Metabolomic and transcriptomic analyses of VOCs functions in different ripening periods tomato resistance responses to Botrytis cinerea infection

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The species and quantity of volatile organic compounds (VOCs) and the disease resistance are different in red and green ripening periods of tomato. In this study, treatments against Botrytis cinerea infections occurred during the red (R B. ) and green (G B. ) ripening periods were investigated. G B. decreased disease incidence rate and enhanced the defense capacity by altering the key defense-related enzymes [NADPH-cytochrome c reductase (NCR), aminopyrine-n-demethylase (AND), aniline-4-hydroxylase (AH) and erythromycin N-demethylase (ERND)] activities. Gray mold development in tomatoes is associated with defense mechanisms and cell degradation. PUFAs are involved in maintaining cell integrity. PUFA-related enzymes, such as lipoxygenase (LOX) and alcohol dehydrogenase (ADH), showed lower activity levels during G B. . Additionally, G B. enhanced the energy level by increasing NAD + , NADH, and ATP amounts. At the metabolic level, the VOCs composition was altered by the G B. , leading to a reduction in key precursors of PUFA synthesis, including aldehydes/alcohols (VAAs). Among them, the concentrations of key disease resistance-associated substances - hexanal, 2-hexanal, and citral - significantly declined during the G B. . Transcriptomic analysis revealed that G B. modulated gene expression changes corresponded to metabolomic changes, with 37 PUFAs-related genes down-regulated and 79 up-regulated compared to R B. . These findings indicate that G B. enhances disease-resistance capability and maintains cellular integrity. Thereby, fewer genes and VOCs need to be mobilized to increase resistance in postharvest tomatoes.