中国毛霉属系统发育研究及DNA条形码筛选

The genus Mucor (Mucorales, Mucoromycotina) are one of the most widespread groups of fungi in nature. They are known as opportunistic pathogens of human and animal, and have been incriminated in spoilage of postharvest fruits and vegetables. On the other hand, Mucor species have significant economic value in diverse biosynthesis and biological transformation. However, only sporadic studies on Mucor have been implemented in China. A lot of researches suggested that the classification of Mucor based on morphological characteristics does not correspond well with their phylogenetic relationships. Species complexes and heterologous strains are both found in some taxa of Mucor. This genus also has been proved to be not monophyletic, which is forming a paraphyletic group with other closely related genera in Mucorales. In addition, reliable and simple methods are needed for species identification, for a number of important strains in Mucor are difficult to recognition in applications. The project will provide a classification based on multigene phylogenetic analyses, combining with morphological and physiological characteristics. The gene markers will include nuclear rDNA (SSU, ITS and LSU), nuclear protein-coding genes (e.g., act1, EF-1α, and MCM7), and mitochondrial protein-coding genes (cox1). The aim of this study is to a) investigate species diversity on Mucor in China; b) reveal the phylogenetic relationships between species in the genus; c) clarify their phylogenetic position in the Mucorales; d) select appropriate DNA barcods for rapid and accurate identification of Mucor species. Our research will provide a more rational taxonomic system for the genus Mucor, and be beneficial to the prevention of harmful species and the application of useful species.

毛霉属是自然界中最为常见的真菌类群之一。部分种类是人和动物的条件致病菌、采摘后果蔬的病原菌；一些种类具有重要的经济价值，应用广泛。目前，该属研究尚不完善，国内资源多样性亟需调查，基于形态的分类系统与系统演化关系很难对应，且其在毛霉目中并非独立演化的单系类群，广泛存在复合种、异源种等问题，现有分类系统亟待更新。此外，在生产应用中，许多重要菌株难以鉴定到种，迫切需要快速、准确的物种识别方法。本项目将在前期丰富材料、经验积累的基础上，结合形态和生理特征，采用nrDNA序列（SSU、ITS、LSU）、核蛋白基因（act1、EF-1α、MCM7等）、线粒体基因（cox1）进行多基因联合系统发育分析。目标在于探明中国毛霉资源多样性，澄清属内种间、种内系统演化关系，明确其在毛霉目的系统发育地位，获得合适的DNA条形码。研究成果将完善毛霉属的分类系统，为有害类群的防治和有益类群的应用奠定基础。

毛霉属是自然界中最为常见的真菌类群之一，该属一些物种是人和动物的条件致病菌或采摘后果蔬的病原菌，另一些种类在工业食品发酵中应用广泛。本项目对来自不同地区自然及发酵环境的基物进行收集和菌种分离，共获得毛霉属真菌394株，包括15种，明确该属在国内分布范围为北京、甘肃、河北、黑龙江等17个省。其中传统发酵来源菌株包括5种，优势物种为卷枝毛霉。结合模式菌株，采用形态学和分子生物学相结合的方法，发现毛霉属为存在多起源现象，广布种卷枝毛霉、黄色毛霉和梨形毛霉为复合种。从nrDNA序列（SSU、ITS、LSU）、核蛋白基因（act1、EF-1α、MCM7等）和线粒体基因（cox1），以PCR扩增成功率、是否存在序列多态性和物种分辨率为标准，筛选获得nrDNA序列LSU和蛋白编码序列MCM7联合可用作毛霉属物种分类鉴定的DNA条形码。此外，测定了部分菌株的生物量、油脂产量、含油率及脂肪酸组成，结果表明该属真菌能够产生不饱和脂肪有9种，多不饱和脂肪酸有5种；莫氏毛霉的生物量、油脂产量和含油率高于其他物种。 本项目全面提高了对我国毛霉属真菌多样性的认识，储备了菌种资源，为该属真菌资源的保护和开发利用提供了基本资料和科学依据。