Systematic analysis of the OSCA family members in Vigna radiata and their involvement in osmotic resistance

Abstract Background Mung bean (Vigna radiata) is a warm-season legume crop and belongs to papilionoid subfamily of the Fabaceae. China is the leading producer of mung bean in the world. It has significant economic and health benefits and is a promising species with broad adaptation and high tolerance to stress environments. The OSCA family members play an important role in the modulation of hypertonic stresses, such as drought and salinity. However, genome-wide analysis of the OSCA family in mung bean is lacking. Results We identified a total of 13 OSCA genes in the mung bean genome and named according to their homology with AtOSCAs. All the OACAs were phylogenetically splitted into four clades. Phylogenetic relationship and synteny analyses showed that the VrOSCAs in mung bean and soybean shared a relatively conserved evolutionary history. In addition, three duplicated VrOSCA gene pairs were identified and the duplicated VrOSCA shave mainly undergone purifying selection pressure during evolution. Protein domain, motif and transmembrane analysis indicated that most of the VrOSCAs shared similar structures with their homologs. The expression pattern showed that exception of VrOSCA2.1, the other 12VrOSCAs were up-regulated expression under treatment with ABA, PEG and NaCl, among which VrOSCA1.4 showed the largest increased expression levels. The duplicated genes VrOSCA2.1/VrOSCA2.2 showed divergence expression, which might experience functionalization during subsequent evolution. The expression profiles under ABA, PEG and NaCl stress revealed a functional divergence of VrOSCA genes, which agreed with the cis-acting elements analysis in the promoter of VrOSCA genes. Conclusions Collectively, the study provided a systematic analysis of the VrOSCA family in mung bean. Our results would lay an important foundation for functional and evolutionary analysis of VrOSCAs, and provide promising genes for further investigation of abiotic stress tolerance in mung bean.