In silico genome-wide analysis of the WRKY gene family in Salix arbutifolia.

The WRKY genes encode transcriptional regulators that function in response to biotic and abiotic stress in plants. Thus far, no detailed classification and expression profiles of WRKY genes are available for willow. In this study, a comprehensive computational analysis identified 89 WRKY family genes in willow (Salix arbutifolia) by the in silico cloning method. Based on the results of phylogenetic analysis and the number of WRKY motifs, the WRKY genes were classified into group I to group III. The expression profile was analyzed by the transcriptome data in different tissues. A comparative analysis of Salix, Populus trichocarpa, and Arabidopsis thaliana were performed, and the Salix WRKY family had a similar number as Populus and a larger size than the Arabidopsis. A detailed phylogenetic analysis between Salix and Populus revealed that the WRKY genes had evolved from the same genome duplication event. These results will be useful for future functional analyses of the WRKY family genes.