A Preliminary Study In Population Genetic Structure Of Phytophthora Infestans Isolates Collected From Anhui Fujian And Hunan Provinces In China

Potato late blight,caused by the Phytophthora infestans is a devastating disease on potato worldwide,Which affected seriously potatoes' quality yield.the structure and variation of Phytophthora infestans population are associated with disease occurrence and epidemics.so strengthen the study on population genetic structure of Phytophthora infestans has an important guiding significance on the prevention and treatment of potato late blight.In this study,we analyzed the population genetic structure of the potato late blight pathogen Phytophthora infestans isolates collected from Anhui Fujian and Hunan provinces.Main results were summarized as follows:1.The experiment determined for mating type of Phytophthora infestans isolates collected from Anhui.Fujian and Hunan province by using the confront culture.The determination result of mating type indicated that:all Phytophthora infestans isolates collected from Anhui province showed A1 mating type,but no detected A2 mating type;A1 and A2 mating type were tested in Fujian,which accounted for 64%and 36%;A1 and self-fertile were found in Hunan,which accounted for 45.9%and 54.1%.2.The experiment determined for physiological races of Phytophthora infestans isolates by inoculating of detached leaves of 12 different hosts that 11 hosts was carrying a single specific gene for resistance against Phytophthora infestans(R1-R11).The result showed that 17 physiological races among the 90 Phytophthora infestans isolates were determined.Of which,the physiological races of highest occurrence frequency is 1,3,4,7,9,10,the frequency of race was accounted for 36.7%.6 physiological races were determined among the 28 Phytophthora infestans isolates collected from Anhui Province.1,3,4,7,9,10 was dominant race with the frequency of 68%.5 physiological races were determined among the 25 Phytophthora infestans isolates collected from Fujian Province.1,3,4,7,9,10 was dominant race with the frequency of 56%.9 physiological races were determined among the 37 Phytophthora infestans isolates collected from Hunan Province.the occurrence frequency of race 1,3,4,7,9 and 1,2,3,4,6,7,9,10,11 was respectively 27%and 24%.3.The study used the six SSR primer combinations of PiG11?PiD13?Pi63?Pi02?PiSSR2 and PiSSR6 identified the SSR genotypes of 90 isolates collected from Anhui.Fujian and Hunan.Fourteen SSR genotypes of P.infestans isolates collected from Hunan province were identified.HN-3 was the dominant genotype with the frequency of 27%.Thirteen SSR genotypes of Phytophthora infestans isolates collected from Fujian province were identified.FJ-1 and AF-1 were the dominant genotype with the same frequency of 16%.Ten SSR genotypes of Phytophthora infestans isolates collected from Anhui province were identified.AF-2 was the dominant genotype with the frequency of 32.1%.Only AF-1 and AF-2 SSR genotypes were found in Anhui and Fujian province,other SSR genotypes were found in one province.The result of clustering analysis indicated that the reference spectrums were found to be far from of SSR genotypes of Phytophthora infestans isolates collected from Anhui.Fujian and Hunan province.4.The experiment determined for the sensitivity of phytophthora infestans isolates collected from Anhui.Fujian and Hunan province to metaiaxyl and mefenoxam by adopting colony diameter method..With reference to Daggett resistance standard and DPS softwares analysis showed Daggett resistance standard has some problems.This study choose two isolates from Anhui,Fujian and Hunan.determined for the sensitivity of ZG1 and ZG2 generation unit cell separation to metaiaxyl.Observe whether change or stable genetic resistance traits in parents.The results howed the isolates collected from Anhui,Fujian and Hunan were basically stable genetic resistance properties.determined for the sensitivity of a part of phytophthora infestans isolates collected from Anhui.Fujian and Hunan province to mefenoxam.The result displays:in Anhui,10 isolates were resistant to metalaxyl as well as mefenoxam,in Fujian,there were 3 islolates intermidate resistant to mefenoxam which were resistant to metalaxyl;in Hunan,there were 6 islolates intermidate resistant to mefenoxam which were resistant to metalaxyl.Thus,mefenoxam starts to lose control effect in Anhui,Fujian and Hunan,there were no sensitive isolates.