Abstract: 【Objective】The composition diversity of common scab pathogens was confirmed by previous researchers. A qualitative detection method for potato scab pathogens was established in this work by screening the universal probe primers among different pathogens. 【Method】 Four typical pathogenic strains which belonged to Streptomyces scabies (CPS-1), S. galilaeus (CPS-2), S. acidiscabies (CPS-3) and S. turgidiscabies (CPS-4) were selected to extract genome DNA. The primers were designed according to the sequences of four genes txtA, txtB, txtC (P450) and txtD (nos) that were from pathogen-specific toxin biosynthesis gene cluster what had registered in the NCBI GenBank. All primers were used for amplification for screening a high specificity and stability primers. After temperature gradient filter for optimizing the reaction system, a detection technology of potato scab pathogens was established. 【Result】 The universal primers B1/B2 obtained in this work showed a good specificity to all tested pathogenic strains. The stable bands were amplified among the pathogenic strains, but nonpathogenic strains didn’t have that band. By using the spore dilution method, the sensitivity of PCR detection method was determined to 20 pg•μL-1. The detection value of the threshold was 4.0 CFU/μL for pathogen spores. The PCR detection results showed that the target bars could be observed in pathogenic Streptomyces, scabby tissue and diseased field soil samples. While the nonpathogenic Streptomyces, healthy potato tissues, scab-free field soil and other test strains did not have corresponding objective band. That suggested the PCR detection method established in this work was specific and stable to common scab pathogens. 【Conclusion】 A qualitative detection method for potato scab pathogens was established in this study, which can quickly detect pathogenic strains from diseased tissues and soil samples.

Key words: common scab pathogens , PCR detection , specific primers