Photoperiod-sensitive plants such as soybean (Glycine max) often face threats from herbivorous insects throughout their whole growth period and especially during flowering; however, little is known about the relationship between plant flowering and insect resistance. Here, we used gene editing, multiple omics, genetic diversity and evolutionary analyses to confirm that the calcium-dependent protein kinase GmCDPK38 plays a dual role in coordinating flowering time regulation and insect resistance of soybean. Haplotype 2 (Hap2)-containing soybeans flowered later and were more resistant to the common cutworm (Spodoptera litura Fabricius) than those of Hap3. gmcdpk38 mutants with Hap3 knocked out exhibited similar flowering and resistance phenotypes as Hap2. Knocking out GmCDPK38 altered numerous flowering- and resistance-related phosphorylated proteins, genes, and metabolites. For example, the S-adenosylmethionine synthase GmSAMS1 was post-translationally upregulated in the gmcdpk38 mutants. GmCDPK38 has abundant genetic diversity in wild soybeans and was likely selected during soybean domestication. We found that Hap2 was mostly distributed at low latitudes and had a higher frequency in cultivars than in wild soybeans, while Hap3 was widely selected at high latitudes. Overall, our results elucidated that the two distinct traits (flowering time and insect resistance) are mediated by GmCDPK38.

Plant stresses causing accumulation of reactive oxidative species (ROS) are scavenged by effective antioxidant defense systems. Therefore, the present study performed genome-wide identification of superoxide dismutase (SOD) and glutathione peroxidase (GPX) gene families in cultivated and wild soybeans, and 11 other legume species. We identified a total of 101 and 95 genes of SOD and GPX, respectively, across thirteen legume species. The highest numbers of SODs and GPXs were identified in cultivated (Glycine max) and wild (Glycine soja). A comparative phylogenetic study revealed highest homology among the SODs and GPXs of cultivated and wild soybeans relative to other legumes. The exon/intron structure, motif and synteny blocks were conserved in both soybean species. According to Ka/Ks, purifying the selection played the major evolutionary role in these gene families, and segmental duplication are major driving force for SODs and GPXs expansion. In addition, the qRT-PCR analysis of the G. max and G. soja SOD and GPX genes revealed significant differential expression of these genes in response to oxidative, drought and salinity stresses in root tissue. In conclusion, our study provides new insights for the evolution of SOD and GPX gene families in legumes, and provides resources for further functional characterization of these genes for multiple stresses.

Soybean is a major source of oil and protein in the human diet and in animal feed. However, as soybean is deficient in sulfur-containing amino acids, its nutritional value is limited. Increasing sulfate assimilation and utilization efficiency is a valuable approach to augment the concentration of sulfur-containing amino acids in soybean seeds, and sulfate transporters play important roles in both sulfate uptake and translocation within plants. In this study, we isolated and characterized a soybean sulfate transporter gene: GmSULTR1;2b. The gene was found to be specifically expressed in root tissues and induced by low-sulfur stress. In addition, GmSULTR1;2b expression in yeast could complement deficiency in the sulfate transporter genes SUL1 and SUL2. Under +S conditions, GmSULTR1;2b-overexpressing tobacco plants accumulated higher levels of organic matter and exhibited enhanced biomass and seed weight compared to control plants. Under -S conditions, acclimation of GmSULTR1;2b-overexpressing plants was much better than control plants. GmSULTR1;2b-overexpressing tobacco seedlings showed better tolerance to drought stress than the control plants, but no significant difference was observed under salt stress. Transcriptome analysis revealed 515 genes with at least a 2-fold change in expression in the leaves of tobacco plants overexpressing GmSULTR1;2b. Of these, 227 gene annotations were classified into 12 functional categories associated with 123 relevant pathways, including biosynthesis and metabolism-related proteins, stress-related proteins, and transporters. The findings reported here indicate that the increased biomass and seed yield observed in transgenic tobacco plants could have resulted from greater nutrient uptake and transport capability as well as enhanced development and accumulation of organic matter. Taken together, our results indicate that GmSULTR1;2b plays an important role in sulfur uptake and could alter the sulfur status of plants. Our study suggests that overexpressing GmSULTR1;2b may enhance plant yield under +S conditions, reduce plant production loss under -S conditions, and improve plant tolerance to sulfur deficiency stress.

Plants have evolved complex defense mechanisms to withstand insect attack. Identification of plant endogenous insect resistance genes is of great significance for understanding plant–herbivore interactions and improving crop insect resistance. Soybean (Glycine max (L.) Merr.) is an important crop that is often attacked by the common cutworm (CCW) (Spodoptera litura Fabricius). In this study, based on our transcriptomic data, the gene GmVQ58, encoding a FxxxVQxxTG (VQ) motif-containing protein, was cloned and characterized. This gene showed the highest expression in the leaves and roots and was up-regulated significantly after CCW attack. Constitutive expression of GmVQ58 rescued the susceptibility of an Arabidopsis mutant to CCW, and interference of GmVQ58 in soybean hairy roots enhanced the resistance to CCW. Furthermore, GmVQ58 was localized to the nucleus and physically interacted with the transcription factor GmWRKY32. The expression of two defense-related genes, GmN:IFR and GmVSPβ, was up-regulated in GmVQ58-RNAi lines. Additionally, the promoter region of GmVQ58 was likely selected during domestication, resulting in different expression patterns in cultivated soybeans relative to wild soybeans. These results suggest that silencing GmVQ58 confers soybean resistance to CCW.

Background: Cotton worm is one of the main insects of soybean in southern China. Plants may acquire defense mechanisms that confer protection from predation by herbivores. Induced responses can lead to increased resistance against herbivores in many species. This study focuses on searching changed proteins in soybean defense response induced by cotton worm feeding. Results: Ten protein spots that are changed in abundance in response to cotton worm feeding were identified by Two-dimensional gel electrophoresis (2-DE). A total of 11 unique proteins from these spots were identified by MALDI-TOF MS. The mRNA and protein relative expression levels of most changed proteins were up-regulated. These proteins were mainly involved in physiological processes, including active oxygen removal, defense signal transduction, and metabolism regulation. Conclusion: This is the first proteomic analysis of the soybean defense response induced by cotton worm. The differentially expressed proteins could work together to play a major role in the induced defense response. PAL and SAMS were up-regulated at both the protein and mRNA levels. These genes can be strongest candidates for further functional research.