Antifungal activity and mechanisms of D-limonene against Fusarium oxysporum, a pathogen of potato dry rot

Abstract

BACKGROUNDPotato dry rot (PDR), caused by Fusarium species, seriously threatens potato production and postharvest quality. Although limonene has demonstrated antifungal activity, previous studies have mainly focused on limonene-containing essential oils or phenotypic growth inhibition, while its cellular and molecular mechanisms and application potential against PDR remain insufficiently understood. RESULTSD-limonene inhibited the growth of Fusarium oxysporum in a concentration-dependent manner, with a half-maximal inhibitory concentration (IC) of 8.32 L/mL. It also altered hyphal morphology, reduced pathogenicity and spore germination, decreased spore viability, and changed the chitin-associated fluorescent brightener 28 staining pattern. Transcriptome analysis identified 1,884 differentially expressed genes, including 1,027 downregulated and 857 upregulated genes. Kyoto Encyclopedia of Genes and Genomes analysis and targeted annotation screening revealed extensive remodeling of cell-wall-related processes. Gene Set Enrichment Analysis further indicated suppression of ergosterol biosynthesis and ribosome biogenesis. D-limonene also increased sensitivity to temperature, salinity, and oxidative stresses and showed additive and synergistic interactions with mancozeb and hymexazol, respectively. CONCLUSIONOur results reveal that D-limonene shows potential as a bio-based component for the integrated management of PDR, providing a theoretical basis for its application.