The Study Of Population Structure Of Phytophthora Infestans In Heilongjiang Province

151 strains of Phytophthora infestans were isolated in the main Potato producing areas of Heilongjiang province from 2012 to 2014. Of which, 20 strains were isolated in 2012, 91 strains were isolated in 2013, 40 strains were isolated in 2014. In order to systematic analyse phenotype of Phytophthora infestans, we determined the mating type, metalaxyl sensitivity and physiological races of P. infestans. The determination results of mating type showed that all strains of P. infestans isolated in 2012 were A1 mating type; A1, A2 and self-fertility were found in strains of P. infestans isolated in 2013, isolation frequency of them were 60.4%, 110% and 28.6%, respectively; three mating types including of A1, A2 and self-fertility were also found strains of P. infestans isolated in 2014, isolation frequency of them were 70.0%, 12.5% and 17.5%, respectively. The determination results of metalaxyl sensitivity showed that among the 20 strains of P. infestans isolated in 2012, 17 strains(85.00%) were resistance, 1 strains(5.0%) were sensitive, 2 strains(10.0%) were moderate resistance; among the 91 strains of P. infestans isolated in 2013, 82 strains(90.11%) were resistance, 3 strains(3.30%) were sensitive, 6 strains(6.59%) were moderate resistance; among the 40 strains of P. infestans isolated in 2014, 37 strains(92.5%) were resistance, 1 strains(2.50%) were sensitive, 2 strains(5.0%) were moderate resistance. Above results suggested that P. infestans collected from Heilongjiang province has developed resistance to metalaxyl.We identified the physiological races of 60 strains of P. infestans isolated from Heilongjiang province by using 12 differential hosts with single gene. Of which, physiological race of high frequency of occurrences were race 1.2.3.4.5.6.7.9.10.11, its frequency of occurrences were 26.7%. The physiological race is the dorminant race in Heilongjiang province.We carried out for analysis of population genetic structure of P. infestans by using SSR molecular markers in this experiment, and improved the molecular maker system of P. infestans in China. The SSR genotypes of the genomic DNA of 151 isolates of P.infestans from Heilongjiang province were identified using the SSR primers of Pi4 B and Pi4 G in analyzing the polymorphism. The determination results of SSR genotype showed that 8 SSR genotypes known and 1SSR genotype unknown were identified in P. infestnas isolated from Heilongjiang province. The 8 SSR genotypes were F-01、F-02、F-03、F-05、D-02、D-03、G-02 and G-03, respectively. Of which, the largest amount of SSR genotype was F-01(111), the frequency of i occurrences was 73.51%. F-01 of SSR genotype was the dorminant SSR genotype. Secondly, high frequency of occurrence of SSR genotype was F-05, the frequency of occurrence was 12.58%. The anlysis results of correlation between mating type and SSR genotype showed that 6 SSR genotypes(F-01、F-02、F-03、F-05、D-02 and G-02)were found in A1 mating type of P. infestans; 5 SSR genotypes(F-01、F-03、F-05、D-03 and G-02) known and 1 SSR genotype unknown(F-X)were found in A2 mating type of P. infestans; 6 SSR genotypes(F-01、F-03、F-05、D-03、G-02 and G-03)) known and 1 SSR genotype unknown(F-X)were found in self-fertility mating type of P. infestans. The anlysis results of correlation between metalaxyl sensitivity and SSR genotype showed that 3 SSR genotypes(F-01、F-05 and D-03)were found in metalaxyl sensitivity isolates of P. infestans; 3 SSR genotypes(F-01、F-05 and D-03) known and 1 SSR genotype unknown(F-X)were found in moderate resistance isolates of P. infestans; 7 SSR genotypes(F-01、F-03、F-05、D-02、G-02 and G-03)known and 1 SSR genotype unknown(F-X)were found in metalaxyl resistance isolates of P. infestans. Above results suggested that there is no correlation between SSR genotypes and mating types and metalaxyl sensitivity.This study method detected three mitochondrial DNA haplotypes of Ia, Ib and IIa by using PCR-RFLP. Of which, the largest number of mt DNA haplotype is IIa(127). IIa type are mainly distributed in Jiamusi city, Keshan county, Yian county, Baiquan county, Lanxi county and Harbin city. P. infestans isolates of Ia type were 20. Of which, 18 strains distributed in Yian County, 2 strains distributed in Harbin city. In the experiment, we did not detect the IIb haplotype.