Mitosis and cytokinesis are essential cellular processes for cell division and proliferation in eukaryotic organisms.Many genes important for cell cycle have been well characterized in Saccharomyces cerevisiae and Schizosaccharomyces pombe, including CDC14 that encodes a member of the dual specificity phosphatase family highly selective for serine-proline phosphorylation sites generated by cyclin-dependent kinase.Interestingly, whereas CDC14 is an essential gene for regulating multiple events during anaphase such as mitotic exit in S.cerevisiae, its ortholog is not essential in S.pombe although it is important for coordinating nuclear division with cytokinesis.CDC14 orthologs are well conserved in filamentous fungi, but none of them have been functionally characterized.In this study, we aimed to determine the functions of CDC14 in growth, development, and pathogenesis in Fusarium graminearum, the causal agent of wheat and barley head blight.Deletion of FgCDC14 is not lethal in F.graminearum but the Fgcdc14 deletion mutant was significantly reduced in vegetative growth, conidiation, and ascospore formation.In self-cross assays, the Fgcdcl4 deletion mutants produced morphologically normal perithecia that contained aborted ascogenous tissues.In plant infection assays, the Fgcdc14 mutant was non-pathogenic.Mutant conidia had abnormal morphology, fewer septa, and more nuclei per compartment compared to the wild-type conidia.Septation in mutant hyphae also was reduced and irregular.Some conidium compartments contained multiple nuclei, indicating that the Fgcdcl4 mutant was defective in the coordination between nuclear division and cytokinesis.Interestingly, foot cells of macroconidia were able to exit G1-arrest and extend and function as conidiogenous cells in the Fgcdc14 mutant, resulting in the production of inter-connected conidia.Some conidia germinated when they were still on the phialides.The germination mainly happened on the foot cell of the conidia but also could be observed on the apical cell.In hyphae,FgCdc14-GFP localized to the nucleus and MTOC during interphase, in M phase it was released into cytoplasm promote mitotic exit and other cellular processes.These results indicate that FgCDC14 plays a role in cell division and septum formation in F.graminearum.