Abstract: Peronospora manshurica(Naoun． )Sydow is one of the important pathogen causing soybean diseases．?A approximately 500 bp fragment was amplified via universal fungal primers ITS1 and ITS4 derived from internal?transcribed spacer region between the 18S － 28S in soybean downy mildew Peronospora manshurica(Naoun． )?Sydow． Specific primer pairs PM1 and PM2 was designed after homological analysis of rDNA ITS sequences among?Peronospora manshurica(Naoun． )Sydow and other species based on soybean downy mildew by cloning and sequencing of ITS sequences in GenBank． A 380bp fragment was amplified with this specific primer from soybean downy?mildew strains and infected leaves，while no PCR products was amplified from other fungi strains and non-infected?leaves． Sensitivity experiments show that the primer PM1 an PM2 can detect target DNA at concentration of 0． 1 pg?as well as the pathogen from the infected leaves 5 days after inoculation． The primers can be used for rapid and accurate detection of soybean downy mildew． The molecular detection method will be benefit of latent downy mildew?infection and disease control measures carried out at early stage．

Key words: Peronospora manshurica(Naoun． )Sydow Soybean, ITS, Molecular probe

CLC Number: 

• S435.651