The importin FgPse1 is required for vegetative development, virulence and DON production by interacting with the nuclear polyadenylated RNA-binding protein FgNab2 in Fusarium graminearum.

Karyopherins are involved in transport through nuclear pore complexes. Karyopherins are required for nuclear import and export pathways by binding to their cargos. Polyadenylation of mRNA is required for various biological processes by regulating gene expression in eukaryotes. Until now, the association of karyopherin with mRNA polyadenylation has been less understood in plant pathogenic fungi. In our study, we focused on the biological functions of the karyopherin FgPse1 in Fusarium graminearum. The results showed that FgPse1 is involved in mycelial growth, asexual reproduction, virulence and DON production. Co-IP and BiFC showed that FgPse1 interacts with the nuclear polyadenylated RNA-binding protein FgNab2. Moreover, a fluorescence localization assay indicated that FgPse1 is required for the nuclear import of FgNab2. The nuclear import of FgNab2 regulates the expression of FgTri4, FgTri5 and FgTri6, which are essential for DON production. Thus, ΔFgPse1 and ΔFgNab2 showed consistent defects in DON production. In summary, our data indicated that FgPse1 is required for mycelial growth, virulence and DON production by interacting with FgNab2 in F. graminearum. These results contribute to improving our understanding of the functions of importins in phytopathogenic fungi.