Fusarium asiaticum FaSdhC2 Point Mutation A83V Confers Resistance to Pydiflumetofen and Development of a Rapid LAMP Detection Method

Fusarium head blight (FHB) caused by Fusarium graminearum species complex (FGSC) is a devastating disease worldwide. The new succinate dehydrogenase inhibitor pydiflumetofen is highly effective against FHB, but its growing use raises resistance concerns. In this study, we identified four resistant Fusarium asiaticum isolates from 4088 field isolates collected across eight provinces in China in 2025. Gene replacement tests confirmed that the single-point mutation A83V of FaSdhC2 confers resistance. Notably, the resistant isolates did not exhibit significant fitness costs related to pydiflumetofen-resistance in terms of mycelial growth, sporulation, pathogenicity, and stress tolerance. To facilitate field monitoring, we developed a loop-mediated isothermal amplification (LAMP) assay targeting the FaSdhC2A83V mutation. This method is easy to operate, provides visual results within 55 min of amplification and is 100-fold more sensitive than conventional PCR. In conclusion, the LAMP assay established in this study provides a practical tool for rapid on-site monitoring of fungicide resistance and can effectively guide the rational use of fungicides in the field.