Genome-wide Identification and Structural, Functional and Evolutionary Analysis of WRKY Components of Mulberry

Mulberry is known to be sensitive to several biotic and abiotic stresses, which in turn have a direct impact on the yield of silk, because it is the sole food source for the silk worm. WRKYs are a family of transcription factors, which play an important role in combating various biotic and abiotic stresses. In this study, we identified 54 genes with conserved WRKY motifs in the Morus notabilis genome. Motif searches coupled with a phylogenetic analysis revealed seven sub-groups as well as the absence of members of Group Ib in mulberry. Analyses of the 2K upstream region in addition to a gene ontology terms enrichment analysis revealed putative functions of mulberry WRKYs under biotic and abiotic stresses. An RNA-seq-based analysis showed that several of the identified WRKYs have shown preferential expression in the leaf, bark, root, male flower and winter bud of M. notabilis. Finally, expression analysis by qPCR under different stress and hormone treatments revealed genotype-specific responses. Taken together, our results briefs about the genome-wide identification of WRKYs as well as their differential response to stresses and hormones. Importantly, these data can also be utilized to identify potential molecular targets for conferring tolerance to various stresses in mulberry.