Monitoring of Benzimidazole Resistance in Botrytis cinerea Isolates from Strawberry in Korea and Development of Detection Method for Benzimidazole Resistance

Abstract

<i>Botrytis cinerea</i> is a major fungal plant pathogen that causes gray mold disease in strawberries, leading to a decrease in strawberry yield. While benzimidazole is widely used as a fungicide for controlling this disease, the increasing prevalence of resistant populations to this fungicide undermines its effectiveness. To investigate benzimidazole resistant <i>B. cinerea</i> in South Korea, 78 strains were isolated from strawberries grown in 78 different farms in 2022, and their EC<sub>50</subb> values for benzimidazole were examined. As a result, 64 strains exhibited resistance to benzimidazole, and experimental tests using detached strawberry leaves and the plants in a greenhouse confirmed the reduced efficacy of benzimidazole to control these strains. The benzimidazole resistant strains identified in this study possessed two types of mutations, E198A or E198V, in the <i>TUB2</i> gene. To detect these mutations, TaqMan probes were designed, enabling rapid identification of benzimidazole resistant <i>B. cinerea</i> in strawberry and tomato farms. This study utilizes TaqMan real-time polymerase chain reaction analysis to swiftly identify benzimidazole resistant <i>B. cinerea</i>, thereby offering the possibility of effective disease management by identifying optimum locations and time of application.