Distribution Of Pathogenic Types And Research For Genetic Diversity Of Phytophthora Infestans From North East China

Potato late blight caused by Phytophthora infestans (Mont.) de Bary is the destructive disease in potato production areas. Understanding distribution of pathogenic types and genetic variation patterns timely and accurately can provide strategic decision and foundation for drawing up measures to prevent and control potato late blight and other potato disease and promoting the sustainable development of potato industrialization. In the former work of our laboratory, the distribution of pathogenic types of several P. infestans collected in Heilongjiang, Jilin, Liaoning and Hebei in 2008 and 2009 had been preliminarily revealed; a relatively perfect SSR reaction system suiting for our laboratory had been formed; and SSR genotypes of some strains in above-mentioned areas had been identified. This article was based on the above research work. More strains of P. infestans in potato planting areas of Heilongjiang, Jilin, Liaoning and Hebei were collected, the distribution of pathogenic types of collected P. infestans were identified, the SSR reaction system was further perfected and the distribution of SSR genotypes of P. infestans between different areas was identified. The major results are as follows:1.Seventy seven strains of P. infestans were successfully isolated and purified from 116 leaves specimens with potato late blight collected from Heilongjiang, Jilin, Liaoning and Hebei, in 2009.The average of successful isolation rate was 66.4%; just four strains of P. infestans were collected in 2010 due to drought.2.Fourteen pathogenic types were identified from 77 strains of P. infestans by identifying virulence genes. Pathogenic type 1.2.3.4.5.6.7.8.9.10.11 was the most universal one among these types, accounting for 41.56%, and it was distributed in the four collecting provinces; Pathogenic type 1.2.3.4.5.6.7.9.10.11 was the second one, accounting for 22.08%, and it was distributed in Hebei and Liaoning.3.Strains which could completely overcome single dominant resistance genes accounted for more than 40% of tested strains. R5, R6, R11 and R7 resistant genes could be overcome by 90.9%, 93.5%, 93.5% and 94.8% of tested strains, respectively.4.Ten SSR genotypes were identified using two pairs of SSR primers, Pi4B and Pi4G. Among them, Genotype F-01 was the leading genotype and accounted for 50.65%; F-07, I-01 and M-01 were the firstly reported. 5. Thirty two genotypes were identified using four pairs of SSR primers. Genotype IV, V and X had high rate among them, and accounted for 11.7%, 9.1% and 10.4%, respectively; strains of other genotypes were decentralized and there were no genotypes of centralized strains.6.Cluster analysis of genotypes showed that there was no relation between strains clustering and geographical origin.7. Analysis of population genetic diversity of P. infestans by POPGENE32 software indicated that genetic diversity of populations was high, duing to more species and more complicated composition of SSR genotypes. But the whole level of genetic variation was not high, genetic difference was small among four provinces.