Characterization, evolutionary analysis, and expression profiling of the VrPYL gene family in mung bean in response...

Abscisic acid (ABA) plays a central role in regulating plant growth and development and in mediating responses to both biotic and abiotic stresses. PYL proteins serve as the core receptors in the ABA signaling pathway. The characteristics of the PYL gene family and its response to abiotic stresses in mung bean (Vigna radiata L.) have not been clarified. In this study, we performed genome-wide screening of mung bean and identified nine PYL genes unevenly distributed across six chromosomes. Bioinformatic predictions revealed that all encoded VrPYL proteins are predicted to be hydrophilic and primarily localized to chloroplasts and the cytoplasm. Segmental duplication was the primary driver of the expansion of this gene family, with duplicated gene pairs having undergone purifying selection during evolution. Phylogenetic analysis showed that VrPYL proteins were divided into three groups, and members within each group exhibited conserved exon-intron structures and motif composition. Homology and synteny analyses indicated that the PYL gene family has remained relatively conserved among mung bean and other plant species. A protein domain analysis demonstrated that all VrPYL proteins contained the "helix-clamp" domain typical of the PYL gene family. Notably, the third and fourth amino acid residues within the CL2 region exhibited marked polymorphism: the valine-valine (VV) motif was the predominant combination, while the valine-threonine (VT) variant displayed mung bean-specific characteristics. Cis-element analysis of the VrPYL gene promoters revealed diverse hormone-responsive and stress-responsive elements. Furthermore, qRT-PCR assays showed that most VrPYL genes responded to ABA, PEG and salt stress treatments, with VrPYL3 and VrPYL4 emerging as promising candidate genes in response to drought and salt stress. Overall, this study lays a foundation for investigating the functions of VrPYL genes in abiotic stress responses and provides valuable genetic resources for molecular breeding.