Transcriptomic and metabolomic responses of Botrytis cinerea under L-carvone fumigation

Abstract Botrytis cinerea , a necrotrophic phytopathogenic fungus with a wide host range, causes severe postharvest gray mold and huge economic losses worldwide. Conventional chemical fungicides easily induce multidrug resistance in field isolates, while the natural monoterpene volatile L-carvone exhibits broad-spectrum antifungal activity. However, the comprehensive molecular mechanism by which L-carvone suppresses B. cinerea remains unclear. In this study, mycelia of B. cinerea were treated with L-carvone at EC 50 concentration with sterile water as blank control. RNA-seq transcriptome and HS-SPME-GC-MS widely-targeted volatile metabolome profiling sequencing were performed to systematically dissect molecular responses via combined transcriptomic and metabolomic analysis. A total of 1,531 DEGs were identified, including 347 upregulated and 1184 downregulated genes. Upregulated DEGs were enriched in sulfur metabolism, cysteine and methionine metabolism involved in transient antioxidant response, whereas downregulated DEGs mainly participated in cell membrane lipid biosynthesis, carbon energy metabolism, phytotoxin synthesis and conidiation. A total of 246 DAMs were screened. Antioxidant terpenoids including γ-cadinene, carvacrol and camphene were significantly accumulated, while lipid precursors for cell membrane assembly and toxic botrydial-derived aldehydes were drastically reduced. L-carvone simultaneously blocked phytotoxin biosynthesis, ergosterol membrane formation, vegetative growth and asexual reproduction of B. cinerea . The fungus only activated short-term ROS scavenging and xenobiotic efflux pathways, whereas the long-term glutathione-dependent antioxidant system was suppressed, leading to irreversible oxidative damage. This study reveals the multi-target antifungal mechanism of L-carvone at transcriptional and metabolic levels, providing theoretical support for green control of gray mold and the development of botanical fungicides with novel modes of action.