华南热带地区无性型白粉菌分子系统学及起源演化研究

白粉菌是一类世界广布且危害严重的植物病原专性寄生真菌。热带地区的白粉菌极少形成有性阶段，以有性型特征为基础的传统白粉菌分类鉴定方法，无法对其物种进行准确有效的界定，也很难清晰追溯无性型与可能的有性型间的相互关联，影响人们对热带地区白粉菌物种的起源演化以及扩散的准确认识。本项目拟对华南热带地区的白粉菌进行广泛系统地采集，通过显微和超微形态特征观测，结合ITS 和28S rDNA、MCM7多基因分子系统发育分析，采用Yule溯祖模型及泊松过程分析法，对无性型白粉菌物种进行准确有效界定，将无性型与可能的有性型关联；结合分子钟和生物地理学理论进行分化时间和祖先分布区重建，旨在：1）明确华南热带地区无性型白粉菌物种及寄主范围，2）澄清华南热带地区白粉菌物种与寄主间的寄生性演化模式，3）阐明华南热带地区白粉菌物种的分化时间及地理起源，为揭示白粉菌物种起源和进化提供重要基础。

Powdery mildews are obligate biotrophic fungi that widely distributed in worldwide, which often cause serious economic losses to agricultural and forestry production. The powdery mildew fungi mostly occur in asexual state and sexual state in their life cycle is rare in tropical area. Based on the morphological characteristics of their sexual state, the traditional classification and identification of powdery mildew fungi cannot accurately and effectively delimit to the species and clearly trace the relationship between the asexual and their sexual state. Therefore, the geographic origin and evolution of powdery mildew species may be misled due to inaccurate species delimitation. Through observation of microscopic and ultramicroscopic features, and analysis of multi-gene molecular phylogeny of combined ITS, 28S rDNA and MCM7, the specimen collected from tropical area of southern China will be accurately and effectively identified by using coalescent method of generalized mixed Yule coalescent (GMYC) and Poisson Tree Processes (PTP) models. As much as possible, the relationship will be established between the asexual states and their sexual states; Based on the theories of molecular clock and biogeography, the divergent time will be estimated and ancestral distribution area will be reconstructed respectively. The current project aims to 1) clarify the clear species status and host range of asexual morphs powdery mildew species in tropical areas of South China; 2) elucidate the pattern of evolution parasitism between asexual morphs powdery mildew species with their hosts in tropical South China; 3) clarify the divergent time and geographical origin of powdery mildew species in tropical South China. This study will provide a basic knowledge for revealing the geographical origin and evolution of powdery mildew.