With-no-lysine kinase (WNK) is a unique serine/threonine kinase family member. WNK differs from other protein kinases by not having a standard lysine in subdomain II of the universally preserved kinase catalytic region. Conversely, the amino acid lysine located in subdomain I plays a crucial role in its phosphorylation. The WNK family has been reported to regulate Arabidopsis flowering, circadian rhythm, and abiotic stress. Eighteen members of the WNK gene family were discovered in apples in this research, and they were primarily grouped into five categories on the phylogenetic tree. Conserved domains and motifs also confirmed their identity as members of the WNK family. Promoter cis-acting element analysis indicated their potential role in responses to both abiotic stress and phytohormones. Furthermore, qRT-PCR analysis showed that the expression of MdWNK family genes was stimulated to different extents by Colletotrichum siamense, NaCl, mannitol, ABA, JA, and SA, with Colletotrichum siamense being the most prominent stimulant. MdWNK family genes were expressed across all apple tissues, with young fruits showing the greatest expression and roots showing the least expression. The research offered detailed insights into the MdWNK gene family, serving as a crucial basis for investigating the biological roles of MdWNK genes.

Taraxacum mongolicum contains various bioactive components. This study investigated the potential of thermostable microRNAs (miRNAs) derived from this plant as cross-kingdom regulators and evaluated their anti-proliferative effects on HepG2 cells. High-throughput sequencing was used to screen thermostable miRNAs and predict their target genes. Enrichment and target gene expression in gavaged mice were analyzed to assess cross-kingdom regulatory potential. Cellular assays evaluated anti-proliferative activity. miR166 was identified as a thermostable miRNA in T. mongolicum, and bioinformatics indicated its possible involvement in cancer-associated mucin-type O-glycan biosynthesis. RT-qPCR revealed that miR166 was negatively correlated with signal transducing adaptor family member 2 (STAP2) mRNA expression. In mice, administration of total RNA extracted from fresh T. mongolicum or its water decoction led to significant changes in miR166 levels in stomach, blood, liver, spleen, and intestine, accompanied by reduced STAP2 mRNA, suggesting cross-kingdom regulation. Overexpression of miR166 induced a delay in G1/S transition in HepG2 cells in a concentration-dependent manner, accompanied by reduced STAP2 expression and decreased cell viability. These findings provide preliminary experimental evidence that thermostable miR166 from T. mongolicum is associated with inhibition of HepG2 proliferation. They also suggest STAP2 as a candidate regulatory target, offer a potential new molecule for further investigation in liver cancer intervention, and provide a preliminary molecular basis for the medicinal and edible value of T. mongolicum.