Center for Agricultural Research

RNA interference (RNAi) targeting lethal genes in insects has great potential for sustainable crop protection. Compared with traditional double-stranded (ds)RNA delivery systems, nanoparticles such as chitosan, liposomes, and cationic dendrimers offer advantages in delivering dsRNA/small interfering (si)RNA to improve RNAi efficiency, thus promoting the development and practice of RNAi-based pest management strategies. Here, we illustrate the limitations of traditional dsRNA delivery systems, reveal the mechanism of nanoparticle-mediated RNAi, summarize the recent progress and successful applications of nanoparticle-mediated RNAi in pest management, and finally address the prospects of nanoparticle-based RNA pesticides.

The application of RNAi promotes the development of novel approaches toward plant protection in a sustainable way. Genetically modified crops expressing dsRNA have been developed as commercial products with great potential in insect pest management. Alternatively, some nontransformative approaches, including foliar spray, irrigation and trunk injection, are favorable in actual utilization. In this review, we summarize the recent progress and successful cases of RNAi-based pest management strategy, explore essential implications and possibilities to improve RNAi efficiency by delivery of dsRNA through transformative and nontransformative approaches, and highlight the remaining challenges and important issues related to the application of this technology.

BACKGROUND: Fulvic acid (FA) is a kind of plant growth regulator, which can promote plant growth, play an important role in fighting against drought, improve plant stress resistance, increase production and improve quality. However, the function of FA in tea plants during drought stress remain largely unknown. RESULTS: Here, we examined the effects of 0.1 g/L FA on genes and metabolites in tea plants at different periods of drought stress using transcriptomics and metabolomics profiles. Totally, 30,702 genes and 892 metabolites were identified. Compared with controlled groups, 604 and 3331 differentially expressed metabolite genes (DEGs) were found in FA-treated tea plants at 4 days and 8 days under drought stress, respectively; 54 and 125 differentially expressed metabolites (DEMs) were also found at two time points, respectively. Bioinformatics analysis showed that DEGs and DEMs participated in diverse biological processes such as ascorbate metabolism (GME, AO, ALDH and L-ascorbate), glutathione metabolism (GST, G6PDH, glutathione reduced form and CYS-GYL), and flavonoids biosynthesis (C4H, CHS, F3'5'H, F3H, kaempferol, quercetin and myricetin). Moreover, the results of co-expression analysis showed that the interactions of identified DEGs and DEMs diversely involved in ascorbate metabolism, glutathione metabolism, and flavonoids biosynthesis, indicating that FA may be involved in the regulation of these processes during drought stress. CONCLUSION: The results indicated that FA enhanced the drought tolerance of tea plants by (i) enhancement of the ascorbate metabolism, (ii) improvement of the glutathione metabolism, as well as (iii) promotion of the flavonoids biosynthesis that significantly improved the antioxidant defense of tea plants during drought stress. This study not only confirmed the main strategies of FA to protect tea plants from drought stress, but also deepened the understanding of the complex molecular mechanism of FA to deal with tea plants to better avoid drought damage.

Abstract We examine the incentives of atomistic producers to differentiate and collectively market products. We analyze market and welfare effects of alternative producer organizations, discuss circumstances under which they will evolve, and describe implications for the ongoing debate between the EU and the United States. As fixed costs of development and marketing increase and the anticipated market size falls, it becomes essential to increase the producer organization's ability to control supply to cover the fixed costs associated with the introduction of differentiated products. Counterintuitively, stronger property right protection for producer organizations may enhance welfare even after a differentiated product has been developed.

Biofertilizers are a key component of organic agriculture. Bacterial biofertilizers enhance plant growth through a variety of mechanisms, including soil compound mobilization and phosphate solubilizing bacteria (PSB), which convert insoluble phosphorus to plant-available forms. This specificity of PSB allows them to be used as biofertilizers in order to increase P availability, which is an immobile element in the soil. The objective of our study is to assess the capacity of PSB strains isolated from phosphate solid sludge to solubilize three forms of inorganic phosphates: tricalcium phosphate (Ca3(PO4)2), aluminum phosphate (AlPO4), and iron phosphate (FePO4), in order to select efficient solubilization strains and use them as biofertilizers in any type of soil, either acidic or calcareous soil. Nine strains were selected and they were evaluated for their ability to dissolve phosphate in the National Botanical Research Institute’s Phosphate (NBRIP) medium with each form of phosphate (Ca3(PO4)2, AlPO4, and FePO4) as the sole source of phosphorus. The phosphate solubilizing activity was assessed by the vanadate-molybdate method. All the strains tested showed significantly (p ≤ 0.05) the ability to solubilize the three different forms of phosphates, with a variation between strains, and all strains solubilized Ca3(PO4)2 more than FePO4 and AlPO4.

During maize production, drought throughout the flowering stage usually induces seed abortion and yield losses. The influence of postpollination drought stress on seed abortion and its underlying mechanisms are not well characterized. By intervening in the competition for assimilates between kernel siblings under different degrees of postpollination drought stresses accompanied by synchronous pollination (SP) and incomplete pollination (ICP) approaches, the mechanisms of postpollination abortion were investigated at physiological and molecular levels. Upon SP treatment, up to 15% of the fertilized apical kernels were aborted in the drought-exacerbated competition for assimilates. The aborted kernels exhibited weak sucrose hydrolysis and starch synthesis but promoted the synthesis of trehalose-6-phosphate and ethylene. In ICP where basal pollination was prevented, apical kernel growth was restored with reinstated sucrose metabolism and starch synthesis and promoted sucrose and hexose levels under drought stress. In addition, the equilibrium between ethylene and polyamine in response to the drought and pollination treatments was associated with the abortion process. We conclude that competition for assimilates drives postpollination kernel abortion, whereas differences in sugar metabolism and the equilibrium between ethylene and polyamines may be relevant to the "live or die" choice of kernel siblings during this competition.

Immune checkpoint inhibitor (ICI) therapy is effective against many cancers for a subset of patients; a large percentage of patients remain unresponsive to this therapy. One contributing factor to ICI resistance is accumulation of monocytic myeloid-derived suppressor cells (M-MDSCs), a subset of innate immune cells with potent immunosuppressive activity against T lymphocytes. Here, using lung, melanoma, and breast cancer mouse models, we show that CD73-expressing M-MDSCs in the tumor microenvironment (TME) exhibit superior T cell suppressor function. Tumor-derived PGE 2 , a prostaglandin, directly induces CD73 expression in M-MDSCs via both Stat3 and CREB. The resulting CD73 overexpression induces elevated levels of adenosine, a nucleoside with T cell–suppressive activity, culminating in suppression of antitumor CD8 + T cell activity. Depletion of adenosine in the TME by the repurposed drug PEGylated adenosine deaminase (PEG-ADA) increases CD8 + T cell activity and enhances response to ICI therapy. Use of PEG-ADA can therefore be a therapeutic option to overcome resistance to ICIs in cancer patients.

The semi arid lands of Jordan are fragile and severely degraded due to low rainfall and mismanagement of natural resources. As human demands increase, sustaining the productivity of land becomes more and more important. Land suitability evaluation can contribute towards better land management; mitigation of land degradation; and designing land use pattern that prevents environmental problems through segregation of competing land uses. Suitability analysis allows identifying the main limiting factors for the agricultural production and enables decision makers to develop crop managements able to increase the land productivity. The purpose of this study was to develop a Geographic Information System (GIS) based approach for land use suitability assessment in order to assist land managers to identify areas with physical limitations for different land use alternatives based on research criteria developed by FAO and modified by stakeholders. This study was conducted using various data and maps incorporated within (GIS) in order to derive potential suitability for different Land Utilization Types (LUTs). Land suitability mapping was developed using an innovative approach that integrates soil and climatic data for land suitability assessment. Suitability maps for each land use were developed to show the suitability classes and display the spatial representation of soils suitable for agriculture. The output of suitability analyses provided not only the type of land use for which the land was suitable, but also information about the type of limitation (s) facing the utilization of the land. Optimum land use alternatives (scenarios) were formulated to improve and optimize the agricultural production in the study area.

Cucumber Fusarium wilt, induced by Fusarium oxysporum f. sp. cucumerinum (FOC), causes severe losses in cucumber yield and quality. Nitrogen (N), as the most important mineral nutrient for plants, plays a critical role in plant–pathogen interactions. Hydroponic assays were conducted to investigate the effects of different N forms (NH4+ vs. NO3‒) and supply levels (low, 1 mM; high, 5 mM) on cucumber Fusarium wilt. The NO3‒-fed cucumber plants were more tolerant to Fusarium wilt compared with NH4+-fed plants, and accompanied by lower leaf temperature after FOC infection. The disease index decreased as the NO3‒ supply increased but increased with the NH4+ level supplied. Although the FOC grew better under high NO3− in vitro, FOC colonization and fusaric acid (FA) production decreased in cucumber plants under high NO3− supply, associated with lower leaf membrane injury. There was a positive correlation between the FA content and the FOC number or relative membrane injury. After the exogenous application of FA, less FA accumulated in the leaves under NO3− feeding, accompanied with a lower leaf membrane injury. In conclusion, higher NO3− supply protected cucumber plants against Fusarium wilt by suppressing FOC colonization and FA production in plants, and increasing the plant tolerance to FA.

ABSTRACT: Nonpoint source pollution in intensively managed agricultural landscapes is of great concern to the general population, farmers and policymakers, as it impacts local water quality and can have large downstream effects, as in the case of hypoxia in the Gulf of Mexico. In this study, we outline a methodology to simultaneously assess economic costs and water quality benefits associated with the hypothetical placement of a broad set of conservation practices. The study, performed for the Iowa Department of Natural Resources, assesses thirteen major subbasins in Iowa by interfacing economic models with the Soil and Water Assessment Tool model. The conservation practices analyzed include land set-aside, terraces, grassed waterways, contouring, conservation tillage, and a simple nutrient reduction strategy. Annual costs range from $300 to $597 million. Predicted sediment, total phosphorus (P), and nitrate decreases range from six to 65 percent, 28 to 59 percent, and six to 20 percent, respectively, relative to the baseline.

SUMMARY Drought is a major abiotic stress reducing maize ( Zea mays ) yield worldwide especially before and during silking. The mechanism underlying drought tolerance in maize and the roles of different organs have not been elucidated. Hence, we conducted field trials under pre‐silking drought conditions using two maize genotypes: FM985 (drought‐tolerant) and ZD958 (drought‐sensitive). The two genotypes did not differ in plant height, grain number, and yield under control conditions. However, the grain number per ear and the yield of FM985 were 38.1 and 35.1% higher and plants were 17.6% shorter than ZD958 under drought conditions. More 13 C photosynthates were transported to the ear in FM985 than in ZD958, which increased floret fertility and grain number. The number of differentially expressed genes was much higher in stem than in other organs. Stem–ear interactions are key determinants of drought tolerance, in which expression of genes related to abscisic acid, lignin, and flavonoid biosynthesis and carbon metabolism in the stem was induced by drought, which inhibited stem elongation and promoted assimilate allocation to the ear in FM985. In comparison with ZD958, the activities of trehalose 6‐phosphate phosphatase and sucrose non‐fermentation‐associated kinase 1 were higher in the stem and lower in the kernel of FM985, which facilitated kernel formation. These results reveal that, beyond the ear response, stem elongation is involved in the whole process of drought tolerance before silking. Abscisic acid together with trehalose 6‐phosphate, lignin, and flavonoid suppresses stem elongation and allocates assimilates into the ear, providing a novel and systematic regulatory pathway for drought tolerance in maize.

Oxidative stress is an important molecular mechanism for kidney injury in mercury poisoning. We studied lycopene, a potent carotenoid found in tomatoes due to its large antioxidant properties, and also evaluated the ability of lycopene to prevent HgCl(2) nephrotoxicity. Rats were injected with HgCl(2) (0 or 5 mg/kg body weight, subcutaneously) 6 hr after lycopene administration (0, 10, 25 or 50 mg/kg by gavage) and were killed 12 hr after HgCl(2) exposure. HgCl(2)-induced inhibition of delta-aminolevulinate dehydratase activity (approximately 35%) and increase of lipid peroxidation in kidney (approximately 37%) were prevented by lycopene. However, lycopene did not prevent the increase of plasma creatinine levels (approximately 123%) and renal tubular necrosis induced by HgCl(2). Glutathione peroxidase and catalase activities were enhanced (approximately 71% and approximately 41%), while superoxide dismutase activity was depressed (approximately 44%) in HgCl(2)-treated rats when compared to control and these effects were prevented by lycopene. Our results indicate that although lycopene did not prevent HgCl(2)-induced renal failure, it could play a beneficial role against HgCl(2) toxicity by preventing lipid peroxidation and changes in the activity of delta-aminolevulinate dehydratase and antioxidant enzymes.

Phage type 99 of Salmonella enterica subsp. enterica serovar Typhimurium variant Copenhagen strains isolated from pigeons were examined for the presence of genotypic and phenotypic characteristics. The pulsed-field gel electrophoresis patterns obtained with XbaI and BlnI from 38 pigeon strains were compared with those obtained from 89 porcine, poultry, and human strains of variant Copenhagen. Identical patterns with XbaI and four closely related patterns with BlnI were obtained with the pigeon strains, whereas 16 XbaI patterns were found with the other strains. The XbaI patterns of the pigeon strains showed a low genetic similarity to the patterns of the porcine, poultry, and human strains and invariably showed a low-molecular-weight band that was absent in the majority of the other strains. The virulence genes shdA, spvR, pefA, sopE, and spvB were uniformly present in six pigeon isolates representing the genetic diversity found with BlnI. These six pigeon-derived strains were highly cytotoxic for pigeon macrophages compared to three porcine strains. After experimental infection of pigeons with a pigeon strain, clinical symptoms, fecal shedding, and colonization of internal organs were more pronounced than those after infection with a porcine strain. These data suggest that the phage type 99 strains used in this study are highly adapted to pigeons and should be classified as a host-restricted lineage of the serovar Typhimurium.

Abstract Fusarium head blight (FHB) is one of the major fungal diseases in wheat throughout the world. To control FHB severity, breeding genetically resistant varieties is thought to be the most promising strategy. In wheat breeding programmes, short cultivars predominantly carrying the Norin 10 derived semi‐dwarfing allele Rht‐D1b ( Rht2 ) are preferred worldwide because of higher achievable grain yields and lower risk of lodging. This study was conducted to determine the influence of different alleles at the Rht‐D1 locus on FHB reaction. Three winter wheat populations were produced by crossing rather susceptible varieties ‘Biscay’, ‘Pirat’ and ‘Rubens’ carrying mutant‐type allele Rht‐D1b with the more resistant varieties ‘Apache’, ‘Romanus’ and ‘History’ containing the Rht‐D1a wild‐type allele ( rht2 ). The 190, 216 and 103 progeny of the F 4 ‐derived populations were assayed for the presence of Rht‐D1a or Rht‐D1b , plant height, and mean FHB rating after spray inoculation at flowering time with a highly aggressive isolate of Fusarium culmorum . Comparably, high mean FHB severities ranging from 28% to 49% for all population × environment combinations were achieved, with significant genotypic variation for FHB rating and plant height within all populations. Both traits were negatively correlated with r ranging from −0.48 to −0.61 in the complete populations. However, within the subpopulations homozygous for one or other height allele these correlations decreased considerably. The Rht‐D1b semi‐dwarfing allele resulted in 7–18% shorter plants, depending on the population, but a considerably increased FHB reaction of 22–53%. Nevertheless, significant genotypic variance for FHB resistance remained in all tested Rht‐D1b subpopulations indicating that selection for moderately FHB resistant genotypes within agronomically beneficial Rht‐D1b genotypes is still feasible.

Contamination of water reservoirs with different toxic metal ions from industrial activities has emerged as one of major issues in recent years. The adsorption of Pb(II) ions from aqueous solution onto Nano platelets kaolinite has been investigated. The adsorption studies were determined as a function of pH, contact time, initial metal ion concentration, adsorbent dosage and temperature. Nano platelets kaolinite prepared from raw Jordanian kaolin clay showed size in the range of 12-80 nm. Maximum adsorption capacity as determined by Langmuir isotherm model is 175.44 mg/g for Pb(II). Thermodynamic parameters, ∆G^o, ∆H^o and ∆S^o were revealed that the adsorption process is spontaneous and endothermic process. The results showed that Nano platelets kaolinite can be efficiently used as a low-cost alternative and eco-friendly adsorbent for the removal of toxic heavy metals from wastewater.

Diet and health attitudes affect food consumption behavior. The National Dairy Board provided information on the benefits of calcium and dairy products in a 1985–86 national advertising campaign. A latent variable measuring consumer attitudes, constructed based on an ad tracking survey, is shown to have a positive effect on both the probability of dairy product purchase as well as the quantity of dairy products purchased. The consumption data were from the USDA "Continuing Survey of Food Intakes by Individuals."

Belowground nitrogen (N) transfer from legumes to non-legumes provides an important N source for crop yield and N utilization. However, whether root contact facilitates N transfer and the extent to which N transfer contributes to crop productivity and N utilization have not been clarified. In our study, two-year rain shelter experiments were conducted to quantify the effect of root contact on N transfer in a maize/alfalfa intercropping system. N transfer occurred mainly one direction from alfalfa to maize during the growth period. Following the N0 treatment, the amount of N transfer from alfalfa to maize was 204.56 mg pot−1 with no root barrier and 165.13 mg pot−1 with a nylon net barrier, accounting for 4.72% and 4.48% of the total N accumulated in maize, respectively. Following the N1 treatment, the amount of N transfer from alfalfa to maize was 197.70 mg pot−1 with no root barrier and 139.04 mg pot−1 with a nylon net barrier, accounting for 3.64% and 2.36% of the total N accumulated in the maize, respectively. Furthermore, the amount of N transfer without no root barrier was 1.24–1.42 times higher than that with a nylon net barrier regardless of the level of N addition. Our results highlight the importance and the relevance of root contact for the enhancement of N transfer in a maize/alfalfa intercropping system.

Soil water balance studies of profile water content, changes in stored water, crop water use, and spatial variability of water content and use require accurate soil water determinations that are representative across at least field‐sized areas. Several capacitance and other electromagnetic (EM) sensors are commercially available for use in access tubes to determine profile water content. Scientists and practitioners need to know if they are suitable replacements for the neutron moisture meter (NMM) in terms of accuracy and utility. In a field calibration of the NMM and three EM sensors in a Panoche clay loam soil in the San Joaquin Valley of California, three access tubes were installed in a site dried by plant water uptake and three were installed in an adjacent plot wetted to saturation and allowed to drain. Sensors were read and volumetric water content samples taken at several depths at each access tube; calibrations of water content vs. sensor reading were calculated for each depth and for appropriate combinations of depths by regression analysis. Calibrations for the EM sensors changed rapidly with depth, often requiring separate calibrations for every 10‐ or 20‐cm depth range, and were relatively inaccurate (RMSE of 0.015–0.063 m 3 m −3 ). The NMM is the preferred choice for accurate profile water content and change in storage determination. In general, the EM sensors cannot be recommended for profile water content or change in storage determinations due to their relatively less accurate (larger RMSE values) calibrations, strong dependence of calibration slopes and exponents on depth, probable dependence of the calibrations on soil bulk electrical conductivity (BEC), and the likelihood of BEC changes in the field during the irrigation season.

Due to the rapid expansion of irrigated agriculture, effi cient use of the limited water resources in arid and semi-arid regions is becoming more and more vital.However, water salinity is a major problem due to its negative infl uence on the yields of many crops.It reduces citrus trees' growth and causes physiological disorders.Primarily salt-stress lowers net CO 2 assimilation, stomatal conductance, and water potential of citrus tree leaves, in addition to accumulation of excessive concentration of Chloride or Sodium in leaves.A great deal of research indicates that citrus have the genetic potential to be salt-sensitive; however inheritance studies in citrus are scarce.In this paper the adverse of effects of salinity on physiological aspects of citrus are reviewed.The review summarizes the prevailing state of knowledge about the responses and tolerance of citrus trees to salinity.

RNA interference (RNAi) is a robust tool to study gene functions as well as potential for insect pest control. Finding suitable target genes is the key step in the development of an efficient RNAi-mediated pest control technique. Based on the transcriptome of Chilo suppressalis, 24 unigenes which putatively associated with insect hormone biosynthesis were identified. Amongst these, four genes involved in ecdysteroidogenesis i.e., ptth, torso, spook and nm-g were evaluated as candidate targets for function study. The partial cDNA of these four genes were cloned and their bacterially expressed dsRNA were fed to the insects. Results revealed a significant reduction in mRNA abundance of target genes after 3 days. Furthermore, knocked down of these four genes resulted in abnormal phenotypes and high larval mortality. After 15 days, the survival rates of insects in dsspook, dsptth, dstorso, and dsnm-g groups were significantly reduced by 32%, 38%, 56%, and 67% respectively, compared with control. Moreover, about 80% of surviving larvae showed retarded development in dsRNA-treated groups. These results suggest that oral ingestion of bacterially expressed dsRNA in C. suppressalis could silence ptth, torso, spook and nm-g. Oral delivery of bacterially expressed dsRNA provides a simple and potential management scheme against C. suppressalis.