To explore genetic differentiation and the genetic relationships of Phytophthora sojae in Anhui Province, the inter-simple sequence repeat (ISSR) technique was used to analyze the genetic diversity of P. sojae. One hundred and sixty ISSR fragments were observed, including 129 (80.6%) polymorphic bands. This suggested that abundant genetic diversity existed among P. sojae in Anhui Province. The pairwise genetic similarity coefficients among the 62 strains ranged from 0.72 to 0.96, with a mean value of 0.85, indicating that there was a high level of genetic variation. Phytophthora sojae strains were divided into five clusters based on neighbor-joining (NJ) analysis, and the clustering was not related to geographic source, according to Mantel’s test (r = 0.3938). In addition, the clustering of strains from the same geographical source had little relationship to the year of collection. Analysis of molecular variance (AMOVA) showed that 16.65% of the genetic variation was derived from the collection area and 83.35% of the genetic variation was within-population variation. The genetic flow between different geographical sources ranged from 0.623 to 2.773, with a mean of 1.325, suggesting that gene exchange was frequent. Genetic distance and the genetic differentiation coefficient were not related to spatial distance.
Genetic Diversity among Isolates of Phytophthora sojae in Anhui Province of China based on ISSR-PCR Markers