Identification, characterization, and expression analysis of WRKY transcription factors in Gynostemma pentaphyllum during tissue growth and cadmium stress

<i>Gynostemma pentaphyllum</i>, a perennial medicinal herb, is widely distributed and exhibits remarkable adaptability to various environments. <i>WRKY</i> transcription factors play critical roles in regulating plant growth and development, as well as abiotic stress responses. However, the <i>WRKY</i> genes in <i>G. pentaphyllum</i> and their expression patterns under different tissues and Cd stress have not been thoroughly investigated, hindering our understanding of their role. In this study, 64 <i>WRKY</i> transcription factors identified in the <i>G. pentaphyllum</i> genome (<i>GpWRKY</i>) were phylogenetically grouped into three major groups and five subgroups and assigned a systematic nomenclature reflecting their positions across the 11 chromosomes. Comprehensive analyses of conserved domains, gene structures and motif features revealed a high degree of conservation with the gene family. Furthermore, seven pairs of segmental and tandem duplication events were detected, suggesting a contribution to the expansion of family. <i>Cis</i>-acting element analysis revealed the presence of hormone-related, stress-related, light-related, and development-related elements in the promoters of the majority of <i>GpWRKY</i> genes. Expression profiling analysis demonstrates that 64 <i>GpWRKY</i> genes were distinct in tissue-specific expression patterns and were substantially induced under Cd stress. Heterologous expression assay confirmed that <i>GpWRKY48</i>, one of the genes highly induced by Cd, positively regulates Cd tolerance. In this study, <i>GpWRKY</i> genes in <i>G. pentaphyllum</i> for the first time systematically identified and further investigated their physicochemical properties, evolution, and expression patterns, providing a theoretical basis for future studies on the functional characterization of <i>G. pentaphyllum WRKY</i> genes during plant growth and development, as well as Cd stress responses.