Soybean Resistance Research Articles

Integrated Transcriptomic, Proteomic, and Metabolomic Analyses Revealed Molecular Mechanism for Salt Resistance in Soybean (Glycine max L.) Seedlings

Salt stress poses a significant challenge to plant growth and restricts agricultural development. To delve into the intricate mechanisms involved in soybean’s response to salt stress and find targets to improve the salt resistance of soybean, this study integrated transcriptomic, proteomic, and metabolomic analyses to explore the regulatory networks involved in soybean salt tolerance. Transcriptomic analysis revealed significant changes in transcription factors, hormone-related groups, and calcium ion signaling. Notably, the biosynthetic pathways of cutin, suberine, and wax biosynthesis play an important role in this process. Proteomic results indicated salt-induced DNA methylation and the enrichment of phosphopyruvate hydrase post-salt stress, as well as its interaction with enzymes from various metabolic pathways. Metabolomic data unveiled the synthesis of various metabolites, including lipids and flavonoids, in soybean following salt stress. Furthermore, the integrated multiomics results highlighted the activation of multiple metabolic pathways in soybean in response to salt stress, with six pathways standing out prominently: stilbenoid, diarylheptanoid, and gingerol biosynthesis; carotenoid biosynthesis; carbon fixation in photosynthetic organisms; alanine, aspartate, and glutamate metabolism; thiamine metabolism; and pyruvate metabolism. These findings not only offer valuable insights into leveraging multiomics profiling techniques for uncovering salt tolerance mechanisms but also identify candidate genes for soybean improvement.

Genome-Wide Identification, Expression and Interaction Analysis of GLN Gene Family in Soybean

As a globally significant economic crop, the seed size of soybean (Glycine max [L.] Merr.) is jointly regulated by internal genetic factors and external environmental signals. This study discovered that the GLN family proteins in soybean are similar to the KIX-PPD-MYC transcriptional repressor complex in Arabidopsis, potentially influencing seed size by regulating the expression of the downstream gene GIF1. Additionally, β-1,3-glucanase (βGlu) plays a crucial role in antifungal activity, cell composition, flower development, pollen development, abiotic resistance, seed germination, and maturation in soybean. Through a detailed analysis of the structure, chromosomal localization, phylogenetic relationships, and expression situations in different tissues at different stages of the soybean GLN gene family members, this research certifies a theoretical foundation for subsequent research on the biological functions of GLN genes in soybean. This research incorporated a comprehensive genomic identification and expression analysis of the GLN gene family in soybean. The results indicate that the 109 soybean GLN genes are unevenly distributed across soybean chromosomes and exhibit diverse expression patterns in different tissues, suggesting they may have distinct functions in soybean morphogenesis. GO enrichment analysis shows that the GLN gene family may participate in a variety of biological activities, cellular components, and molecular biological processes, particularly in catalytic activity, cellular components, and metabolic processes. These findings provide important information for comprehending the role of the GLN gene family in soybean and offer potential targets for molecular breeding of soybean.

Investigating the Role of Soybean Genetic Resistance on the Production of Sclerotinia sclerotiorum Sclerotia.

Sclerotia serve as survival structures for many plant pathogens, including Sclerotinia sclerotiorum, which causes Sclerotinia stem rot (SSR) in soybeans and leads to significant yield losses. While partially resistant soybean varieties are effective in reducing SSR incidence, the relationship between resistance and sclerotial production remains unclear. This study investigated the sclerotial production of two soybean recombinant inbred lines (RILs) with differential levels of SSR resistance under both greenhouse and field conditions. In the greenhouse, three S. sclerotiorum isolates of varying aggressiveness were used to screen the two RILs, revealing differences in disease development and sclerotial characteristics. Under greenhouse conditions, the susceptible RIL resulted in greater SSR development, higher total sclerotia production, and greater sclerotial mass per plant than the resistant RIL. Field trials in 2022 and 2023 with the same two soybean RILs, demonstrated that the susceptible RIL consistently produced more sclerotia than the resistant. Further linear regressions between the SSR incidence (DI, %) and sclerotial mass were examined for the susceptible and resistant RILs, where on the susceptible each 10% increase in DI resulted in 28.5 kg ha-1 of sclerotia produced, and on the resistant RIL each 10% increase in DI resulted in 16.2 kg ha-1. These findings provide new insights into the impact of SSR resistance in soybeans on sclerotial production and highlight the importance of selecting resistant soybean varieties to reduce potential build-up of long-lasting inoculum loads.

Using red–green–blue vegetation indices to evaluate complex agronomical traits in soybean breeding

AbstractHigh‐throughput phenotyping is an emerging tool that allows access to identify simple and complex traits, accelerating genetic discoveries and selection. Vegetation indices strongly correlate with several economic crop traits, allowing plant breeders to detect variation in breeding populations. Thus, this study used red–green–blue (RGB) vegetation indices to evaluate the influence of the stink bug complex (Euschistus heros, Piezodorus guildinii, Nezara viridula, Dichelops melacanthus, and Edessa meditabunda) on the agronomical traits of soybean (Glycine max) lineages. For instance, two experiments were conducted to assess soybean resistance to the stink bug complex, (1) with and (2) without pesticide control. An unmanned aerial vehicle coupled with an RGB camera acquired aerial photography over the field during the R5 stage. Four vegetation indices and canopy were estimated from the orthomosaic, and the genotypes were evaluated based on agronomical traits. Linear mixed models were used to estimate the variance and significance test of each trait using the likelihood ratio test, and the principal component analysis was performed to verify the multivariate pattern among genotypes. The results showed significant genotypic effects for most traits with high broad‐sense heritability for agronomical traits and moderate for vegetation indices. Significant correlations using best linear unbiased predictions were observed among the agronomical traits with the vegetation indices and canopy coverage, which can be used as a tool for the indirect selection of soybean lineages in the breeding pipeline.

Rapid Identification of Soybean SC15 Resistance Locus to Soybean Mosaic Virus by BSA-seq

Rapid Identification of Soybean SC15 Resistance Locus to Soybean Mosaic Virus by BSA-seq

Transcriptome Comparison between Resistant and Susceptible Soybean Cultivars in Response to Inoculation of Phytophthora sojae.

Phytophthora root and stem rot, caused by Phytophthora sojae, considerably reduces soybean yield worldwide. Our previous study identified two genomic regions on chromosome 18 (2.1-2.6 and 53.1-53.3 Mbp) that confer resistance to the P. sojae isolate 2457, through linkage analysis using progenies derived from the Daepung × Socheong2 population. These two regions contained 51 and 19 annotated genes, respectively. However, the specific gene responsible for resistance to P. sojae isolate 2457 has yet to be identified. In this study, we performed a comparative transcriptomic analysis of Socheong2 and Daepung, two Korean soybean varieties identified as resistant and susceptible to P. sojae isolate 2457, respectively. RNA sequencing was conducted on tissue samples collected at 0, 6, and 12 hours after inoculation (HAI), and significant differences in the expression of defense-related genes were observed across time points and between the two cultivars. Genes associated with the jasmonic acid, salicylic acid, ethylene, and systemic acquired resistance pathways were upregulated in both cultivars at 6 and 12 HAI compared to 0 HAI, with these biological processes were more strongly upregulated in Socheong2 compared to Daepung at 6 and 12 HAI. A comparison of differentially expressed genes (DEGs) and candidate genes within the previously identified QTL regions revealed an ortholog of the HS1 PRO-1 2 gene from Arabidopsis thaliana among the upregulated DEGs in Socheong2, particularly at 12 HAI compared to 0 HAI. This study will aid in targeted breeding efforts to develop soybean varieties with improved resistance to P. sojae.

Creeping Stem 1 regulates directional auxin transport for lodging resistance in soybean.

Soybean, a staple crop on a global scale, frequently encounters challenges due to lodging under high planting densities, which results in significant yield losses. Despite extensive research, the fundamental genetic mechanisms governing lodging resistance in soybeans remain elusive. In this study, we identify and characterize the Creeping Stem 1 (CS1) gene, which plays a crucial role in conferring lodging resistance in soybeans. The CS1 gene encodes a HEAT-repeat protein that modulates hypocotyl gravitropism by regulating amyloplast sedimentation. Functional analysis reveals that the loss of CS1 activity disrupts polar auxin transport, vascular bundle development and the biosynthesis of cellulose and lignin, ultimately leading to premature lodging and aberrant root development. Conversely, increasing CS1 expression significantly enhances lodging resistance and improves yield under conditions of high planting density. Our findings shed light on the genetic mechanisms that underlie lodging resistance in soybeans and highlight the potential of CS1 as a valuable target for genetic engineering to improve crop lodging resistance and yield.

Dual activation of soybean resistance against Phytophthora sojae by pectin lyase and degraded pectin oligosaccharides.

Phytophthora pathogens secrete numerous apoplastic effectors to manipulate host immunity. Herein, we identified a polysaccharide lyase 1 protein, PsPL1, which acts as an essential virulence factor of P. sojae infection in soybean. However, the overexpression of PsPL1 in P. sojae reduced infection and triggered enhanced immune responses in soybean. PsPL1 exhibited pectin lyase activity and degraded plant pectin to generate pectin oligosaccharides (POSs) with a polymerization degree of 3-14, exhibiting different levels of acetylation and methylation modifications. PsPL1 and the degraded pectin products triggered immune responses in soybean and different Solanaceous plants. The PsPL1-triggered immune responses required RSPL1, a membrane-localized leucine-rich repeat receptor-like protein, which is essential for Phytophthora resistance. Conversely, the PsPL1-degraded product-triggered immune responses depended on the membrane-localized lysin motif receptor-like kinase CERK1. This study reveals that the pectin lyase exhibits a dual immunogenic role during P. sojae infection, which activates plant resistance through different immune receptors and provides novel insights into the function of pectin lyase in host-pathogen interactions.

GmTRAB1, a Basic Leucine Zipper Transcription Factor, Positively Regulates Drought Tolerance in Soybean (Glycine max. L).

The basic leucine zipper (bZIP) transcription factors play crucial roles in plant resistance to environmental challenges, but the biological functions of soybean bZIP members are still unclear. In this study, a drought-related soybean bZIP gene, GmTRAB1, was analyzed. The transcript of GmTRAB1 was upregulated under drought, ABA, and oxidative stresses. Overexpression of GmTRAB1 improved the osmotic stress tolerance of transgenic Arabidopsis and soybean hairy roots associated with increased proline content and activity of antioxidant enzymes and reduced accumulations of malonaldehyde and reactive oxide species. However, RNA interference silencing of GmTRAB1 in the soybean hairy roots improved drought sensitivity. Furthermore, GmTRAB1 increased the sensitivity of transgenic plants to ABA and participated in modulating ABA-regulated stomatal closure upon drought stress. In addition, GmTRAB1 stimulated the transcript accumulation of drought-, ABA-, and antioxidant-related genes to respond to drought. Collectively, this research will contribute to understanding the molecular mechanisms of bZIP transcription factors in soybean's resistance to drought.

GmWRKY33A positively regulates disease resistance in soybean (Glycine max)

The WRKY transcription factor gene family is a plant-specific transcription factor that plays important roles defense responses. Studies in model plant Arabidopsis demonstrated that WRKYs function downstream of mitogen activated-protein kinase (MAPK) signaling cascade and participate in defense responses through activating the expression of defense-related genes. However, the roles of WRKYs in defense responses have not been previously investigated in paleopolyploidy soybean. Bioinfomatic analysis revealed that there are three pair of GmWRKY33 genes in the soybean genome. The identity of first two pair of GmWRKY33 genes is greater than 84% (named as GmWRKY33A). The identity of genes within the same pair is greater than 95%. A 300 bp fragment highly homologous to these four GmWRKY33A was chosen to clone into bean pod mosaic virus (BPMV)-based silencing vector (BPMV-VIGS) to achieve the goal of silencing four GmWRKY33A genes simultaneously. In this study, we simultaneously silenced four homologous genes of GmWRKY33A using a bean pod mottle virus (BPMV) vector carrying a single fragment of GmWRKY33A. Comparing the silenced plants with the vector control plants, no evident morphological phenotypes were observed. However, the GmWRKY33A-silenced plants exhibited significantly reduced resistance to Pseudomonas syringae pv. glycinea (Psg), Xanthomonas axonopodis pv. glycine (Xag), as well as to soybean mosaic virus (SMV). Furthermore, we demonstrated that silencing these GmWRKY33A genes significantly inhibited the activation of GmMPK3/GmMPK6 induced by Psg infection. Collectively, our results suggest that GmWRKY33As are involved in soybean immunity through regulating the transcription of GmMPK3/6 genes or activating the kinase activities of GmMPK3/6. Taken together, our results demonstrated that GmWRKY33As are positive regulators of soybean immune responses.

Key structural role of a conserved cis-proline revealed by the P285S variant of soybean serine hydroxymethyltransferase 8.

The enzyme serine hydroxymethyltransferase (SHMT) plays a key role in folate metabolism and is conserved in all kingdoms of life. SHMT is a pyridoxal 5'-phosphate (PLP) - dependent enzyme that catalyzes the conversion of L-serine and (6S)-tetrahydrofolate to glycine and 5,10-methylene tetrahydrofolate. Crystal structures of multiple members of the SHMT family have shown that the enzyme has a single conserved cis proline, which is located near the active site. Here, we have characterized a Pro to Ser amino acid variant (P285S) that affects this conserved cis proline in soybean SHMT8. P285S was identified as one of a set of mutations that affect the resistance of soybean to the agricultural pathogen soybean cyst nematode. We find that replacement of Pro285 by serine eliminates PLP-mediated catalytic activity of SHMT8, reduces folate binding, decreases enzyme stability, and affects the dimer-tetramer ratio of the enzyme in solution. Crystal structures at 1.9-2.2 Å resolution reveal a local reordering of the polypeptide chain that extends an α-helix and shifts a turn region into the active site. This results in a dramatically perturbed PLP-binding pose, where the ring of the cofactor is flipped by ∼180° with concomitant loss of conserved enzyme-PLP interactions. A nearby region of the polypeptide becomes disordered, evidenced by missing electron density for ∼10 residues. These structural perturbations are consistent with the loss of enzyme activity and folate binding and underscore the important role of the Pro285 cis-peptide in SHMT structure and function.

Identification of candidate genes associating with soybean cyst nematode in soybean (Glycine max L.) using BSA-seq.

Soybean cyst nematode disease represents the major soil-borne disease of soybean. Identifying disease-resistant genes in soybean has a substantial impact on breeding of disease-resistant crops and genetic improvement. The present work created the F2 population with the disease-resistant line H-10 and disease-susceptible line Chidou4. 30 respective F2disease-resistant and disease-susceptible individuals for forming two DNA pools for whole-genome re-sequencing were selected. As a result, a total of 11,522,230 single nucleotide polymorphism (SNPs) markers from these two parental lines and two mixed pools were obtained. Accordng to SNP-index based association analysis, there were altogether 741 genes out of 99% confidence interval, which were mainly enriched into regions of 38,524,128∼39,849,988 bp with a total length of 1.33 Mb contain 111 genes on chromosome 2, 27,821,012∼29,612,574 bp with a total length of 1.79 Mb contain 92 genes on chromosome 3, 308∼348,214 bp with a total of length 0.35 Mb contain 34 genes on chromosome 10, and 53,867,581∼58,017, 852 bp with a total length of 4.15 Mb contain 504 genes on chromosome 18. Bulk segregant analysis in F2 generations (BSA-seq) was correlated with a disease resistance interval containing 15 genes. Then, using bioinformatics analysis and differential expression analysis, five candidate genes were identified: Glyma.02G211400, Glyma.18G252800, Glyma.18G285800, Glyma.18G287400 and Glyma.18G298200. Our results provides a key basis for analyzing the soybean resistance mechanism against soybean cyst nematode and cloning soybean resistance genes.

Identification of genes governing YMD resistance in soybean cultivar SL 958.

Yellow mosaic disease (YMD) is the most devastating disease of soybean under north Indian conditions. A recombinant inbred line population derived from SL 958 (R) × AGS 456 (S) was used to map the genes imparting YMD resistance. Genotyping by sequencing (GBS) of 148 individuals and the parents was used to identify polymorphic SNPs in the population. These were used to generate linkage maps and subsequently map the QTL. A QTL, MYMIV 1-1.1, was mapped onto chromosome 6. The QTL was mapped at a genetic distance of 114.31 cM, with likelihood ratio of 81.34 (LOD 17.68), explaining 33.80% of the variation for the trait, with an additive effect of 1.22. MYMIV 1-1.1 was flanked by SNPs Gm06_12614920 explaining 33.80% of variation and Gm06_12887789 explaining 31.04% of the variation. The QTL region spanned for a total of 2.798 Mbp. The QTL was mapped in an approximately 4 cM region. Flanking SNPs can be developed into linked markers for effective marker-assisted selection. Out of the genes in the QTL region, Glyma.06G161700 (Suppressor of Gene Silencing/SGS3) is the strongest contender for the resistance gene. This is the first study documenting GBS-based mapping of YMD resistance in soybean. © 2024 Society of Chemical Industry.

Multi-functional PGPR Serratia liquefaciens confers enhanced resistance to lead stress and bacterial blight in soybean (Glycine max L.)

Lead toxicity and bacterial blight disease caused by Pseudomonas savastanoi pv. glycinea have destructive impacts on soybean growth and productivity. Plant growth-promoting rhizobacteria have been used as an eco-friendly approach for augmenting crop growth and stress resistance. The current study investigated the efficacy of Serratia liquefaciens ZM6 strain in enhancing soybean resistance to lead (Pb) stress and bacterial blight. Two pot experiments were performed. In the first pot experiment, soybean plants were inoculated with S. liquefaciens ZM6 and grown under variable Pb stress levels (0, 200 and 400 µM of Pb(NO3)2). In the second experiment, S. liquefaciens-inoculated soybean plants were infected with P. savastanoi pv. glycinea, and disease severity was assessed two weeks post infection. The results revealed that S. liquefaciens strain resisted Pb stress up to 400 µM Pb(NO3)2 and exhibited the highest levels of solubilized phosphate, solubilized zinc, siderophore, indole acetic acid, exopolysaccharide, trehalose and antioxidant enzymes at 400 µM Pb compared to the other treatments. Moreover, Pb stress (200 and 400 µM) significantly decreased the growth, yield, nutrient uptake, gas exchange, and contents of chlorophyll, soluble proteins, sugars, and phenolics of soybean plants. Pb stress also induced the levels of proline, glycine betaine, Pb, oxidative stress markers, antioxidant enzymes, ascorbate, glutathione and expression of stress-responsive genes (CAT, APX, POD, Fe-SOD, CHS7, CHI1A, PAL, IFS2, P5CS and WRKY54) in soybean plants. On the other hand, S. liquefaciens application markedly boosted the growth, yield and levels of nutrients, gas-exchange, chlorophyll, osmolytes, antioxidant enzymes and expression of stress-tolerant genes of Pb-stressed soybean plants. The bacterial inoculation significantly diminished oxidative stress indicators and Pb content in stressed plants. Inoculation of soybean plants with S. liquefaciens also caused significant reductions in blight disease symptoms in P. savastanoi pv. glycinea-infected plants, indicating the efficiency of this strain in controlling harmful blight disease. Overall, this study demonstrated S. liquefaciens ZM6 effectiveness in enhancing soybean resistance to Pb stress and bacterial blight.

A Soybean Pyrroline-5-Carboxylate Dehydrogenase GmP5CDH1 Modulates Plant Growth and Proline Sensitivity

Soybean [Glycine max (L.) Merr.], as a globally commercialized crop, is an important source of protein and oil for both humans and livestock. With more frequent extreme weather disasters, abiotic stress has become one of the critical factors restricting soybean production. Proline (Pro) is a well-known substance in plants that responds to abiotic stress. To identify potential effector genes involved in soybean resistance to abiotic stress, we focused on the pyrroline-5-carboxylate dehydrogenase (P5CDH) which is a key enzyme in the degradation process of Pro. Through homologous sequence alignment, phylogenetic tree, and predicted expression, we chose GmP5CDH1 (Glyma.05G029200) for further research. Tissue-specific expression assay showed that GmP5CDH1 had higher expression levels in soybean seed and cotyledon development. Subcellular localization assay revealed that GmP5CDH1 was a nuclear-membrane-localized protein. As the result of the predicted cis-acting regulatory element indicates, the expression level of GmP5CDH1 was induced by low temperature, drought, salt stress, and ABA in soybean. Next, we constructed transgenic Arabidopsis overexpressing GmP5CDH1. The results showed that GmP5CDH1 also strongly responded to exogenous Pro, and overcame the toxicity of abiotic stress on plants by regulating the endogenous concentration of Pro. The interaction between GmP5CDH1 and GmSAM1 was validated through yeast two-hybrid, LUC fluorescence complementary, and BIFC. In conclusion, overexpression of a soybean pyrroline-5-carboxylate dehydrogenase GmP5CDH1 regulates the development of Arabidopsis thaliana by altering proline content dynamically under salt stress, especially improving the growth of plants under exogenous Pro.

Effect of postemergence applications of aminocyclopyrachlor, aminopyralid, 2,4-D, and dicamba on non–auxin resistant soybean

Abstract Soybean [Glycine max (L.) Merr.] that lack resistance to auxin herbicides [i.e., not genetically modified for resistance] have well-documented responses to those particular herbicides, with yield loss being probable. When a soybean field is injured by auxin herbicides, regulatory authorities often collect a plant sample from that field. This research attempted to simulate soybean exposures due to accidental mixing of incorrect herbicides, tank contamination, or particle drift. This research examined whether analytical testing of herbicide residues on soybean to aminocyclopyrachlor (ACP), aminopyralid, 2,4-D, or dicamba would be related to the visual observations and yield responses from these herbicides. ACP and aminopyralid were applied to R1 soybean at 0.1, 1, and 10 g ae ha−1; 2,4-D and dicamba were applied at 1, 10, and 100 g ae ha−1. Visual evaluations and plant sample collections were undertaken at 1, 3, 7, 14, and 21 d after treatment (DAT), and yield was measured. The conservative limits of detection for the four herbicides in this project were 5, 10, 5, and 5 ng g−1 fresh weight of soybean for ACP, aminopyralid, 2,4-D, and dicamba, respectively. Many of the plant samples were non-detects, especially at lower application dosages. All herbicide concentrations rapidly declined soon after application, and many reached nondetectable limits by 14 DAT. All herbicide treatments caused soybean injury, although the response to 2,4-D was markedly lower than the responses to the other three herbicides. There was no apparent correlation between herbicide concentrations (which were declining over time) and the observed soybean injury (which was increasing over time or staying the same). This research indicated that plant samples should be collected as soon as possible after soybean exposure to auxin herbicides.

Biocontrol Potential of Bacillus strains against soybean cyst nematode (Heterodera glycines) and for promotion of soybean growth

The soybean cyst nematode (SCN, Heterodera glycines) is the most yield-limiting pathogen in soybeans worldwide. Using chemical pesticides to control this disease is harmful to human and environment. It is urgent to develop environment-friendly nematicides. The aim of this study was to discover novel biocontrol agents on H. glycines control and soybean growth under greenhouse and field conditions Eight Bacillus strains were isolated from soil rhizosphere soils and the stability and efficiency of H. glycines was assessed in greenhouse and field experiments in 2021 and 2022. In particular, the Ba2-6 strain had the highest potential, because it was a biocontrol agent against H. glycines shown to cause 93.85% juvenile mortality. Furthermore, strains Ba 1–7, Ba2-4, and Ba2-6 effectively reduced the number of females and improved the soybean seed number per plant. Based on their morphological, physiological, biochemical and molecular (16 S rRNA) characteristics, the three strains were identified as B. aryabhattai (Ba1-7), B. megatherium (Ba2-4), and B. halotolerans (Ba2-6). The ability of Ba2-6 to induce systemic resistance to H. glycines in soybeans was investigated by the split-root system and real-time quantitative PCR experiments. The results indicated that the Ba2-6 strain induced systemic resistance to suppress the penetration of H. glycines, and enhanced gene expression of PR1, PR3a, PR5, and NPR1-2, involved in the salicylic acid and jasmonic acid pathways. The study suggests that the strains of B. aryabhattai Ba1-7, B. megatherium Ba2-4, and B. halotolerans Ba2-6 can be considered as effective biocontrol agents to control H. glycines. Further, B. halotolerans Ba2-6 not only promotes soybean growth but also enhances resistance to H. glycines by regulating defense-related gene expression and inducing systemic resistance in soybean.

Integrated Management of Sclerotinia Stem Rot of Soybean Including Organically-Allowed Fungicides in the Midwest United States

Sclerotinia stem rot (SSR) is an economically important disease of soybean, especially in the Great Lakes region of the United States. Few studies on SSR have considered organic management practices and how integrated management techniques best apply in these systems. Trials in Wisconsin and Indiana aimed to evaluate management techniques available to organic farmers for their efficacy in SSR control while preserving yield. The practices evaluated included genetically resistant cultivars, tillage techniques, and the application of Organic Materials Review Institute (OMRI) listed foliar fungicides. The resistant cultivar had significantly lower SSR than the susceptible cultivar in three site-years (P < 0.01). The resistant cultivar also had significantly greater yield than the susceptible cultivar in two site-years (P < 0.05). Using a roller-crimped rye cover crop resulted in mixed results on SSR and yield. No effect on SSR or yield by OMRI listed foliar fungicides was observed (P > 0.05). Overall, the results emphasize the importance of planting a resistant soybean cultivar to manage SSR in organic farming systems in the Midwestern United States.

Functional Identification of miR2119 Targeting ADHs in Modulating Soybean Resistance to Heterodera glycines.

Soybean cyst nematode (SCN, Heterodera glycines) is a sedentary endoparasite nematode that results in severe economic losses in soybean crops. miRNAs play crucial roles in plant responses to nematode. However, the role of miR2119 responding to SCN stress in soybean. Here, we demonstrated that the transcript levels of polycistronic precursors containing miR2119 and miR398a were significantly reduced in soybean upon nematode infection. Promoter of the miR2119-398a precursor analysis was conducted containing a GUS reporter gene. GUS activity assays demonstrated a decrease in miR2119-398a promoter during SCN infection. Overexpression of polycistronic precursor miR2119-398a (OE-premiR2119-398a) and miR2119 precursor (OE-premiR2119) rendered soybean more susceptible to SCN. Conversely, silencing miR2119 (STTM2119) increased soybean resistance against SCN. Furthermore, RNA-seq analysis revealed that miR2119 is involved in many defense signaling pathways. GUS reporter gene assays demonstrated that miR2119 targets GmADH1.1a and GmADH1.1b. Functional analysis indicated that ADHs act as a major role in responding to H. glycines by modulating reactive oxygen species (ROS) levels. Together, the findings reveal a novel mechanism by which the polycistronic precursor miR2119-398a coordinately regulates in response to H. glycines. Additionally, miR2119 becomes an essential element contributing to H. glycines by modulating ADH activity and ROS homeostasis in soybean.

Overexpression of GmSRC2 confers resistance to Phytophthora sojae in soybean

Phytophthora root and stem rot caused by Phytophthora sojae (P. sojae) is one of the most destructive diseases to affect soybean (Glycine max (L.) Merr) production. GmSRC2 that encodes a C2 domain-containing protein can respond to various stresses, however, the molecular mechanism of GmSRC2 in resistance of soybean to P. sojae is yet to be fully elucidated. In this study, GmSRC2 was found to be significantly up-regulated under P. sojae treatment; GmSRC2-overexpression (OE) transgenic lines and GmSRC2-silencing transient plants were generated via Agrobacterium tumefaciens mediated transformation and virus-induced gene silencing (VIGS) system, respectively. Infected leaves and cotyledons of OE-GmSRC2–1 and OE-GmSRC2–2 lines showed significant decreases in the disease symptoms and P. sojae biomass than those of wild type (WT); the activities of superoxide dismutase (SOD) and peroxidase (POD) confirmed the accumulation of reactive oxygen species (ROS) in overexpressed transgenic lines. Whereas, silencing of GmSRC2 severely increased the disease symptoms and the biomass of P. sojae. Further, we confirmed that GmSRC2 interacted with the effector PsAvh23 of P. sojae, and the C2 domain was crucial for the interaction. Overexpression of GmSRC2 upregulated the ADA2/GCN5 module upon P. sojae. The aforementioned results demonstrated that GmSRC2 played vital roles in regulating soybean resistance to oomycetes.