WRKY transcription factors (TFs) comprise a major and well-characterized gene family in plants and play distinctive and crucial roles in plant development and responses to various external stresses. Despite the extensive identification of WRKY gene family across various species, information regarding this family in Litchi chinensis remains limited. This study identified the 56 WRKY (designated as LcWRKY) genes from the L. chinensis genome and divided them into three major groups with seven subgroups according to their structural and phylogenetic features. The closely linked subgroups exhibited greater similarity concerning gene structures and motif compositions. Segmental duplication (SD) and purifying selection were identified as the primary forces propelling the expansion of the LcWRKY genes. Moreover, we predicted numerous cis-acting elements in the promoter regions of the LcWRKY genes, involving those responsive to light, growth factors, phytohormones, and adverse conditions. The expression levels of the LcWRKY genes, confirmed by quantitative real-time PCR (qRT-PCR) to be induced by cold, heat, drought, and salt stresses, were also demonstrated to positively correlate with variations in key physiological parameters under abiotic stresses. Subcellular localization experiments indicated that LcWRKY7 and LcWRKY13 were localized in nuclei and non-nuclear compartments. Furthermore, we investigated physicochemical properties, secondary structures, gene ontology (GO) annotations, protein–protein interactions, and expression profiling of the LcWRKY genes. This work provides comprehensive information on the LcWRKY family while laying a groundwork for further functional characterization of these genes during stress resistance and anti-stress gene selection as well as stress-resistant breeding in L. chinensis.
Yang et al. (Fri,) studied this question.