A nitrogen-responsive gene affects virulence in Fusarium graminearum

Emerging models indicate that nitrogen availability is an important environmental cue for the induction of virulence in pathogenic fungi. This study explored gene expression patterns of the nitrogen-responsive gene FGSG_03881 and its role in virulence and toxin production in Fusarium graminearum. Using transcriptional fusion pFGSG_03881::GFP, we showed that FGSG_03881 exhibits differential expression profiles in 22 different nitrogen compounds. Since the growth patterns of the fungus also change under these conditions, a mathematical equation was derived to normalize the growth with the expression of FGSG_03881. We determined that expression of FGSG_03881 increased in the non-preferred sources of nitrogen, and decreased in the preferred nitrogen sources like glutamine. Additionally, we determined that this gene is neither linked to the biosynthesis of the mycotoxin DON nor regulated by the global regulator Tri6. Disruption of FGSG_03881 also resulted in increased infection and disease symptoms on wheat. Cumulatively, we suggest that FGSG_03881 is responsive to nitrogen availability and affects virulence in F. graminearum.