基于核和线粒体基因组的广义耳霉属系统发育研究

As one of the most important groups in the entomophthoroid fungi, the genus Conidiobolus has been widely used in biological control and has been paid attention for a long time. It was divided into three subgenera based on the types of secondary conidia. Preliminarily, the phylogeny indicated that it is a polyphyletic group, but the branches do not match the three subgenera based on morphological characteristics. Therefore, we classfied them as Conidiobolus sensu lato temporarily. In this project, the genomes of 40 ex-type strains of Conidiobolus throughout the world will be sequenced using the high-throughput sequencing technology. The protein coding genes of single-copy orthologs from nuclear and mitochondrial genomes will be choosen for phylogeny. Combined with mophylogical characteristics, the numbers of nuclei within the primary conidia, the maximum growth temperature and the phylogenetic relationship of Conidiobolus sensu lato, the taxonomic status of the three subgenera will be clarified. Meanwhile, a monophyletic system will be revised from polyphyletic groups of Conidiobolus s.l. and a more natural classification of this genus will be established. Furthermore, the result of this project will provide evidence for phylogenomics of entomophthoroid fungi and zygomycetes as a whole and provide theoretical basis for biological control of insects.

耳霉属是虫霉真菌的重要类群之一，广泛应用于生物防治而受到重视。基于耳霉次生分生孢子产生方式，耳霉属划分为三个亚属；分子系统发育研究初步表明耳霉属是一多系类群，但其分支方式和前述形态三亚属之间却不能很好地对应，因此暂时将该类群作为广义耳霉属处理。本项目拟对该属全球范围所有40株耳霉模式菌种进行全基因组测序，筛选核基因组和线粒体基因组中编码蛋白的单拷贝直系同源基因位点进行分子系统发育分析，结合形态学、初生分生孢子细胞核数及最高生长温度等特征，阐明广义耳霉属内各分支间的亲缘关系，明确三个耳霉亚属的分类地位，将多系的广义耳霉属修订为单系的分类系统，从而建立趋于自然的耳霉分类系统，同时为虫霉真菌整体乃至接合菌整体的系统发育组学研究奠定基础，为昆虫生物防治提供理论依据。

耳霉属在世界范围内广泛分布，是生态环境中重要的分解者，有些种可用于害虫生物防治，前期研究发现形态学特征与分子系统发育分析结果无法相互印证，该属的分类系统有待完善。项目补充收齐耳霉模式菌株，进行基因组测序，运用核和线粒体基因组进行系统发育基因组分析，结合表型特征对耳霉属的分类系统进行深入研究。研究结果如下：1）成立了3个新科和4个新属：毛管霉科（Capillidiaceae）包含1个毛管霉属（Capillidium）；耳霉科（Conidiobolaceae）包含狭义耳霉属（Conidiobolus s.s.）、小耳霉属（Microconidiobolus）和假接合孢属（Azygosporus）等3个属，新耳霉科（Neoconidiobolaceae）包含1个新耳霉属（Neoconidiobolus）；2）发表了分离自中国的8个耳霉新种：Azygosporus macropapillatus、Capillidium jiangsuense、Capillidium macrocapilliconidium、Conidiobolus bifurcatus、Conidiobolus taihushanensis、Conidiobolus variabilis、Neoconidiobolus pseudothromboides和Neoconidiobolus kunyushanensis；3）测定了14个耳霉模式菌株的基因组序列，首次鉴定了异形孢毛管霉（CGMCC 3.15857）编码P450酶的两个基因家族CYP5014和CYP5136，发表了8个耳霉模式菌株的线粒体基因组，对该类真菌的线粒体基因组特征进行了比较分析。本项目建立了更趋自然的耳霉分类系统，为虫霉真菌的系统发育组学研究奠定基础，为昆虫生物防治提供理论依据。发表SCI论文14篇，申请发明专利1项，培养硕士研究生2人。