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

摘要： 根据GenBank已登录序列中黄瓜多主棒孢琥珀酸脱氢酶B 亚基（SdhB）基因序列差异，针对SdhB-H278Y 突变设计特异性引物，建立SdhB-H278Y突变实时荧光定量PCR（real-time PCR）检测体系。结果表明：供试多主棒孢携带SdhBH278Y、SdhB-I280V突变；SdhB-H278Y突变株对啶酰菌胺抗性较强，EC₅₀值为21.47 μg·mL^-1 或＞ 30 μg·mL^-1；建立的real-time PCR检测体系具有良好的线性关系，相关系数R² = 0.992 9，可特异性检测SdhB-H278Y突变，灵敏度为3.6 × 10^-4 ng·μL^-1，为AS-PCR的10倍。利用携带SdhB-H278Y突变不同比例的基因组DNA 对检测体系进行验证，预期值与检测值具有很高的相关性，R² = 0.999 7；利用该检测体系对山东地区黄瓜棒孢叶斑病病斑中多主棒孢SdhB-H278Y突变株所占比例进行检测，检测结果为0.12%～2.69%。综上，本试验建立的real-time PCR检测体系高效、灵敏、定量，可用于多主棒孢SdhB-H278Y突变的检测，为黄瓜棒孢叶斑病抗性治理提供技术支持。

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