CfAtg8在调控果生刺盘孢正负菌株分化中的功能

由果生刺盘孢Colletotrichum fructicola引起的炭疽叶枯病严重危害苹果果实和叶片。刺盘孢属真菌可以产生具有形态和遗传差异的正型(+)和负型(-)菌株,但其分化的分子机制目前尚不清楚。本研究通过同源重组对CfAtg8功能进行分析,结果显示,CfAtg8显著影响果生刺盘孢正菌株(1104-7)菌落颜色和气生菌丝茂密程度,但不影响负菌株(1104-6);正菌株突变体不产生子囊壳,负菌株突变体子囊壳变小、数量增多;正菌株突变体与负菌株野生型1104-6杂交不形成交配线,负菌株突变体与正菌株野生型1104-7杂交形成正常交配线;此外,CfAtg8还影响正、负菌株分生孢子萌发、附着胞形成及致病性等。这些结果表明自噬基因CfAtg8是影响果生刺盘孢正负菌株分化、形态发育和致病的重要基因。

Function of CfAtg8 in regulating the differentiation of plus and minus strains of Colletotrichum fructicola

Glomerella leaf spot caused by Colletotrichum fructicola is a severe disease on apple fruit and leaves in China. There are plus and minus strains with morphological and genetic differentiation in Colletotrichum fungi. However, the mechanisms underlying the differentiation between two types of strains remain poorly understood. The functions of CfAtg8 were analyzed based on gene deletion analysis with homologous recombination and PEG-mediated protoplast transformation. It was found that CfAtg8 significantly affected the colony color and aerial hypha density of the plus strain (1104-7), but it did not affect the minus strain (1104-6). CfAtg8 regulated the perithecial development. The plus mutant could not produce perithecia and the perithecia produced by minus mutant were more compacted and smaller in size. When Δ+CfAtg8/1104-6 was co-cultured, mating line formation failed, while a strong mating line developed at the contact zone between Δ-CfAtg8/1104-7. Additionally, CfAtg8 is involved in conidial germination, appressorium formation and pathogenicity in plus and minus strains. Our results reveal that CfAtg8 is an important gene regulating genetic differentiation of plus-minus strains, morphological development and pathogenicity in Colletotrichum fructicola.