稻瘟病菌群体的分子遗传学研究——广东省稻瘟病菌群体遗传及致病型结构的时空变化分析

Molecular Genetic Studies on the Rice Blast Fungus Population —— Dynamics of Genetic and Pathotypic Structures of Three Rice Blast Fungus Populations Originated from Guangdong Province in 2000 to 2002

为了全面、系统地了解最近几年来广东省稻瘟病菌群体遗传及致病型结构的时空变化特征,通过基于SRAP(sequence-relatedamplifiedpolymorphism)标记的分子指纹方法对由广东省2000～2002年度各83个菌株构成的试验群体进行了遗传结构分析。结果表明,当相似性系数为0.92时,3个年度的供试菌株分别被分为33、25和13个遗传宗谱,其宗谱频率分别为39.8%、30.1%和15.7%。由此推测,广东省稻瘟病菌群体在这3年间其遗传多样性呈减少趋势,而且2001～2002年度的减少幅度要比2000～2001年度的大。另一方面,对上述3个群体进行了基于中国鉴别品种的致病型结构分析。结果表明,上述3个群体分别被划分为20、17和15个致病型,其致病型频率分别为24.4%、20.5%和18.1%。由此说明,3个稻瘟病菌群体的致病型多样性大体上也呈减少趋势。本文对稻瘟病菌群体遗传结构与致病型结构的互动关系,以及稻瘟病菌群体致病性遗传结构与寄主群体抗性遗传结构的互动关系进行了分析。据此推测,广东省水稻品种抗性遗传结构的稳定化和简单化是造成其稻瘟病菌群体的遗传和致病型多样性减少的主要因素。

In order to characterize the dynamics of genetic and pathotypic structures of the rice blast fungus population in Guangdong , three subpopulations each consists of 83 isolates derived from 2000 to 2002,respectively, were used as a experimental population. Genetic structures of the three subpopulations were characterized by the SRAP (sequence-related amplified polymorphism) marker-based DNA fingerprinting using the same ten pairs of SRAP primers. Three subpopulations were clustered into 33,25 and 13 genetic lineages, respectively, at the similarity coefficient of 0.92, indicating that genetic diversities of the rice blast fungus populations have been diminished in the recent years. On the other hand, pathotypic structures of the three subpopulations were characterized by the Chinese differentials. Three subpopulations were classified into 20,17 and 15 pathotypes, respectively, indicating that pathotypic diversities of the subpopulations have also decreased in the recent years. Since the genetic diversity of rice cultivars (hybrids) released has decreased in recent years in Guangdong, it, therefore, might be the most important fact to determine the dynamics of genetic and pathotypic structures of the population in Guangdong.