Abstract: In order to study the spatial-temporal dynamics of physiological races and virulence structure of Phytophthora sojae, the soil samples were collected from four destructive fields in Eastern Heilongjiang Province for four years, and the P.sojae isolates were isolated by modified leaf disc baiting method. The isolates were acquired after morphological and DNA molecular identification, and their physiological races and virulence structure were identified using the universal hypocotyl inoculation method. The results showed that the 497 isolates included 135 pathotyps with 29 races, 1 IRT and 105 new pathotyps, of which races 16, 18, 22, 28 and 35 were first reported in China, while races 4, 33, 38, 39, 43, 48 and 49 were not detected. Race 13 had the highest isolation frequency of 3.2%, and race 1 was only 2.4%. It suggested that the virulence of P.sojae population in Eastern Heilongjiang was weak. The virulence frequencies to eight Rps genes varied from 27.8% to 53.1%, of which the virulence frequencies to Rps1k, Rps3a, Rps1c and Rps6 genes were less than 35%, but that to Rps7 gene reached to 53.1%, indicating that the soybean cultivars containing Rps1k, Rps3a, Rps1c or Rps6 were safer in Eastern Heilongjiang and that containing Rps7 was more dangerous. The races and pathotypes of P.sojae in Eastern Heilongjiang differentiated rapidly with time, their virulence and population pathogenicity had enhanced, and the virulence frequencies to majority of Rps genes increased. The number of races and new pathotypes had no significant difference between the production field and the experimental field, but their types were quite different and the virulence of single isolate and population in experimental fields was stronger.

Key words: Phytophthora sojae, Physiological race, Virulence structure, Spatial-temporal dynamics, Eastern Heilongjiang

CLC Number: 

• S432.1