Involvement of FfP450s in the development and pathogenicity of Fusarium fujikuroi and the bio‐control potential

BACKGROUND: Rice bakanae disease (RBD) is a seed-borne disease known for its excessive elongation of rice seedlings due to high gibberellic acid (GA) production by the causal pathogen, Fusarium fujikuroi. At present, fungicide seed treatment is the main control strategy against RBD, but F. fujikuroi has developed resistance to almost all fungicides applied in practice, namely carbendazim, prochloraz, and phenamacril. In this study, we constructed deletion mutants of four FfP450 genes involved in GA biosynthesis in F. fujikuroi, determined the role of FfP450s in growth, development, and pathogenicity of F. fujikuroi, and investigated the bio-control potential of these deletion mutants in RBD management. RESULTS: None of the four FfP450 genes were involved in mycelial growth or adaptation to environmental stress. However, a higher sporulation and germination but significantly decreased gibberellin A3 production were observed in the mutants. In addition, excessive rice seedling elongation was not triggered by the mutants. In co-inoculation experiments, the FfP450-2 and FfP450-4 deletion mutants were more competitive than wild-type F. fujikuroi. Treatment with these deletion mutants resulted in good protective efficacy against RBD. CONCLUSION: The FfP450 genes were involved in the development, GA production, and pathogenicity of F. fujikuroi. ∆P450-2 and ∆P450-4 showed meaningful bio-control potential against RBD. © 2026 Society of Chemical Industry.