Genetic Diversity Of Phytophthora Infestans Of Potato In Sichuan

Potato (Solanum tuberosum) is the fourth most worldwide crop in the world after wheat, corn and rice, which plays an important role in food security now. Potato late blight that is caused by Phytophthora infestans is the most devastating disease to potato production in Sichuan. in this study, Genetic diversity carried out by the study of Mating type, Physiological race, Metalaxyl sensitivity, Oospores phenotypically and mtDNA haplotype of P.infestans population that were isolated from Sichuan during 2008 to 2010, and this study will set up the foundation for Potato late blight control and prevention. The main results in this study are as follows:1. Among 188 isolates of P. infestans,53 isolates belonged to A1 mating type with the frequency of 28.2%; 87 were A2 mating type with the frequency of 46.3%; 6 were A1,A2 mating type with the frequency of 3.2%; 41 were self-fertile mating type with the frequency 21.8%; 1 was unknown mating type with the frequency of 0.5%.2.55 physiological races were detected in the 148 isolates, each type contains an average of 8.7 virulence factors, and race 1.2.3.4.5.6.7.8.10.11 was the dominant race with the frequency of 16.22%, followed by race 1.2.3.4.5.6.7.9.10.11 with the frequency of 10.14%, and race 1.2.3.4.5.6.7.8.9.10.11 contain all known virulence genes with the frequency of 7.43%.3.100 isolates of P. infestans were tested with metalaxyl, the results showed that resistant and moderately resistant isolates to metalaxyl were common lineages on potato in Sichuan and the ratio of resistant, moderately resistant and sensitive isolates was 63.0%,22.0% and 15.0% respectively, the EC50 were 0.0025μg/mL-1911.344μg/mL.4.30 F1 generations of oospores between isolates crosses (ZJ09-2×JL10-1, ZJ09-2×PG10-1, ZJ09-1×BM09-1) were obtained and the phenotype were tested, the results showed that 7 resistant isolates with the frequency of 23.3%,21 moderately resistant isolates with the frequency of 70.0% and 2 sensitive isolates with the frequency of 6.7%; 17 isolates were A1 mating type,7 were A2 mating type and 6 were self-fertile mating type indicated that A1 mating type and A2 mating type were not a 1:1 proportion in progenies. 5.77 isolates of P. infestans were tested, the results showed that Two mtDNA haplotypes I a and II a were detected from P.infestans populations on potato in Sichuan, I a haplotype were 75 with the frequency of 97.4%, spreading all potato production regions, and II a haplotype were 2 with the frequency of 2.6% from Xindu area and Daofu county.