Genome-Wide Identification of WRKY Gene Family in Artemisia and Its Expression Analysis of Aphid Resistance

WRKY is a crucial transcription factor involved in plant growth, development, and responses to abiotic stress. In the present study, a total of 182 AaWRKY transcription factor members were identified across the Artemisia argyi genome and found to be distributed across 17 chromosomes. Evolutionary analysis revealed that segmental duplication served as the primary driver for family expansion, with the evolutionary trajectory shaped by strong purifying selection (Ka/Ks < 1.0). Phylogenetic classification categorized these members into seven highly conserved subgroups, while physicochemical analysis indicated that most AaWRKYs are unstable, hydrophilic proteins, consistent with the rapid turnover required for transcriptional switches. Transcriptomic profiling unveiled significant tissue-specific expression patterns, with over 50% of the members predominantly enriched in roots and specific genes, such as AaWRKY11, implicated in the regulation of leaf senescence. Protein–protein interaction (PPI) network analysis identified AaWRKY110 as a central regulatory hub linking the MAPK signaling pathway with the isoflavonoid biosynthetic machinery. Furthermore, comparative transcriptomic analysis between aphid-resistant (Ai20K) and susceptible (Ai72G) cultivars demonstrated that resistance is conferred by a priming mechanism involving high basal expression of key candidates, including AaWRKY82, 108, 128, and 71. In contrast, the susceptible genotype exhibited a delayed and ineffective hypersensitive-like response. Collectively, these findings elucidate the evolutionary dynamics of the AaWRKY family and provide critical genetic targets for the concurrent improvement of medicinal metabolite accumulation and biotic stress resilience in Artemisia argyi via molecular breeding.