Biosynthetic and genetic relationships of B-series fumonisins produced byGibberella fujikuroi mating population A

Abstract

Fumonisins are mycotoxins produced by the maize pathogen Gibberella fujikuroi mating population A and frequently contaminate maize. Wild-type G. fujikuroi produces four B-series fumonisins, FB1, FB2, FR3 and FB4. These toxins are identical in structure except for the number and positions of hydroxyls along their linear carbon backbone. To elucidate the genetic and biosynthetic relationships among these fumonisins, we conducted meiotic and biochemical analyses of G. fujikuroi mutants with altered fumonisin production that resulted from defective alleles at three loci, Fum1, Fum2 and Fum3. These mutants produced either no fumonisins, only FR2 and FB4, or only FR3 and FR4. Genetic analyses revealed the orientation of the Fum loci along linkage group 1 of the fungus. The mutants were grown together in pair-wise combinations to determine if their fumonisin production phenotypes could be complemented. When FR3- and FB2-producing mutants were grown together, complementation occurred. However, when a nonproducing mutant was grown with a FR2- or FB3-producing mutant, complementation did not occur or was incomplete. When purified FR2, FR3, or FB4 was fed to mutant cultures, FR4 was converted primarily to FR2, FR3 was converted to FB1 and FB2 was not converted. The results from these assays suggest a previously unrecognized branch in the fumonisin biosynthetic pathway.

Loss of Gibberellin Production in Fusarium verticillioides ( Gibberella fujikuroi MP-A) Is Due to a Deletion in the Gibberellic Acid Gene Cluster

“…Differences in metabolic chemotypes were part of recent investigations to characterize different Fusarium strains of this species complex (27,33,47,52). F. verticillioides (G. fujikuroi MP-A) isolates from various areas and host plants produce large amounts of the mycotoxin fumonisin (7, 11, 12, 25).…”

Fumonisin Production in the Maize Pathogen Fusarium verticillioides: Genetic Basis of Naturally Occurring Chemical Variation

“…The nucleotide sequences of such fragments were determined to confirm that no errors were introduced during PCR. Sequencing reactions were done with the BigDye Terminator Cycle Sequencing (version 3.1, Applied Biosystems, Foster City, CA) a Fumonisin production phenotypes and genotypes were determined previously by LC-MS and meiotic analyses (13,21). Fum1-1 and Fum2-1 are functional alleles.…”

Lae1 regulates expression of multiple secondary metabolite gene clusters in Fusarium verticillioides

“…The fumonisin biosynthetic gene (FUM) cluster consists of 17 genes and is located on F. verticillioides chromosome 1 (Butchko et al, 2003Proctor et al, 1999aProctor et al, ,b, 2003Seo et al, 2001;Zaleta-Rivera et al, 2006). Fum21 is a fumonisin pathway-specific regulator; it is a Zn(II)2Cys6 zinc binuclear DNA binding protein and activates transcription of other FUM cluster genes .…”