Genome-Wide Analysis of the WRKY Transcription Factor Gene Family and Their Response to Salt Stress in Rubber Tree.

The multigene family WRKY is plant-specific transcription factors, which is involved in numerous aspects of plant growth and development. Here, we report a genome-wide search for the rubber tree WRKY (HbWRKY) genes and their expression profiles at various tissues including latexes. We also present a comprehensive overview of whole HbWRKY gene family, including gene structure, chromosomal locations, conserved protein domains, gene duplications and phylogenetic inferences. We identify a total of 108 full-length HbWRKY genes, which were classified into the three major subgroups. The genome-scale syntenic analysis showed that WGDs might have played a major role in the evolution of the HbWRKY gene family. Our further real-time reverse transcription-PCR (qRT-PCR) experiments validated that the HbWRKY genes are divergently expressed and gene expression divergence seemingly existed among the duplicated WRKY genes, suggesting a fundamentally functional divergence of the duplicated WRKY paralogs in rubber tree. We also investigated the gene expression profiling of the HbWRKYs under salt stress, to which the majority of genes differentially responded. This study acquires a new insight into the evolution of the HbWRKYs, which will help further functional characterization of theses candidate genes in rubber tree. [ABSTRACT FROM AUTHOR]