Genome-wide identification and integrated analysis of the WNK kinase gene family and expression analysis of PgWNK genes under methyl jasmonate treatment in Panax ginseng

Ginseng (Panax ginseng) is a globally renowned medicinal plant. The primary active compounds in ginseng are ginsenosides, which have been shown to possess preventive and therapeutic properties against a range of ailments. WNK (with no lysine) kinases is a subfamily of serine/threonine protein kinases. Members of the WNK gene family play vital roles in the regulation of plant growth, development, and biological processes. Several studies have shown that jasmine methyl ester treatment can increase the content of protopanaxatriol-type ginsenosides in adventitious ginseng roots. However, there are no reports on the effects of WNK in ginseng under methyl jasmonate (MeJA) treatment. In this study, we conducted a detailed screening, identification, and systematic research on the WNK gene family in ginseng, including phylogenetic relationships, gene structure, chromosomal distribution, GO functional classification, cis-regulatory elements, co-expression network analysis, and gene expression pattern analysis. Furthermore, we identified candidate genes of PgWNK that could significantly respond to methyl jasmonate regulation and conducted an in-depth study of their expression patterns to explore the impact of these candidate genes on the variation in triterpenoid ginsenoside content. We identified 32 WNK genes in ginseng that were unevenly distributed across 11 of the 24 chromosomes in the ginseng genome. GO functional annotation and enrichment analysis of the PgWNK genes revealed their involvement in numerous biological processes, including ginseng growth, development, and biosynthesis of secondary metabolites. Through expression network analysis, we further understand that there are complex interactions among members of the PgWNK gene family. In addition, 17 non-biological stress response components related to hormone response, growth, and development were predicted in the promoter area of the PgWNK gene. At the same time, we studied the gene expression of PgWNK after MeJA treatment and found that the expression related to ginsenoside biosynthesis was significantly increased as the regulation time was prolonged. Following MeJA regulation, the content of five protopanaxatriol-type ginsenosides (Re, Rf, Rg1, Rg2, and Rh1) increased owing to the adjustment of PgWNK05 gene expression. Therefore, our results provide an important theoretical foundation for understanding the molecular characteristics, genetic evolution, genetic functions, expression patterns, and non-biological coercion of the WNK gene family in ginseng. The underlying research on the biological synthesis of ginsenosides provides a foundation and theoretical support.