Antifungal activity and mechanisms of ε-poly-l-lysine (ε-PL) against Colletotrichum lagenarium in marrow squash

Fungal diseases are major adverse factors leading to quality deterioration and spoilage of postharvest horticultural products. ε-PL is widely recognized as a natural antibacterial agent because of its broad spectrum antimicrobial property. The objective of this study was to investigate the antifungal activity of ε-PL against C.lagenarium, and elucidate the underlying mechanism involved. In vivo were also confirmed that ε-PL treatment showed an obvious inhibitory effect for control of anthracnose caused by C.lagenarium in marrow squash. Moreover, in vitro assay showed that ε-PL exerted strongly antifungal activity against mycelial growth on colony diameter, spore germination and mycelium dry weight of C.lagenarium, with the increase of the concentration of ε-PL. Furthermore, compared with the control, damage the cell membrane of C.lagenarium and increase MDA content, significant leakages of intercellular electrolytes, nucleic acid, protein and sugar, suggested that ε-PL treatment increased the membrane permeability of C.lagenarium. Simultaneously, ε-PL significantly inhibited the activity of enzyme related to energy metabolism in C.lagenarium. The results were observed by SEM and TEM that ε-PL treatment damaged the morphology of C.lagenarium. In conclusion, ε-PL concentration higher than 400 mg L−1 might be used as an antifungal agents to control anthracnose caused by C.lagenarium in marrow squash.