<i>trans‐</i> 2‐Hexenal exposure enhances disease resistance against <i>Penicillium digitatum</i> by stimulating phenylpropanoid biosynthesis and antioxidant capacity in postharvest citrus fruit

BACKGROUND: trans-2-Hexenal (TH) is a promising alternative to chemical fungicide in controlling postharvest disease in fruits. This research sought to disclose how TH controls citrus green mold and induces fruit resistance through RNA-Seq, physiochemical and natural decay. RESULTS: . Correspondingly, the protective effects of TH on citrus fruits decreased its susceptibility to Penicillium digitatum. CONCLUSION: induces disease resistance against P. digitatum by stimulating the biosynthesis of lignin and flavonoid, along with the AsA-GSH cycle in the peel of citrus fruit, thus improving antioxidant capacity and maintaining redox balance in the citrus fruit. These findings suggest that TH has potential for use as a protective measure against P. digitatum in citrus fruit. © 2026 Society of Chemical Industry.