Resistance risk and mechanism of prochloraz in Fusarium solani.

Peanut root rot (PRR) is caused by Fusarium solani, which severely affects the yield and quality of peanuts. Prochloraz is a triazole-based demethylation inhibitor (DMIs) fungicide with antifungal activity against Fusarium spp. However, the resistance risk and resistance mechanisms of F. solani to prochloraz remain poorly understood. In the current study, the EC values of 98 F. solani isolates to prochloraz ranged from 0.029 to 0.40 μg/mL, with a mean of 0.14 ± 0.07 μg/mL, and the sensitivity exhibited a unimodal distribution. Seven prochloraz-resistant (ProR) mutants were obtained through fungicide adaptation, and the resistance factor (RF) ranged from 5.81 to 83.33. The mutants demonstrated reduced fitness in mycelial dry weight and asexual reproduction. No cross-resistance was observed between prochloraz and other fungicides, including tebuconazole, pyraclostrobin, and fluazinam. Overexpression of FsCYP51A, FsCYP51B, FsMFS1, and FsMFS2 genes was detected in the resistant mutants. These results demonstrate that the risk of F. solani developing resistance to prochloraz is relatively low, and the overexpression of FsCYP51 and FsMFS may contribute to prochloraz resistance in F. solani. This study provides essential data for the resistance monitoring and resistance management strategies for prochloraz.