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

Molecular Genetic Studies on the Rice Blast Fungus Population——Comparison of Genetic and Pathotypic Structures of Two Rice Blast Fungus Populations Originated from Guangdong and Jiangsu Provinces,China

通过基于SRAP标记的分子指纹分析法对由广东省40个菌株和江苏省42个菌株构成的试验群体进行了遗传结构分析。结果表明,在相似性系数取0.83时,82个供试菌株被分为27个宗谱;其中广东群体16个宗谱,其宗谱频率为59.3%;江苏群体12个宗谱,其宗谱频率为44.4%,由此说明前者比后者的遗传多样性丰富。值得指出的是,在全部27个宗谱中,只有1个宗谱是两个群体共有的,由此推测二者之间存在明显的遗传特异性。另一方面,利用中国、日本和IRRI的三套鉴别品种分别对82个供试菌株进行了致病型结构分析。结果表明,在上述三套鉴别品种上,广东群体分别被划分为16、30和20个小种(致病型),其小种频率分别为40.0%、75.0%和50.0%;而江苏群体则被分为8、23和11个小种,其小种频率分别为19.0%、54.8%和26.2%。由此说明广东群体的致病型多样性也比江苏群体的丰富;在两个群体之间致病型多样性与遗传结构多样性存在相关关系。此外,对两个群体的致病型特异性和优势小种的构成进行了比较分析。结果显示,在两个群体之间存在高度的致病型特异性;优势小种的构成亦存在分明的差别。由此说明在两个群体之间致病型特异性与遗传结构特异性也是密切相关的。本研究的结果再一次说明,在进行有关病原菌群体的分子遗传学研究时,应该分别从遗传宗谱和致?

Genetic structure of a rice blast fungus population, which is composed of two subpopulations, one consists of 40 isolates derived from Guangdong Province (GD) and another consists of 42 isolates derived from Jiangsu Province (JS) in China, was characterized by the SRAP (sequence-related amplified polymorphism) marker-based DNA fingerprinting. A total of 82 isolates were separated into 27 genetic lineages at the similarity coefficient of 0.83. Among the 27 lineages, 16 and 12 lineages were detected in GD and JS subpopulations, respectively, indicating that genetic diversity of GD subpopulation is certainly higher than that of JS subpopulation. Moreover, there is only one lineage consisted by isolates from both subpopulations, indicating that there is a high genetic specificity / heterogeneity between the two subpopulations. On the other hand, pathotypic structures of the two subpopulations were characterized with three sets of differential cultivars constructed in China, Japan, and IRRI (International Rice Research Institute). By the three differential sets, 16, 30 and 20 pathotypes were determined in GD subpopulation, respectively, while 8, 23 and 11 pathotypes were determined in JS subpopulation, respectively, indicating that pathotypic diversity of GD subpopulation is also certainly higher than that of JS subpopulation. Furthermore, there are 12, 49, and 23 pathotypes determined by the three sets of differentials, respectively, which are specific to each subpopulation, indicating that there is a high pathotypic specificity between the two subpopulations. And, the constitution of the dominant pathotypes is considerably different between the two subpopulations. The results from this study further suggested that genetic and pathotypic structures of the pathogen populations should be dissected with their diversity and specificity, respectively.