Abstract: The inhibitory effect of ε-polylysine on the vegetative growth of Alternaria alternata isolated from pears with black spot and its effect on black spot control in pears artificially infected with this fungus were determined by the colony diameter and lesion diameter, and the possible mechanism of its antifungal activity was also evaluated by determining cell membrane integrity, mitochondrial membrane potential and related metabolites levels. The results showed that ε-polylysine significantly inhibited the mycelial growth of A. alternata in a concentration-dependent manner (P < 0.05). After 7-day cultured with ε-polylysine at concentrations of 100 and 200 mg/L, the colony diameter was 43.24% and 29.54% as compared to the control group, respectively. The development of black spot in ε-polylysine-treated pears was also inhibited. Further research showed that ε-polylysine treatment severely damaged the integrity of A. alternata cell membrane and mitochondria, and increased the mycelium conductivity. ε-Polylysine treatment promoted the production of melanin and mycotoxins including alternariol, altenuene, andalternariol monomethyl ether, while it inhibited the production of tentoxin in A. alternata. These results suggested that ε-polylysine might reduce the pathogenicity of A. alternata through delaying its growth and destroying the integrity of the cell membrane and mitochondria.

Key words: ε-polylysine; black spot of pear fruit; Alternaria alternata; cell membrane; mitochondria; mycotoxins