互补交配型配对诱导蛹虫草有性子实体形成

前期我们获得了优良性状蛹虫草Cordyceps militaris野生菌株W141436，其子实体虫草素含量高达3.72 mg/kg干重，子实体多糖高达6.7 g/100 g干重，但在大规模应用中发现它发生退化。针对蛹虫草人工栽培退化问题，我们提出蛹虫草子实体形成是有性生殖过程，其两种交配型发生交配是蛹虫草子实体形成的必要条件。本文基于交配型基因分子标记研究了优良性状蛹虫草野生菌株W141436的退化机制。具体地，采用单孢子分离的方法对蛹虫草野生分离株W141436的子囊孢子进行分离，得到了72个单孢菌株。进一步采用PCR方法对单孢菌株及亲本菌株进行了交配型基因类型鉴定。在72个单孢菌株中，28株为Mat1-1类型交配基因型，31株为Mat1-2类型交配基因型，13株含有与亲本相同的交配型基因。根据鉴定结果，对2株Mat1-1型(SP28、SP33)和2株Mat1-2型(SP15、SP32)菌株进行了栽培实验。结果表明，形成子实体的栽培用亲本菌株同时含有Mat1-1和Mat1-2两种交配类型基因，即只有含不同交配型基因的菌株具有发育为子实体的能力，而含同种交配型基因的菌株则不能发育为子实体。本研究为防止蛹虫草在大规模种植中退化提供了理论依据。

Induction of sexual fruiting-body formation by pairing the opposite mating-type isolates of Cordyceps militaris

A wild strain Cordyceps militaris W141436 obtained previously with merits of high cordycepin content reaching 3.72 mg/kg (dried weight) and high polysaccharide content reaching 6.7 g/100 g (dried weight) in fruit bodies was found to be degraded in large scale cultivations. We hypothesized that mating is a process of sexual reproduction and an essential prerequisite for the fruit body development of C. militaris. This study focused on the degradation of C. militaris based on mating type gene markers. In total, 72 single spore strains were isolated from C. militaris W141436 ascospores according to single spore isolating method. The mating-type genes of the obtained single spore strains and parent strains were identified by PCR and the results showed that 28 strains were Mat1-1 (MAT-alpha) type, 31 Mat1-2 (MAT-HMG) and 13 parental type in the obtained 72 single spore strains. Pairing cultivation of two strains with Mat1-1 type (SP28, SP33) and two strains with Mate1-2 type (SP15, SP32) demonstrated that cross-mating between the strains with opposite mating type genes produced well-developed fruit bodies, while cross-mating between the same mating type isolates did not produce fruit bodies. This research provided a theoretical basis for preventing C. militaris from degradation in the large scale production.