Relationship between virulence and DNA polymorphism of Phytophthora sojae

Twenty isolates of Phytophthora sojae isolated from the field of Heilongjiang and Jilin Province were inoculated in eight soybean varieties carrying Rps in order to test virulence of the isolates. The isolates were divided into 6 virulence groups according to resistant/susceptible reaction to the pathogen. Of 151 RAPD 101 which were amplified with 22 random decamer primers, 66.90% were polymorphic. Genetic distance between each of the isolates were calculated, and cluster analysis was used to generate dendrogram showing relationship between them. The results showed that genetic diversity existed between the isolates. The relationship between virulence and DNA polymorphism was presented in some isolates.