• The Plant Pathology Journal
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• v.24 no.1
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• pp.8-16
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• 2008

Aurofusarin is a polyketide pigment produced by some Fusarium species. The PKS12 and GIP1 genes, which encode a putative type I polyketide synthase (PKS) and a fungal laccase, respectively, are known to be required for aurofusarin biosynthesis in Gibberella zeae (anamorph: Fusarium graminearum). The ten additional genes, which are located within a 30 kb region of PKS12 and GIP1 and regulated by a putative transcription factor (GIP2), organize the aurofusarin biosynthetic cluster. To determine if they are essential for aurofusarin production in G. zeae, we have employed targeted gene deletion, complementation, and chemical analyses. GIP7, which encodes O-methyltransferase, is confirmed to be required for the conversion of norrubrofusarin to rubrofusarin, an intermediate of aurofusarin. GIP1-, GIP3-, and GIP8-deleted strains accumulated rubrofusarin, indicating those gene products are essential enzymes for the conversion of rubrofusarin to aurofusarin. Based on the phenotypic changes in the gene deletion strains examined, we propose a possible pathway for aurofusarin biosynthesis in G. zeae. Our results would provide important information for better understanding of naphthoquinone biosynthesis in other fdarnentous fungi as well as the aurofusarin biosynthesis in G. zeae.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.3
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• pp.434-440
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• 2004

The aim of this study was to evaluate effects of modified glucomannan ($Mycosorb^{TM}$) on the antioxidant profile of egg yolk and tissues of newly hatched quail after aurofusarin inclusion in the maternal diet. Fifty-four 45 day-old Japanese quail were divided into three groups and were fed a corn-soya diet balanced in all nutrients ad libitum. The diet of the experimental quail was supplemented with aurofusarin at the level of 26.4 mg/kg feed in the form of Fusarium graminearum culture enriched with aurofusarin or with aurofusarin plus $Mycosorb^{TM}$ at 1 g/kg feed. Eggs obtained after 8 weeks of feeding were analysed and incubated in standard conditions of $37.5^{\circ}C$/55% RH. Samples of quail tissues were collected from newly hatched quail. The main carotenoids, retinol, retinyl esters and malondialdehyde were analysed by HPLC-based methods. Inclusion of aurofusarin in the maternal diet was associated with decreased carotenoid and vitamin A concentrations in egg yolk and liver of newly-hatched quail. Furthermore, lipid peroxidation in quail tissues was enhanced. Inclusion of modified glucomannan ($Mycosorb^{TM}$) in the toxin-contaminated diet provided a significant protective effect against changes in antioxidant composition in the egg yolk and liver. It is suggested that a combination of mycotoxin adsorbents and natural antioxidants could be the next step in counteracting mycotoxins in animal feed.

• The Plant Pathology Journal
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• v.22 no.3
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• pp.215-221
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• 2006

Gibberella zeae (anamorph: Fusarium graminearum) is an important pathogen of cereal crops. This fungus produces a broad range of secondary metabolites, including polyketides such as aurofusarin (a red pigment) and zearalenone (an estrogenic mycotoxin), which are important mycological characteristics of this species. A screen of G. zeae insertional mutants, generated using a restriction enzyme-mediated integration (REMI) procedure, led to the isolation of a mutant (Z43R606) that produced neither aurofusarin nor zearalenone yet showed normal female fertility and virulence on host plants. Outcrossing analysis confirmed that both the albino and zearalenone-deficient mutations are linked to the insertional vector in Z43R606. Molecular characterization of Z43R606 revealed a deletion of at least 220 kb of the genome at the vector insertion site, including the gene clusters required for the biosynthesis of aurofusarin and zearalenone, respectively. A re-creation of the insertional event of Z43R606 in the wild-type strain demonstrated that the 220-kb deletion is responsible for the phenotypic changes in Z43R606 and that a large region of genomic DNA can be efficiently deleted in G. zeae by double homologous recombination. The results showed that 52 putative genes located in the deleted genomic region are not essential for phenotypes other than the production of both aurofusarin and zearalenone. This is the first report of the molecular characterization of a large genomic deletion in G. zeae mediated by the REMI procedure.

• Journal of Microbiology and Biotechnology
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• v.16 no.9
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• pp.1392-1398
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• 2006

We investigated a possible coordination between the biosyntheses of two polyketides in the cereal head blight fungus Gibberella zeae, zearalenone (ZEA) and aurofusarin (AUR), which are catalyzed by the polyketide synthases (PKS) PKS4/PKS13 and PKS12, respectively. To determine if the production of one polyketide influences that of the other, we used four different transgenic strains of G zeae; three were deficient for either ZEA or AUR or both, and one was an AUR-overproducing strain. The mycelia of both the wild-type and ${\Delta}PKS4$ strain deficient for ZEA produced AUR normally, whereas the mycelia of both the ${\Delta}PKS12$ and ${\Delta}PKS4::{\Delta}PKS12$ strain showed no AUR accumulation. All the examined deletion strains caused necrotic spots on the surface of com kernels and were found to produce the nonpolyketide mycotoxins trichothecenes to the same amount as the wild-type strain. In contrast, the AUR-deficient ${\Delta}PKS12$ strains produced greater quantities of ZEA and its derivatives than the wild-type progenitor on both a rice substrate and a liquid medium; the AUR-overproducing strain did not produce ZEA on either medium. Furthermore, the expression of both PKS4 and PKS13 was induced earlier in the ${\Delta}PKS12$ strains than in the wild-type strain, and there was no difference in the transcription of PKS12 between the two strains. Therefore, these results indicate that the ZEA biosynthetic pathway is negatively regulated by the accumulation of another polyketide (AUR) in G zeae.