Abstract
BACKGROUND: The WRKY gene family plays important roles in plant growth, development, and response to various stresses. Despite the significance of Sainfoin (Onobrychis viciifolia) as an important forage legume species, WRKY genes in this species have not been studied thoroughly. The aim of this study was to identify WRKY genes family in Sainfoin genome, particularly those linked to response to drought, salt, and alkali stresses. RESULTS: A total of 253 WRKY genes (OvWRKY) were identified in Sainfoin. Phylogenetic analysis and conserved domain analysis divided these genes into seven subfamilies with similar conserved motifs but different gene structures. Collinearity analysis identified 232 duplicated gene pairs, including four tandem repeat pairs, indicating role of segmental duplication in the expansion of the OvWRKY gene family. Transcriptome analysis revealed that highly expressed genes under drought, salt, and alkali stress mostly belonged to groups I, III, IId, IIa, and IIb. OvWRKY89 was down-regulated, and OvWRKY147 was up-regulated by drought, salt, and alkali treatments. OvWRKY240 and OvWRKY164 were down-regulated by both drought and salt stress, and OvWRKY36, OvWRKY107, OvWRKY65, and OvWRKY200 were down-regulated by both salt and alkali stress. Protein association network analysis using STRING suggested that OvWRKY89 is functionally associated with five other WRKY proteins and four stress-related proteins. CONCLUSIONS: In this study, we identified and analyzed the WRKY gene family members in Sainfoin for their physicochemical properties, gene structures, conserved motifs, phylogenetic relationships, and expression under drought, salt, and alkali stresses. Some key genes were identified based on enrichment analysis, potential protein network, and the expression under drought, salt, and alkali stress. This study provides insights into the diversity of the WRKY gene family and their roles in drought, salt, and alkali stress responses in Sainfoin.