Genome-Wide Identification of the Phosphoglycerate Kinases and Functional Analysis of GmPGK5 in Regulating Oil Accumulation in Soybean

Phosphoglycerate kinase (PGK) is a vital glycolytic enzyme that provides energy and carbon skeletons to support fatty acid synthesis. However, the PGK gene family has not been characterized in soybean (Glycine max), and its role in soybean oil accumulation remains unclear. Here, we identified six GmPGK genes in soybean, all of which encode proteins containing conserved PGK domains. Phylogenetic analysis clustered soybean PGK proteins into three groups. Analysis of GmPGK promoters revealed relatively abundant cis-elements related to plant growth, development, and phytohormone response. Expression profiling showed that GmPGK5 transcript abundance increases progressively with oil accumulation during seed development, and is significantly higher in the high-oil variety NN1138-2. Overexpression of GmPGK5 significantly increased total fatty acid content in soybean hairy roots. A single nucleotide polymorphism (SNP) located at Chr15:49447855 within the GmPGK5 promoter was significantly associated with both seed oil content and seed weight in natural soybean accessions. Based on this SNP, a derived cleaved amplified polymorphic sequence (dCAPS) marker was developed to facilitate soybean molecular breeding. Our findings suggest that GmPGK5 may positively regulate fatty acid accumulation in soybean. The identified natural variation and dCAPS marker provide potential valuable tools for marker-assisted selection to improve soybean oil content and seed weight.