(E)-2-Hexenal-based coating induced acquired resistance in apple and its antifungal effects against Penicillium expansum

Abstract

(E)-2-Hexenal is one of the most prevalent and abundant volatile substances in fruits. Many researchers have attempted fumigation with (E)-2-hexenal to control fungal diseases with poor or no results; the key is the inability to maintain an effective concentration for a long time. Therefore, a new starch-based antifungal coating with (E)-2-hexenal microcapsules was prepared. The obtained results showed that the microcapsule embedding rate reached 78.95% by orthogonal optimization experiments and that the (E)-2-hexenal-based coating was effective at reducing the lesion diameter of apple fruit during storage at 25 °C after Penicillium expansum infection, and in other fruits; it also achieved a good antifungal effect. Moreover, the activities of the main defense-related enzymes and the expression of key genes involved in the salicylic acid (SA) signaling pathway, such as CHI, GLU, PAL, NPR1, and PR1, were enhanced by (E)-2-hexenal-based coating treatment. These findings suggest that the (E)-2-hexenal-based coating has the dual effect of direct antifungal and induction of apple system resistance. E2H-based coating is a promising approach to control postharvest Penicillium expansum in fruit.