High-vigor soybean seeds are critical for efficient production owing to their favorable growth properties and high yield potential. The evaluation and identification of high-vigor germplasms are essential for increasing soybean production capacity. Currently, there is no universally accepted evaluation system to test for soybean seed vigor. In this study, 11 seed vigor-related traits were measured across 126 soybean landraces via an artificial accelerated aging technique. The ratios of these 11 traits, which were calculated before and after artificial accelerated aging, were used as vigor indicators in principal component analysis (PCA), ultimately yielding two principal component factors. These factors were then combined via membership function standardization to calculate a comprehensive seed vigor evaluation value (V value), thereby establishing an evaluation system. Cluster analysis based on the V value was used to classify seed vigor into five levels and identify seven high-vigor germplasms: ZDD12322, ZDD06438, ZDD11951, ZDD08251, ZDD12436, ZDD02315, and ZDD15624. Through stepwise regression analysis, the optimal seed vigor predictive model was defined as V = -0.026 + 0.625 x RSL + 0.485 x RGI. This model revealed that the relative seedling length (RSL) and relative germination index (RGI) had significant positive effects on seed vigor. This study provides a valuable framework for seed quality control and selection, facilitating presowing vigor assessments to increase soybean planting efficiency and yield.

Seed hardness is an important quality trait of vegetable soybean. To determine the factors underlying seed hardness, two landraces with contrasting seed hardness, Niumaohuang (low seed hardness) and Pixiansilicao (high seed hardness), were selected from 216 soybean accessions originating from 26 provinces in China. The contents of the main components in vegetable soybean seeds such as water, soluble sugar, starch, protein and oil were measured, and transcriptome analyses performed during five stages of seed developmental. Transcriptome analysis indicates that during the middle and late stages of seed development, a large number of genes involved in the synthesis or degradation of starch, storage protein, and fatty acids were differentially expressed, leading to differences in the accumulation of stored substances during seed maturation among Niumaohuang and Pixiansilicao. The activity of cell proliferation and the formation of cell walls in the middle and late stages of seed development may also affect the hardness of seeds to a certain extent. In addition, weighted gene co-expression network analysis (WGCNA) was undertaken to identify co-expressed gene modules and hub genes that regulate seed hardness. Overexpression of a candidate seed hardness regulatory hub gene, GmSWEET2, resulted in increased seed hardness. In this study, the important role of GmSWEET2 in regulating the hardness of vegetable soybean seeds was verified and numerous potential key regulators controlling seed hardness and the proportion of seed components were identified, laying the groundwork for improving the texture of vegetable soybean.

Soybean production is significantly impacted by Phytophthora root rot (PRR), which is caused by Phytophthora sojae. The nucleotide-binding leucine-rich repeat (NLR) gene family plays a crucial role in plant disease resistance. However, current understanding of the function of soybean NLR genes in resistance to PRR is limited. To address this knowledge gap, transgenic soybean plants overexpressing the NLR gene (Glyma.18g283200) were generated to elucidate the molecular mechanism of resistance. Here, transcript changes and metabolic differences were investigated at three time points (12, 24, and 36 h) after P. sojae infection in hypocotyls of two soybean lines, Dongnong 50 (susceptible line, WT) and Glyma.18g283200 overexpression line (resistant line, OE). Based on the changes in differentially expressed genes (DEGs) in response to P. sojae infection in different lines and at different time points, it was speculated that HOPZ-ACTIVATED RESISTANCE 1 (ZAR1), valine, leucine, and isoleucine degradation, and phytohormone signaling may be involved in the defense response of soybean to P. sojae at the transcriptome level by GO term and KEGG pathway enrichment analysis. Differentially accumulated metabolites (DAMs) analysis revealed that a total of 223 and 210 differential metabolites were identified in the positive ion (POS) and negative ion (NEG) modes, respectively. An integrated pathway-level analysis of transcriptomics (obtained by RNA-seq) and metabolomics data revealed that isoflavone biosynthesis was associated with disease resistance. This work provides valuable insights that can be used in breeding programs aiming to enhance soybean resistance against PRR.

Vegetable soybean is an important legume vegetable. High sucrose content is a significant quality characteristic of vegetable soybean that influences consumers’ taste. However, the genetic basis of sucrose content in vegetable soybean is currently unclear. In this study, the genome-wide association study (GWAS) of sucrose content in vegetable soybean was performed using Chinese soybean mini-core collection. The results showed a wide genetic variation for the sucrose content in the mini-core collection. The sucrose content of genotypes from HHR (Huanghuai region) and SR (Southern region) was higher than that of genotypes from NER (Northeast region) and NR (Northern region). Furthermore, 82,187 high quality SNPs (Single nucleotide polymorphism) were used for GWAS of sucrose content. Based on SNPs detected in multiple environments, the chromosome 8 19,496,314–19,698,413 bp interval was identified as the candidate interval. And Glyma.08g234100 was most likely to affect the sucrose content of vegetable soybean seeds. This study has created new details to be used for breeding for high sucrose content in vegetable soybean.

[Objectives]This study aimed to analyze the relationship between soybean DREB（dehydration responsive element-binding protein）transcription factor gene GmDREB8 and drought stress, which laid a foundation for the study of the molecular mechanism of DREB transcription factors participating in soybean drought stress and provided new gene resources for soybean drought tolerant transgenic breeding. [Methods]The soybean variety ’Tianlong 1’ was used as experiment material. Quantitative real time polymerase chain reaction（RT-qPCR）was used to analyze the expression patterns of 10 DREB genes induced by drought treatment, as well as the differential expression of GmDREB8 in different soybean tissues and plant hormones. Bioinformatics methods were used to analyze the conserved motif and subcellular localization prediction of GmDREB8. Subcellular localization of GmDREB8 protein was carried out by Agrobacterium tumefaciens mediated tobacco transient expression system. Arabidopsis with heterologous expression of GmDREB8 and soybean plants silenced by VIGS（virus induced gene silencing）technology were used to analyze the function of GmDREB8 in Arabidopsis and soybean under drought stress. [Results]Ten DREB genes were induced to express under drought stress, and most of their expression patterns were different. GmDREB8 was screened and cloned, which was located on soybean chromosome 17 and contained an AP2 domain with a molecular weight of 19.79×10~3 and isoelectric point of 9.76. GmDREB8 gene was induced by plant hormones abscisic acid（ABA）and salicylic acid（SA）. GmDREB8 protein was located in the nucleus. The root length of transgenic Arabidopsis heterologous expressing GmDREB8 was more inhibited than wild type（WT）under different concentrations of mannitol, and it was more sensitive to drought stress. Compared with empty plasmid control group, the leaves of GmDREB8 silent soybean lines had lower relative conductivity, relative water loss rate, malondialdehyde（MDA）content and higher free proline（Pro）content after drought treatment, as a result of stronger drought tolerance. [Conclusions]GmDREB8 can negatively regulate the drought tolerance of plants.

The Ethylene Response Factor (ERF) transcription factors form a subfamily of the AP2/ERF family that is instrumental in mediating plant responses to diverse abiotic stressors. Herein, we present the isolation and characterization of the GmERF105 gene from Williams 82 (W82), which is rapidly induced by salt, drought, and abscisic acid (ABA) treatments in soybean. The GmERF105 protein contains an AP2 domain and localizes to the nucleus. GmERF105 was selectively bound to GCC-box by gel migration experiments. Under salt stress, overexpression of GmERF105 in Arabidopsis significantly reduced seed germination rate, fresh weight, and antioxidant enzyme activity; meanwhile, sodium ion content, malonic dialdehyde (MDA) content, and reactive oxygen species (ROS) levels were markedly elevated compared to the wild type. It was further found that the transcription levels of CSD1 and CDS2 of two SOD genes were reduced in OE lines. Furthermore, the GmERF105 transgenic plants displayed suppressed expression of stress response marker genes, including KIN1, LEA14, NCED3, RD29A, and COR15A/B, under salt treatment. Our findings suggest that GmERF105 can act as a negative regulator in plant salt tolerance pathways by affecting ROS scavenging systems and the transcription of stress response marker genes.

Drought is a major environmental constraint that causes substantial reductions in plant growth and yield. Expression of stress-related genes is largely regulated by transcription factors (TFs), including in soybean [Glycine max (L.) Merr.]. In this study, 301 GmAP2/ERF genes that encode TFs were identified in the soybean genome. The TFs were divided into five categories according to their homology. Results of previous studies were then used to select the target gene GmAP2/ERF144 from among those up-regulated by drought and salt stress in the transcriptome. According to respective tissue expression analysis and subcellular determination, the gene was highly expressed in leaves and encoded a nuclear-localized protein. To validate the function of GmAP2/ERF144, the gene was overexpressed in soybean using Agrobacterium-mediated transformation. Compared with wild-type soybean, drought resistance of overexpression lines increased significantly. Under drought treatment, leaf relative water content was significantly higher in overexpressed lines than in the wild-type genotype, whereas malondialdehyde content and electrical conductivity were significantly lower than those in the wild type. Thus, drought resistance of transgenic soybean increased with overexpression of GmAP2/ERF144. To understand overall function of the gene, network analysis was used to predict the genes that interacted with GmAP2/ERF144. Reverse-transcription quantitative PCR showed that expression of those interacting genes in two transgenic lines was 3 to 30 times higher than that in the wild type. Therefore, GmAP2/ERF144 likely interacted with those genes; however, that conclusion needs to be verified in further specific experiments.

Seedling drought stress is one of the most important constraints affecting soybean yield and quality. To unravel the molecular mechanisms under soybean drought tolerance, we conducted comprehensive comparative transcriptome analyses of drought-tolerant genotype Jindou 21 (JD) and drought-sensitive genotype Tianlong No.1 (N1) seedlings that had been exposed to drought treatment. A total of 6038 and 4112 differentially expressed genes (DEGs) were identified in drought-tolerant JD and drought-sensitive N1, respectively. Subsequent KEGG pathway analyses showed that numerous DEGs in JD are predominately involved in signal transduction pathways, including plant hormone signaling pathway, calcium signaling pathway, and MAPK signaling pathway. Interestingly, JA and BR plant hormone signal transduction pathways were found specifically participating in drought-tolerant JD. Meanwhile, the differentially expressed CPKs, CIPKs, MAPKs, and MAP3Ks of calcium and MAPK signaling pathway were only identified in JD. The number of DEGs involved in transcription factors (TFs) is larger in JD than that of in N1. Moreover, some differently expressed transcriptional factor genes were only identified in drought-tolerant JD, including FAR1, RAV, LSD1, EIL, and HB-PHD. In addition, this study suggested that JD could respond to drought stress by regulating the cell wall remodeling and stress-related protein genes such as EXPs, CALSs, CBPs, BBXs, and RD22s. JD is more drought tolerant than N1 owing to more DEGs being involved in multiple signal transduction pathways (JA, BR, calcium, MAPK signaling pathway), stress-related TFs, and proteins. The above valuable genes and pathways will deepen the understanding of the molecular mechanisms under drought stress in soybean.

Phytophthora root rot, caused by Phytophthora sojae (P. sojae), is one of the most devastating diseases limiting soybean production worldwide. microRNAs (miRNAs) play major roles in regulating plant defense against pathogens. To understand the roles of soybean miRNAs during P. sojae infection, we analyzed four small RNA libraries from two soybean germplasms before and after P. sojae isolate JS08-12 infection. The cultivar Nannong 10-1 was resistant to JS08-12, whereas the 06-070583 line was susceptible to JS08-12. In total, 528 known and 555 putative novel miRNAs in soybean were identified from 97 million reads; 74 known miRNAs and 75 novel miRNAs that might be specifically related to Nannong10-1 responses to P. sojae; and 55 known and 43 novel miRNAs expressed before and after infection in the susceptible line 06-070583. qRT-PCR provided similar miRNA expression patterns to those obtained by the small-RNA sequencing of the four libraries. Then, the potential target genes of these differentially expressed miRNA were predicted, which encoded transcriptional factors, resistance proteins and transporters. Finally, we focused on the targets of the three legume-specific miRNAs (gma-miR1508, gma-miR1509, and gma-miR1510) and charted the miRNA–target interactions and networks based on the published degradome data.

Plant architecture traits are closely related to plant biomass, lodging, and photosynthetic efficiency, which in turn affect soybean yield. In this study, we investigated a Chinese soybean mini core collection consisting of 224 germplasm accessions for four plant architecture-related traits (plant height (PH), number of nodes on main stem (NN), branch number (BN), and stem diameter (DI)) under three environments and conducted a genome-wide association study (GWAS) based on 1514 single nucleotide polymorphisms (SNPs). A total of 41 SNPs were found to be significantly associated with PH, NN, BN, and DI in two or more environments. Among these SNPs, 15 were located in regions in which plant architecture-related QTLs had been reported in previous studies, and 26 were new genetic loci. In addition, 18 potential candidate genes for plant architecture-related traits were obtained by predicting the genes in the interval of four large-effect markers (BARC-017097-02199, Map-2213, BARC-014639-01604, and Map-2223). This research will help to illuminate the genetic basis of soybean plant architecture-related traits and accelerate the process of plant architecture breeding by molecular marker-assisted selection in soybean.

Phytophthora root rot (PRR), caused by Phytophthora sojae, is a devastating disease of soybean. The NBS-LRR gene family is a class of plant genes involved in disease resistance. miRNA mediates plant response to biotic stresses by regulating the expression of target genes at the transcriptional or post-translational level. Glyma.16G135500, encoding an NBS-LRR-type protein, is a target of gma-miR1510 that responds to pathogen infections. We cloned and overexpressed Glyma.16G135500 (naming it GmTNL16) and knocked down miR1510 using short tandem target mimic technology to identify the roles of the GmTNL16/gma-miR1510 pair in the interaction of soybean and the oomycete. By overexpressing GmTNL16 in transgenic hairy roots of soybean, we showed that biomass of P. sojae was lower in overexpressing hairy roots than in control roots. Thus, miR1510 expression was reduced upon P. sojae infection, reflecting the induced expression of GmTNL16 conferring resistance to P. sojae in soybean. Differentially expressed genes were enriched in plant-pathogen interaction, plant hormone signal transduction, and secondary metabolism by RNA sequencing analyze. In particular, jasmonate and salicylic acid pathway-associated genes, including JAZ, COI1, TGA, and PR, responded to P. sojae infection. All of these results indicate that the GmTNL16/gma-miR1510 pair participates in soybean defense response via the JA and SA pathways.

Background: In agriculture, supplemental calcium was applied to alleviate plant growth and development inhibition causing by various stresses. However, calcium overload is toxic to plants, which may prevent the germination of seeds and reduce plant growth rates. Hsp90 is an important molecular chaperone distributing in all living organisms and a series of studies have shown that Hsp90 and Ca2+ have closely relationship. To better understanding the relationship between GmHsp90s and calcium stress, we conducted a series of experiments and reported in this research article. Methods: The study was performed by three techniques: 1) Quantitative RT-PCR with five GmHsp90 genes viz., GmHsp90A2, GmHsp90A4, GmHsp90B1, GmHsp90C1.1 and GmHsp90C2.1, 2) MDA, O2- and chlorophyll content assay of transgenic plants after calcium stress and 3) Phenotype analysis of transgenic plants in pod setting period after three days treatment of water or 80 mM CaCl2. Result: Quantitative RT-PCR with the five genes showed that they were all CaCl2 inducible. MDA, O2- and chlorophyll content assay showed that GmHsp90A2 and GmHsp90A4 transgenic lines significantly relieved the damage caused by CaCl2 and oxidative stress. The secondary stress damage, including the effect on plant height and pod setting rate, was also reduced in transgenic lines, especially GmHsp90B1 and GmHsp90C1.1 transgenic lines. Collectively, this study reveals the response of GmHsp90s to calcium and their potential function in coping with calcium stress.

为探明花期高温对大豆结荚和产量的影响及其生理机制,以大豆品种濉科12为材料,于盛花期(R2)在大棚内进行连续3 d高温处理(9:00-16:00,45±2℃;16:00—次日9:00,自然环境温度),研究盛花期高温胁迫对大豆结荚状况、荚和荚柄内部解剖结构、荚的氧化胁迫和产量构成的影响.结果表明:盛花期高温对大豆叶片的影响是非延续性的且对后期的"源"没有影响,但会导致受高温影响的花后期形成荚的H2O2和MDA含量上升;部分荚的荚柄细胞崩溃呈丝状、荚壳维管束变稀疏,导致"流"不畅,籽粒内部细胞中空,减少"库"的数量,造成落荚,空瘪荚、缺粒荚增多,总粒数减少,粒重降低,产量下降;副花序可在一定程度上补偿高温带来的产量损失.因此盛花期高温对大豆"流"和"库"造成影响,最终导致减产.

Background Plant architecture-related traits (e.g., plant height (PH), number of nodes on main stem (NN), branch number (BN) and stem diameter (DI)) and 100-seed weight (100-SW) are important agronomic traits and are closely related to soybean yield. However, the genetic basis and breeding potential of these important agronomic traits remain largely ambiguous in soybean ( Glycine max (L.) Merr.). Results In this study, we collected 133 soybean landraces from China, phenotyped them in two years at two locations for the above five traits and conducted a genome-wide association study (GWAS) using 82,187 single nucleotide polymorphisms (SNPs). As a result, we found that a total of 59 SNPs were repeatedly detected in at least two environments. There were 12, 12, 4, 4 and 27 SNPs associated with PH, NN, BN, DI and 100-SW, respectively. Among these markers, seven SNPs (AX-90380587, AX-90406013, AX-90387160, AX-90317160, AX-90449770, AX-90460927 and AX-90520043) were large-effect markers for PH, NN, BN, DI and 100-SW, and 15 potential candidate genes were predicted to be in linkage disequilibrium (LD) decay distance or LD block. In addition, real-time quantitative PCR (qRT-PCR) analysis was performed on four 100-SW potential candidate genes, three of them showed significantly different expression levels between the extreme materials at the seed development stage. Therefore, Glyma.05 g127900 , Glyma.05 g128000 and Glyma.05 g129000 were considered as candidate genes with 100-SW in soybean. Conclusions These findings shed light on the genetic basis of plant architecture-related traits and 100-SW in soybean, and candidate genes could be used for further positional cloning.

BACKGROUND:Soybean (Glycine max (L.) Merr.) is an economically important crop for vegetable oil and protein production, and yield is a critical trait for grain/vegetable uses of soybean. However, our knowledge of the genes controlling the vegetable soybean yield remains limited.OBJECTIVE:To better understand the genetic basis of the vegetable soybean yield.METHODS:The 100-pod fresh weight (PFW), 100-seed fresh weight (SFW), kernel percent (KP) and moisture content of fresh seeds (MCFS) at the R6 stage are four yield-related traits for vegetable soybean. We investigated a soybean mini core collection composed of 224 germplasm accessions for four yield-related traits in two consecutive years. Based on 1514 single nucleotide polymorphisms (SNPs), genome-wide association studies (GWAS) were conducted using a mixed linear model (MLM).RESULTS:Extensive phenotypic variation existed in the soybean mini core collection and significant positive correlations were shown among most of traits. A total of 16 SNP markers for PFW, SFW, KP and MCFS were detected in all environments via GWAS. Nine SNP markers were repeatedly identified in two environments. Among these markers, eight were located in or near regions where yield-related QTLs have been reported in previous studies, and one was a novel genetic locus identified in this study. In addition, we conducted candidate gene analysis to the large-effect SNP markers, a total of twelve genes were proposed as potential candidate genes of soybean yield at the R6 stage.CONCLUSION:These results will be beneficial for understanding the genetic basis of soybean yield at the R6 stage and facilitating the pyramiding of favourable alleles for future high-yield breeding by marker-assisted selection in vegetable soybean.

为进一步解析中国大豆种质水溶性蛋白的遗传基础,为大豆高水溶性蛋白质的分子标记辅助选择育种及品质改良提供理论依据,本研究以224份大豆种质为试验材料,于2017和2018年对大豆水溶性蛋白质含量进行测定,利用1 514个高质量的SNP标记分别对2017、2018年水溶性蛋白质含量及两年均值进行全基因组关联分析,共检测到18个显著关联的SNP标记,这些SNP标记涉及16个位点,有8个位点至少被检测到2次,其余8个位点仅被检测到1次,表明其受环境因素影响较大.16个位点中有7个尚未见报道,分别位于8、11、13、14和15号染色体上,是新发现的控制大豆水溶性蛋白的位点.对表型变异解释率较高且稳定关联的2个位点qWSPC7和qWSPC8-1候选区间内的基因进行预测,共获得25个候选基因,其中有7个基因(Glyma.07g195000、Glyma.08g103100、Glyma.08g108900、Glyma.08g105100、Glyma.08g107800、Glyma.08g107700和Glyma.08G115800)在大豆籽粒、根或根瘤中具有较高的表达水平.这些基因可作为水溶性蛋白质的候选基因,可能具有调控大豆水溶性蛋白质的功能.

NAC proteins represent one of the largest transcription factor (TF) families involved in the regulation of plant development and the response to abiotic stress. In the present study, we elucidated the detailed role of GmNAC8 in the regulation of drought stress tolerance in soybean. The GmNAC8 protein was localized in the nucleus, and expression of the GmNAC8 gene was significantly induced in response to drought, abscisic acid (ABA), ethylene (ETH) and salicylic acid (SA) treatments. Thus, we generated GmNAC8 overexpression (OE1 and OE2) and GmNAC8 knockout (KO1 and KO2) lines to determine the role of GmNAC8 in drought stress tolerance. Our results revealed that, compared with the wild type (WT) plant, GmNAC8 overexpression and GmNAC8 knockout lines exhibited significantly higher and lower drought tolerance, respectively. Furthermore, the SOD activity and proline content were significantly higher in the GmNAC8 overexpression lines and significantly lower in the GmNAC8 knockout lines than in the WT plants under drought stress. In addition, GmNAC8 protein was found to physically interact with the drought-induced protein GmDi19-3 in the nucleus. Moreover, the GmDi19-3 expression pattern showed the same trend as the GmNAC8 gene did under drought and hormone (ABA, ETH and SA) treatments, and GmDi19-3 overexpression lines (GmDi19-3-OE9, GmDi19-3-OE10 and GmDi19-3-OE31) showed enhanced drought tolerance compared to that of the WT plants. Hence, the above results indicated that GmNAC8 acts as a positive regulator of drought tolerance in soybean and inferred that GmNAC8 probably functions by interacting with another positive regulatory protein, GmDi19-3.

大豆(Glycine max(L.)Merr.)起源于中国,可以为人类提供主要的植物蛋白和油脂.随着环境条件的日渐恶劣,中国干旱与半干旱的地区发生干旱、高温、盐渍等非生物胁迫的频率日渐增高,严重影响了中国大豆的生产.转基因技术的出现使培育植物新品种的效率大大提高.利用转基因技术提高大豆对非生物胁迫耐受性的报道已经日渐增多.因此,对利用转基因技术来提高大豆对非生物胁迫耐受性的研究进行综述对于大豆生物工程育种具有十分重要的意义.

转基因大豆油是否可以安全食用,目前仍困扰着大部分中国消费者.鉴于此,文中从大豆的重要性、什么是转基因大豆、抗草甘膦大豆品种的创制及对根际微生物群落的影响、中美两国对转基因大豆的标识问题等方面进行了科普.目前中国已经建立一套适合中国国情的转基因生物安全法律法规和管理条例,为转基因大豆的研究和应用保驾护航.