稻瘟病菌群体的分子遗传学研究——广东省与云南省稻瘟病菌群体遗传及致病型结构的比较分析

Studies on Molecular Genetics of Rice Blast Fungus Population——Comparison of Genetic and Pathotypic Structures of Two Rice Blast Fungus Populations Derived from Guangdong and Yunnan Provinces of China

通过基于SRAP标记的分子指纹分析法对由广东省和云南省各40个菌株构成的试验群体进行了遗传结构分析。在相似性系数取0.83时,80个供试菌株被分为25个宗谱;其中广东群体9个宗谱,宗谱频率为22.5%;云南群体16个宗谱,宗谱频率为40.0%,由此说明,后者比前者的遗传多样性高。有趣的是,在25个宗谱中并不存在两个群体共有的宗谱,由此推测它们之间存在明显的遗传特异性或异质性。另一方面,利用中国、日本和IRRI的3套鉴别品种分别对80个供试菌株进行了致病型结构分析。结果表明,在上述3套鉴别品种中,广东群体分别被划分为16、30和20个致病型;而云南群体则分别被划分为12、31和16个致病型。由此说明,两个群体之间遗传多样性方面的差异并没有反映于致病型多样性上。但是,通过对两个群体致病型结构的比较分析表明,两个群体之间存在高度的致病型特异性,这一特性则充分地反映于两者的遗传特异性上。研究结果表明,从多样性和特异性这两方面来进行病原菌群体遗传宗谱和致病型结构分析可能更加合理和全面一些。

Genetic structure of the rice blast fungus population, which is composed of two subpopulations and eachconsists of 40 isolates derived from Guangdong (GD) and Yunnan (YN) Provinces of China, was characterized by SRAP(sequence-related amplified polymorphism) marker-based DNA fingerprinting. A total of 80 isolates were divided into 25genetic lineages at similarity coefficient of 0.83. Among the 25 lineages, 9 and 16 lineages were belong to GD and YNsubpopulations, respectively, indicating that genetic diversity of YN subpopulation is certainly higher than that of GDsubpopulation. Interestingly, there is no any common lineage to both subpopulations, indicating that there is a high geneticspecificity / heterogenecity between the two subpopulations. On the other hand, pathotypic structures of the twosubpopulations were characterized with three sets of differential cultivars constructed in China, Japan, and IRRI (InternationalRice Research Institute). By the three differential sets, 16, 30 and 20 pathotypes were detected in GD subpopulation, while12, 31 and 16 pathotypes were detected in YN subpopulation, indicating that genetic diversity can not be accounted for thepathotypic diversity presented in the two subpopulations. However, there is a high pathotypic specificity between the twosubpopulations, which is consistent with the genetic specificity characterized by the DNA fingerprinting. The results fromthis study suggest that genetic and pathotypic structures of the pathogen populations should be dissected with theirdiversity and specificity, respectively.