects of CEC exposure in earthworms showed somewhat similar trends. For example, a study exploring the biochemical and genetic toxicity of triclosan in E. fetida showed a dose-dependent hormesis effect over time for both CAT and GST activity, with increasing activity being observed after a 2 d exposure at low doses and an inhibition of enzyme activity being observed after 14 d at high doses. Further, similar studies considering oxidative stress in E. fetida exposed to herbicides showed an increase in enzyme activities at lower concentrations and a suppression of enzyme activities at high concentrations .Currently we are experiencing a series of global trends that are creating unique challenges for the future of sustainable development. These trends include shifting precipitations patterns, rising temperatures, growing human populations, and rapid urbanization. In order to meet these challenges, traditionally under-utilized resources, such as treated wastewater and bio solids, will have to be harnessed.

These resources are derived from wastewater treatment plants and contain biologically active, pseudo-persistent, trace chemicals referred to as contaminants of emerging concern . Land application of TWW and bio solids for agriculture and landscaping has the potential to introduce CECs into terrestrial ecosystems, from where they could accumulate, be metabolized and/or cause adverse effects in terrestrial organisms. This dissertation has described the ability of terrestrial plants and invertebrates to take up and metabolize CECs and highlighted the potential for these trace contaminants to induce biochemical changes in non-target terrestrial organisms. The findings of this project, overall conclusions, and recommendations for future work are summarized below. In arid and semi-arid areas, TWW reuse is becoming increasingly prevalent for agricultural irrigation. However, irrigation with TWW has the potential to introduce CECs including antibiotics into agroecosystems. One of the most commonly prescribed and environmentally relevant antibiotics is sulfamethoxazole. However, little is known about the fate of sulfamethoxazole in terrestrial plants. In this study, sulfamethoxazole was observed to be taken up and actively metabolized by Arabidopsis thaliana cells into six transformation products. The transformation products included oxidation of the amine group, producing Phase I metabolites, which was followed by conjugations with glutathione, glucuronic acid and leucine, producing Phase II metabolites. Phase III metabolism was assessed by determining the mass balance of 14C-sulfamethoxazole in A. thaliana cells and cucumber seedlings. Non-extractable 14C-sulfamethoxazole increased over time in both A. thaliana cells and cucumber seedlings, indicating that Phase III metabolism significantly contributed to the fate of sulfamethoxazole in A. thaliana cells and cucumbers. Further,macetas de 7 litros in A. thaliana cells and cucumber seedlings, the mass balances were calculated to range from 80-120% and 80-94%, suggesting a minor role of mineralization. The results from this study highlighted the potential of terrestrial plants to transform pharmaceuticals, forming both bio-active Phase I metabolites and Phase II conjugates, and store them as in the form of bound residues as Phase III metabolism. Plant uptake of CECs from TWW reuse and bio-solid application has been documented in agroecosystems. Previous studies suggested that plants were capable of metabolizing CECs after uptake. However, these studies often reported different results even with the same CECs, likely due to the use of different plant species and/or different laboratory conditions. In this study, the metabolism of the benzodiazepine diazepam was explored in three different plant species, A. thaliana, cucumber , and radish . The plants were exposed to diazepam in laboratory under three different laboratory exposure conditions that included a 6 d cell culture, an acute /high concentration hydroponic cultivation, and a chronic /low concentration hydroponic cultivation. 14C-Diazepam was incubated concurrently with non-labeled diazepam to determine the fractions of extractable and non-extractable radioactivity to quantify Phase III metabolism. Diazepam was taken up and metabolized in all plant species under the different exposure conditions. A. thaliana cells actively transformed diazepam into temazepam and nordiazepam via Phase I metabolism.

This metabolism mimicked human metabolism, as temazepam and nordiazepam are the minor and major metabolites, respectively, formed during human metabolism of diazepam. Intriguingly, both of these metabolites are bio-active and prescribed pharmaceuticals in their own right, alluding to a potential for increased risk from consumption not considered in previous studies. The fraction of non-extractable residue increased over the 6 d incubation, indicating extensive Phase III metabolism over time in A. thaliana cells. In cucumber and radish seedlings, a similar Phase I metabolism pattern was observed, with nordiazepam being the most prevalent metabolite at the end of the 7 d and 28 d cultivations. However, significant differences in phase III metabolism were observed between the radish and cucumber plants. For example, after the acute exposure, diazepam mass balance was 99.3% for cucumber seedlings but only 58.1% for radish seedlings, indicating increased mineralization in the radish system. Diazepam induced changes in the regulation of glycosyltransferase activity in both cucumber and radish seedlings, indicating the formation of Phase II metabolites. The results from this study showed that exposure conditions and plant species can influence the metabolism of diazepam, and formation of bio-active transformation intermediates and different phases of metabolism should be considered in order to achieve a comprehensive understanding of risks of CECs in agroecosystems.Exposure of terrestrial invertebrates to CECs will likely increase with increasing TWW reuse and bio-solid application. However, currently there is limited information on the fate and effects of CECs in terrestrial organisms. In this study, the earthworm E. fetida was exposed to three pharmaceuticals, i.e., sulfamethoxazole, diazepam, and naproxen, and one preservative, i.e., methyl paraben, for 21 d in an artificial soil. Methyl paraben did not accumulate in the earthworm tissue, likely due to its rapid degradation in the soil. The other CECs showed an accumulation in earthworm tissues from the soil/soil porewater. The presence of E. fetida did not significantly affect the adsorption of these CECs to the soil. The presence of primary metabolites in the treated soil suggested that E. fetida were capable of actively metabolizing the three pharmaceuticals and excreting the metabolites. However, the metabolism was chemical-specific, and only N4- acetylsulfamethoxazole was detected in earthworm tissues. Exposure to the four CECs also resulted in the up-regulation of several antioxidant enzymes, including glutathione-S-transferase, superoxide dismutase, and catalase, and an increase in malondialdehyde, indicating oxidative stress in the exposed E. fetida. Results from this study highlighted the need to consider the role of, and effects on terrestrial invertebrates when understanding risks of CECs in agroecosystems. Our findings illuminate the complexity of the interactions between contaminants of emerging concern and terrestrial organisms. The dissertation highlights the ability of terrestrial organisms to take up and transform CECs through metabolism, which results in both bio-activation and detoxification of the target contaminants. This project also demonstrates the ability of CECs to alter the biochemistry of the studied terrestrial organisms by changing the regulation of enzymes associated with oxidative stress and metabolism. The use of cell cultivations, hydroponic studies, and artificial soil allowed us to examine the metabolism and effects of CECs in terrestrial organisms with limited confounding factors. However, it is highly likely that similar studies conducted in soils may show low rates of uptake and different patterns in metabolism. Our research suggests that scientifically sound understanding of fate of, and risks from, CECs in the environment cannot solely rely on the assessment of the parent compound and/or only consider the potential for human exposure to CECs.

¿Se ofrecen opciones ecológicas de macetas plásticas al por mayor?

Sí, en la actualidad hay opciones ecológicas de macetas plásticas disponibles al por mayor. Estas macetas suelen estar fabricadas con materiales plásticos biodegradables, compostables o reciclados, lo que ayuda a reducir el impacto ambiental en comparación con las macetas plásticas convencionales. Algunas características comunes de estas opciones ecológicas incluyen:

  1. Materiales biodegradables: Las macetas están hechas de plásticos biodegradables, lo que significa que se descomponen naturalmente con el tiempo, reduciendo así la acumulación de residuos plásticos.
  2. Materiales compostables: Algunas macetas plásticas ecológicas están hechas de materiales compostables, lo que significa que pueden descomponerse en condiciones de compostaje, convirtiéndose en nutrientes para el suelo.
  3. Plástico reciclado: Otras opciones utilizan plástico reciclado en su fabricación, contribuyendo a reducir la cantidad de plástico nuevo producido y fomentando la economía circular.
  4. Diseños sostenibles: Además de los materiales utilizados,cultivo de la frambuesa algunas empresas se esfuerzan por adoptar prácticas sostenibles en la fabricación y diseño de las macetas, minimizando el uso de recursos y energía.

Al buscar opciones ecológicas al por mayor, es recomendable contactar a proveedores especializados en productos sostenibles, empresas de suministros para jardinería e incluso explorar opciones en ferias comerciales relacionadas con la horticultura y la jardinería sostenible. La demanda de productos respetuosos con el medio ambiente está en aumento, lo que ha llevado a un aumento en la disponibilidad de opciones ecológicas en varios sectores, incluido el de las macetas plásticas.

¿Cuáles son las opciones más económicas de macetas plásticas al por mayor?

Las opciones más económicas de macetas plásticas al por mayor pueden variar según varios factores, como el proveedor, la calidad del material y el tamaño de la orden. Aquí hay algunas sugerencias para encontrar opciones económicas:

  1. Comparar Precios: Investiga y compara precios de diferentes proveedores. Puedes hacer esto visitando sus sitios web,macetas por mayor contactándolos directamente o utilizando plataformas en línea especializadas en ventas al por mayor.
  2. Negociar Descuentos por Volumen: Muchos proveedores ofrecen descuentos por volumen o compras al por mayor. Negocia con los proveedores para obtener precios más bajos al realizar pedidos de mayor cantidad.
  3. Proveedores en Línea: Explora plataformas en línea que conectan a compradores con proveedores al por mayor. Estos sitios a menudo tienen una amplia variedad de opciones y competencia, lo que puede llevar a mejores precios.
  4. Buscar Ofertas y Promociones: Estate atento a ofertas especiales, promociones o liquidaciones. Algunos proveedores ofrecen descuentos temporales o promociones para compras al por mayor en determinados momentos del año.
  5. Proveedores Directos: Considera contactar directamente a fabricantes de macetas plásticas. Al eliminar intermediarios, es posible que encuentres precios más competitivos.
  6. Comprar en Temporada Baja: En algunos casos, los precios pueden ser más bajos durante la temporada baja de jardinería. Aprovecha estos momentos para obtener mejores ofertas.
  7. Explorar Proveedores Locales: Busca proveedores locales que puedan ofrecer precios competitivos debido a menores costos de envío.
  8. Tiendas de Outlet o Liquidación: Algunas tiendas de outlet o liquidación pueden tener existencias de macetas plásticas a precios reducidos. Sin embargo, esto puede variar según la ubicación y la disponibilidad.

Recuerda siempre equilibrar el precio con la calidad del producto. Asegúrate de que las macetas plásticas cumplan con tus estándares de durabilidad y funcionalidad, incluso al buscar opciones más económicas.

Formas Creativas de Reutilizar Macetas de Plástico: Más Allá del Jardín

Las macetas de plástico desempeñan un papel vital en el cuidado de nuestras plantas, pero ¿qué sucede cuando ya no son necesarias para su propósito original? En lugar de relegarlas al contenedor de reciclaje, considera las numerosas formas creativas de reutilizar las macetas de plástico. Desde la organización doméstica hasta soluciones innovadoras de jardinería,cultivar frambuesas estos versátiles contenedores pueden encontrar una nueva vida en varios aspectos de tu hogar y jardín.

Almacenamiento en Interiores y Exteriores:

Las macetas de plástico, especialmente las más grandes, se pueden reutilizar como contenedores de almacenamiento. Úsalas para organizar herramientas pequeñas, guantes de jardinería o incluso juguetes infantiles. La durabilidad de las macetas las hace adecuadas para soluciones de almacenamiento tanto en interiores como en exteriores. Lienzos de Pintura para la Creatividad:

Convierte tus macetas de plástico en obras maestras artísticas utilizándolas como lienzos. Deja que fluya tu creatividad con pinturas, marcadores o decoupage para transformar macetas simples en piezas decorativas únicas. Estas creaciones personalizadas pueden agregar un toque de estilo a tu jardín o espacio interior. Comederos o Baños para Aves DIY:

Convierte las macetas de plástico más pequeñas en comederos o baños para aves. Cuélgalas de las ramas de los árboles o colócalas estratégicamente en tu jardín. Agrega perchas o crea recipientes de agua poco profundos para atraer a tus amigos emplumados, convirtiendo tu jardín en un refugio para la vida silvestre local. Innovaciones en Jardinería Vertical:

Apila macetas de plástico más pequeñas verticalmente para crear un jardín de hierbas único o una exhibición floral. Este enfoque de jardinería vertical no solo maximiza el espacio, sino que también añade un elemento estéticamente agradable a tu jardín o balcón. Organizadores de Hierbas y Especias:

Coloca macetas de plástico en una bandeja o estante para crear una estación compacta y organizada de hierbas y especias. Etiqueta cada maceta con el nombre de la hierba o especia, facilitando el acceso y el mantenimiento de un jardín de cocina bien ordenado. Bandejitas para Germinación de Semillas:

Las macetas de plástico son excelentes para iniciar plántulas. Reutilízalas como bandejitas para la germinación de semillas colocando varias macetas pequeñas dentro de un contenedor más grande. Este vivero improvisado de plántulas se puede mover fácilmente para optimizar la exposición al sol. Portavelas para Ambiente:

Corta la parte superior de las macetas de plástico para crear elegantes portavelas. Coloca macetas de diferentes tamaños para añadir un toque único a tu espacio exterior. La naturaleza translúcida de algunos plásticos puede crear hermosos patrones cuando se iluminan con la luz de las velas. Marcadores de Plantas DIY:

Corta macetas de plástico más grandes en tiras y úsalas como marcadores de plantas DIY. Etiqueta cada tira con el nombre de la planta e insértala en el suelo. Esta solución simple pero efectiva te ayuda a realizar un seguimiento de la diversa vida vegetal de tu jardín. Proyectos de Manualidades para Niños:

Las macetas de plástico son un recurso fantástico para proyectos de manualidades infantiles. Desde crear mini jardines hasta construir esculturas imaginativas,maceta 30 litros la naturaleza resistente y liviana de estas macetas las hace ideales para emprendimientos creativos y prácticos. Separadores Organizativos:

Las macetas de plástico más grandes se pueden cortar en secciones y reutilizar como separadores en cajones o estantes. Úsalas para mantener artículos como calcetines, accesorios o suministros de oficina separados y organizados. Conclusión:

Reutilizar las macetas de plástico no solo reduce los residuos, sino que también abre la puerta a un mundo de posibilidades creativas. Ya sea que busques mejorar tu experiencia en jardinería o agregar un toque de innovación a tu hogar, estas ideas muestran la versatilidad de las macetas de plástico más allá de su propósito inicial. Aprovecha tu creatividad y dale a estos modestos contenedores una segunda vida en tu hogar y jardín.

Efficient Indoor Gardening: Discover the Benefits of Hydroponic Grow Systems

Triclocarban and triclosan have been reported to be taken up by several crop species from hydroponic solutions. For example, after exposure to an aqueous solution mixture of triclocarban and triclosan 11 different food crops, cucumber, tomato, cabbage, okra , pepper , potato , beet, onion , broccoli, celery , and asparagus , were capable of taking up both compounds. However, translocation from roots to the aerial tissue was ≤1.9% for triclocarban and ≤ 3.7% for triclosan after 1 month of exposure . Similarly, Wu et al. found triclocarban and triclosan to have a translocation factor < 0.01 in four vegetables cultivated in a hydroponic solution with two initial exposure concentrations . In a greenhouse study, triclocarban and triclosan were taken up in radish, carrot, and soybeans from bio solid-amended soils and, the greatest concentration was observed in the carrot root after 45 d of treatment and decreased thereafter . However, in a three-year field study in which soils were amended with bio solids in accordance with Ontario providence agricultural practices, the concentration of triclosan and triclocarban in the plant tissues was relatively steady and low . Plants have also been shown to metabolize triclosan, forming 33 metabolites in horseradish cell cultures with the majority being phase II conjugates . Further, one transformation product of the triclosan, methyl-triclosan, has been widely detected in environmental samples and is known to have greater toxicity than the parent compound . Parabens are common preservatives used in cosmetics, and among the most commonly detected CECs in TWW and bio-solid. Parabens are of concern due to their endocrine disrupting potential . Parabens have been widely detected in surface waters and sediments . However,raspberry container knowledge of their behavior, uptake, and transformation in terrestrial systems is comparatively limited.

Methyl paraben was unstable in soil after application of bio-solids, with the maximum concentration of 14.1 µg kg-1 reached after 5 h and decreasing to < 1 µg kg-1 after 35 d . In a bio solid amended field, methyl paraben was the lone paraben detected in the bio solids but was not quantifiable in tomatoes, sweet corn, carrot and potatoes . The above studies highlight the potential for CECs to enter the terrestrial environment, accumulate in plant tissues, and undergo transformations in plants. However, the wide variations in plant uptake and translocation rates under different soil and environmental conditions are currently not well understood and warrant further investigation. Further, it must be noted that the majority of currently published studies have focused on many of the same 20 or so CECs and explored their uptake in mostly the same plant species . There are over 1500 pharmaceutical compounds, alone, currently in circulation . Further, many of the current models have been shown to overestimate the concentration of CECs in plant tissues . In addition, no models have been able to take into account plant metabolism when determining the concentration and risk of CECs in terrestrial plants. More research is needed on a wider swath of CECs with different physicochemical properties in a wider range of plants to improve risk assessment. Transformation of CECs in the environment, including through plant metabolism also needs to be further investigated to better understand their fate and risks in the terrestrial environment. Antibiotic exposure in plants has been widely studied due to previously observed phenotypic toxicity. Several studies showed decreases in root length and changes in shoot development of various plants exposed to several different classes of antibiotics including sulfamides, fluoroquinolones, and penicillins . Most of these studies were conducted at antibiotic concentrations greater than those of environmental relevance and/or utilized artificial or hydroponic growth media. For instance, shoot and root growth of pinto beans grown in a nutrient solution spiked with two antibiotics, chlortetracycline and oxytetracycline, significantly decreased in a dose-dependent manner . Enrofloxacin, a fluoroquinolone, induced hormetic and toxic effects on post-germination growth in lettuce, cucumber, radish and barley plants at concentrations ranging from 0.005 to 50 mg L-1 in laboratory conditions . Seed germination has also been studied as a potential biological end-point to assess toxicity to antibiotic exposure . The exposure effects on seed germination vary considerably by plant species and exposure chemical. In filter paper tests, sweet oat , rice and cucumber seeds were negatively impacted when the seeds were exposed to aqueous solutions of increasing concentrations of six antibiotics, i.e., chlortetracycline, tetracycline, tylosin, sulfamethoxazole, sulfamethazine, and trimethoprim .

The EC10 and EC50 for seed germination were, however, significantly different depending on the antibiotic and the plant species. Rice seeds exposed to sulfamethoxazole were the most sensitive with an EC10 of 0.1 mg L-1 but tylosin had an EC10 > 500 mg L.-1 On the other hand, cucumber seeds exposed to sulfamethoxazole had an EC10 > 300 mg L-1 but an EC10 of 0.17 mg L-1 for chlortetracycline . Exposure to antibiotics can also change plant nutrient and chemical compositions. For example, irrigation with water spiked with sulfamethoxazole and trimethoprim increased production in carbohydrate and soluble solid contents in tomatoes as compared to the plants irrigated with untreated water . The mechanisms driving the phytotoxicity of antibiotics have also been explored. Antibiotics can be directly toxic to or indirectly affect plants. Indirect adverse effects can arise from antibiotic exposure that detrimentally affects mycorrhizal fungi, a vital plant-microbe interaction . Direct toxicity can result when antibiotics interfere with plant hormones or chemical synthesis pathways, or damage chloroplasts, etc. For example, sulfamethoxazole was shown to directly disrupt the folate synthesis pathway in plants by blocking the action of dihydropteroate synthase . Tetracyclines was shown to interrupt mitochondrial proteostasis and damage plant chloroplasts . Interactions with plant hormones may also play a role in the observed phenotypic phytotoxicity. Erythromycin and tetracycline can promote the production of abscisic acid in plants . Abscisic acid, a stress hormone, is crucial for plant responses to drought, salinity, heavy metals, among other stressors , but antibiotic-induced production of this hormone can cause premature leaf and fruit detachment and inhibit seed germination. Plants, depending upon species, can also detoxify antibiotics through reactions with phase II metabolic enzymes . However, studies so far have shown significant variations among plant species. For example, the antibiotic chlortetracycline was detoxified by glutathione conjugation via glutathione-Stransferase in maize , but glutathione-S-transferase did not efficiently catalyze the conjugation in pinto beans . These detoxification reactions, likely produce a series of conjugated metabolites that have yet to be characterized. Understanding the extent of such conjugation is crucial for estimating the total antibiotic uptake, accumulation, and translocation of antibiotics in plants as the formation of conjugates may mask the total concentration, even though some of these conjugates may retain biological activity .

Several widely used NSAIDs, such as ibuprofen, acetaminophen, and diclofenac are amongst the most studied pharmaceuticals in the environment. Studies have shown that NSAIDs can induce toxicity to plants . Phytotoxicity, however, is often plant species and NSAID specific. For example, ibuprofen has been shown to inhibited root elongation in Sorghum bicolor at high concentrations, with EC50 of 232.64 mg L-1 . However,plastic plants pots in seed germination tests exposure to a hydroponic solution containing 1 mg L-1 ibuprofen, along with other fenamic acid class NSAIDs, increased the length of the primary root in lettuce but had no effect on radish . In the same study, diclofenac was observed to decrease the root-to-shoot ratio in radish seedlings cultivated in a sand/spiked-nutrient solution , but did not significantly affect the seed germination. However, protein content was not affected in maize cultivated in soils irrigated twice with different concentrations of acetaminophen but grain yields and seed germination were negatively impacted in a dose dependent-manner . Plants can metabolize and detoxify NSAIDs. For example, plants were found to detoxify acetaminophen by conjugation with glutathione followed by conversion to cysteine and acetylcysteine conjugates . Similarly, diclofenac was found to be converted to glucose conjugates in barley and horseradish and glutamic acid conjugates in Arabidopsis thaliana . Arabidopsis thaliana cell cultures can detoxify ibuprofen via conjugation with sugars and amino acids .As mentioned above, pharmaceuticals used to treat psychiatric disorders are another group of frequently detected pharmaceuticals in environmental samples, particularly the anticonvulsant carbamazepine . Carbamazepine exposure has been seen to exhibit mycotoxicity to carrot mycorrhizal endpoints by decreasing the production of fungal spores . Similarly, carbamazepine induced leaf necrosis, altered plant hormones and macronutrient concentrations, and reduced root growth at plant tissue concentrations of 1 to 4 mg kg-1 in zucchini cultivated in soil spiked with chemical at 0.1 – 20 mg kg-1 . Information on the toxicity of benzodiazepines and fluoxetine in terrestrial plants is still limited; however, toxicity has been reported in aquatic plantsfor these compounds, indicating that toxicity may also occur after exposure in terrestrial plants .Antimicrobials and preservatives are often added to personal care products to increase shelf life. They pass from the human body, largely unchanged, and ultimately end up in TWW, bio solids, and sewage sludge. . Antimicrobials and preservatives have been detected in agricultural soils after irrigation with TWW and/or the application of bio solids, and can be taken up by plants . Two antimicrobials, triclosan and triclocarban, have attracted more attention because of their potential for endocrine disruption and phytotoxicity . For example, triclosan significantly inhibited plant growth in cucumber and rice seedlings with EC50 of 108 mg kg-1 and 57 mg kg-1 , respectively . Lettuce shoot mass also decreased in a dose-dependent manner after cultivation in soil amended with triclocarban-spiked bio solids . On the other hand, growth of radish, carrot, soybean, spring wheat, and corn plants grown in soils amended with bio solids containing environmentally relevant concentrations of triclosan and triclocarban, improved compared to un-amended soils; likely due to the positive impacts of bio solids addition . Thus, plant species, concentrations, and growth media can significantly affect phytotoxicity of these CECs. Studies exploring the phytotoxicity of individual pharmaceuticals or classes of pharmaceuticals are useful to highlight high-risk compounds and/or the potential mechanism of toxicity.

CECs are, however, often introduced into the environment in complex mixtures and these mixtures can affect the uptake and translocation of individual compounds . Some studies report positive effects on plants exposed to CEC mixtures under environmentally relevant conditions. For instance, TWW irrigation increased tomato and lettuce yield compared to freshwater irrigation . Exposure of lettuce seedlings to a mixture of 11 CECs significantly altered plant metabolic pathways, including the citric acid cycle and pentose phosphate pathway, and decreased chlorophyll content in a dose-dependent manner . Also, exposure to 18 CECs at concentrations ranging from 5 to 50 µg L,-1 induced oxidative stress in cucumber seedlings and caused up regulation of enzymes associated with detoxification reactions . Literature on the toxicity of a number significant CECs to terrestrial plants is still very limited, and many of the studies have utilized concentrations that are orders of magnitude higher than those seen in the environment. Studies on the toxicity of mixtures in terrestrial plants are also limited, but warrant attention as several studies have indicated that mixtures can induce effects not observed from individual compounds . The ability of plants to detoxify these compounds through metabolism also merit further research. Overall, more research is needed on the toxicity of a wider range of CECs in plants under environmentally relevant conditions to more accurately assess the impacts of CECs in the agro-environment. The potential for exposure to, and toxicity of, CECs has been investigated in several aquatic invertebrate species. Toxicity end-points such as endocrine disruption, changes in growth, time to development, and mortality rates have been considered in these studies . Studies addressing the effects of CECs on terrestrial invertebrates are, however, few. Of the published studies on terrestrial invertebrates, the earthworm Eisenia fetida has been examined mainly due to their increased susceptibility and ecological importance . Literature pertaining to toxicities of various classes of CECs to terrestrial invertebrates is discussed below. Like in terrestrial plants, antibiotics can also induce toxicity in terrestrial invertebrates. Exposure to environmentally relevant concentrations of antibiotics caused mortality to earthworms and/or induced oxidative stress and genotoxicity in E. fetida. For instance, high concentrations of tetracycline and chlortetracycline inhibited antioxidant enzymes superoxide dismutase and catalase while these enzymes were stimulated at lower doses , and DNA damage was induced along a dose-dependent curve . Also, chlortetracycline can reduced juvenile earthworm and cocoon counts in E. fetida .

Hydroponics 101: A Comprehensive Guide to Soilless Agriculture

The observations indicated that the increased root biomass phenotype in the activation lines was due to the elevated OsZHD2 expression levels. In addition to the root phenotype, the OX plants and the T-DNA activation line influenced leaf development, so that abaxially curled leaves were observed . The OsZHD2-OX plants exhibited markedly increased root development at 14 DAG . Fresh and dry weights of roots were higher for the transgenic lines than for the out segregated WT . To examine whether the increase in biomass improved nutrient uptake, we analyzed the rate at which N was absorbed from a liquid growth medium containing KNO3. Based on the amount of residual N in the medium, the N concentration reduced rapidly and at a higher rate in OX plants than in the WT plants . The results suggested that the former had a higher N uptake capacity via the roots, which would also imply that the OX plants had a higher capacity to tolerate low-N conditions. To test the hypothesis, we grew the plants under low-N conditions in a growth chamber . In mature plants at the booting stage, the N concentration was 1.5- fold higher in the flag leaves of OsZHD2-OX compared with the flag leaves of the WT . The Pi accumulation rate was also 1.5-fold higher in the flag leaves of OsZHD2-OX than in the WT plants . Seed fertility was markedly higher in the over expression plants. Although <30% of the WT seeds were fertile, >50% of the grains from the OX plants were fertile . The results indicated that the uptake of nutrients increased in OsZHD2-overexpressing plants.

Plants were grown in a paddy field under normal N supply. There were no obvious phenotypic differences between the over expression plants and the WT up to maturity. Their architectures were almost identical,growing blueberries including plant height, panicle length, total spikelet number, and fertile seed number . However, the 100-grain weight was higher in the OsZHD2 OX lines . The increase in seed weight was potentially due to increased N uptake.Lateral roots began to emerge from both the WT and the activation lines at 3 DAG. By 4 DAG, the WT laterals were ~0.5 cm long, while those of the activation line were slightly longer . The difference in lengths became more pronounced as the plants grew . We performed transcriptome analyses using mRNA prepared from the total root samples of WT and OsZHD2-D plants at 4 DAG and at 6 DAG . At 4 DAG, 68 genes were up-regulated and 384 genes were down-regulated at least 2-fold in OsZHD2-D . At 6 DAG, 513 genes were up-regulated and 524 were down-regulated at least 2-fold in OsZHD2-D plants . At both stages, 22 transcripts were commonly up-regulated while 54 transcripts were down-regulated at least 2-fold . To verify the RNA sequencing data, we selected four genes that were up-regulated at both stages, in addition to CYCD4;1 and ERF3, which increased only at 6 DAG, and ABCC7 and PUB64, which were down-regulated at both stages . qRT-PCR analyses revealed that their expression patterns were similar to the patterns observed in the results of our RNA sequencing analyses . The findings suggested that the sequence data were reliable.The 22 genes that were up-regulated at both 4 and 6 DAG included two associated with ethylene biosynthesis, S-adenosylmethionine synthetase 2 and ACC oxidase 2 , which suggested that ethylene influenced the root phenotypes .

Ethylene biosynthesis begins with the conversion of methionine to S-adenosylmethione by S-adenosylmethione synthetase, with ATP as a co-substrate . In the following step, ACC is formed from S-adenosylmethione by ACC synthase . The final step is the synthesis of ethylene from ACC by ACC oxidase . Our qRT-PCR assay confirmed that the expression of OsSAM2 and OsACO2 indeed increased in OsZHD2-D lateral roots at both stages . Genes encoding ACS were not placed on the list of induced genes because the differences in transcript levels between WT plants and transgenic plants were <2-fold. However, qRT-PCR analyses revealed that ACS5 transcript levels increased in OsZHD2-D at both stages . Ethylene production measurements from 8 DAG plants showed that OsZHD2-D samples accumulated more ethylene in their roots , shoots , and the whole plant when compared with the WT plants. To examine whether OsZHD2 binds directly to ethylene biosynthesis genes, we performed ChIP assays using transgenic plants over expressing OsZHD2-Myc. Promoter regions P3, P4, and P5 of ACS5 chromatin were enriched by Myc antibodies .To investigate whether the accumulation of ethylene was the major factor responsible for the OsZHD2-D seedling root phenotypes, we investigated the effects of an ethylene biosynthesis inhibitor AVG which reduces ethylene production by blocking ACS activity . The addition of 3 µM AVG reduced lateral root growth in WT plants and rescued the enhanced lateral root growth phenotypes of OsZHD2-D . However, low concentrations of AVG did not affect the lateral growth of OsZHD2-D as well as that of the WT . To examine whether the restoration was due to decreased meristem activity, we performed EdU labeling. The results of the experiment demonstrated that the application of AVG reduced the root meristem activity of the WT and OsZHD2-D significantly .

The results suggest that OsZHD2 enhances meristem activity in the apical region of roots by inducing ethylene accumulation.To determine whether exogenous ethylene treatment promotes root development, 3 DAG seedlings were transferred to MS medium containing various concentrations of ACC. Lateral root length increased significantly when plants were supplied with 10 nM ACC . Previously reported results have suggested that ethylene induces auxin biosynthesis by stimulating the expression of Rice Anthranilate Synthase Alpha-subunit, which encodes an enzyme producing anthranilate, a precursor of Trp . To investigate whether ethylene increases auxin concentrations in rice, we generated transgenic DR5::GUS plants expressing the GUS gene under the synthetic auxin-responsive promoter and their lateral roots exhibited weak GUS expression at the tips and in the basal regions . When plants were exposed to 10 nM ACC, GUS activity was higher in the treated roots than in the control plants grown in the absence of ACC . Staining was also observed in the area between the tips and basal regions where GUS activity had not been observed prior to treatment with ACC. Consistent with the GUS assay results, the GUS transcript levels increased in ACC-treated roots . We also used a DR5::VENUS plant that expressed the yellow fluorescent protein under the influence of the DR5 promoter . The treatment of the plants with ACC increased VENUS signal in the tips and the central stele of the lateral roots . The results of such experiments suggest that ethylene induced auxin biosynthesis in the RAM. The results of qRT-PCR analyses revealed that 10 nM ACC induced the expression of OASA2 as well as auxin biosynthesis genes, TAR2 and YUCCA7, with peaks observed 6 h after treatment . According to the observations, a low concentration of ethylene could induce auxin biosynthesis in rice lateral roots. In Arabidopsis,square plant pot ethylene enhances auxin biosynthesis by increasing the expression of WEI2/ASA1 and WEI7/ASB1, two genes encoding AS sub-units . In rice, OASA1 and OASA2 encode the AS α-subunit . According to the RNA-Seq assay results, OASA2 expression was higher in OsZHD2-D roots , which was validated using qRT-PCR analyses . The major IAA biosynthesis route is the IPyA pathway, which is mediated by TAA/TARs and YUCCA in Arabidopsis . Our RT-PCR results showed that TAR2 was induced in OsZHD2-D roots . We also observed that YUCCA7 expression was higher in the activation line . An analysis of the DR5::GUS plants showed that the expression levels of the GUS reporter were significantly higher in OsZHD2-D roots . All the findings above suggested that OsZHD2 induced IAA biosynthesis. Notably, strong staining was observed in the proximal area of the root tips of OsZHD2-D, which also indicated that OsZHD2 promoted auxin accumulation in the growing region.

To investigate whether AVG treatment affects DR5::GUS expression in OsZHD2-D, we applied 3 µM AVG to the DR5::GUS plants in the WT and OsZHD2-D background. Visualization of GUS expression showed that the reporter expression was decreased by AVG in both plants . This observation supports that the increased auxin biosynthesis in OsZHD2-D was due to elevated ethylene levels. To examine whether OsZHD2 binds directly to auxin biosynthesis genes, we performed ChIP assays using transgenic plants over expressing OsZHD2-Myc. However, we were unable to observe any significant binding of OsZHD2 to the promoter regions of TAR2 and YUCCA7 . To confirm OsZHD2-D phenotypes, we analyzed expression patterns of ethylene and auxin biosynthesis genes in OsZHD2-overexpressing plants. The results of qRT-PCR analyses revealed that expression levels of ethylene and auxin biosynthesis genes are increased in OsZHD2-overexpressing plants .To further study the functional role of OsZHD2, we generated oszhd2 null mutants using the CRISPR/Cas9 [clustered regularly inter spaced short palindromic repeats / CRISPR-associated protein 9] system . Analyses of two independently obtained bi-allelic oszhd2 mutants revealed that the lengths of their seminal roots and lateral roots did not vary considerably from those of the WT and heterozygous plants. The lack of obvious phenotypic changes was potentially due to genetic redundancy. OsZHD2 encodes ZF-HDs, a protein group that includes 11 members in rice . Among them, OsZHD2 is the most homologous to OsZHD1, with 80% identity and 84% similarity at the amino acid sequence level. Plants that over express OsZHD1 exhibit an abaxially curled and drooping leaf phenotype similar to that observed in OsZHD2-OX plants. We isolated a T-DNA tagging line in which T-DNA was inserted 136 bp upstream of the start ATG codon . The expression of OsZHD1 was reduced significantly in the tagging line . For the mutant, no obvious alteration was observed in the phenotype .Since oszhd1 and oszhd2 single mutants exhibited normal root growth, we generated oszhd1 oszhd2 double mutants using the CRISPR/Cas9 system to target the conserved sequence . In the double mutants, lateral root development diminished significantly , indicating that OsZHD1 and OsZHD2 redundantly play roles in the regulation of such development. The transcript levels of SAM2, ACS5, ACO2, OASA2, TAR2, and YUCCA7 also decreased in the oszhd1 oszhd2 double mutants , supporting our hypothesis that the OsZHD genes are involved in the control of the biosynthesis of ethylene and auxin. To observe whether exogenous ethylene treatment would stimulate lateral root development in oszhd1 oszhd2 double mutants, seedlings were grown on N6 medium with or without 1 µM ACC . In the ACC-treated plants, the lengths of the lateral roots of oszhd1 oszhd2 double mutants increased more than the lengths of the lateral roots of the WT plants . These results indicate that the changes in the root architecture observed in oszhd1 oszhd2 double mutants are at least in part due to the defective ethylene biosynthesis.The over expression of OsZHD2 increased ethylene levels and enhanced the expression of genes linked to its biosynthesis. The OsZHD2 transcript is preferentially present in the meristem regions where ACS5 is expressed . Therefore, the primary role of OsZHD2 in root development appears to be the induction of ethylene production by inducing ACS5 expression. Although ethylene generally functions as a growth inhibitor, it occasionally promotes growth, particularly in semi-aquatic plants . Leaf, stem, and root development can be positively regulated by ethylene at relatively low concentrations . In addition, ethylene induces lateral root initiation near the growing root tip and promotes the emergence of lateral root primordia . The overproduction of ethylene through the application of exogenous ACC inhibits lateral root initiation but induces outgrowth of already existing primordia . These observations reported in previous studies support our hypothesis that OsZHD2 enhances root growth by increasing ethylene production in the root tips.Using plants expressing the GUS or VENUS markers under the influence of the DR5 promoter, we showed that a low concentration of ACC induced auxin accumulation in the growing region of lateral roots. We also demonstrated that ethylene increases the expression of auxin biosynthesis genes, including OASA2, TAR2, and YUCCA7 . Expression of the marker genes was promoted strongly in the region near the root tips of OsZHD2-D plants . The above expression trend was similar to that for ACC-induced GUS activity .

Cultivating the Future: The Rise and Benefits of Hydroponic Farming

Few studies have investigated the influence of environmental conditions on ENM uptake and toxicity, particularly throughout the entire plant life cycle. Here, soil-grown plants were exposed until maturity to TiO2, CeO2, or Cu2 ENMs under different illumination intensities, in different soils, and with different nutrient levels. Fluorescence and gas exchange measurements were recorded throughout growth and tissue samples from mature plants were analyzed for metal content. ENM uptake was observed in all plant species, but was seen to vary significantly with ENM type, light intensity, nutrient levels, and soil type. Light intensity in particular was found to be important in controlling uptake, likely as a result of plants increasing or decreasing transpiration in response to light. Significant impacts on plant transpiration, photosynthetic rate, CO2 assimilation efficiency, water use efficiency, and other parameters related to physiological fitness were seen. The impacts were highly dependent on environmental conditions as well as ENM and soil type. Notably, many of these effects were found to be mitigated in soils with limited ENM mobility due to decreased uptake. These results show that abiotic conditions play an important role in mediating the uptake and physiological impacts of ENMs in terrestrial plants.Nanotechnology has the potential to enhance or revolutionize many fields of study, including medicine, transportation, energy storage, personal care, construction, environmental remediation, military applications, manufacturing, and scientific research. Reflecting this broad applicability, nanotechnology has become a multi-billion dollar industry in spite of being in its infancy, and is expected to reach a global market value of over half a trillion U.S. dollars by the end of the decade.With this in mind, and with nanomaterials currently used in nearly 2000 consumer products and many industrial applications,plastic planting pots concerns have naturally arisen about the health and environmental impacts of the manufacture, use, and disposal of this new and extremely varied class of materials.

A nanomaterial is defined as a material with at least one dimension in the size range of approximately 1 to 100 nm.3 Here, the term “engineered nanomaterial”is used to differentiate intentionally designed and manufactured nanomaterials from those produced incidentally by natural or anthropogenic processes. The extreme size of ENMs, and the high surface area to volume ratio that comes along with it, typically results in unique properties not found in larger scale or dissolved materials of the same composition. For example, quantum dots, nanoscale particles composed of semiconducting materials , can utilize quantum band gap phenomena to fluoresce in a narrow range of wavelengths, which are highly dependent on their diameter.4 Additionally, ENMs can be extremely reactive due to their high surface area relative to their volume . These novel properties are simultaneously the source of global interest in ENMs and the main issue of concern in terms of the impacts to human health and environmental safety, as regulations for a bulk or dissolved material may not be appropriate for ENMs of the same composition. Additionally, since ENMs can have radically different behavior depending on their composition, size, shape, doping agents, coatings, and/or the characteristics of the media they are present in, a predictive framework for the fate, transport, and toxicity of ENMs in a variety of environments and organisms is needed to effectively regulate ENMs throughout their life cycles. The majority of the current production, use, and disposal of engineered nanomaterials occur in terrestrial environments, and consequently terrestrial ecosystems are and will increasingly be some of the largest receptors of ENMs at all stages of their life cycles.

In particular, soil is predicted to be one of the major receptors of ENMs due to ENM–contaminated bio–solid fertilizer and nanopesticide application to agricultural fields, runoff from landfills or ENM-bearing paints, or atmospheric deposition.Both agricultural and natural systems are at risk to ENM contamination via these release scenarios, which makes it necessary to understand the interactions between ENMs, soils, and soil organisms such as plants in order to predict their impacts in real-world scenarios.The goal of the research presented in this thesis was to uncover some of the underlying mechanisms controlling the following processes under environmentally relevant conditions: how ENMs move through unsaturated soils, the effects ENMs have on key soil properties, the uptake and distribution of ENMs in plants, and how ENMs influence plant growth and physiology. These topics were addressed using methods approximating real-world scenarios as closely as possible while maintaining reproducibility and analytical power. The holistic approach utilized here differs fundamentally from that of many studies currently published on these subjects, which use reductionist experimental design to attempt to break down the complex ENM-soil-plant system into simplified components. Reductionist methods can be powerful in providing detailed information about well-understood systems, but when addressing systems as complex and poorly-understood as these designing experiments to closely mimic real-world scenarios can give insight into key controlling mechanisms that can then be targeted for further study. An example of this can be found in Chapter 2, which shows that the main mechanism impeding ENM transport through unsaturated natural soils is physical straining of large ENM aggregates formed via interaction with ions in the soil solution, not through electrostatic attraction or repulsion as was predicted by several studies using well-dispersed ENMs in typical saturated columns of washed quartz sand.As mentioned, Chapter 2 discusses tracking the movement and characteristics of three metal oxide ENMs through three soils, with ENMs being either coated with natural organic matter or uncoated.

In contrast to studies such as those cited above, which use active pumping to push ENMs through water-saturated media, ENM transport in this study was in unsaturated soils and was driven solely by gravity. This was done in order to more closely simulate conditions likely to occur in the real world, as some of the major predicted exposure scenarios involve ENMs entering from the top layers of soil, which are typically unsaturated. Chapter 3 looks at the effects ENM contamination has on several soil properties, which is a subject that is poorly represented in the literature. Metal oxide ENMs like those used in this study have characteristics that make them likely to influence soil properties in some way, such as being similar in composition to naturally-occurring clay minerals that are important in controlling nutrient retention, soil porosity, and organic content.Additionally, they are amphoteric, that is, capable of producing both H+ and OH–ions depending on their crystal structure and the composition of the media they are in and thus potentially altering soil pH. Soil pH and nutrient availability are both critically important to plants and other soil organisms and were therefore targeted in this chapter. Chapters 4 and 5 explore two aspects of the same system: how plants grown to maturity in ENM-contaminated soils uptake and distribute ENMs throughout their tissues,plastic grow pots and how their growth and physiological processes are affected by the presence of ENMs. Keeping with the theme of designing experiments to predict ENM behavior in real-world scenarios, aspects of the environmental conditions the plants were grown under, specifically illumination intensity and soil nutrient levels, were varied in order to mimic some of the range of conditions plants growing under real conditions would experience.

This was done in a series of three experiments. First, the model plant Clarkia unguiculata was grown to maturity under two illumination intensities in a potting soil with and without receiving additional fertilizer in order to determine the effects of nutrient and light stress. Second, C. unguiculata was again grown to maturity under two illumination intensities, but this time in two natural soils, a grassland soil and an agricultural soil. This was done to see how these plants respond to ENM exposure in soils with different properties beyond nutrient levels. Finally, two crop plants, wheat and radishes, were grown to maturity under two illumination intensities in the grassland and agricultural soils, respectively. This was done in order to see the effects of ENM exposure on plants from different taxonomic groups that are also economically important. By varying one condition throughout this set of experiments, information can be passed from one to the next that could provide additional insight into the key factors at play. ENM mobility in the subsurface is governed by several processes of varying influence, including dissolved ion and pH-induced aggregation, coating by organic and inorganic molecules, sorption to organisms and other media components, and physical straining through soil pore spaces. In particular, chemical and electrostatic interactions with soil clay particles have been implicated as key factors in the subsurface movement of raw or coated ENMs. This has been demonstrated for TiO2 1 and uncoated, citrate-coated, and phosphate–coated CeO2 ENMs2 in soil and implied as the method of retention in other studies.Sorption can occur via electrostatic attraction between charged clay surfaces and oppositely charged ENMs5 or chemically through a dehydration reaction similar to the binding of phosphate or iron oxides to clays. Sorption to organic matter and organisms in soil may also take place through similar mechanisms. The specific organic compounds present in subsurface waters will also differ over geographic area with soil and vegetation type due to the presence of plant root exudates and bacterial communities, which will result in different coatings being available to ENMs in different areas. There is also the possibility of physical straining and collection at air–water-soil interfaces when flowing through porous media like soil. Physical straining of high aspect ratio ENMs in soil has been demonstrated with single-walled carbon nanotubes and implicated as a primary retention mechanism for nanoscale Fe0 in a sandy loam soil.

As aggregation caused by high ionic strength, pHs near the PZC, or coatings increases, physical straining becomes more likely, particularly in soils like Vertisols or Ultisols that are characterized by small pore sizes. Two hypotheses were addressed in these series of experiments. The first hypothesis was that ENM transport would be limited to the upper layers of soil, but particles coated with NOM would penetrate further into the soil due to increased electrostatic repulsive forces as a result of their more negative surface charge.The second hypothesis was that particles would be transported further through potting soil than agricultural or grassland soils due to the greater density and clay contents of the two natural soils causing increased physical straining and electrostatic/chemical sorption. Stock suspensions of CeO2, Cu2, and TiO2 ENMs were prepared by suspending dry ENM powders in 18.2 MΩ cm Nanopure water and sonicating for 30 min in a bath sonicator . Stock suspensions were sonicated for 10 min after dilution to the desired concentration and used within 24 hr. Suwannee River NOM stock solutions were prepared as described in Zhou and Keller 18 . Hydrodynamic diameter and ζ-potential of TiO2, CeO2, and Cu2 ENMs with and without NOM were measured via dynamic light scattering at 20oC by preparing 10 mg L-1 ENM suspensions with and without the addition of 1 mg L-1 NOM in Nanopure water and in soil solution extracts through dilution of a 100 mg L-1 stock, probe sonicating for 2 sec at 20% amplitude with a Misonix Sonicator S- 4000 .ENM transport through the three soils was tested by loosely packing 2.5 cm diameter x 16.34 cm long cylindrical plastic columns with air-dried soil. Due to their different densities, 17.5 ± 0.1 g potting soil, 136 ± 1 g grass soil, or 167 ± 1 g farm soil were needed to completely fill the columns. To simulate gravity-driven transport of ENMs in suspension, 50 mL of 100 mg L-1 TiO2, CeO2, or Cu2 ENM suspensions with or without the addition of 10 mg L-1 NOM were slowly applied to the top of the column. The resulting soil ENM concentrations were on the high end of those currently predicted for metal oxides in soil,but were well within the concentrations predicted for biosolids.Hence, the soil ENM concentrations used in this experiment may be indicative of those found in soils repeatedly amended with biosolids. After ENM application, columns were allowed to drain overnight, oven dried at 60°C for 72 hours, and split into 3 cm segments, ~0.3 g sub–samples of which were weighed, digested, in 10 mL 1:3 HNO3:HCl at 200°C for 1.5 hours in a microwave digestion system followed by analysis via inductively coupled plasma atomic emission spectroscopy . This technique was sufficient to dissolve the soil and ≥90% of TiO2, CeO2, and Cu2. Detection limits for all elements tested were approximately 5 μg L-1 . Standard solutions and blanks were measured every 15-20 samples for quality assurance.