Lysophosphatidic acid acyltransferase (LPAT) enzymes are widely expressed in various plant species, and they contribute to growth, development, and stress responses. Currently, information regarding the LPAT gene family in soybeans is limited. In this study, genome-wide analyses identified 15 soybean LPATs, which were then evaluated for their conserved protein motifs. These genes were grouped into three clusters based on their phylogenetic relationships. Confocal microscopy was used to visualize the localization of six GmLPATs within Arabidopsis mesophyll protoplasts. cis-Acting regulatory element analyses and qRT-PCR experiments revealed that these GmLPATs were upregulated in response to hormonal stimulation or exposure to abiotic stressors, including drought, alkaline conditions, and salt stress. The expression patterns of these GmLPATs varied among different soybean tissue types. One member of the solLPAT1 subtype (GmLPAT11) was found to be upregulated in response to a range of treatments, highlighting its role in soybean salt stress responses. GmLPAT11 expression in Escherichia coli confirmed the LPAT activity of this recombinant enzyme, and overexpressing this LPAT reduced reactive oxygen species production in transgenic soybean plants, thereby enhancing their salt stress tolerance. Gene association analyses indicated that GmLPAT11 variants are closely associated with seedling salt tolerance, and a polymorphism in the GmLPAT11 CDS region was potentially associated with salt tolerance. These results provide new insights into the nature of the LPAT gene family in soybeans while also identifying promising candidate genes for future research efforts to enhance the overall salt tolerance of soybean crops.

Malate dehydrogenase (MDH) is a widely expressed enzyme that plays a key role in plant growth, development, and stress responses. However, information on MDH genes in the soybean genome is limited. Seventeen members of the soybean MDH family were identified by genome-wide analysis, and the genes were analyzed for the presence of conserved protein motifs. The genes were divided into five clusters according to their phylogenetic relationships. The intracellular localizations of six GmMDHs were determined by confocal microscopy of Arabidopsis mesophyll protoplasts. Transcripts of GmMDHs were significantly increased by abiotic stress (drought, salt, and alkalinity) and hormone treatments, as shown by an analysis of cis-regulatory elements and quantitative real-time polymerase chain reaction (qRT-PCR). The GmMDHs displayed unique expression patterns in various soybean tissues. Notably, the expression levels of a chloroplast isoform (GmMDH2) were unusually high under salt stress, presumably indicating a critical role in soybean responses to salinity. Expression of GmMDH2 in Escherichia coli showed that the recombinant enzyme has nicotinamide adenine dinucleotide phosphate (NADP)-dependent MDH activity. The redox states of the NADP (reduced form) (NADPH) pool and antioxidant activities were shown to be modulated by GmMDH2 gene overexpression, which in turn reduced reactive oxygen species (ROS) formation in transgenic soybean, significantly enhancing the salt stress resistance. Gene-based association analysis showed that variations in GmMDH2 were strongly linked to seedling salt tolerance. A polymorphism potentially associated with salt tolerance was discovered in the promoter region of GmMDH2. These findings not only improve our understanding of the stress response mechanism by identifying and characterizing the MDH gene family throughout the soybean genome but they also identified a potential candidate gene for the future enhancement of salt tolerance in soybean.

Plant DnaJA proteins act as molecular chaperones in response to environmental stressors. The purpose of this study was to characterize the function and regulatory mechanisms of DnaJA genes in soybean. Gene expression profiles in various soybean tissues at various stages of development indicated that GmDnaJAs function in the coordination of stress and plant hormone responses. GmDnaJA6 was identified as a candidate regulator of saline and alkaline stress resistance and GmDnaJA6 overexpression lines showed increased soybean saline and alkaline tolerance. DnaJ interacted with Hsp70, and GmHsp70 increased the saline and alkaline tolerance of plants with chimeric soybean hairy roots.