Genome-wide analysis of soybean MLPs reveals evolutionary and structural insights into drought, salt stress and ABA responses

The major latex protein (MLP) gene family, which is part of the Bet v 1 superfamily, is known for its roles in plant development and stress responses. However, the MLP gene family in soybean (Glycine max) remains insufficiently characterized. In this study, we systematically identified 17 MLP genes (GmMLPs) containing the conserved Bet v 1 domain within the soybean genome. These genes were classified into three subgroups—Type I, Type II, and Type III—based on sequence similarity and phylogenetic analysis. Chromosomal mapping revealed an uneven distribution of GmMLPs across the 20 soybean chromosomes, with a tendency to cluster in the lower arm regions, indicating nonrandom chromosomal localization. Gene structure analysis revealed that most GmMLPs contain a single intron, whereas a few, such as GmMLP3 and GmMLP4, possess multiple introns, reflecting structural diversity within the gene family. Expression profiling using qRT‒PCR demonstrated that several GmMLPs are responsive to abscisic acid (ABA), drought, and salt stress, suggesting potential roles in abiotic stress responses. These findings provide a comprehensive foundation for future functional studies of the role of GmMLPs in stress tolerance and adaptation in soybean.