Epsilon-poly-L-lysine (ε-PL) exhibits antifungal activity in vivo and in vitro against Botrytis cinerea and mechanism involved

epsilon-Poly-L-lysine (epsilon-PL) is a non-toxic food preservative, but the antifungal effect of epsilon-PL against postharvest pathogenic fungi has rarely been reported. Grey mold caused by Botrytis cinerea is one of the main postharvest diseases on fruit and vegetables. The objective of this study was to investigate the antifungal activity of epsilon-PL against B. cinerea in vivo and in vitro, and elucidate the underlying mechanism involved. epsilon-PL treatment sig-nificantly inhibited the incidence of grey mold rot on cherry tomato, strawberry, grape, and green pepper caused by B. cinerea. Moreover, in vitro assay showed that epsilon-PL exerted strongly antifungal activity against mycelial growth, spore germination, and germ tube elongation of B. cinerea, with the increase of the concentration of epsilon-PL. Furthermore, significant leakages of intercellular electrolytes and protein suggested that epsilon-PL treatment increased the membrane permeability of B. cinerea. Malondialdehyde (MDA) content and Annexin V-FITC/propidium iodide (PI) double staining assay confirmed that epsilon-PL treatment induced membrane disruption of the test pathogen. Morphological alterations after epsilon-PL treatment revealed severe damage to B. cinerea mycelia, which resulted in distortion and shriveling of mycelial surface. The results indicated that epsilon-PL exerted antifungal activity by inducing the membrane damage of B. cinerea, and epsilon-PL treatment was a promising approach to controlling postharvest grey mold on fruit and vegetables.