The GhWRKY70-GhAOS1 Axis Integrates Jasmonate Pathway Signaling to Regulate Cotton Immunity Against Verticillium dahliae

Verticillium wilt (VW), caused by the soil-borne phytopathogen Verticillium dahliae, is a devastating vascular disease that severely threatens global cotton production and causes substantial economic losses. Jasmonic acid (JA) signaling plays a crucial role in plant innate immunity; however, the molecular mechanisms governing JA biosynthesis during cotton defense responses to V. dahliae infection remain largely elusive. In this study, we identified that GhAOS1 (allene oxide synthase 1), a key rate-limiting enzyme-encoding gene in the JA biosynthetic pathway, was rapidly and significantly induced by V. dahliae infection and exclusively localized in chloroplasts. Functional analysis in GhAOS1-silenced cotton and overexpressing Arabidopsis plants demonstrated that GhAOS1 positively regulates resistance to V. dahliae. Transcriptome analysis of GhAOS1-silenced cotton plants showed that DEGs are significantly enriched in phenylpropanoid biosynthesis, flavonoid biosynthesis, and α-linolenic acid metabolism pathways. Consistent with these findings, silencing GhAOS1 significantly reduced endogenous JA levels and suppressed the expression of defense-related genes and JA biosynthetic genes in cotton. Furthermore, we identified that the transcription factor GhWRKY70 directly binds to the W-box cis-acting element in the GhAOS1 promoter through Y1H, LUC, and EMSA, which activated GhAOS1 transcription. Silencing GhWRKY70 in cotton significantly enhanced plant susceptibility to V. dahliae and suppressed the expression of JA signaling pathway-related genes. Collectively, our results elucidate that GhWRKY70 positively regulates cotton resistance to VW by activating GhAOS1-mediated JA biosynthesis, revealing a novel GhWRKY70-GhAOS1 regulatory module that integrates JA signaling to coordinate cotton immune responses against V. dahliae. This study provides new insights into the molecular mechanism of JA-mediated defense and offers potential targets for molecular breeding of VW-resistant cotton.