Characteristics of ZJS-178 resistant mutants of Fusarium pseudograminearum

Fusarium pseudograminearum is a major causal agent of Fusarium crown rot (FCR) in wheat worldwide. ZJS-178, a cyanoacrylate fungicide and phenamacril derivative, has shown strong inhibitory activity against Fusarium species. However, its resistance risk and underlying resistance mechanisms in F. pseudograminearum remain unexplored. In this study, three sensitive F. pseudograminearum isolates were subjected to fungicide adaptation in the laboratory, resulting in 35 ZJS-178 resistant mutants, 22 of which exhibited high-level resistance. Compared to their parental strains, resistant mutants displayed reduced fitness, including impaired mycelial growth, conidiation, conidial germination, deoxynivalenol production, and virulence. Cross-resistance analysis revealed a positive correlation between ZJS-178 and phenamacril, but no cross-resistance with fludioxonil, tebuconazole, carbendazim, or prochloraz. Sequence alignment and gene replacement assays identified 10 point-mutations in the FpMyoI gene (encoding myosin I) as the genetic basis for resistance. Molecular docking analysis further confirmed that these mutations interfere with fungicide binding. This study provides critical insights into the molecular basis of ZJS-178 resistance and offers valuable guidance for resistance monitoring and management strategies in FCR control.