壳二胞属物种分类研究

The genus Ascochyta is ubiquitous and species-rich, and includes many important plant pathogens, which often cause heavy losses of the plant production. Nearly 1500 Ascochyta epithets have been recorded, and admittedly the traditional host association based nomenclature led to this number, of which some names have been treated as synonyms. Ascochyta has been shown to be highly polyphyletic in recent studies, and the generic circumstance of Ascochyta has been revised. Nevertheless, most of the Ascochyta species have not been studied using modern polyphasic approaches and their phylogenetic affinities and taxonomic placements remained unknown. The objectives of this project are: to determine the phylogenetic relationships of 50–80 worldwide un-studied species in Ascochyta using multi-locus sequences data, in combination with the morphological examinations; re-inventory of the genus Ascochyta; to designate neotypes and epitypes to stablilise the application of names within this genus; to elucidate the host specificity of Ascochyta species. This project has important scientific significance in the identification and utilization of Ascochyta species and control and management of plant diseases.

壳二胞属物种分布广泛，多样性丰富，大部分为植物病原真菌，造成严重的经济损失。在早期寄主专化性为基础的分类方法下，该属物种记录达近1500个，后来部分名称基于形态特征做了合并处理，近期研究发现壳二胞属为多系类群，并依据模式种的表型特征和系统发育地位对该属属征进行了修订，构建了新的分类系统。但壳二胞属内大部分物种名称还未得到研究和处理，系统演化关系和分类归属不明。本项目拟在新分类体系的基础上，采用形态学观察结合多位点系统发育分析的方法，对全球范围内主要寄生在禾本科和豆科植物的50–80个分类归属不明的壳二胞属物种进行重新鉴定并作出科学的分类学处理，更新物种名录，并为10个物种引入新模式或注释模式，为物种鉴定提供可靠的研究参照，并探究壳二胞属真菌的寄主特异性规律。本项目的开展对物种正确识别、植物病害防治以及新型生防制剂的开发利用具有重要的理论和实际意义。

壳二胞属物种大部分为植物病原真菌，导致严重的经济损失。该属近期被修订为单系类群，但其中大部分物种的名称未得到研究和处理，系统演化关系和分类归属不明。本项目收集到全世界范围内16个国家的壳二胞属菌株及标本材料，通过对这些材料进行形态学观察、多基因序列扩增测序、系统发育分析等，对4个错误鉴定的菌株进行了名称更正，将分类地位存在问题的物种进行了检查并修订其分类地位，建立7个新组合；为缺乏模式材料的物种Ascochyta ferulae指定新模式，补充了A. clinopodiicola的无性阶段形态特征描述，并引入来自不同寄主的4个壳二胞属新物种。此外，还系统分析了壳二胞属物种的寄主相关性，揭示该属物种对豆科植物存在较高的寄主专一性。基于代表性或模式材料，构建壳二胞属系统发育骨架树，结合形态学特征，对壳二胞属的物种名录进行了更新，确认了壳二胞属内约20个物种及其名称。研究结果为今后该属物种识别、病原物准确鉴定，以及物种分类地位修订等工作提供了良好的研究基础。