Downy mildew of onion and lettuce, caused by Peronospora destructor and Bremia lactucae, respectively, is distributed worldwide. Control of these serious diseases largely relies on oomycete fungicides including quinone-outside inhibitors (QoIs) and carboxylic acid amides (CAAs), both of which bear the risk of resistance development in pathogens. Resistance to QoI and CAA fungicides has not been confirmed in field isolates of onion and lettuce downy mildews to date, and monitoring using biological methods is challenging as both pathogens are obligate biotrophs and cannot be grown in agar culture. In this study, the RFLP-method using PCR-amplified gene fragments encoding the fungicide targets cytochrome b (cytb) and cellulose synthase 3 (CesA3) has been developed for detecting potential QoI and CAA resistance in P. destructor and B. lactucae, as this is likely to develop in the future. This method will make it possible to diagnose resistance prior to efficacy reduction of fungicides contributing to sustainable disease control.

分别由Peronospora destructor和Bremia lactucae引起的洋葱和生菜的霜霉病在世界范围内分布。这些严重疾病的控制在很大程度上依赖于卵菌类杀菌剂，包括醌外抑制剂 (QoIs) 和羧酸酰胺 (CAAs)，这两种杀菌剂都存在病原体产生耐药性的风险。迄今为止，尚未在洋葱和生菜霜霉病的田间分离株中证实对 QoI 和 CAA 杀菌剂的抗性，并且使用生物学方法进行监测具有挑战性，因为这两种病原体都是专性生物营养菌，不能在琼脂培养物中生长。在这项研究中，使用 PCR 扩增基因片段的 RFLP 方法编码杀真菌剂靶向细胞色素 b ( cytb ) 和纤维素合酶 3 ( CesA3) 已开发用于检测P. destructor和B. lactucae中潜在的 QoI 和 CAA 抗性，因为这可能会在未来发展。这种方法可以在有助于可持续疾病控制的杀菌剂功效降低之前诊断耐药性。