Identification of soybean GolS gene family and analysis of expression patterns under salt and drought stresses

Abstract

Galactinol synthase (GolS) is a key enzyme in the biosynthetic pathway of raffinose family oligosaccharides (RFOs) and plays an important role in plant responses to abiotic stresses. However, the molecular characteristics of the GolS family members in soybean was not well-known. In this study, six members of GmGolS gene family were genome-widely identified, and their physicochemical properties, chromosomal localization, evolutionary relationship, gene structure, conserved motifs, secondary structure, tertiary structure, tissue-specific expression patterns and the expression levels under salt and drought stresses were analyzed. The results showed that six soybean GolS genes were unevenly distributed on four chromosomes, the range of the isoelectric points of six GmGolS proteins was 5.45-6.08, the molecular weight range was 37 567.07-38 817.59 Da, and the number of amino acids was 324-339 aa. The results of subcellular localization showed that 4 proteins were located in the chloroplast, and 2 proteins in the cytoplasm. Phylogenetic tree analysis showed that the members of the soybean GolS gene family were closely adjacent to each other, and were evolutionarily conservative. Six gene members contain 3 or 4 exons. Prediction of secondary and tertiary structures showed that the spatial structure of proteins of all family members was mainly composed of α-helix and random coil structure, with less β-turn and extended chain structure. Tissue-specific expression analysis showed that six GmGolS members expressed to variable degrees in seeds, roots, root hairs, flowers, stems, pods, nodules and leaves. Expression analysis based on qRT-PCR showed that all GmGolS genes showed different degrees of up-regulated expression under salt and drought treatment, indicating that these genes may be related to the response of plants to salt-tolerance and drought-resistance. These results may facilitate subsequent functional analysis of soybean GolS genes.