关键词: 黄瓜, 多主棒孢, real-time PCR, 抗药性, 啶酰菌胺

Abstract: Based on the differences of SdhB gene of Corynespora cassiicola registered in GenBank，specific primers were designed for SdhB-H278Y mutation，and the real-time PCR detection system was established for detecting SdhB-H278Y mutation．The results showed that C. cassiicola carried SdhB-H278Y and SdhB-I280V mutations．The SdhB-H278Y mutants have high resistance to boscalid，the EC₅₀ value of SdhB-H278Y mutants was 21.47 μg·mL^-1 or ＞ 30 μg·μL^-1．The established standard curve of detection system existed a favorable linear correlation（R² = 0.992 9）．The detection system can detect the SdhB-H278Y mutation specifically with sensitivity of 3.6 × 10^-4 ng·μL^-1，which was 10 times of AS-PCR．The expected values were highly correlated with the detected values by verifying genomic DNA carrying different mutation ratios of SdhB-H278Y（R² = 0.999 7）．The system could also be used to detect the proportion of SdhB-H278Y mutant in the disease spot of corynespora leaf spot of cucumber，and the detection values were 0.12%-2.69% in Shandong．An efficient，sensitive and quantitative real-time PCR system was established for detecting SdhBH278Y mutation，providing technical support for corynespora leaf spot of cucumber controlling．

Key words: cucumber, Corynespora cassiicola, real-time PCR, resistance, boscalid