ResearchPad - soybean Default RSS Feed en-us © 2020 Newgen KnowledgeWorks <![CDATA[Genome-wide association study of partial resistance to sclerotinia stem rot of cultivated soybean based on the detached leaf method]]> Sclerotinia stem rot (SSR) is a devastating fungal disease that causes severe yield losses of soybean worldwide. In the present study, a representative population of 185 soybean accessions was selected and utilized to identify the quantitative trait nucleotide (QTN) of partial resistance to soybean SSR via a genome-wide association study (GWAS). A total of 22,048 single-nucleotide polymorphisms (SNPs) with minor allele frequencies (MAF) > 5% and missing data < 3% were used to assess linkage disequilibrium (LD) levels. Association signals associated with SSR partial resistance were identified by two models, including compressed mixed linear model (CMLM) and multi-locus random-SNP-effect mixed linear model (mrMLM). Finally, seven QTNs with major effects (a known locus and six novel loci) via CMLM and nine novel QTNs with minor effects via mrMLM were detected in relation to partial resistance to SSR, respectively. One of all the novel loci (Gm05:14834789 on Chr.05), which was co-located by these two methods, might be a stable one that showed high significance in SSR partial resistance. Additionally, a total of 71 major and 85 minor candidate genes located in the 200-kb genomic region of each peak SNP detected by CMLM and mrMLM were found, respectively. By using a gene-based association, a total of six SNPs from three major effects genes and eight SNPs from four minor effects genes were identified. Of them, Glyma.18G012200 has been characterized as a significant element in controlling fungal disease in plants.

<![CDATA[A cation diffusion facilitator, GmCDF1, negatively regulates salt tolerance in soybean]]>

Salt stress is one of the major abiotic factors that affect the metabolism, growth and development of plants, and soybean [Glycine max (L.) Merr.] germination is sensitive to salt stress. Thus, to ensure the successful establishment and productivity of soybeans in saline soil, the genetic mechanisms of salt tolerance at the soybean germination stage need to be explored. In this study, a population of 184 recombinant inbred lines (RILs) was utilized to map quantitative trait loci (QTLs) related to salt tolerance. A major QTL related to salt tolerance at the soybean germination stage named qST-8 was closely linked with the marker Sat_162 and detected on chromosome 8. Interestingly, a genome-wide association study (GWAS) identified several single nucleotide polymorphisms (SNPs) significantly associated with salt tolerance in the same genetic region on chromosome 8. Resequencing, bioinformatics and gene expression analyses were implemented to identify the candidate gene Glyma.08g102000, which belongs to the cation diffusion facilitator (CDF) family and was named GmCDF1. Overexpression and RNA interference of GmCDF1 in soybean hairy roots resulted in increased sensitivity and tolerance to salt stress, respectively. This report provides the first demonstration that GmCDF1 negatively regulates salt tolerance by maintaining K+-Na+ homeostasis in soybean. In addition, GmCDF1 affected the expression of two ion homeostasis-associated genes, salt overly sensitive 1 (GmSOS1) and Na+/H+ exchanger 1 (GmNHX1), in transgenic hairy roots. Moreover, a haplotype analysis detected ten haplotypes of GmCDF1 in 31 soybean genotypes. A candidate-gene association analysis showed that two SNPs in GmCDF1 were significantly associated with salt tolerance and that Hap1 was more sensitive to salt stress than Hap2. The results demonstrated that the expression level of GmCDF1 was negatively correlated with salt tolerance in the 31 soybean accessions (r = -0.56, P < 0.01). Taken together, these results not only indicate that GmCDF1 plays a negative role in soybean salt tolerance but also help elucidate the molecular mechanisms of salt tolerance and accelerate the breeding of salt-tolerant soybean.

<![CDATA[Analysis of bone osteometry, mineralization, mechanical and histomorphometrical properties of tibiotarsus in broiler chickens demonstrates a influence of dietary chickpea seeds (Cicer arietinum L.) inclusion as a primary protein source]]>

This study was focused on analyzing the effects of dietary inclusion of raw chickpea seed as a replacement of soybean meal as a primary protein source on bone structure in broiler chickens. Broiler chickens (n = 160) received in their diet either soybean meal (SBM) or raw chickpea seeds (CPS) as a primary protein source throughout the whole rearing period (n = 80 in each group). On the 42th day randomly selected chickens from each group (n = 8) were slaughtered. Collected tibiotarsus were subjected to examination of the biomechanical characteristics of bone mid-diaphysis, microstructure of the growth plate and articular cartilages; the analysis of mineral content and crystallinity of mineral phase, and the measurements of thermal stability of collagen in hyaline cartilage were also carried out. The inclusion of chickpea seeds resulted in increase of bone osteometric parameters (weight, length and mid-diaphysis cross-sectional area) and mechanical endurance (yield load, ultimate load, stiffness, Young modulus). However, when loads were adjusted to bone shape (yield and ultimate stress) both groups did not differ. Mineral density determined by means of densitometric measurements did not differ between groups, however the detailed analysis revealed the differences in the macro- and microelements composition. The results of FT-IR and XRD analyses showed no effect of diet type on mineral phase crystallinity and hydroxyapatite nanocrystallites size. In trabecular bone, the increase of real bone volume (BV/TV) and number of trabeculae was observed in the CPS group. Total thickness of articular cartilage was the same in both groups, save the transitional zone, which was thicker in the SBM group. The total thickness of the growth plate cartilage was significantly increased in the CPS group. The area of the most intense presence of proteoglycans was wider in the SBM group. The structural analysis of fibrous components of bone revealed the increase of fraction of thin, immature collagen content in articular cartilage, trabeculae and compact bone in the CPS group. The dietary inclusion of CPS affected the thermal stability of collagen, as decrease of net denaturation enthalpy was observed. This study showed a beneficial effect of CPS on the skeletal development, improving the overall bone development and the microarchitecture of cancellous bone. It suggests that CPS can be a promising replacement for SBM in broilers feeding in the aspect of animal welfare related to the development of the skeletal system.

<![CDATA[Effects of acute exposures of 2,4,6-trinitrotoluene and inorganic lead on the fecal microbiome of the green anole (Anolis carolinensis)]]>

Microbiome studies focused on ecologically relevant vertebrate models like reptiles have been limited. Because of their relatively small home range, fast maturation, and high fecundity, lizards are an excellent reptilian terrestrial indicator species. For this study we used the green anole, Anolis carolinensis, to assess the impact of military relevant contaminants on fecal microbiome composition. Fourteen day sub-acute exposures were conducted via oral gavage with 2,4,6-Trinitrotoluene (TNT) and inorganic lead at doses of 60 mg/kg and 20 mg/kg of body weight, respectively. Body weights and food consumption were monitored and fecal samples were collected for high-throughput 16S rRNA gene amplicon sequencing and analytical chemistry at days 0 and 15. At the end of the study, liver and gut were harvested for body burden data. Chemical analysis confirmed accumulation of TNT, TNT transformation products, and lead in liver tissue and fecal samples. Bacterial community analysis of fecal material revealed significant differences between day 0 and day 15 of TNT exposed anoles with an operational taxonomic unit (OTU) within the genus Erwinia representing 32% of the microbial community in TNT exposed anoles. Predictable changes in gut microbiome composition could offer an easily assayed, noninvasive biomarker for specific chemical exposure providing enhanced scientific support to risk assessments on military installations.

<![CDATA[GmCYP82A3, a Soybean Cytochrome P450 Family Gene Involved in the Jasmonic Acid and Ethylene Signaling Pathway, Enhances Plant Resistance to Biotic and Abiotic Stresses]]>

The cytochrome P450 monooxygenases (P450s) represent a large and important enzyme superfamily in plants. They catalyze numerous monooxygenation/hydroxylation reactions in biochemical pathways, P450s are involved in a variety of metabolic pathways and participate in the homeostasis of phytohormones. The CYP82 family genes specifically reside in dicots and are usually induced by distinct environmental stresses. However, their functions are largely unknown, especially in soybean (Glycine max L.). Here, we report the function of GmCYP82A3, a gene from soybean CYP82 family. Its expression was induced by Phytophthora sojae infection, salinity and drought stresses, and treatment with methyl jasmonate (MeJA) or ethephon (ETH). Its expression levels were consistently high in resistant cultivars. Transgenic Nicotiana benthamiana plants overexpressing GmCYP82A3 exhibited strong resistance to Botrytis cinerea and Phytophthora parasitica, and enhanced tolerance to salinity and drought stresses. Furthermore, transgenic plants were less sensitive to jasmonic acid (JA), and the enhanced resistance was accompanied with increased expression of the JA/ET signaling pathway-related genes.

<![CDATA[Virus-induced down-regulation of GmERA1A and GmERA1B genes enhances the stomatal response to abscisic acid and drought resistance in soybean]]>

Drought is a major threat to global soybean production. The limited transformation potential and polyploid nature of soybean have hindered functional analysis of soybean genes. Previous research has implicated farnesylation in the plant’s response to abscisic acid (ABA) and drought tolerance. We therefore used virus-induced gene silencing (VIGS) to evaluate farnesyltransferase genes, GmERA1A and GmERA1B (Glycine max Enhanced Response to ABA1-A and -B), as potential targets for increasing drought resistance in soybean. Apple latent spherical virus (ALSV)-mediated GmERA1-down-regulated soybean leaves displayed an enhanced stomatal response to ABA and reduced water loss and wilting under dehydration conditions, suggesting that GmERA1A and GmERA1B negatively regulate ABA signaling in soybean guard cells. The findings provide evidence that the ALSV-VIGS system, which bypasses the need to generate transgenic plants, is a useful tool for analyzing gene function using only a single down-regulated leaf. Thus, the ALSV-VIGS system could constitute part of a next-generation molecular breeding pipeline to accelerate drought resistance breeding in soybean.

<![CDATA[A Genome-Wide Association Study for Agronomic Traits in Soybean Using SNP Markers and SNP-Based Haplotype Analysis]]>

Mapping quantitative trait loci through the use of linkage disequilibrium (LD) in populations of unrelated individuals provides a valuable approach for dissecting the genetic basis of complex traits in soybean (Glycine max). The haplotype-based genome-wide association study (GWAS) has now been proposed as a complementary approach to intensify benefits from LD, which enable to assess the genetic determinants of agronomic traits. In this study a GWAS was undertaken to identify genomic regions that control 100-seed weight (SW), plant height (PH) and seed yield (SY) in a soybean association mapping panel using single nucleotide polymorphism (SNP) markers and haplotype information. The soybean cultivars (N = 169) were field-evaluated across four locations of southern Brazil. The genome-wide haplotype association analysis (941 haplotypes) identified eleven, seventeen and fifty-nine SNP-based haplotypes significantly associated with SY, SW and PH, respectively. Although most marker-trait associations were environment and trait specific, stable haplotype associations were identified for SY and SW across environments (i.e., haplotypes Gm12_Hap12). The haplotype block 42 on Chr19 (Gm19_Hap42) was confirmed to be associated with PH in two environments. These findings enable us to refine the breeding strategy for tropical soybean, which confirm that haplotype-based GWAS can provide new insights on the genetic determinants that are not captured by the single-marker approach.

<![CDATA[Bayesian Inference of Baseline Fertility and Treatment Effects via a Crop Yield-Fertility Model]]>

To effectively manage soil fertility, knowledge is needed of how a crop uses nutrients from fertilizer applied to the soil. Soil quality is a combination of biological, chemical and physical properties and is hard to assess directly because of collective and multiple functional effects. In this paper, we focus on the application of these concepts to agriculture. We define the baseline fertility of soil as the level of fertility that a crop can acquire for growth from the soil. With this strict definition, we propose a new crop yield-fertility model that enables quantification of the process of improving baseline fertility and the effects of treatments solely from the time series of crop yields. The model was modified from Michaelis-Menten kinetics and measured the additional effects of the treatments given the baseline fertility. Using more than 30 years of experimental data, we used the Bayesian framework to estimate the improvements in baseline fertility and the effects of fertilizer and farmyard manure (FYM) on maize (Zea mays), barley (Hordeum vulgare), and soybean (Glycine max) yields. Fertilizer contributed the most to the barley yield and FYM contributed the most to the soybean yield among the three crops. The baseline fertility of the subsurface soil was very low for maize and barley prior to fertilization. In contrast, the baseline fertility in this soil approximated half-saturated fertility for the soybean crop. The long-term soil fertility was increased by adding FYM, but the effect of FYM addition was reduced by the addition of fertilizer. Our results provide evidence that long-term soil fertility under continuous farming was maintained, or increased, by the application of natural nutrients compared with the application of synthetic fertilizer.

<![CDATA[Effects of diesel exhaust particle exposure on a murine model of asthma due to soybean]]>


Exposure to soybean allergens has been linked to asthma outbreaks. Exposure to diesel exhaust particles (DEP) has been associated with an increase in the risk of asthma and asthma exacerbation; however, in both cases the underlying mechanisms remain poorly understood, as does the possible interaction between the two entities.


To investigate how the combination of soybean allergens and DEP can affect the induction or exacerbation of asthma in a murine model.


BALB/c mice received intranasal instillations of saline, 3 or 5 mg protein/ml soybean hull extract (SHE), or a combination of one of these three solutions with DEP. Airway hyperresponsiveness (AHR), pulmonary inflammation in bronchoalveolar lavage, total serum immunoglobulin E and histological studies were assessed.


A 5 mg protein/ml SHE solution was able by itself to enhance AHR (p = 0.0033), increase eosinophilic inflammation (p = 0.0003), increase levels of IL-4, IL-5, IL-13, IL-17A, IL-17F and CCL20, and reduce levels of IFN-γ. The combination of 5 mg protein/ml SHE with DEP also produced an increase in AHR and eosinophilic inflammation, but presented a slightly different cytokine profile with higher levels of Th17-related cytokines. However, while the 3 mg protein/ml SHE solution did not induce asthma, co-exposure with DEP resulted in a markedly enhanced AHR (p = 0.002) and eosinophilic inflammation (p = 0.004), with increased levels of IL-5, IL-17F and CCL20 and decreased levels of IFN-γ.

Conclusions & clinical relevance

The combination of soybean allergens and DEP is capable of triggering an asthmatic response through a Th17-related mechanism when the soybean allergen concentration is too low to promote a response by itself. DEP monitoring may be a useful addition to allergen monitoring in order to prevent new asthma outbreaks.

<![CDATA[Root Parameters Show How Management Alters Resource Distribution and Soil Quality in Conventional and Low-Input Cropping Systems in Central Iowa]]>

Plant-soil relations may explain why low-external input (LEI) diversified cropping systems are more efficient than their conventional counterparts. This work sought to identify links between management practices, soil quality changes, and root responses in a long-term cropping systems experiment in Iowa where grain yields of 3-year and 4-year LEI rotations have matched or exceeded yield achieved by a 2-year maize (Zea mays L.) and soybean (Glycine max L.) rotation. The 2-year system was conventionally managed and chisel-ploughed, whereas the 3-year and 4-year systems received plant residues and animal manures and were periodically moldboard ploughed. We expected changes in soil quality to be driven by organic matter inputs, and root growth to reflect spatial and temporal fluctuations in soil quality resulting from those additions. We constructed a carbon budget and measured soil quality indicators (SQIs) and rooting characteristics using samples taken from two depths of all crop-phases of each rotation system on multiple dates. Stocks of particulate organic matter carbon (POM-C) and potentially mineralizable nitrogen (PMN) were greater and more evenly distributed in the LEI than conventional systems. Organic C inputs, which were 58% and 36% greater in the 3-year rotation than in the 4-year and 2-year rotations, respectively, did not account for differences in SQI abundance or distribution. Surprisingly, SQIs did not vary with crop-phase or date. All biochemical SQIs were more stratified (p<0.001) in the conventionally-managed soils. While POM-C and PMN in the top 10 cm were similar in all three systems, stocks in the 10–20 cm depth of the conventional system were less than half the size of those found in the LEI systems. This distribution was mirrored by maize root length density, which was also concentrated in the top 10 cm of the conventionally managed plots and evenly distributed between depths in the LEI systems. The plow-down of organic amendments and manures established meaningful differences in SQIs and extended the rhizosphere of the LEI systems. Resulting efficiencies observed in the LEI grain crops indicate that resource distribution as well as abundance is an important component of soil function that helps explain how LEI systems can maintain similar or greater yields with fewer inputs than achieved by their conventional counterparts.

<![CDATA[Genetic variation of maturity groups and four E genes in the Chinese soybean mini core collection]]>

The mini core collection (MCC) has been established by streamlining core collection (CC) chosen from China National Genebank including 23,587 soybean (Glycine max) accessions by morphological traits and simple sequence repeat (SSR) markers. Few studies have been focused on the maturity that has been considered as one of the most critical traits for the determination of the adaptation-growing region of the soybean. In the current study, two hundred and ninty-nine accessions of MCC planted for two years at four locations namely in Heihe, Harbin, Jining and Wuhan cities in China were used to assess the variation of maturity in MCC and identify the integrated effect of 4 E loci on flowering and maturity time in soybean. Forty-two North American varieties served as references of maturity groups (MG). Each accession in MCC was classified by comparing with the MG references in the days from VE (emergence) and physiological maturity (R7). The results showed that MCC covered a large range of MGs from MG000 to MGIX/X. Original locations and sowing types were revealed as the major affecting factors for maturity groups of the MCC accessions. The ratio of the reproductive period to the vegetative period (R/V) varied among MCC accessions. Genotyping of 4 maturity genes (i.e. E1, E2, E3 and E4) in 228 accessions indicated that recessive alleles e1, e2, e3 and e4 promoted earlier flowering and shortened the maturity time with different effects, while the dominate alleles were always detected in accessions with longer maturity. The allelic combinations determined the diversification of soybean maturity groups and adaptation to different regions. Our results indicated that the maturity of Chinese soybean MCC showed genetic diversities in phenotype and genotype, which provided information for further MG classification, geographic adaptation analysis of Chinese soybean cultivars, as well as developing new soybean varieties with adaptation to specific regions.

<![CDATA[Contrasting Role of Temperature in Structuring Regional Patterns of Invasive and Native Pestilential Stink Bugs]]>


Assessment and identification of spatial structures in the distribution and abundance of invasive species is important for unraveling the underlying ecological processes. The invasive agricultural insect pest Halyomorpha halys that causes severe economic losses in the United States is currently expanding both within United States and across Europe. We examined the drivers of H. halys invasion by characterizing the distribution and abundance patterns of H. halys and native stink bugs (Chinavia hilaris and Euschistus servus) across eight different spatial scales. We then quantified the interactive and individual influences of temperature, and measures of resource availability and distance from source populations, and their relevant spatial scales. We used Moran’s Eigenvector Maps based on Gabriel graph framework to quantify spatial relationships among the soybean fields in mid-Atlantic Unites States surveyed for stink bugs.


Results from the multi-spatial scale, multivariate analyses showed that temperature and its interaction with resource availability and distance from source populations structures the patterns in H. halys at very broad spatial scale. H. halys abundance decreased with increasing average June temperature and distance from source population. H. halys were not recorded at fields with average June temperature higher than 23.5°C. In parts with suitable climate, high H. halys abundance was positively associated with percentage developed open area and percentage deciduous forests at 250m scale. Broad scale patterns in native stink bugs were positively associated with increasing forest cover and, in contrast to the invasive H. halys, increasing mean July temperature. Our results identify the contrasting role of temperature in structuring regional patterns in H. halys and native stink bugs, while demonstrating its interaction with resource availability and distance from source populations for structuring H. halys patterns.


These results help predicting the pest potential of H. halys and vulnerability of agricultural systems at various regions, given the climatic conditions, and its interaction with resource availability and distance from source populations. Monitoring and control efforts within parts of the United States and Europe with more suitable climate could focus in areas of peri-urban developments with deciduous forests and other host plants, along with efforts to reduce propagule pressure.

<![CDATA[Genetic diversity, QoI fungicide resistance, and mating type distribution of Cercospora sojina—Implications for the disease dynamics of frogeye leaf spot on soybean]]>

Frogeye leaf spot (FLS), caused by Cercospora sojina, causes significant damage to soybean in the U.S. One control strategy is the use of quinone outside inhibitor (QoI) fungicides. QoI resistant isolates were first reported in Tennessee (TN) in 2010. To investigate the disease dynamics of C. sojina, we collected 437 C. sojina isolates in 2015 from Jackson and Milan, TN and used 40 historical isolates collected from 2006–2009 from TN and ten additional states for comparison. A subset of 186 isolates, including historical isolates, were genotyped for 49 single nucleotide polymorphism (SNP) markers and the QoI resistance locus, revealing 35 unique genotypes. The genotypes clustered into three groups with two groups containing only sensitive isolates and the remaining group containing all resistant isolates and a dominant clonal lineage of 130 isolates. All 477 C. sojina isolates were genotyped for the QoI locus revealing 344 resistant and 133 sensitive isolates. All isolates collected prior to 2015 were QoI sensitive. Both mating type alleles (MAT1-1-1 and MAT1-2) were found in Jackson and Milan, TN and recovered from single lesions suggesting sexual recombination may play a role in the epidemiology of field populations. Analysis of C. sojina isolates using SNP markers proved useful to investigate population diversity and to elaborate on diversity as it relates to QoI resistance and mating type.

<![CDATA[Intercropping Enhances Productivity and Maintains the Most Soil Fertility Properties Relative to Sole Cropping]]>

Yield and nutrient acquisition advantages are frequently found in intercropping systems. However, there are few published reports on soil fertility in intercropping relative to monocultures. A field experiment was therefore established in 2009 in Gansu province, northwest China. The treatments comprised maize/faba bean, maize/soybean, maize/chickpea and maize/turnip intercropping, and their correspoding monocropping. In 2011 (the 3rd year) and 2012 (the 4th year) the yields and some soil chemical properties and enzyme activities were examined after all crop species were harvested or at later growth stages. Both grain yields and nutrient acquisition were significantly greater in all four intercropping systems than corresponding monocropping over two years. Generally, soil organic matter (OM) did not differ significantly from monocropping but did increase in maize/chickpea in 2012 and maize/turnip in both years. Soil total N (TN) did not differ between intercropping and monocropping in either year with the sole exception of maize/faba bean intercropping receiving 80 kg P ha−1 in 2011. Intercropping significantly reduced soil Olsen-P only in 2012, soil exchangeable K in both years, soil cation exchangeable capacity (CEC) in 2012, and soil pH in 2012. In the majority of cases soil enzyme activities did not differ across all the cropping systems at different P application rates compared to monocrops, with the exception of soil acid phosphatase activity which was higher in maize/legume intercropping than in the corresponding monocrops at 40 kg ha−1 P in 2011. P fertilization can alleviate the decline in soil Olsen-P and in soil CEC to some extent. In summary, intercropping enhanced productivity and maintained the majority of soil fertility properties for at least three to four years, especially at suitable P application rates. The results indicate that maize-based intercropping may be an efficient cropping system for sustainable agriculture with carefully managed fertilizer inputs.

<![CDATA[Comparison of Metabolites Variation and Antiobesity Effects of Fermented versus Nonfermented Mixtures of Cudrania tricuspidata, Lonicera caerulea, and Soybean According to Fermentation In Vitro and In Vivo]]>

We used ultra-performance-liquid-chromatography with quadrupole-time-of-flight mass spectrometry to study the changes in metabolites in the mixture of Cudrania tricuspidata, Lonicera caerulea, and soybean (CLM) during fermentation. Additionally, the antiobesity effects of CLM and fermented-CLM (FCLM) were studied based on the analysis of plasma from high-fat diet (HFD)-fed mice. The levels of cyanidin and the glycosides of luteolin, quercetin, and cyanidin derived from L. caerulea were decreased, whereas the levels of luteolin and quercetin were increased during fermentation. Isoflavone glycosides and soyasaponins originating from the soybean were decreased, whereas their aglycones such as daidzein, glycitein, and genistein were increased. As for prenylated flavonoids from C. tricuspidata, these metabolites were decreased at the early stage of fermentation, and were increased at end of the fermentation. In terms of the functional food product, various metabolites derived from diverse natural products in CLM had complementary effects and demonstrated higher antioxidant and pancreatic lipase inhibition activities after fermentation; these activities were closely related to flavonoid aglycones including genistein, daidzein, glycitein, luteolin, and quercetin. In an in vivo experiment, several clinical parameters affected by HFD were improved by the administration of either CLM or FCLM, but there was a difference in the antiobesity effects. The levels of lysoPCs with C20:4, C16:0, and C22:6 were significantly attenuated by CLM administration, while the attenuated levels of lysoPCs with C20:4 and C18:2 were significantly restored by FCLM administration. These metabolites may explain the above-mentioned differences in antiobesity effects. Although only the changes in plasma lysophospholipids could not fully explain antiobesity effects between non-fermented and fermented plant mixtures from our results, we suggest that metabolomics approach could provide a way to reveal the metabolite alterations in the complex fermentation process and understand the differences or changes in bioactivity according to fermentation.

<![CDATA[Bacillus aryabhattai SRB02 tolerates oxidative and nitrosative stress and promotes the growth of soybean by modulating the production of phytohormones]]>

Plant growth promoting rhizobacteria (PGPR) are diverse, naturally occurring bacteria that establish a close association with plant roots and promote the growth and immunity of plants. Established mechanisms involved in PGPR-mediated plant growth promotion include regulation of phytohormones, improved nutrient availability, and antagonistic effects on plant pathogens. In this study, we isolated a bacterium from the rhizospheric soil of a soybean field in Chungcheong buk-do, South Korea. Using 16S rRNA sequencing, the bacterium was identified as Bacillus aryabhattai strain SRB02. Here we show that this strain significantly promotes the growth of soybean. Gas chromatography—mass spectrometry analysis showed that SRB02 produced significant amounts of abscisic acid, indole acetic acid, cytokinin and different gibberellic acids in culture. SRB02-treated soybean plants showed significantly better heat stress tolerance than did untreated plants. These plants also produced consistent levels of ABA under heat stress and exhibited ABA-mediated stomatal closure. High levels of IAA, JA, GA12, GA4, and GA7, were recorded in SRB02-treated plants. These plants produced longer roots and shoots than those of control plants. B. aryabhattai SRB02 was found to be highly tolerant to oxidative stress induced by H2O2 and MV potentiated by high catalase (CAT) and superoxide dismutase (SOD) activities. SRB02 also tolerated high nitrosative stress induced by the nitric oxide donors GSNO and CysNO. Because of these attributes, B. aryabhattai SRB02 may prove to be a valuable resource for incorporation in biofertilizers and other soil amendments that seek to improve crop productivity.

<![CDATA[A Landscape View of Agricultural Insecticide Use across the Conterminous US from 1997 through 2012]]>

Simplification of agricultural landscapes is expected to have positive effects on many crop pests and negative effects on their natural enemies, potentially leading to increased pest pressure, decreased crop yield, and increased insecticide use. While many intermediate links in this causal chain have empirical support, there is mixed evidence for ultimate relationships between landscape simplification, crop yield, and insecticide use, especially at large spatial and temporal scales. We explored relationships between landscape simplification (proportion of a county in harvested cropland) and insecticide use (proportion of harvested cropland treated with insecticides), using county-level data from the US Census of Agriculture and a variety of standard and spatiotemporal regression techniques. The best model indicated that insecticide use across the US has increased between 1997 and 2012, was strongly dependent on the crops grown in a county, increased with average farm income and size, and increased with annual growing degree days. After accounting for those variables, and other unidentified spatial and temporal structure in the data, there remained a statistically significant, moderate, positive relationship between insecticide use and landscape simplification. These results lend general support to the causal chain outlined above, and to the notion that a landscape perspective is useful for managing ecosystem services that are provided by mobile organisms and valuable to agriculture.

<![CDATA[SNP-SNP Interaction Analysis on Soybean Oil Content under Multi-Environments]]>

Soybean oil content is one of main quality traits. In this study, we used the multifactor dimensionality reduction (MDR) method and a soybean high-density genetic map including 5,308 markers to identify stable single nucleotide polymorphism (SNP)—SNP interactions controlling oil content in soybean across 23 environments. In total, 36,442,756 SNP-SNP interaction pairs were detected, 1865 of all interaction pairs associated with soybean oil content were identified under multiple environments by the Bonferroni correction with p <3.55×10−11. Two and 1863 SNP-SNP interaction pairs detected stable across 12 and 11 environments, respectively, which account around 50% of total environments. Epistasis values and contribution rates of stable interaction (the SNP interaction pairs were detected in more than 2 environments) pairs were detected by the two way ANOVA test, the available interaction pairs were ranged 0.01 to 0.89 and from 0.01 to 0.85, respectively. Some of one side of the interaction pairs were identified with previously research as a major QTL without epistasis effects. The results of this study provide insights into the genetic architecture of soybean oil content and can serve as a basis for marker-assisted selection breeding.

<![CDATA[Beneficial rhizobacteria immobilized in nanofibers for potential application as soybean seed bioinoculants]]>

Seed inoculation with plant growth promoting rhizobacteria (PGPR) is an ideal tool to supply the soil with a high density of beneficial microorganisms. However, maintaining viable microorganisms is a major problem during seed treatment and storage. In this work, an evaluation was made of the effect of bacterial immobilization in nanofibers on the stability (viability and maintenance of beneficial properties) of two potential PGPR, Pantoea agglomerans ISIB55 and Burkholderia caribensis ISIB40. Moreover, the impact of soybean seed coating with nanofiber-immobilized rhizobacteria on bacterial survival during seed storage and on germination and plant growth parameters was determined. Bacterial nanoimmobilization and subsequent seed coating with nanofiber-immobilized rhizobacteria were carried out by electrospinning. The results demonstrate that this technique successfully immobilized P. agglomerans ISIB55 and B. caribensis ISIB40 because it did not affect the viability or beneficial properties of either rhizobacteria. Seed coating with nanofiber-immobilized rhizobacteria improved P. agglomerans ISIB55 and B. caribensis ISIB40 survival on seeds stored for 30 days and contributed to the successful colonization of both bacteria on the plant root. Moreover, seed coating with P. agglomerans ISIB55 increased germination, length and dry weight of the root. Furthermore, seed coating with B. caribensis ISIB40 increased leaf number and dry weight of the shoot. Therefore, the technique applied in the present work to coat seeds with nanofiber-immobilized PGPR could be considered a promising eco-friendly approach to improve soybean production using a microbial inoculant.

<![CDATA[Characterization of Natural and Simulated Herbivory on Wild Soybean (Glycine soja Seib. et Zucc.) for Use in Ecological Risk Assessment of Insect Protected Soybean]]>

Insect-protected soybean (Glycine max (L.) Merr.) was developed to protect against foliage feeding by certain Lepidopteran insects. The assessment of potential consequences of transgene introgression from soybean to wild soybean (Glycine soja Seib. et Zucc.) is required as one aspect of the environmental risk assessment (ERA) in Japan. A potential hazard of insect-protected soybean may be hypothesized as transfer of a trait by gene flow to wild soybean and subsequent reduction in foliage feeding by Lepidopteran insects that result in increased weediness of wild soybean in Japan. To assess this potential hazard two studies were conducted. A three-year survey of wild soybean populations in Japan was conducted to establish basic information on foliage damage caused by different herbivores. When assessed across all populations and years within each prefecture, the total foliage from different herbivores was ≤ 30%, with the lowest levels of defoliation (< 2%) caused by Lepidopteran insects. A separate experiment using five levels of simulated defoliation (0%, 10%, 25%, 50% and 100%) was conducted to assess the impact on pod and seed production and time to maturity of wild soybean. The results indicated that there was no decrease in wild soybean plants pod or seed number or time to maturity at defoliation rates up to 50%. The results from these experiments indicate that wild soybean is not limited by lepidopteran feeding and has an ability to compensate for defoliation levels observed in nature. Therefore, the potential hazard to wild soybean from the importation of insect-protected soybean for food and feed into Japan is negligible.