Polarisome core component FgPea2 regulates FgBoi2-mediated polarized growth, pathogenicity and environmental stress in Fusarium graminearum

Fusarium graminearum is a devastating plant pathogenic fungus that is the predominant causal agent of Fusarium head blight. Our previous study showed that the polarisome core component FgPea2 regulates polarized growth, deoxynivalenol (DON) production and virulence of F. graminearum. To further investigate the regulatory network of FgPea2, FgPea2-GFP pull down was performed and the anillin-related protein FgBoi2 was identified. FgBoi2 interacts with FgPea2 and exhibits partial co-localization at the hyphal tips of F. graminearum. Interestingly, FgPea2 regulates the polarized localization of FgBoi2-GFP, suggesting that FgPea2 functions upstream of FgBoi2. Furthermore, deletion of FgBOI2 resulted in a significant reduction in vegetative growth, conidiation, DON production and pathogenicity, as well as increased hyphal branching in F. graminearum. Structural analysis revealed that FgBoi2 contains SH3, SAM and PH domains. Further domain deletion experiments showed that the PH domain is crucial for vegetative growth, hyphae branching and polarized localization of FgBoi2. In addition, FgBoi2 negatively regulates the cell wall integrity and oxidative stress response pathways. FgPea2 and FgBoi2 modulate susceptibility to the fungicides tebuconazole, carbendazim, phenamacril and difenoconazole. In conclusion, this study shows that FgPea2 interacts with FgBoi2 and regulates FgBoi2-mediated polarized growth, stress tolerance, pathogenicity and fungicide resistance in F. graminearum.