Identification, characterization, and expression analysis of the glutathione peroxidase (GPX) family genes related to abiotic stress in Medicago truncatula

Plant glutathione peroxidase (GPX) is an important antioxidant enzyme to maintain H2O2 homeostasis and regulate diverse essential processes in plant growth and development, and response to abiotic stress. However, the GPX gene family has not been comprehensively identified in Medicago truncatula. Here, we identified 7 MtGPX genes distributed on 8 chromosomes in the M. truncatula genome based on their conserved GPX domains. The physiological and biochemical properties, protein structures, phosphorylation sites, conserved motifs, and exon-intron structures of the MtGPX genes were analyzed. The phylogenetic analysis classified GPXs from different plants into four groups, and members of the same group had similar conserved motifs and gene structures. Expression pattern analysis showed that several MtGPX genes had a broad or tissue-specific expression pattern. In addition, we also studied the expression levels of MtGPX genes under various abiotic stresses. It revealed that the most MtGPX genes were regulated by drought and salt stress treatments, and MtGPX6 was shown to had more abundant up-regulated expression under all the three tested abiotic stress treatments. These findings provide information on the possible roles of MtGPX genes in M. truncatula growth and development, and responses to various environmental stresses.