Genome-wide identification, sequence variation, and expression of the GPAT gene family in Medicago truncatula

Glycerol-3-phosphate acyltransferase (GPAT) is a rate-limiting enzyme in the biosynthesis of triacylglycerol (TAG). GPAT catalyzes the initial step of TAG biosynthesis, provides substrates for synthesis of a variety of lipids, and is directly involved in plant growth, plant development, and stress resistance. Medicago truncatula, a leguminous model plant, has the characteristics of a small genome, short growth cycle, and high genetic transformation efficiency. Thus, the genome of M. truncatula was selected as the research object in this study to understand the role of the GPAT gene in alfalfa stress resistance, especially in salt tolerance. Twenty-four mtGPAT genes were identified from the genome of M. truncatula by BLASTp and HMM domain searches. According to the phylogenetic analysis, gene structure, and domain differences, the genes can be divided into three subfamilies. Chromosome mapping analysis showed that 24 mtGPAT genes were unevenly distributed on 7 alfalfa chromosomes, and 2～5 genes were distributed on each chromosome. Finally, gene expression pattern analysis showed that the GPAT gene of M. truncatula was organ-specific and involved in salt stress response. These results can provide a theoretical basis for further study of the function of GPAT family genes in M. truncatula.