Genome-wide analysis of WRKY family of transcription factors in common bean, Phaseolus vulgaris: Chromosomal localization, structure, evolution and expression divergence

• Genome-wide analysis identified 90 WRKY genes in P. vulgaris that were classified into three groups.
• All the WRKY genes were located on chromosomes 1 to 11 with a non-uniformed distribution.
• Both tandem and segmental duplications played an important role in the evolution and diversification of the WRKY genes.
• Tissue-specific expression of most WRKY genes suggests expression and function divergence during the growth of common bean.

WRKY transcription factors play critical roles in plant growth and development, as well as the response to biotic and abiotic stresses. Despite the fact that WRKY gene family has been characterized in a number of plant species, very little is known in the common bean, Phaseolus vulgaris. The recently released genome sequences provide us a good opportunity for genome-wide analysis of WRKY genes in this legume crop. In this study, a total of 90 WRKY genes (PvWRKYs) were identified and classified into three groups, of which the second group was further separated into five subgroups based on the structure of the conserved domains. All the WRKY genes were located on chromosomes 1 to 11 with a non-uniformed distribution. The phylogenetic analysis revealed that the majority of the PvWRKY genes were clustered with those from soybean, indicating that most of the WRKY genes may be originated from the same ancestor with Glycine max; both tandem and segmental duplications have played an important role in the evolution and diversification of the WRKY gene family in P. vulgaris. The variety and complexity of protein structure indicate that WRKY genes may be of significance in plant growth regulation and stress responses. The analysis of expression profiles revealed that the majority of WRKY genes showed tissue-specific expression, which is indicative of diverged expression during the development of common bean.