Identification of the WRKY Gene Family and Characterization of Stress-Responsive Genes in Taraxacum kok-saghyz Rodin

WRKY transcription factors present unusual research value because of their critical roles in plant physiological processes and stress responses. Taraxacum kok-saghyz Rodin (TKS) is a perennial herb of dandelion in the Asteraceae family. However, the research on TKS WRKY TFs is limited. In this study, 72 TKS WRKY TFs were identified and named. Further comparison of the core motifs and the structure of the WRKY motif was analyzed. These TFs were divided into three groups through phylogenetic analysis. Genes in the same group of TkWRKY usually exhibit a similar exon-intron structure and motif composition. In addition, virtually all the TKS WRKY genes contained several cis-elements related to stress response. Expression profiling of the TkWRKY genes was assessed using transcriptome data sets and Real-Time RT-PCR data in tissues during physiological development, under abiotic stress and hormonal treatments. For instance, the TkWRKY18, TkWRKY23, and TkWRKY38 genes were significantly upregulated during cold stress, whereas the TkWRKY21 gene was upregulated under heat-stress conditions. These results could provide a basis for further studies on the function of the TKS WRKY gene family and genetic amelioration of TKS germplasm.

Automated summary

WRKY transcription factors play critical roles in plant physiological processes and stress responses, and TKS WRKY TFs have unique characteristics compared to other plant WRKY TFs. In this study, 72 TKS WRKY TFs were identified and named, and the core motifs and structure of the WRKY motif were analyzed. Phylogenetic analysis divided these TFs into three groups, and genes in the same group usually showed similar exon-intron structure and motif composition. Additionally, almost all TKS WRKY genes contained cis-elements related to stress response. Expression profiling of TkWRKY genes revealed significant upregulation under cold or heat stress conditions. These findings provide insights into the function of the TKS WRKY gene family and its potential for genetic improvement.