蛹虫草交配系统与营养体亲和性研究

Preliminary Study on Mating System and Vegetative Compatibility in Cordyceps militaris

【目的】蛹虫草是一种药(食)用真菌,属典型的子囊菌异宗交配系统,研究蛹虫草交配系统和营养体亲和性。【方法】从蛹虫草子实体进行单孢子分离,获得不同的单子囊孢子群体。选取单子囊孢子菌株进行培养并提取菌丝体DNA,设计特异性引物对其交配型目的基因进行PCR扩增,明确不同群体内部各单子囊孢子菌株的交配型类型并分析其分离比例。随机选取不同交配型代表菌种采用对峙培养方法对相同和不同的交配型菌株的营养体亲和性进行检测。【结果】所有检测的菌株均具有两种交配型MAT1-1或MAT1-2之一。检测的不同群体菌株中两种交配型的分离比例,卡方检验均符合1∶1的理论比值。随机选取不同交配型的菌株进行营养体亲和性对峙培养试验,所选菌株被初步分为4个不同的营养亲和群,蛹虫草存在潜在的遗传分化。相同交配型菌株之间的营养亲和性较高(90%);相反不同交配型菌种之间的营养亲和性比例较低(60%)。【结论】所有供试单子囊菌株只具有一种交配型且未出现偏分离现象,其交配系统与营养体亲和性之间存在一定的相关性,相同交配型菌株组合比不同交配型菌株组合的营养亲和性更普遍,因此利用不同交配型且菌丝体营养亲和性较高的菌种组合,则更有利于发育产生原基,形成子实体。

[ Objective ] Cordyceps militaris is a kind of medical and edible fungus, which is a typically heterothallic ascomycetous fungus. This project aims to conduct a preliminary investigation of the correlation of mating system and vegetative compatibility. [ Method ] In this paper, different single - spore groups were obtained through single ascospore isolation from the different fruiting bodies of C. militaris. The isolated strains were cultured and mycelial DNA was extracted. Design specific primers were designed for PCR amplification of mating type gene to identify the mating types and segregation ratio. Some strains were randomly selected to detect vegetative compatibility between the same and/or the different mating type strains using the confrontation training method between paired cultures. [ Result] The results showed that all detected strains were either mating type MAT 1 - 1 or MAT 1 - 2 . Difference sampling groups were determined and thereafter the segregation ratio was analyzed by Chi - square, which indicated that the ratio of two mating types was consistent with a theoretical segregation ratio of 1： 1. The strains with the different mating type were randomly chosen to investigate the vegetative compatibility using crossing culture between paired strains. The results indicated that the strains were divided into four vegetative compatibility groups, which indicated the potentially genetic differenti- ation. Vegetative compatibility between the strains between the same mating type （s） was higher （90%） than those between the different mating types （60%）. [ Conclusion ] All the tested single ascospores only showed one of mating types and the population sample did not present segregation distortion. The correlation of mating system and vegetative compatibility in C. militaris was possible. The vegetative compatibility of strain in combination with the same mating type was more widespread than that of different mating types. Thereafter, the combination of the strains with different mating types and vegetative compatibility suggested utilization for development of stroma and formation of fruiting body.