Genome-Wide Identification of NAC Transcription Factor Family and Functional Analysis of the Abiotic Stress-Responsive Genes in Medicago sativa L.

Plant-specific NAC (NAM, ATAF, and CUC2) transcription factors (TFs) are a large gene family in plants that have been shown to play important roles in regulating many developmental processes and abiotic stress resistance. Here, a total of 113 Medicago sativa NAC (MsNAC) TFs, known as MsNAC001 to MsNAC113, were identified and divided into 15 distinct subgroups. A comprehensive bioinformatics analysis of the MsNAC TFs is presented, including phylogenetic relationships, membrane-bound, and conserved motifs. Fourteen MsNAC genes grouped into stress-related subgroup were isolated, and the cis-elements and potentially biological functions of these genes were further investigated. Coupled with expression analysis and qRT-PCR testing, differential expression profiles over time in response to drought and salinity treatments were observed. In transgenic yeast, overexpression of MsNAC001 and MsNAC058 increased tolerance to salt (both) and drought (MsNAC058) stresses. Our findings will provide a starting point for the functional investigation and application of this gene family for crop improvement, especially in legume species.