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Variation in type A trichothecene production and trichothecene biosynthetic genes in Fusarium goolgardi from natural ecosystems of Australia.

Rocha LO, Laurence MH, Proctor RH, McCormick SP, Summerell BA, Liew EC - Toxins (Basel) (2015)

Bottom Line: Other isolates (50%) produced only DAS (DAS chemotype).However, the relationships of F. goolgardi to the other species varied depending on whether phylogenies were inferred from RPB1 and RPB2, the 12-gene TRI cluster, the two-gene TRI1-TRI16 locus, or the single-gene TRI101 locus.Sequence analysis indicated that TRI1 and TRI16 are functional in F. goolgardi isolates with the DAS-NEO-T2 chemotype, but non-functional in isolates with DAS chemotype due to the presence of premature stop codons caused by a point mutation.

View Article: PubMed Central - PubMed

Affiliation: The Royal Botanic Gardens and Domain Trust, Mrs Macquaries Rd, Sydney, NSW 2000, Australia. lilianarocha@usp.br.

ABSTRACT
Fusarium goolgardi, isolated from the grass tree Xanthorrhoea glauca in natural ecosystems of Australia, is closely related to fusaria that produce a subgroup of trichothecene (type A) mycotoxins that lack a carbonyl group at carbon atom 8 (C-8). Mass spectrometric analysis revealed that F. goolgardi isolates produce type A trichothecenes, but exhibited one of two chemotypes. Some isolates (50%) produced multiple type A trichothecenes, including 4,15-diacetoxyscirpenol (DAS), neosolaniol (NEO), 8-acetylneosolaniol (Ac-NEO) and T-2 toxin (DAS-NEO-T2 chemotype). Other isolates (50%) produced only DAS (DAS chemotype). In the phylogenies inferred from DNA sequences of genes encoding the RNA polymerase II largest (RPB1) and second largest (RPB2) subunits as well as the trichothecene biosynthetic genes (TRI), F. goolgardi isolates were resolved as a monophyletic clade, distinct from other type A trichothecene-producing species. However, the relationships of F. goolgardi to the other species varied depending on whether phylogenies were inferred from RPB1 and RPB2, the 12-gene TRI cluster, the two-gene TRI1-TRI16 locus, or the single-gene TRI101 locus. Phylogenies based on different TRI loci resolved isolates with different chemotypes into distinct clades, even though only the TRI1-TRI16 locus is responsible for structural variation at C-8. Sequence analysis indicated that TRI1 and TRI16 are functional in F. goolgardi isolates with the DAS-NEO-T2 chemotype, but non-functional in isolates with DAS chemotype due to the presence of premature stop codons caused by a point mutation.

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Alignment of the nucleotides and the predicted amino acid sequences of TRI1 and TRI16 for F. goolgardi. (a) Alignment of the nucleotide and the predicted amino acid sequences of TRI1 from F. goolgardi DAS-NEO-T2 and DAS lineages and F. sporotrichioides NRRL 29978; (b) Alignment of the nucleotide and the predicted amino acid sequences of TRI16 from F. goolgardi DAS-NEO-T2 and DAS lineages and F. sporotrichioides NRRL 3299.
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toxins-07-04577-f002: Alignment of the nucleotides and the predicted amino acid sequences of TRI1 and TRI16 for F. goolgardi. (a) Alignment of the nucleotide and the predicted amino acid sequences of TRI1 from F. goolgardi DAS-NEO-T2 and DAS lineages and F. sporotrichioides NRRL 29978; (b) Alignment of the nucleotide and the predicted amino acid sequences of TRI16 from F. goolgardi DAS-NEO-T2 and DAS lineages and F. sporotrichioides NRRL 3299.

Mentions: Nucleotide sequence data generated in this study for selected TRI genes from F. goolgardi were aligned against reference sequences from F. sporotrichioides strains NRRL 3299 and NRRL 29978. No major differences were observed in the coding region sequences of the two species for the cluster genes TRI3, TRI4, TRI5, TRI7, TRI8, TRI11, and TRI13 or for TRI101. However, sequences of TRI1, and TRI16 in F. goolgardi isolates with the DAS chemotype exhibited significant differences from the F. sporotrichioides sequences. These isolates exhibited a C-to-T transition that resulted in a premature stop codon (nonsense mutation) in the fourth exon at position 1045 of the TRI1 coding region (Figure 2). The TRI16 coding region of DAS-chemotype isolates exhibited a single-nucleotide deletion at position 174, which caused a frame shift mutation and introduced premature stop codons at positions 320–322 and 383–385 of this gene (Figure 2). TRI1 and TRI16 orthologs from the other Fusarium species examined, including the F. goolgardi DAS-NEO-T2 strains, did not exhibit these or any other nonsense or frame shift mutations.


Variation in type A trichothecene production and trichothecene biosynthetic genes in Fusarium goolgardi from natural ecosystems of Australia.

Rocha LO, Laurence MH, Proctor RH, McCormick SP, Summerell BA, Liew EC - Toxins (Basel) (2015)

Alignment of the nucleotides and the predicted amino acid sequences of TRI1 and TRI16 for F. goolgardi. (a) Alignment of the nucleotide and the predicted amino acid sequences of TRI1 from F. goolgardi DAS-NEO-T2 and DAS lineages and F. sporotrichioides NRRL 29978; (b) Alignment of the nucleotide and the predicted amino acid sequences of TRI16 from F. goolgardi DAS-NEO-T2 and DAS lineages and F. sporotrichioides NRRL 3299.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663521&req=5

toxins-07-04577-f002: Alignment of the nucleotides and the predicted amino acid sequences of TRI1 and TRI16 for F. goolgardi. (a) Alignment of the nucleotide and the predicted amino acid sequences of TRI1 from F. goolgardi DAS-NEO-T2 and DAS lineages and F. sporotrichioides NRRL 29978; (b) Alignment of the nucleotide and the predicted amino acid sequences of TRI16 from F. goolgardi DAS-NEO-T2 and DAS lineages and F. sporotrichioides NRRL 3299.
Mentions: Nucleotide sequence data generated in this study for selected TRI genes from F. goolgardi were aligned against reference sequences from F. sporotrichioides strains NRRL 3299 and NRRL 29978. No major differences were observed in the coding region sequences of the two species for the cluster genes TRI3, TRI4, TRI5, TRI7, TRI8, TRI11, and TRI13 or for TRI101. However, sequences of TRI1, and TRI16 in F. goolgardi isolates with the DAS chemotype exhibited significant differences from the F. sporotrichioides sequences. These isolates exhibited a C-to-T transition that resulted in a premature stop codon (nonsense mutation) in the fourth exon at position 1045 of the TRI1 coding region (Figure 2). The TRI16 coding region of DAS-chemotype isolates exhibited a single-nucleotide deletion at position 174, which caused a frame shift mutation and introduced premature stop codons at positions 320–322 and 383–385 of this gene (Figure 2). TRI1 and TRI16 orthologs from the other Fusarium species examined, including the F. goolgardi DAS-NEO-T2 strains, did not exhibit these or any other nonsense or frame shift mutations.

Bottom Line: Other isolates (50%) produced only DAS (DAS chemotype).However, the relationships of F. goolgardi to the other species varied depending on whether phylogenies were inferred from RPB1 and RPB2, the 12-gene TRI cluster, the two-gene TRI1-TRI16 locus, or the single-gene TRI101 locus.Sequence analysis indicated that TRI1 and TRI16 are functional in F. goolgardi isolates with the DAS-NEO-T2 chemotype, but non-functional in isolates with DAS chemotype due to the presence of premature stop codons caused by a point mutation.

View Article: PubMed Central - PubMed

Affiliation: The Royal Botanic Gardens and Domain Trust, Mrs Macquaries Rd, Sydney, NSW 2000, Australia. lilianarocha@usp.br.

ABSTRACT
Fusarium goolgardi, isolated from the grass tree Xanthorrhoea glauca in natural ecosystems of Australia, is closely related to fusaria that produce a subgroup of trichothecene (type A) mycotoxins that lack a carbonyl group at carbon atom 8 (C-8). Mass spectrometric analysis revealed that F. goolgardi isolates produce type A trichothecenes, but exhibited one of two chemotypes. Some isolates (50%) produced multiple type A trichothecenes, including 4,15-diacetoxyscirpenol (DAS), neosolaniol (NEO), 8-acetylneosolaniol (Ac-NEO) and T-2 toxin (DAS-NEO-T2 chemotype). Other isolates (50%) produced only DAS (DAS chemotype). In the phylogenies inferred from DNA sequences of genes encoding the RNA polymerase II largest (RPB1) and second largest (RPB2) subunits as well as the trichothecene biosynthetic genes (TRI), F. goolgardi isolates were resolved as a monophyletic clade, distinct from other type A trichothecene-producing species. However, the relationships of F. goolgardi to the other species varied depending on whether phylogenies were inferred from RPB1 and RPB2, the 12-gene TRI cluster, the two-gene TRI1-TRI16 locus, or the single-gene TRI101 locus. Phylogenies based on different TRI loci resolved isolates with different chemotypes into distinct clades, even though only the TRI1-TRI16 locus is responsible for structural variation at C-8. Sequence analysis indicated that TRI1 and TRI16 are functional in F. goolgardi isolates with the DAS-NEO-T2 chemotype, but non-functional in isolates with DAS chemotype due to the presence of premature stop codons caused by a point mutation.

Show MeSH
Related in: MedlinePlus