The Analysis Of Phenotype And SSR Genotype Of Phytophthora Infestans

The experiment determined for mating type of Phytophthora infestans isolates collected from the major Potato production area of Heilongjiang province by using the confront culture. The determination result of mating type indicated that the mating type of all P. infestans isolates collected from Heilongjiang province showed A1mating type, but no detected A2mating type. The result suggested that the dominant mating type of P. infestans isolates in Heilongjiang province was A,.The experitment determined for the sensitivity and cross resistance of41Phytophthora infestans isolates collected from Heilongjiang province to metalaxyl and cymoxanil. As for metalaxyl resistance,14.63%isolates were sensitive,58.54%isolates were intermediate resistant, and58.54%isolates were resistant. The results suggested that P. infestans isolates collected from Heilongjiang province have been occurred resistance to metalaxyl. As for cymoxanil, the EC5o values ranged from0.0630to2.1289μg·mL-1, with the EC50values of the most insensitive isolate being33.79times the most sensitive, and the value of base line sensitivity was0.1879μg·mL-1. The results of cross resistance indicated that no cross resistant isolates was73.16%, and cross resistant isolates was26.34%. Above results suggested that cymoxanil can not be cross used with metalaxyl.The experiment determined for physiological races of41P. infestans isolates collected from Heilongjiang province by using12differential hosts that11hosts was carrying a single specific gene fro resistance against P. infestans (R1～R10) and the cultivar "Atlantic" contained no known R gene. The result showed that15physiological races among the41P. infestans isolates were determined. Of which, the physiological races of highest occurrence frequency is0.1.2.3.4.5.6.7.9.10.11, the frequency of race was accounted for24.39%. Next, the occurrence frequency of race0.1.2.3.4.5.6.7.8.9.10.11and race0.1.2.3.4.5.6.7.10.11was12.2%and9.76%, respectively.The SSR genotypes of92isolates of P. infestans collected from Heilongjiang and Jilin provinces were identified using the two SSR primer combinations of Pi4B and Pi4G. Six SSR genotypes of P. infestans isolates collected from Heilongjiang province were identified. The six SSR genotypes are F-01, F02, F03, F05, F-06and G-02, respectively. Two SSR genotypes of P. infestans isolates collected from Jilin province were identified. The two genotypes are F-01and F-06, respectively. F-01was the dominant SSR genotype of the P. infestans isolates collected from the two provinces. The P. infestans isolates of the same mating type may consist in different SSR genotypes. The P. infestans isolates of the same SSR genotype may be difference on the sensitivity to Metalaxyl. Above results suggested that there was no correlation between the SSR genotype and the mating type or response to Metalaxyl. The result of clustering analysis indicated that the SSR genotype F-01of the highest occurrence frequency were found to have very close genetic relationship with F-05, then F-02.The SSR genotype G-02was found to be far from of other SSR genotypes.