Anthracnose, caused by Colletotrichum species, poses a significant threat to global tea (Camellia sinensis) production, yet its inducible resistance mechanisms remain largely uncharacterized. Through integrated transcriptomic and metabolomic analyses of the anthracnose-resistant cultivar ‘Zijuan’ and the susceptible cultivar ‘Longjing43’, we identified sakuranetin as a key phytoalexin in tea plants and elucidated a complete jasmonic acid (JA)-mediated defense pathway. Our functional characterization revealed that CsNOMT (Cha09g008790), a naringenin 7-O-methyltransferase, catalyzes sakuranetin biosynthesis with high substrate specificity. Following infection with Colletotrichum camelliae, sakuranetin accumulated exclusively in resistant cultivars, exhibiting superior antifungal activity compared to major tea catechins. Functional validation demonstrated that overexpression of CsNOMT enhanced both sakuranetin accumulation and disease resistance, while gene silencing compromised both traits. Mechanistically, we established that the JA-responsive transcription factor CsMYC2.1 directly activates CsNOMT transcription via G-box binding, establishing a novel JA–CsMYC2.1–CsNOMT–sakuranetin defense axis that distinguishes resistant from susceptible tea cultivars. This study represents the first comprehensive characterization of inducible phytoalexin-mediated immunity in tea, providing immediate applications for sustainable tea production. CsNOMT serves as a valuable functional marker for resistance breeding, while sakuranetin emerges as a promising natural biopesticide to reduce reliance on synthetic fungicides.

Full text PDF download