橡胶树多主棒孢病菌Cassiicolin基因条形码数据库构建及分子检测技术

Construction of Cassiicolin Genes Barcode Database and Molecular Detection Technology of Corynespora cassiicola from Hevea brasiliensis in China

多主棒孢(Corynespora cassiicola)是为害我国主要热带作物的植物病原真菌,其寄主范围广、形态差异显著、症状类型多样,且含有一种寄主专化性毒素Cassiicolin,存在6种毒素类型。本研究利用已公布的Cassiicolin毒素基因(Cas1~Cas6型),构建了含287个菌株的国内橡胶树和部分热带作物多主棒孢Cassiicolin基因条形码数据库,建立了一套特异性强、灵敏度高的分子检测技术,可检测100pg/μL的目标基因组DNA,系统分析了我国橡胶树、木薯、番木瓜、瓜菜等主要热带作物的919株多主棒孢的毒素类型,发现国内仅存在Cas2和Cas5这2种毒素类型,其中Cas5型的菌株占94.8%,为橡胶树多主棒孢的优势种群和特有毒素类型。而Cas2型是橡胶树和其他作物多主棒孢共有的毒素型。系统发育分析发现,不同毒素类型的多主棒孢菌株与寄主来源密切相关,但与地理来源没有明显的相关性,且Cas5型多主棒孢具有明显的寄主专化性。通过构建多主棒孢Cassiicolin基因条形码数据库,为明确我国主要热带作物多主棒孢病菌的种群结构和优势种群情况,发掘、保存多主棒孢菌种资源以及制定病害的防治策略上具有重要的指导意义。

Corynespora cassiicola is a plant pathogenic fungus,which is harmful to major tropical crops in China. It has a wide range of hosts,significant morphological differences,diverse symptoms and contains a host-specific toxin, which encoding up to six distinct protein isoforms. In the study,we used public database to construct Cassiicolin genes barcode database of C. cassiicola form major tropical crops in China. At the same time,we established a set of molecular detection techniques with high specificity and sensitivity,which could detect 100 pg/μL target genomic DNA. Then, we systematically detected the isoforms cassiicolin of C. cassiicola,which were isolated from rubber tree,cassava,papaya, melon and vegetable in China. There were only two isoforms Cassiicolin in China,among which the Cas5 isoform Cassiicolin accounted for 94.8%,and had obvious host specificity and was specific and advantage population on rubber tree in China. Phylogenetic tree analysis showed that distinct isoforms Cassiicolin of C. cassiicola was closely related to host origin,but not to geographical origin. The results of the research would significantly contribute to the population genetic structure,dominant population,preservation of C. cassiicola and control strategies.