title: HXK1 regulates carbon catabolism, sporulation, fumonisin B₁ production and pathogenesis in Fusarium verticillioides.
abstract: In Fusarium verticillioides, a ubiquitous pathogen of maize, virulence and mycotoxigenesis are regulated in response to the types and amounts of carbohydrates present in maize kernels. In this study, we investigated the role of a putative hexokinase-encoding gene (HXK1) in growth, development and pathogenesis. A deletion mutant (Δhxk1) of HXK1 was not able to grow when supplied with fructose as the sole carbon source, and growth was impaired when glucose, sucrose or maltotriose was provided. Additionally, the Δhxk1 mutant produced unusual swollen hyphae when provided with fructose, but not glucose, as the sole carbon source. Moreover, the Δhxk1 mutant was impaired in fructose uptake, although glucose uptake was unaffected. On maize kernels, the Δhxk1 mutant was substantially less virulent than the wild-type, but virulence on maize stalks was not impaired, possibly indicating a metabolic response to tissue-specific differences in plant carbohydrate content. Finally, disruption of HXK1 had a pronounced effect on fungal metabolites produced during colonization of maize kernels; the Δhxk1 mutant produced approximately 50 % less trehalose and 80 % less fumonisin B₁ (FB₁) than the wild-type. The reduction in trehalose biosynthesis likely explains observations of increased sensitivity to osmotic stress in the Δhxk1 mutant. In summary, this study links early events in carbohydrate sensing and glycolysis to virulence and secondary metabolism in F. verticillioides, and thus provides a new foothold from which the genetic regulatory networks that underlie pathogenesis and mycotoxigenesis can be unravelled and defined.
authors: Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907, USA.|Department of Plant Pathology, University of Arkansas, Fayetteville, AR 72701, USA.
authors: Hun
authors: H
authors: Kim
authors: Department of Plant Pathology, University of Arkansas, Fayetteville, AR 72701, USA.
authors: Jonathon E
authors: JE
authors: Smith
authors: Department of Plant Pathology, University of Arkansas, Fayetteville, AR 72701, USA.
authors: John B
authors: JB
authors: Ridenour
authors: Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907, USA.
authors: Charles P
authors: CP
authors: Woloshuk
authors: Department of Plant Pathology, University of Arkansas, Fayetteville, AR 72701, USA.
authors: Burton H
authors: BH
authors: Bluhm
mesh_terms: D002244:Carbon / Q000378:metabolism*; D005632:Fructose / Q000378:metabolism; D037341:Fumonisins / Q000378:metabolism*; D005670:Fusarium / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity*; D017353:Gene Deletion; D023061:Gene Order; D018390:Gene Targeting; D006593:Hexokinase / Q000235:genetics / Q000378:metabolism*; D025301:Hyphae; D009997:Osmotic Pressure; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology; D013172:Spores, Fungal / Q000378:metabolism*; D014774:Virulence / Q000235:genetics; D003313:Zea mays / Q000382:microbiology
chemical_list: D037341:Fumonisins; D005632:Fructose; C056933:fumonisin B1; D002244:Carbon; D006593:Hexokinase