ε-聚赖氨酸对梨果实黑斑病菌Alternaria alternata的抑制作用及其机理

Antifungal Effect ofε-Polylysine on Alternaria alternata Isolated from Pears with Black Spot and Its Possible Mechanism

本实验以梨果实黑斑病菌Alternaria alternata为研究对象,通过测定菌落直径与病斑直径研究ε-聚赖氨酸(ε-poly-L-lysine,ε-PL)对A.alternata生长的抑制作用和对黑斑病的控制作用,并进一步通过测定细胞膜完整性、线粒体膜电位及其代谢产物水平探讨其抑菌作用的机理。结果表明:ε-聚赖氨酸能显著抑制A.alternata的菌丝生长(P<0.05),且其抑制作用存在浓度依赖效应关系,其中100 mg/L和200 mg/L的ε-PL处理7 d时菌落直径仅分别为对照组的43.24%和29.54%,同时ε-PL处理能有效控制梨果实黑斑病的扩展。进一步的研究表明ε-PL处理严重破坏了A.alternata孢子细胞膜和线粒体的完整性,提高了菌丝体电导率。但同时研究发现,ε-PL促进了A.alternata黑色素及链格孢酚、交链格烯、链格孢酚单甲醚3种毒素的产生,而对腾毒素的产生起抑制作用。综上,ε-PL主要通过延缓A.alternata生长、破坏孢子细胞膜和线粒体完整性而降低A.alternata的致病性。

The inhibitory effect ofε-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 thatε-polylysine significantly inhibited the mycelial growth of A.alternata in a concentration-dependent manner(P<0.05).After 7-day cultured withε-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 inε-polylysine-treated pears was also inhibited.Further research showed thatε-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 thatε-polylysine might reduce the pathogenicity of A.alternata through delaying its growth and destroying the integrity of the cell membrane and mitochondria.