FvatfA regulates growth, stress tolerance as well as mycotoxin and pigment productions in Fusarium verticillioides

FvatfAfrom the maize pathogenFusarium verticillioidesputatively encodes theAspergillus nidulansAtfA andSchizasaccharomyces pombeAtf1 orthologous bZIP-type transcription factor, FvAtfA. In this study, a Delta FvatfAdeletion mutant was constructed and then genetically complemented with the fully functionalFvatfAgene. Comparing phenotypic features of the wild-type parental, the deletion mutant and the restored strains shed light on the versatile regulatory functions played by FvAtfA in (i) the maintenance of vegetative growth on Czapek-Dox and Potato Dextrose agars and invasive growth on unwounded tomato fruits, (ii) the preservation of conidiospore yield and size, (iii) the orchestration of oxidative (H2O2, menadione sodium bisulphite) and cell wall integrity (Congo Red) stress defences and (iv) the regulation of mycotoxin (fumonisins) and pigment (bikaverin, carotenoid) productions. Expression of selected biosynthetic genes both in the fumonisin (fum1,fum8) and the carotenoid (carRA,carB) pathways were down-regulated in the Delta FvatfAstrain resulting in defected fumonisin production and considerably decreased carotenoid yields. The expression ofbik1, encoding the polyketide synthase needed in bikaverin biosynthesis, was not up-regulated by the deletion ofFvatfAmeanwhile the Delta FvatfAstrain produced approximately ten times more bikaverin than the wild-type or the genetically complemented strains. The abolishment of fumonisin production of the Delta FvatfAstrain may lead to the development of new-type, biology-based mycotoxin control strategies. The novel information gained on the regulation of pigment production by this fungus can be interesting for experts working on new,Fusarium-based biomass and pigment production technologies.