Dissecting the genomic landscape of ERD genes in alfalfa (Medicago sativa): the effect of melatonin and low selenium under salt stress

Abstract

The early response to dehydration (ERD) gene family plays a central role in abiotic stress regulation, plant development and defense mechanisms, particularly under dehydration conditions. However, the genomic characterization and functional roles of ERD genes in alfalfa (Medicago sativa) remain largely unexplored. This study aims to identify and analyze ERD genes in alfalfa to understand their evolutionary conservation and involvement in stress responses. A total of 27 ERD genes were identified and categorized into five distinct phylogenetic groups (Group˗1 to Group˗5) based on comparative analysis with homologs from Glycine max, Medicago truncatula, Lotus japonicus and Arabidopsis thaliana. Comprehensive analyses of gene structure, chromosomal localization, conserved protein motifs, cis-elements, synteny and transcriptomic profiles were conducted to uncover the structural and functional attributes of the MsERD genes. Notably, the results indicated that MsERD2, MsERD15 and MsERD27 were significantly overexpressed in response to low selenium concentrations and salt stress mediated by melatonin pathways. Evidence of segmental duplication and motif conservation implies evolutionary conservation and potential functional redundancy. Differential expression patterns in leaf tissues emphasize their roles in adaptive stress responses. This comprehensive genomic and expression study provides valuable insights into the molecular regulation of ERD genes in alfalfa. The findings underscore the potential roles of specific MsERD genes in abiotic stress tolerance and mineral homeostasis, highlighting potential targets for the genetic improvement of stress-resilient alfalfa cultivars.