Tag: macetas cultivo

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.

Seven replications of 10-tree plots received the pruning and nutritional treatment combinations

A number of transcriptome studies have been conducted and reported to characterize the gene expression dynamics in citrus-HLB interactions. These studies indicated that many citrus genes/pathways were modulated by HLB. The present study was conducted to gain comprehensive insight about the underlying molecular mechanisms in citrus-HLB interactions. Twenty-two publicly available citrus gene expression datasets, including 18 from HLB-susceptible and four from HLB-resistant citrus selections, were retrieved; and previously identified, differentially expressed genes were analyzed using the LIMMA and the RankProd methods. Out of a combined list of 7,412 DEGs, we identified the most significant 65 common genes and 30 R-dataset-specific DEGs. Gene Ontology analysis of these DEGs suggested that carbohydrate metabolism and transport, and stress response were the core pathways in citrus modulated by HLB. The 30 Rdataset-specific DEGs were mainly coded for LRR proteins, chitinases, CDR, miraculins, or lectins. Weighted gene co-expression network analysis of 2,499 DEGs revealed 21 modules with major hub genes. The miRNA nested network analysis suggested that csi-miR167 and csimiR396 could affect citrus transporters and defense response pathways, respectively. Collectively, these meta-analyses suggested candidate genes for further gene expression analysis,macetas de 5 litros over-expression analysis, or other genetic modification towards increased HLB resistance in citrus. Citrus Greening was first detected in Puerto Rico in 2009 affecting orange and lemon .

The causal agent was confirmed as Candidatus Liberibacter asiaticus. CG is transmitted by the Asian Citrus Psyllid Diaphorina citri Kuwayana and by human mediated grafting transmission. A survey conducted in 2010–2012 showed that the disease is widely spread in Puerto Rico. Consequently, efforts on an education program were established by the Extension Service to train agricultural agents on identification of CG and citrus orchard management practices. In order to maintain pathogen-free bud wood material, the Agricultural Experiment Station of the University of Puerto Rico, Mayagüez Campus has moved all the germplasm to insect-proof screen houses. Initially, all the germplasm was located on AES at Isabela, Puerto Rico. Currently, new collections have been moved to AES at Rio Piedras and Adjuntas, Puerto Rico. AES is the only one that has protected citrus bud wood that is certified CG free in Puerto Rico. In 2014, AES started a new institutional initiative to integrate various researchers to work with the critical citrus situation. The new initiative formed the project Production of Healthy Citrus Plants in Puerto Rico. This project combines the certification of disease free citrus plants and the development of new methodology on the production of pathogen-free citrus plants in screen-protected houses. The certification will detect citrus greening, citrus variegated chlorosis, citrus leprosis, citrus exocortis, and citrus canker. On the other hand, the new methodology will explore different media components, fertilization, container design and size, different rootstock and varieties in order to accelerate root growth and whole plant development. Current status of the screen-protected houses, current germplasm collection, and practices will be presented.In the state of Colima, Mexico, there are 20,000 hectares of Mexican lime . The Asian citrus psyllid has been present there since 2004, while the ‘Huanglongbing’ disease was detected in 2010. Seven months after the first detection, HLB positive trees were found in all producing areas of the state.

In June 2013, a systematic sampling was done in 299 orchards checking 7500 trees, resulting that 100% of the orchards and 100% of the sampled trees had HLB symptoms, which had a canopy portion affected by the disease ranging from 25 to 75%. During 2010, 2011, and 2012, the number of fruits per square meter of canopy in different orchards was quantified. In these 3 years, the results were similar; it was observed that trees with HLB symptoms in over 75% of the canopy tend to reduce their production of fruit between 40 and 60%. Also, it was evident that asymptomatic sectors in HLB-affected trees present good production and good fruit size. And contrary to that, symptomatic sectors have chlorotic foliage, a reduced yield, and a fruit size slightly smaller in comparison with fruits from healthy trees. Until nowadays, in Mexican lime, it has not been detected misshapen fruit, inverted ripening, or an increased number of aborted seeds related to HLB. During 2013, an average yield of 14.4 t/ha was recorded, representing a reduction of 23.4 and 39.7% compared to that recorded in 2010 and 2012, respectively. This partly reflects the effect of HLB on Mexican lime production in Colima. It has been observed that an integrated crop management, with special emphasis on nutrition, although with a lower yield, allows HLB-affected trees to continue producing fruit. This represents an option for producers while HLB tolerant varieties are generated.Severe pruning has been suggested as a strategy to rejuvenate citrus trees which have been adversely affected by HLB. Pruning rebalances a tree’s root to canopy ratio and thus allows an infected tree to increase its capacity to set fruit. An experiment was initiated at the UF/IFAS Southwest REC in February 2010 to measure the effects from severely pruning HLB-infected trees. Four years of data including shoot growth, canopy development, and fruit yield were collected from 2010 through 2013. Fifteen-year-old Valencia orange on Swingle citrumelo root stock grown on two-row beds typical of citrus in the Florida flat woods were selected, pruning one row and leaving the other row unpruned.

Three foliar nutritional treatments plus a standard grower fertilizer program were applied to both pruned and unpruned trees.The harvestable yield from pruned trees was minimal in 2010, the year of pruning, and constituted the largest financial penalty when attempting to rejuvenate HLB-infected trees through severe pruning. Production from pruned trees recovered during the second season and was statistically equal to production from unpruned trees. In 2012 and 2013, production from pruned trees surpassed the production from unpruned trees. Juice quality data generally showed no significant differences between pruned and unpruned trees. Cost effectiveness of pruning, however, depended on the enhanced foliar nutritional program. Pruned trees on two of the three nutritional programs produced nearly a box more fruit than unpruned trees receiving the same nutritional program. The increase in net returns was estimated to nearly $4 per tree. The cost of severe pruning plus the value of yield loss in the first year after pruning was estimated to be less than $2.30 per tree. Foliar nutritional programs have been adopted by nearly all Florida citrus growers as a strategy to maintain production from HLB-infected trees. Important questions arise, however, as to the relative importance and necessary quantity of micro- and macro-nutrients. Five years of production and cost data were collected from a trial on a commercial block of Valencia on Swingle on which various combinations of nutritional supplements were applied three times a year corresponding to the spring, summer, and fall flushes. Nine foliar treatments were designed and replicated five times over a 30-acre block. All treatments received a uniform ground fertilizer application and a uniform psyllid control spray program. The foliar treatments represented various combinations of micro- and macro-nutrients. Annual fruit yield and juice quality were recorded for each treatment and analyzed both by individual year and cumulatively across the 5-year period. Fruit revenue was estimated using average fruit prices reported in the Annual Citrus Summary . The costs of the individual nutritional treatments were itemized using 2013 retail fertilizer prices. Significant yield differences between all foliar nutritional programs and a standard were noted starting in the second year of the trial.

Those treatments that combined both micro- and macro-nutrients yielded the greatest yield benefits. While the treatment with the greatest complement of microand macro-nutrients resulted in the largest numerical yield gain, the yield differences among most of the foliar nutritional programs were not significantly different. The costs of nutritional products, however, ranged significantly from $100 to $550 per acre.Huanglongbing or citrus greening, caused by the phloem-limited bacterium Liberibacter asiaticus , is threatening the viability of the citrus industry in the United States. The search for an effective treatment of HLB is imperative. Using the closest culturable relative to Las, Liberibacter crescens ,macetas cultivo as a model organism, we have quickly and inexpensively screened a variety of likely phloem mobile compounds for effectiveness prior to field experiments. An existing model describes the optimal chemical characteristics of phloem mobile xenobiotics as: an octanol/water partition coefficient between -1.5 and 2.5, a molar volume ≤300 cm3mol- 1 , and ionizability between 2 and 15 . Following these assumptions, we selected and screened 145 compounds for Lc sensitivity using a high-throughput 96-well assay method. The percent inhibition was evaluated for multiple concentrations of each compound and the MIC90 and MIC50 was noted. Of the 145 screened compounds, 50 showed ≥90% inhibition at one or more concentrations. Of those, 12 were penicillins, 16 were cephalsporins, 2 were carbapenems, 7 were tetracyclines, 6 were aromatic hydrocarbons, 3 were nitro compounds, and 4 were organic chemicals . The 27 quinolines and 20 sulfones tested showed little impact on Lc growth. Our next step is to test the phytotoxicity of those antimicrobials that are phloem mobile and inhibit Lc. Oxytetracycline fits these criteria and showed no phytotoxicity after repeated foliar sprays at 200 ppm. Using this selection and assay method, we can efficiently sift through multiple treatment options and only select the most suitable for more laborious field-testing, and ideally provide a short-term treatment option for commercial citrus growers. Eventually, these results could help guide the production of effective novel compounds that will provide additional treatment options.Current strategies for managing Huanglongbing include area–wide psyllid vector control, inoculum removal, use of clean planting stock, and foliar nutritional supplements to sustain productivity of groves with infected trees. Foliar nutritional supplementation has had mixed results, in part, because the basis for such supplementation to suppress HLB has either not been established or is useful in correcting specific nutrient deficiencies observed in trees. The possibility that other mechanisms such as toxicity and other nutrient interactions could be interfering with tree metabolism has not been addressed. In this multi-year field/lab study , the impact of HLB infection on leaf mineral contents of adequately-fertilized grapefruit and sweet orange trees was investigated in Texas. Symptomatic and non-symptomatic leaves from known HLB-infected trees and leaves from non-infected trees, selected based on visual observations and qPCR tests, were analyzed for mineral composition .

Leaves from HLB-infected trees had significantly higher TNC levels than leaves from healthy trees. HLB-infected trees also exhibited significant decreases in leaf nitrogen , phosphorus , magnesium , calcium and zinc , and significant increases in sodium , copper , and boron concentrations of symptomatic leaves compared to healthy trees, whereas asymptomatic leaves from HLB-infected trees had intermediate values. Significant correlations were obtained between leaf nutrient concentration and CT values. The present observations shed further light on the physiological and biochemical changes associated with HLB disease development. Since these groves were well fertilized, the observed differences seem to arise, at least in part, from an imbalance in uptake of soil minerals, suggesting that the decline in leaf/tree physiological function may be due to toxicity associated with elevated tissue concentrations of Na and other trace elements.In 2011, we have demonstrated that feeding dsRNA targeting specific genes within the insect are toxic through RNA silencing mechanisms. This approach opened the door to use psyllid specific dsRNAs that high amounts are by citrus tristeza virus in the phloem, the site of the viral replication and D. citri site of feeding. Some of the dsRNA molecules can move in the citrus once expressed in the phloem into the xylem a minor site of psyllids feeding. Two important targets were selected: a) important gut digestive enzyme and b) enzymes that control synthesis and metabolism of juvenile hormone, an important hormone that controls metamorphism, egg development, and behavior. D. citri infected with Liberibacter asiaticus were allowed to feed on citrus trees that were transfected with CTV synthesizing dsRNA targeting digestive and juvenile hormone synthesis and metabolic enzymes. Adult D. citri were assayed initially by PCR for L. asiaticus and allowed to lay eggs on the leaves and the newly emerged adults were assayed for number of surviving adults and for L. asiaticus titers using PCR. A marked decrease in the number of the surviving adults was noted when compared with controls citrus trees that did not express dsRNA. The surviving adults when assayed by PCR were negative for L. asiaticus indicating that expressing specific dsRNA molecules in citrus can be highly effective against the spread of L. asiaticus by D. citri. A road map to control psyllid infestations and L. asiaticus spread will be discussed. Only two therapies have been shown to be effective for treating trees infected with “Candidatus Liberibacter asiaticus” : thermal therapy and bactericide therapy. There have been reports of several bactericides reducing CLas titer and alleviating HLB symptoms.