Cloning and expression analysis of VrNAC13 gene in mung bean

To explore the role of NAC transcription factors in mung bean (Vigna ratiata), we here comprehensively analyzed VrNAC13 structure and expression patterns in the mung bean cultivar "Yulin No.1". The nucleotide sequence of VrNAC13 (GenBank accession number xp014518431.1) was determined by cloning and sequencing the gene. A predicted transcriptional activation domain in VrNAC13 was validated with a yeast one-hybrid assay. The composition and functional characteristics of VrNAC13 were analyzed using basic bioinformatics techniques, and the expression characteristics of VrNAC13 were analyzed via quantitative reverse transcription-PCR. The results showed that VrNAC13 was 1,068 bp in length and encoded a product of 355 amino acids. VrNAC13 was predicted to contain a NAM domain and to belong to the NAC transcription factor family. The protein was hydrophilic and contained several threonine phosphorylation sites. Phylogenetic analysis showed that VrNAC13 was highly similar in sequence to two Arabidopsis thaliana NAC proteins; we hypothesize that VrNAC13 may perform functions in mung bean similar to those of the two closely related proteins in Arabidopsis. Promoter analysis of VrNAC13 revealed cis-acting elements predicted to respond to abscisic acid (ABA), gibberellin, auxin, light, drought, low temperature, and other stressors. VrNAC13 was most highly expressed in the leaves and expressed at very low levels in the stem and root. It was experimentally determined to be induced by drought and ABA. Based on these results, VrNAC13 appears to regulate stress resistance in mung bean.