Identification and expression analysis of WRKY superfamily genes under lychee downy blight stress in lychee

Abstract WRKY proteins comprise a large family of transcription factors that play important roles in plant growth, development, and responses to stress, but little information is available about these genes in lychee ( Litchi chinensis Sonn.). Despite being a popular fruit worldwide, lychee is highly vulnerable to lychee downy blight (LDB; caused by Peronophythora litchii ), a major disease affecting lychee. Based on lychee whole‐genome data, a total of 50 LcWRKY genes were identified across 15 chromosomes. According to a conserved domain and phylogenetic analysis, these 50 LcWRKYs were classified into three distinct subfamilies. Gene structure analysis revealed the presence of 2–11 exons in the LcWRKYs . Cis ‐acting regulatory element analysis identified many stress‐response elements in LcWRKY promoters. Moreover, a comprehensive 2‐year investigation involving the screening of a lychee natural population led to the identification of Guiwei and Yurong1 as displaying stable susceptibility and resistance against LDB, respectively. Furthermore, expression patterns indicated that LcWRKY13 , LcWRKY17 , and LcWRKY34 were significantly upregulated in response to LDB induction, while LDB suppressed the expression of LcWRKY11 . These findings suggest that these four genes may play a crucial role in lychee resistance to LDB. The present study has provided a foundation for future investigations of LcWRKY gene function in lychee.