中国块菌属分类学及分子系统学研究

Tuber is a genus of hypogeous ascomycetous fungi and all of the species in this genus form ectomycorrhizae with various kinds of shrubs and trees. The hypogenous ascocarps of the Tuber species have been called 'Truffles' commercially and some species, like the famous black truffle (T. melanosporum) and white truffle (T. magnatum), are the most precious edible and medicinal mushroom historically and have great economic value today in the world. The literature review and the previous research conducted by the applicants of the project showed that China seems to be extremely rich in Tuber species and high ratio of endemic species also is one of the characteristics of Chinese Tuber flora. The current research on this genus in China is in the beginning stage, and surely there still remain many species undiscovered and undocumented. The analysis of multigenes with nITS-rDNA、nLSU-rDNA、β-tubulin and mtLSU rDNA are applied for this project to erect a phylogenetic tree of Tuber. The phylogenetic relationships within the taxa and the value of morphological characters for taxonomy of Tuber will be analyzed. We try to erect a natural and rational phylogenetic tree for Tuber, and explore the relationships and boundaries of species within Tuber through the combination between phylogenetic analyses data and morphological characters. The species and distribution in China for Tuber will be clarified. On the basis of molecular phylogenetic studies, we try to screen the molecular markers and explore the possibility erecting a series of identification techniques used as the identification of the strains of Tuber, mycorrhizae formed by Tuber species and immature or damaged specimens of Tuber. These techniques will be useful in the development of forest and mushroom eco-economy. The strains of Tuber species with practical significances will be isolated and preserved as far as possible. These strains are likely to be resources available in the future for the findings of bioactive chemicals, health products and new medicines. This project has very important meanings for molecular phylogenetics of fungi and the application for truffles.

块菌是最珍贵的食药用菌。中国块菌资源丰富，特有种比例高，对块菌的研究处于起步阶段，有大量种类资源有待挖掘。本项目采用经典形态学分类与包括nrDNA-ITS、nrDNA-LSU、β-tubulin和mtLSU rDNA等基因的多基因分子系统学分析相结合的方法研究中国块菌属种间的进化关系，弄清形态特征在块菌属种的界定上的分类学意义，建立一个能够真实反映种间亲缘关系、自然、合理与实用的块菌属分类系统。尝试将分子系统学研究结果与形态特征相结合的方法用于块菌属种的鉴定，澄清和订正分类和命名上存在的问题，搞清块菌属真菌在中国的种类和分布。建立块菌属种类鉴定的分子标记，用于对块菌菌株、菌根以及未成熟或残缺材料的鉴定，这一技术对林业-菌类生态经济的发展有重要意义。对有应用价值的种类分离并保存其活体菌株，为生物活性物质研究或保健品、新药发现等储备资源。本研究在块菌属真菌资源的利用上有重要的理论和实际意义。

块菌属Tuber真菌俗称松露，是世界上最珍贵的药食两用菌。项目组成员采集我国块菌属标本630份，采用光学显微镜、电子显微镜和分子系统学方法对这些标本的形态特征进行观察，对分子系统学研究用基因的序列进行测定，获得我国块菌属物种的nLSU rDNA、ITS rDNA、RPB2及EF1α等基因序列2582条；对NCBI数据库中有关我国块菌属物种的DNA分子序列进行了研究，筛选可信序列324条；基于上述原始数据，采用形态学观察与多基因分子系统学分析相结合的方法建立了真实体现种间亲缘关系、全面系统反映中国块菌属物种多样性的分类系统，发现我国块菌属物种分别归属于9个系统发育谱系，即Aestivum、Excavatum、Latisporum、Macrosporum、Maculatum、Rufum、Melanosporum、Puberulum和Turmericum，其中Latisporum为我们发现的新谱系，其所包括的种类均来自亚洲，是亚洲特有的块菌属演化分支；确定了块菌属真菌在我国分布有65种，其中本项目组发现了44种（已发表新种31个，待发表新种13个，中国新记录种2个）；建立了这65种块菌的物种分子鉴定用数据库，可用于对中国块菌属物种进行快速准确鉴定；整理了记载有我国块菌属真菌的文献，研究了相关记录所依据的标本，发现所有以前文献记载的在中国存在的欧美物种（包括T. borchii、T. borchii var. sphaerosppermum、T. excavatum、T. oligospermum、T .rufum、T. nitidum、T. californicum）在我国均没有分布，这些报告均源于错误的物种鉴定，到目前为止，我们确认在中国与欧美共享（或外来）的物种只有2个，即T. maculatum和T. pacificum，为本项目研究发现的中国新记录种；发现多种中国特有的具重要经济价值的块菌新物种，如李玉块菌T. liyuanum、假球孢块菌T. pseudosphaerosporum、中华球孢块菌T. sinosphaerosporum和姜黄块菌T. turmericum，为我国林下经济开发增添了新的物种资源。这些研究结果表明中国是世界范围内块菌属现存物种多样性最丰富的国家之一，是块菌属物种的现代演化中心地区之一，且特有种比例极高。发表SCI刊源学术论文9篇。