Research On The Population Genetic Diversity Of Phytophthora Infestans In Investigated Areas Of China

Potato late blight, the devastating disease has been threatening to the production of potato. Epidemic of the disease was getting more severe in rescent years in China. The occurrence and epidemic of this disease were related to the composition and variation of P. infestans population. It s necessary to production of potato to strengthen the research on population structure. This study focuses on the phenotypic(mating type and resistance to Metalaxyl ) and SSR genotypic diversity of P. infestans population in investigated areas in China. The results are as follow:1. The sensitivity to Metalaxyl and mating type of 26 isolates of P. infestans collected from Weichang County, Hebei in 2004 was evaluated. Results suggested that 23 strains were highly resistant to Metalaxyl, accounting for 88.5%, the others were highly sensitive, sensitive and intermediately resistant to Metalaxyl, respectively, each accounting for 3.85%. 14 highly resistant, 1 highly sesitive and 1 sensitive isolates out of 26 were selected to assess the resistant level against Metalaxyl. The result showed that EC50 value of the highly resistant and highly sensitive isolates were 866.4μg/mL and 0.05262μg/mL, respectively. The result also indicated that the mating type of the isolates from Weichang in 2004 were all Al mating type.2. Sixty-six isolates from 13 different production areas in Heilongjiang, Yunnan, Hebei, Sichuan were detected. Seven SSR genotypes were recognized, which are D-03, D-05, D-06, F-01, G-02, H-01 and F-06. SSR genotype F-02 was a new genotype. It was firstly reported in the worldwide.3. Three SSR genotypes were identified from 31 isolates in Weichang of Hebei, which were F-01, G-02 and D-03. Genotype F-01 dominated the population(87.9% of isolates).4. The result of test showed that the SSR genotype was not correlated with mating type or sensitivity to phenylamide fungicides.5. The SSR genotypes of the sexual progeny were not same as their parents completely, which indicated that the sexual reproduction was one of the important ways to make variation of P. infestans.