Genome-wide characterization of the rose (Rosa chinensis) WRKY family and role of RcWRKY41 in gray mold resistance

BACKGROUND: The WRKYs are a major family of plant transcription factors that play roles in the responses to biotic and abiotic stresses; however, a comprehensive study of the WRKY family in roses (Rosa sp.) has not previously been performed. RESULTS: In the present study, we performed a genome-wide analysis of the WRKY genes in the rose (Rosa chinensis), including their phylogenetic relationships, gene structure, chromosomal locations, and collinearity. Using a phylogenetic analysis, we divided the 56 RcWRKY genes into three subgroups. The RcWRKYs were unevenly distributed across all seven rose chromosomes, and a study of their collinearity suggested that genome duplication may have played a major role in RcWRKY gene duplication. A Ka/Ks analysis indicated that they mainly underwent purifying selection. Botrytis cinerea infection induced the expression of 19 RcWRKYs, most of which had undergone gene duplication during evolution. These RcWRKYs may regulate rose resistance against B. cinerea. Based on our phylogenetic and expression analyses, RcWRKY41 was identified as a candidate regulatory gene in the response to B. cinerea infection, which was confirmed using virus-induced gene silencing. CONCLUSIONS: This study provides useful information to facilitate the further study of the function of the rose WRKY gene family.