This study aimed to clarify the antibacterial effect and mechanism of trans, trans-2,4-nonadienal (E24 N) on Colletotrichum acutatum, the dominant postharvest pathogen of loquat.The effects of different concentrations of E24 N on C.acutatum were investigated by physicochemical analysis and microstructural observation.Results showed that the minimum inhibitory concentration and minimum bactericidal concentration of E24 N against C.acutatum determined by the agar dilution method were both 0.4 mL/L.The germination of spores treated with 0.05 mL/L E24 N solution for 12 hours was only (7.01±1.98)%, significantly lower than the control group spore germination rate of (85.41±4.75)% (P<0.05).Observations of morphological changes in C.acutatum using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that treatment with E24 N disrupted the fungal hyphae, destroyed the integrity of the cells, and rendered the organelle structures unrecognizable.Additionally, treatment with E24 N altered the cell permeability of C.acutatum, leading to the leakage of proteins and nucleic acids, an increase in relative conductivity, enhanced lipid peroxidation in the membrane, and accumulation of reactive oxygen species.The results of the fruit experiment indicated that treating loquat fruits with E24 N could delay the progression of anthracnose in loquat fruits, with an inhibitory effect superior to that of citral, a commonly used aliphatic aldehyde preservative in production.In conclusion, E24 N inhibited the germination of C.acutatum spores and mycelial growth, disrupted its cellular structure, and promoted lipid peroxidation and the accumulation of reactive oxygen species, thereby affecting its normal physiological functions and suppressing the occurrence of anthracnose on loquat fruits.This study provides new theoretical evidence for the application of aliphatic aldehyde compounds in the prevention and control of anthracnose in loquats.
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