Genome-Wide Identification and Characterization of WRKY Gene Family of Brassica

The WRKY proteins, one of the largest transcription factor in higher plants, having one or two conserved WRKY domains followed by the novel C₂H₂ or C₂HC zinc finger motif. Evidences are to suggest that the WRKY proteins are involved in multiple biological processes like plant development, metabolism, and responses to biotic and abiotic stresses. In this study, we identified 145 WRKY genes designated as Brassica rapa WRKY (BrWRKY) through a genome-wide survey of the B. rapa database and performed extensive analysis on gene structures, gene duplication, chromosome locations and conserved motif organizations etc. Basic structures and Phylogeny analysis of these genes and WRKY genes of other species have been clustered into three major groups (Group-I, II and III) with further five subgroups of the Group-II. Subsequently, we selected 41 BrWRKY genes with differential expression from a low temperature treated whole genome microarray dataset and analyzed their expression in cold, salt and drought stress treated B. rapa plants at certain time courses. Several genes among them showed differential expression under all these stresses treated. These above results will provide a platform on the functions of BrWRKY genes and might be valuable resources for the improvement of existing cultivars of Brassica.