Two types of amino acid substitutions in the succinate dehydrogenase complex subunit confer resistance to benzovindiflupyr in Colletotrichum sublineola.

Background: Colletotrichum sublineola is the pathogenic fungus that causes sorghum anthracnose, which seriously threatens sorghum yield. Benzovindiflupyr is a succinate dehydrogenase inhibitor with good control effects on various crop diseases. However, the control of sorghum anthracnose by benzovindiflupyr and the risk of resistance to benzovindiflupyr in this pathogen are not well studied. Therefore, this study aimed to evaluate the benzovindiflupyr resistance and underlying mechanisms in C. sublineola.

Results: Analysis of the sensitivity of 126 C. sublineola strains to benzovindiflupyr revealed that the average EC₅₀ of the fungicide was 0.0503 ± 0.0189 μg mL^-1, with a unimodal normal distribution curve. The survival fitness of 10 benzovindiflupyr-resistant strains decreased to varying degrees compared with that of the wild-type parental strains. Additionally, a significant positive cross-resistance was observed between benzovindiflupyr and carboxin. Sequencing analyses identified two mutation sites, CsSdhB^H249Y and CsSdhC^G81V, in the resistant strains. Further molecular docking and site-directed mutagenesis experiments confirmed that the CsSdhB^H249Y and CsSdhC^G81V substitutions conferred resistance to benzovindiflupyr in C. sublineola.

Conclusion: Colletotrichum sublineola is sensitive to benzovindiflupyr and shows a moderate resistance risk to benzovindiflupyr. Two specific point substitutions, CsSdhB^H249Y and CsSdhC^G81V, are responsible for the resistance of C. sublineola to benzovindiflupyr. These findings offer a theoretical foundation for strategic application of the fungicide in controlling sorghum anthracnose, and for potentially delaying the emergence and progression of resistance. © 2024 Society of Chemical Industry.