板栗疫病菌cpomt基因的功能

Function of cpomt Gene in Chestnut Blight Fungus

板栗疫病菌(Cryphonectria parasitica)是引起板栗疫病的一种丝状子囊菌。UV57是一个不支持病毒复制且致病力丧失的C.parasitica紫外诱变突变株。前期蛋白质组研究结果显示,蛋白86233(一种甲基转移酶)只在UV57中出现,而在野生型对照株EP155中没有检测到。为研究编码86233蛋白的cpomt基因的功能,本研究通过同源重组方法成功构建了缺失突变体Δcpomt及其互补转化株。与野生型EP155相比,Δcpomt菌株生长缓慢,色素分泌减少,产孢量降低,菌丝形态异常,对休眠板栗树枝的致病性显著降低。而在互补转化株Δcpomt-com中,这些表型及致病力变化均可以恢复到野生型水平。cpomt基因的缺失对低毒病毒CHV1-EP713的复制累积量没有影响,但导致抗逆相关基因G-α,产孢基因CLS-32,色素合成酶基因PKS转录水平明显下调。本研究为阐明甲基转移酶在病原真菌中的作用提供了新的知识。

Cryphonectria parasitica is a filamentous ascomycete which is responsible for the chestnut blight. UV57 is a L/V-induced C. parasitica mutant which lacks the ability of replicating virus and loses pathogenicity. In our previous proteomic analysis, protein 86233 （a methyltransferase） was only observed in UV57 as compared with the wild-type EP155. To investigate the function ofcpomt gene in protein 86233, we successfully constructed Acpomt deletion mutant and its complementation strain by homologous recombination. Compared with the wild-type EP 155, the △cpomt mutant showed a phenotype of slower growth rate, fewer orange pigmentation, lower level of sporulation, abnormal hyphae, and significantly reduced virulence on dormant chestnut branches. However, the phenotype and virulence could be restored to the wild-type level by re-introducing a copy of the wild-type cpomt gene into the mutant. Deletion of epomt gene did not influence the replication and accumulation of the hypovirus CHV1-EP713, but the transcriptional analysis showed that it reduced the transcriptional le level of resistance-related gene G-α, sporulation gene CLS-32 and pigment biosynthesis gene PKS. All in all, our results provided new knowledge for understanding the role ofmethyltransferase in a pathogenic fungus.