有性生殖对栗疫病菌群体结构的影响

Influence of sexual reproduction in Cryphonectria parasitica on the fungal population structure

采用RAPD方法对来源于栗疫病菌8个不同子囊壳的子囊孢子后代和无性生殖的对照群体各23个菌株进行了群体结构的比较。从RAPD随机引物中筛选出扩增多态性丰富的4条引物,共扩增出条带73条,多态性检测率为100%。研究结果表明,在8个子囊壳和无性生殖群体中的基因多样性,64.27%由群体内部引起,只有35.73%的多样性由群体之间的基因差异引起。各子囊壳群体间存在的基因流动很小(Nm=0.8994)。有性群体和无性群体之间的遗传距离为0.1389,基因流动值为3.4212,说明子囊壳群体和无性生殖群体之间存在一定的系统关系。分析表明栗疫病菌子囊孢子后代在自然界的传播对自然界的病菌的多样性起重要的作用。

The population structure of Cryphonectria parasitica was analyzed using random amplified polymorphic DNA （RAPD）. 23 isolates of each of eight perithecia and the fungal asexual populations as the samples collected from natural garden, and assayed for genetic diversity by using 4 RAPD primers with abundant polymorphisms. 73 RAPD mark bands were obtained and 100% of them were polymorphic. Ascospore swains from peritheria showed much more variability among themself, in contrast with field asexual isolates showing lower genetic diversity. Genetic diversity and UPGMA dendrogram were analyzed by use of Popgen Version 1.31, and the results showed that the genetic variation between perithecia were rich： 64.27 % was attributed to diversity within populations, as compared with 35.73 % among populations. Gene flow value （Nm） was 0.8994 between different peritheria while the genetic distance among sexual and asexual populations was 0.1389, but the gene flow estimate was 3.4212 among sexual and asexual populations. Dendrogram suggested that there was gene flow between the sexual and asexual population and the sex offspring of Cryphonectria parasitica will make much more diversity in nature.