Genome-wide identification and expression analysis of the GST gene family of Betula platyphylla

Glutathione-S-transferase (GST, EC2.5.1.18) multifunctional protease is important for detoxification, defense against biotic and abiotic stresses, and secondary metabolic material transport for plant growth and development. In this study, 71 members of the BpGST family were identified from the entire Betula platyphylla Suk. genome. Most of the members encode proteins with amino acid lengths ranging from 101 to 875 and were localized to the cytoplasm by a prediction. BpGSTs can be divided into seven subfamilies, with a majority of birch U and F subfamily members according to gene structure, conserved motifs and evolutionary analysis. GST family genes showed collinearity with 22 genes in Oryza sativa L., and three genes in Arabidopsis thaliana; promoter cis-acting elements predicted that the GST gene family is functional in growth, hormone regulation, and abiotic stress response. Most members of the F subfamily of GST (BpGSTFs) were expressed in roots, stems, leaves, and petioles, with the most expression observed in leaves. On the basis of the expression profiles of F subfamily genes (BpGSTF1 to BpGSTF13) during salt, mannitol and ABA stress, BpGSTF proteins seem to have multiple functions depending on the type of abiotic stress; for instance, BpGSTs may function at different times during abiotic stress. This study enhances understanding of the GST gene family and provides a basis for further exploration of their function in birch.