The G protein β subunit FGB1 regulates development and pathogenicity in Fusarium oxysporym

The cloning of fgb1, the gene encoding a heterotrimeric G protein beta subunit FGB1 in Fusarium oxysporum, was performed by standard PCR techniques to evaluate the role of G protein signaling in this fungus. The full-length open reading frame spanned 1,077 nucleotides and the deduced primary structure of the protein (359 amino acid residues) showed high identity with Gbeta subunits from other organisms. Disruption of fgb1 led to decreased intracellular cAMP levels, reduced pathogenicity, and alterations in physiological characteristics, including heat resistance, colony morphology, conidia formation and germination frequency. We previously showed that most of these alterations (except germination frequency) were also observed in the disruptants of fga1, the gene for Galpha subunit FGA1 in F. oxysporum. These results suggest that FGA1 and FGB1 have partially overlapping functions in the regulation of development and pathogenicity in F. oxysporum.