Fungal response to oxidative stress during infection on postharvest fruit is largely unknown. Here, we found that hydrogen peroxide (H2O2) treatment inhibited the growth of Fusarium proliferatum causing crown rot of banana fruit, confirmed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observation. H2O2 exposure increased endogenous reactive oxygen species (ROS) and fumonisin B1 (FB1) production in F. proliferatum, possibly by modulating FUM or ROS-related gene expression. Importantly, H2O2 treatment inhibited F. proliferatum growth in vivo but induced FB1 accumulation in banana peel. Finally, we constructed the FpFUM21 deletion mutant (ΔFpfum21) of F. proliferatum that was attenuated in FB1 biosynthesis and less tolerant to oxidative stress. Moreover, the ΔFpfum21 strain was less virulent compared to the wild type (WT) due to the inability to induce FB1 production in the banana host. These results suggested that FB1 biosynthesis is associated with oxidative stress in F. proliferatum and contributes to fungal infection on banana fruit.
