WRKY Transcription Factors in Medicago sativa L.: Genome-Wide Identification and Expression Analysis Under Abiotic Stress.

Alfalfa (Medicago sativa L.) is the most widely cultivated leguminous herb in the world. Its agricultural development has been restricted by various adverse environmental conditions, including water deficiency, high salinity, and low temperature. WRKY transcription factors (TFs) serve important roles in the regulation of plant development and stress responses. Research on the WRKY gene family has been reported for several species, but minimal information is available for alfalfa. In the present study, a total of 107 WRKY genes were identified in alfalfa and divided into 3 main groups. The classification, evolution, conserved motifs, and tissue expression were comprehensively analyzed. Meanwhile, 27 MsWRKY candidate genes that may be involved in abiotic stress were isolated through an analysis of gene expression profiles under different stresses, including cold, abscisic acid, drought, and salt treatments. Additionally, investigation of the cis-elements and potential biological functions of these genes further revealed that MsWRKY TFs may serve important roles in multiple stress resistance in alfalfa. This study provides an important foundation for future cloning and functional studies of WRKY genes in alfalfa.