Comprehensive analysis of the function of the GolS family and LpGols7 in Lespedeza potaninii under drought stress.

Seven LpGolS genes were identified in Lespedeza potaninii and showed tissue-specific expression and drought induction. Overexpression of LpGolS7 improves drought tolerance. Galactinol synthase (GolS) is a key enzyme in the biosynthetic pathway of raffinose family oligosaccharides (RFOs) that plays a crucial role in mediating plant responses to abiotic stress. However, the evolutionary relationships and biological functions of the GolS family in xerophytic Lespedeza potaninii remain unclear. In this study, we identified seven members of the GolS gene family at the whole-genome level in L. potaninii. Phylogenetic analysis revealed that the GolS family members from 18 plants could be divided into 4 subfamilies. Groups I, II, and III were mainly composed of dicotyledonous genes, while Group IV was dominated by monocotyledonous genes. Expression profiling analysis revealed a specific LpGolS gene expression phenomenon, in which they were highly expressed in the roots and seeds. Transcriptomic and qRT-PCR analyses revealed that the expression levels of LpGolS genes in the shoots and roots of L. potaninii were significantly induced by drought stress. These findings indicate that LpGolS genes play important roles in the drought response of L. potaninii. Heterologous expression analysis indicated that the heterologous expression of LpGolS4 and LpGolS7 enhanced yeast tolerance to polyethylene glycol (PEG) stress. Subcellular localisation analysis revealed that GFP (Green fluorescent protein)-LpGolS7 fusion protein expression was distributed throughout both the nucleus and the cytoplasm. Overexpression of LpGolS7 improved the drought tolerance of L. potaninii by increasing the soluble sugar content. These results provide a foundation for subsequent functional analysis of the GolS gene in L. potaninii.