Analysis On Phenotypic And Genotypic Variation Of Phytophthora Infestans In Sichuan-Chongqing Region

Potato late blight, caused by Phytophthora infestans, is the most destructive disease of potato. In order to analyze P. infestans populations systematically from Sichuan and Chongqing, the population diversity were identified by phenotypic and genotypic analysis in this study. The mating type, metalaxyl sensitivity and virulence test were included in phenotypic analysis and SSR genotype was used in genotype identificationMating typies of 43 populations of P. infestans collected from 11 counties of Sichuan and Chongqing in 2010 to 2012 were detected using the standard strains A1 and A2. The results showed that, 2 of them were A1 mating type, accounting for 4.7% of the tested strains, 29 were A2 mating type accounting for 67.4%, and 12 were self-fertile(SF) accounting for 27.9% of the tested strains. The kinds of mating type A1, A2 and SF, distributed in Daofu and Kangding. The mating type A2 and SF distributed in Pengzhou, Wanzhou and Zhongxian. But in Beichuan Luding Shangba Shizhu and Zhaojue just had mating type A2. In Guangyuan only had mating type SF.Tested the metalaxyl sensitivity of P. infestans group in Sichuan Province, the result that have 3 types of sensitivity. The 3 types were sensitive, the antiresistance and high resistance. There were 3 sensitive strains accounting for 7% of the tested strains, The three potato late blight fungus distribution mainly in Daofu, Kangding and Zhongxian. There were 22 antiresistance strains accounting for 51.2% of the tested strains distribution mainly in Pengzhou, followed by Luding, Zhongxian, Daofu, Guangyuan, Shizhu, Wanzhou and Zhao Jiao, finally in Kangding and Shangba. There were 18 high resistance strains accounting for 41.8% of the tested strains. distribution in Beichuan, Daofu, Guangyuan, Kangding, Luding, Pengzhou, Shangba, Shizhu, Zhao Jiao and Zhongxian.This experiment adopted 11 contains the main effect resistance genes R1-R11 disease-resistant varieties and 1 infected material without resistance genes r identification of potato late blight fungus group in Sichuan province. The result was that 43 strains identified 11 physiological race. There 11 virulence physiological race were tested In this Population, distribution mainly in Luding, Pengzhou, Shangba, Shizhu and Zhongxian. Then race 1,2,3,4,5,6,7,8,10,11 had 5 mainly distribution in the Shangba, Zhao Jue, Kangding, Guangyuan and Zhongxian, accounting for 11.6% of the tested strains. There was virulence physiological race no found in Beichuan, Daofu, Kangding, Guangyuan, Wanzhou and Zhaojue. Isolates with full virulence races were dominant in local potato fields. The results of study could provide a scientific basis for controlling potato late blight in Sichuan Province.This research study in genotype contains SSR molecular marker analysis only 43 strains of potato late blight fungus. This experiment used five fluorescent primer SSR2, SSR3, SSR4, SSR6 and SSR8. The genotypic analysis results showed that 10 SSR genotypes were found and 16 alleles were yielded in 43 isolates with an average of 3.2 allele per locus. The mean PIC value was 0.46. SSR4 was the most informative SSR, with the highest PIC value(0.76). A2 and SF isolates were grouped to the same clusterusing phylogeny analysis in this study through clustering figure, A1 mating type and A2 mating type respectively belong to two different branches. We also found that compared to genetic relationship is 0.7 similarity coefficient relatively poor internal related genetic of potato late blight fungus species in Sichuan Province.