核盘菌自噬相关基因SsATG5和SsATG8的功能分析

Functional analysis of autophagy-related genes SsATG5 and SsATG8 in pathogenic fungus Sclerotinia sclerotiorum

为探究自噬在核盘菌Sclerotinia sclerotiorum致病过程中的作用,利用酵母Saccharomyces自噬相关基因(autophagy-related gene,ATG)编码的蛋白序列比对核盘菌基因组,获得核盘菌假定ATG,并以核盘菌1980菌株为出发菌株,基于同源重组的原理对假定ATG进行敲除和回补,并测定不同突变体的生长表型和致病能力。结果表明,从核盘菌基因组中比对到2个ATG,分别命名为SsATG5和SsATG8,两者在核盘菌致病过程中均上调表达。SsATG5和SsATG8敲除突变体在菌丝生长、产草酸和侵染垫形成方面与野生型菌株无明显差异,但SsATG5敲除突变体在离体拟南芥Arabidopsis thaliana叶片上的致病力显著下降了约40%,在活体拟南芥植株上的致病力显著下降了约80%,同时SsATG5回补突变体恢复了正常的致病力。表明SsATG5参与了核盘菌的致病过程,证实自噬在核盘菌致病过程中发挥着重要作用。

In order to explore the functions of autophagy in the pathogenesis of Sclerotinia sclerotiorum,the putative autophagy-related gene(ATG)was identified by homologous alignment of protein sequences of yeast autophagy-related genes.According to the principle of homologous recombination,the ATG was knocked out and then complemented in the S.sclerotiorum strain 1980,and then the phenotype of growth and virulence of different mutants were determined.The results showed that SsATG5 and SsATG8 were identified in S.sclerotiorum,and the expression of both of them were significantly upregulated during the infection of S.sclerotiorum.There was no significant difference between SsATG5 and SsATG8 knockout mutants and wild-type strain 1980 in mycelial growth,oxalic acid production and infection cushion formation.However,the virulence of SsATG5 knockout mutants significantly decreased by about 40%on the detached leaves of A.thaliana,while it significantly decreased by about 80%on A.thaliana plants.Importantly,the virulence of SsATG5 complementary strain was not different from that of the wild-type strain 1980.The results indicated that SsATG5 was involved in the pathogenesis of S.sclerotiorum,and suggested that the autophagy pathway played important roles in the pathogenesis of S.sclerotiorum.