Abstract:

Arabidopsis VAS1 gene encodes a pyridoxal-phosphate-dependent aminotransferase, which regulates the auxin amount through converting the indole pyruvic acid to tryptophan. Genome-wide characterization and expression pattern analysis of soybean aminotransferase VAS1 was conducted to explore their roles in root development, for laying foundation in further mining biological functions of VAS1 in soybean plant（Glycine max）. Bioinformatics approaches were used to identify and analyze the gene members of the soybean VAS1 family, and then fluorescence quantitative analysis was used to analyze the expression pattern of this gene family under different stress treatments. In addition, GmVAS1-1 gene was cloned for further functional analysis. The interaction factors of GmVAS1-1 were screened through yeast two-hybrid method. The results showed that there were two members in the soybean VAS1 gene family, and were named as GmVAS1-1 and GmVAS1-2. Phylogenetic tree，gene structure and conserved motifs analysis indicated that soybean VAS1 was more closely related to legumes（Phaseolus vulgaris，Medicago truncatula，Vigna unguiculata，Lotus corniculatus and Cicer arietinum）. There were multiple stress or light response elements in the promoter region. Expression pattern analysis showed that soybean VAS1 genes were highly expressed in the endosperm at the different seed development stages. Fluorescent quantitative PCR analysis revealed that the expression of GmVAS1 was significantly up-regulated in soybean roots under drought or salt stress condition. The number of lateral roots in overexpressed GmVAS1-1 Arabidopsis was significantly less than that of wild type, suggesting that GmVAS1-1 was involved in regulating lateral root development in plants. A total of 17 proteins interacting with GmVAS1-1 were screened by yeast two-hybrid assays and network prediction, which laid a molecular theoretical basis for further exploring the function and mechanism of GmVAS1-1 gene. In summary, soybean VAS1 gene family are highly expressed in the endosperm and respond to various abiotic and nutritional stresses, among which GmVAS1-1 is involved in the development of lateral root.

Key words: soybean, auxin, aminotransferase VAS1, abiotic stress, root development