Genome-Wide Identification and Expression Profiling of the Lipid Phosphate Phosphatase Gene Family Reveals Its Potential Roles in Abiotic Stress Responses in Soybean

Lipid phosphate phosphatases (LPPs) are critical regulatory factors in plant membrane lipid metabolism and lipid signal transduction, exerting key roles in membrane lipid remodeling, signal attenuation, and adaptation to abiotic stresses. However, the systematic identification of the soybean GmLPP gene family and its expression profiles in response to abiotic stresses remains largely unclear. In this study, a total of nine GmLPP family members were identified in the soybean genome, which were further classified into three subgroups based on their phylogenetic relationships. qRT-PCR analysis demonstrated that the majority of GmLPP genes responded to NaCl, PEG6000, NaHCO3, JA, and SA treatments to varying extents, among which GmLPP7 exhibited the most pronounced response to salt stress. Subcellular localization assays demonstrated that the GmLPP7 protein is primarily localized to the cell membrane. Further haplotype analysis was performed on 160 soybean germplasm accessions, leading to the identification of five SNP loci within the GmLPP7 gene region. Among these, two SNPs were significantly associated with the relative germination index (STGI) and formed two distinct haplotypes. Notably, Hap2 exhibited a significantly higher STGI value, thus representing a superior salt-tolerant haplotype. In summary, this study systematically elucidates the evolutionary and expression profiles of the GmLPP gene family, identifies GmLPP7 as a candidate gene significantly associated with salt tolerance during soybean germination, and its superior haplotype Hap2, thereby providing novel genetic resources for the molecular improvement of salt tolerance in soybean.