The molecular mechanism of chitosan-based OEO nanoemulsion edible film in controlling Alternaria alternata and in application for apricot preservation

Abstract

Alternaria alternata is the primary pathogen responsible for postharvest black spot disease in apricots. This study investigates the antifungal mechanisms of chitosan-based oregano essential oil nanoemulsion films (CS-OEOFs) and evaluates their potential application in preserving apricot fruit quality. CS-OEOFs disrupt the cell membrane integrity and permeability of A. alternata, leading to the leakage of nucleic acids and proteins, as well as a reduction in ergosterol content. Furthermore, they effectively inhibit fungal growth in a concentration-dependent manner. At 1 % and 1.5 % OEO concentrations, nucleic acid leakage increased by 1.32- and 1.37-fold, respectively, while ergosterol content decreased by 10.23 % and 18.95 %, respectively (p < 0.05). Transcriptomic analysis revealed that CS-OEOFs downregulated genes involved in biosynthetic pathways and upregulated genes associated with fatty acid degradation, thereby disrupting pathways related to energy metabolism, membrane transport, and signal transduction. Additionally, CS-OEOFs reduced postharvest weight loss and decay rates, while maintaining elevated levels of phenolic compounds, such as protocatechuic acid, chlorogenic acid, and (+)-catechin, thus prolonging the shelf life of the fruit. These findings highlight the potential of CS-OEOFs as an environmentally friendly and effective postharvest preservation strategy for controlling fungal decay and maintaining fruit quality.