Genome-wide identification and expression profiles of AP2/ERF transcription factor family in mung bean (Vigna radiata L.)

Mung bean (Vigna radiata L. Wilczek) is an economically important grain legume crop in Asia, with high nutritional quality and potential in other parts of the world particularly arid and semiarid regions. Considering the potential adverse effects of drought, high salt, and other abiotic stresses on crop yield, significant efforts have been made to understand the underlying molecular mechanisms of tolerance to these abiotic stresses in legumes. In this study, a total of 186 putative AP2/ERF genes were identified, which were named VrERF1-186. These VrERF genes were classified into four main subfamilies according to the number of AP2 domains and sequence similarity, including 24 AP2 gene members, 81 ERF gene members, 79 DREB gene members, and 2 RAV members. VrERF genes are scattered across all 11 chromosomes and form small gene clusters on chromosomes due to segmental or tandem duplication. Promoter analysis revealed various cis-acting elements related to light, hormones, and stress responsiveness processes. The expression profiles of the VrERF genes in tissues during development and in response to abiotic stresses were assessed by transcriptome sequencing, and the selected reference genes were validated by qRT-PCR. A total of 174 VrERF genes were expressed in at least one of five tissues, while others showed distinct expression patterns in different tissues or under specific abiotic stress treatments, which indicates that VrERF genes are involved in developmental and environmental stress responses in V. radiata. In conclusion, the genome localization, genome-wide characterization, gene duplication, phylogenetic relationships, and expression pattern of VrERF genes in V. radiata were analyzed, and these results will lay the foundation for further functional analysis of these genes and improve stress tolerance to adverse conditions in plants.