Fusarium head blight (FHB) caused by the plant-pathogenic fungus Fusarium graminearum reduces wheat yields and produces the mycotoxins DON, ZEA, and NIV in the infected grain.The molecular mechanisms of pathogenicity, mycotoxin production, and fungicide resistance for this pathogen and disease are not well understood.To investigate these mechanisms, the two F.graminearum β-tubulin genes, β1tub and β2tub, were identified and functionally analyzed.Expression of both genes was studied by analysis of mRNA transcription and by observation of GFP-tagged fusion proteins.Both genes were expressed during life cycle of the fungus, though expression level was more stable for β1tub than for β2tub.Deletion of β2tub resulted in reduction of growth and reduced asexual and sexual development, while deletion of β1tub, which is a higher homolog of the Aspergillus nidulans β-tubulin gene benA, produced a mutant similar to the wild-type strain.Importantly, both β-tubulin genes affected pathogenicity.The results showed that β2tub is essential for F.graminearum.Although promoter swapping experiments indicated that β1tub was partially complementary to β2tub, simultaneous deletion of both β2tub and β1tub failed to produce viable mutants.