The Impact Of FgβNAC Gene On The Growth And Development And Pathogenicity Of Fusarium Graminearum

Fusarium head blight (FHB) is a worldwide economically devastating disease of wheat, barley and other small grain cereals. During storage, the infected corn and wheat produce trichothecene mycotoxins and estrogenic compounds which are detrimental to human and animal health, posing serious threat to food safety. FHB of wheat is caused by a complex of Fusarium species. Fusarium graminearum (teleomorph Gibberella zeae) was the primary causal agent of FHB.In fission yeast(Schizosaccharomyces pombe) the NAC protein is a heterodimers which is composed of α and β subunits separately encoded by two genes. They play an important role in yeast growth and development and stress response process. Besides NAC protein complex functioning as a dimer, each individual subunit has its specific features. In this study, we found a homologous protein of fission yeast β subunits in the Fusarium graminearum genome database, which is FGSG08675.3and named it FgβNAC.Through the gene knockout technology, we obtained the deletion mutants of the FgβNAC gene in F. graminearum. Further, we obtained the complemented strain of Fgβnac. Comparing the wild-type strains, the deletion mutants and the complemented strains, the following results have been obtained:1. Determination of mycelial growth and colony morphologyThe deletion mutants fgβnac growth rate was significantly reduced than wild type PH-1in solid medium PDA, it was almost equal to half of the wild type’s growth rate, and aerial mycelium became denser than PH-1;The mycelium dry weight of knockout mutant strain was account for56%of the wild type in liquid PD medium cultured for three days.2. Conidial sporulation statistics and observation of the peritheciaConidia produced by the deletion mutants decreased by78.5%compared with the wild-type strain. It was not able to produce in the carrot agar solid medium.3. Pathogeni city TestThrough the wheat spikes inoculatioin, the fgβnac mutant was significantly reduced in virulence. They were limited to the inoculation site and could not invade the vascular tissue to cause ear blight symptoms.4. Producing DON toxin abilityHPLC analyzing of the DON toxin results showed that the DON toxin production of deletion mutants fgβnac was0.186ug/mL, it was decreased by67%compared with that of wild type strains PH-1.These results showed that FgβNAC gene play an important role in the mycelial growth, asexual and sexual development as well as virulence of Fusarium graminearum. The results of this study provide a basis for further studies on the pathogenicity mechanisms of Fusarium graminearum and also provide an important directional significance for the development of new type fungicides.