Metabolic fingerprinting reveals a new genetic linkage between ambient pH and metabolites associated with desiccation tolerance in Fusarium verticillioides

Abstract

Fusarium verticillioides, a kernel-rotting pathogen of maize, produces fumonisin mycotoxins that are detrimental to both human and animal health. Current knowledge about the environmental regulation of fumonisin biosynthesis is centered on the influence of pH and carbohydrate availability. In this study, we report metabolic changes in F. verticillioides associated with conditions that are conducive (pH 3) or repressive (pH 8) for fumonisin biosynthesis, as well as changes associated with targeted disruption of PAC1, a pH-responsive transcription factor. To this end, metabolic fingerprints were generated from F. verticillioides with gas chromatography–mass spectrometry. A total of 46 metabolites were detected, of which approximately one third matched reference spectra of various carbohydrates and fatty acids. Analysis of wild type and Δpac1 fingerprints by principal component analysis revealed that the biosynthesis of arabitol, mannitol, and trehalose was significantly affected by pH and disruption of PAC1. Consistent with this finding, the expression of genes involved in trehalose biosynthesis was significantly reduced in the Δpac1 strain. This study is the first report linking PAC1 to polyol biosynthesis in F. verticillioides, and could indicate a broadly conserved function for PAC1 orthologs among filamentous fungi. Additionally, by presenting a metabolic fingerprinting technique for F. verticillioides, this study provides a new resource to understand pathogenesis and mycotoxigenesis through functional genomics.