Fusarium graminearum is a plant filamentous pathogenic fungi and the predominant causal agent of Fusarium head blight (FHB) in cereals worldwide. The regulators of the secretory pathway contribute significantly to fungal mycotoxin synthesis, development, and virulence. However, their roles in these processes in F. graminearum remain poorly understood. Here, we identified and functionally characterized the endoplasmic reticulum (ER) cargo receptor FgErv14 in F. graminearum. Firstly, it was observed that FgErv14 is mainly localized in the ER. Then, we constructed the FgErv14 deletion mutant (ΔFgerv14) and found that the absence of the FgErv14 caused a serious reduction in vegetative growth, significant defects in asexual and sexual reproduction, and severely impaired virulence. Furthermore, we found that the ΔFgerv14 mutant exhibited a reduced expression of TRI genes and defective toxisome generation, both of which are critical for deoxynivalenol (DON) biosynthesis. Importantly, we found the green fluorescent protein (GFP)-tagged FgRud3 was dispersed in the cytoplasm, whereas GFP-FgSnc1-PEM was partially trapped in the late Golgi in ΔFgerv14 mutant. These results demonstrate that FgErv14 mediates anterograde ER-to-Golgi transport as well as late secretory Golgi-to-Plasma membrane transport and is necessary for DON biosynthesis, asexual and sexual reproduction, vegetative growth, and pathogenicity in F. graminearum.

Vesicular trafficking is a conserved material transport process in eukaryotic cells. The GGA family proteins are clathrin adaptors that are involved in eukaryotic vesicle transport, but their functions in phytopathogenic filamentous fungi remain unexplored. Here, we examined the only GGA family protein in Fusarium graminearum, FgGga1, which localizes to both the late Golgi and endosomes. In the absence of FgGga1, the fungal mutant exhibited defects in vegetative growth, DON biosynthesis, ascospore discharge and virulence. Fluorescence microscopy analysis revealed that FgGga1 is associated with trans-Golgi network (TGN)-to-plasma membrane, endosome-to-TGN and endosome-to-vacuole transport. Mutational analysis on the five domains of FgGga1 showed that the VHS domain was required for endosome-to-TGN transport while the GAT and the hinge domains were required for both endosome-to-TGN and endosome-to-vacuole transport. Importantly, the deletion of the FgGga1 domains that are required in vesicular trafficking also inhibited vegetative growth and virulence of F. graminearum. In addition, FgGga1 interacted with the ascospore discharge regulator Ca 2+ ATPase FgNeo1, whose transport to the vacuole is dependent on FgGga1-mediated endosome-to-vacuole transport. Our results suggest that FgGga1 is required for fungal development and virulence via FgGga1-mediated vesicular trafficking, and FgGga1-mediated endosome-to-vacuole transport facilitates ascospore discharge in F. graminearum.