中国黑痣菌属分类及分子系统学研究

Phyllachora is an important genus which attack plants' leaves, causing tar spots on them. The symptoms are visualized on one or both leaf surfaces by elongated grayish violet to dark green spots which later become glossy black. Some species can cause disease of many plants, so it has important economical significance. Phyllachora is the type genus of the family Phyllachoraceae, and about 944 species of Phyllachora have been reported wordwide. All species of the genus are obligate parasites, making them difficult to connect anamorphs and teleomorphs experimentally. As a consequence, their complete life cycle is practically unknown. In general, most Phyllachora produce an ascocarp embedded in the host tissue, mostly within a pseustroma which composed of both plant and fungus tissue. Most of the early classification schemes of the genus were artificial, traditional taxonomy of Phyllachora is mainly based on characters of ascospores, such as the shape of ascospores and the size of ascospores. The classificational character can be used to distinguish species in the genus is few, so the characters between species are similar and are difficult to be used to reflect the natural evolutional relationships of the genus. In the initial eatablishment stage of genus, the species were identified according to host plants, that means the species on different host plants were given different names even they had similar taxonomic characters. That's the reason why some species in Phyllachora have many synonyms. The phylogenetic relationship between species are artificial because of controversial classification frame. We plan to use multi-gene to analyse molecular systematics of Phyllachora based on molecular information combined with morphological classification. By evaluating interspecific variability of Phyllachora based on the sequences of ITS、β-tublin and EF-1α according to morphological classification, we will screen out the suitable molecular sequence to analyse interspecific genetic relationship. The research results of molecular data will be used to evaluate morphological classification frame and classification criteria, to claryify some puzzled species' classification status. Combining morphological characters with information of molecular systematics of development, we will establish a more natural classification system of the genus and the species. The research will provide technical data and support for phylogenetic systematics of Phyllachora and relative genera, especially for obligate plant pathogen. The project has important significance for exploring biodiversity and resource utilization of the genus in the world. The project will contribute significantly to improving our leading position about the genus research and utilization.

黑痣菌是一类重要的植物病原菌，常引起农作物及牧草病害，造成严重经济损失。黑痣菌属的传统分类主要依据子囊孢子形态及大小，种间分类特征较少，形态特征重叠，难以反映自然类群的进化关系，造成同物异名及疑难种较多，种间系统演化关系一直存在争议。本项目拟在形态分类基础上，利用多基因分析法进行分子系统学研究：对转录间隔区（ITS）、β-微管蛋白（β-tublin）、转录延长因子（EF-1α）等基因序列信息于黑痣菌属内种间变异性进行评价，筛选出适合分析种间亲缘关系的基因进行分子系统学研究；综合评价形态学分类体系与种级分类标准，重新界定部分疑难种的分类地位；结合形态特征和分子系统发育信息数据，建立更趋于自然的分类系统，为黑痣菌目及其他专性植物寄生菌的系统分类研究提供技术资料。同时该研究对于挖掘我国黑痣菌属资源、丰富真菌生物多样性及真菌病害防治具有重要理论和实践意义。

黑痣菌是一类重要的植物病原菌，常引起农作物及牧草病害，造成严重经济损失。黑痣菌属的传统分类主要依据子囊孢子形态及大小，种间分类特征较少，形态特征重叠，难以反映自然类群的进化关系，造成同物异名及疑难种较多，种间系统演化关系一直存在争议。本项目在形态分类基础上，利用多基因分析法进行分子系统学研究：对转录间隔区（ITS）、β-微管蛋白（β-tublin）、转录延长因子（EF-1α）等基因序列信息于黑痣菌属内种间变异性进行评价，筛选出适合分析种间亲缘关系的基因进行分子系统学研究；综合评价形态学分类体系与种级分类标准，重新界定部分疑难种的分类地位；结合形态特征和分子系统发育信息数据，建立更趋于自然的分类系统，为黑痣菌目及其他专性植物寄生菌的系统分类研究提供技术资料。同时该研究对于挖掘我国黑痣菌属资源、丰富真菌生物多样性及真菌病害防治具有重要理论和实践意义。本课题所研究的标本来自中国科学院菌物标本馆（HMAS），及采自贵州、河南、广州、广西、江西、海南等地的标本，共180余份。通过对黑痣菌属标本进行研究，共鉴定了37个种，其中包括4个新种和8个中国新纪录种。从已获得的标本中筛选出形态特征稳定的21个代表种，对它们的ITS、β-tubulin和EF-1α分别进行扩增、克隆及序列测定，筛选出适于黑痣菌属种间系统发育研究的基因序列。结果表明：ITS基因的扩增率达100%，可将大部分种区分开，种内遗传距离最小，种间遗传距离最大，适于黑痣菌属系统学研究。对已获得的其余50份标本进行ITS基因序列扩增、克隆及序列测定，构建系统发育树。结果表明：寄主植物为同科的黑痣菌聚集在同一分支，同种黑痣菌聚集在同一亚支。利用形态学对黑痣菌属进行命名与系统学研究所建立的系统发育树基本相吻合，为黑痣菌属的深入研究提供科学准确的依据。