Molecular Phylogenetic, Morphological, and Mycotoxin Data Support Reidentification of the Quorn Mycoprotein Fungus asFusarium venenatum

O’Donnell, Kerry; Cigelnik, Elizabeth; Casper, Howard H.

doi:10.1006/fgbi.1997.1018

Cited by 124 publications

(57 citation statements)

References 20 publications

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“…3) provides a robust initial hypothesis of phylogenetic relationships among these agronomically important fusaria as judged by high bootstrap values (100% for all seven lineages within the Fg clade) and decay indices. Furthermore, although not suggested by previous studies (15,18), the African endemic F. lunulosporum was resolved as sister to the Fg clade. The sister relationship of these taxa and the reconstruction by MACCLADE (21) suggest that the ancestral area of the latter clade may be in Africa rather than in South America.…”

Section: Discussioncontrasting

confidence: 69%

“…All strains were stored in liquid nitrogen vapor at Ϫ175°C in the Agricultural Research Service Culture Collection (National Center for Agricultural Utilization Research, Peoria, IL). Methods for culturing strains and DNA isolation have been described (9,15).…”

Section: Methodsmentioning

confidence: 99%

“…Strains were cultured on sterile rice grains as described (15). Mycotoxins were extracted from 1 g of ground culture material with 40 ml of acetonitrile:water (84:16, vol͞vol) for 1 h on a horizontal shaker.…”

Section: Methodsmentioning

confidence: 99%

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Gene genealogies reveal global phylogeographic structure and reproductive isolation among lineages of Fusarium graminearum , the fungus causing wheat scab

O’Donnell

Kistler

Tacke

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

759

580

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During the past decade, the plant disease called scab or Fusarium head blight of wheat and barley has reached epidemic proportions in North America and elsewhere in the world. Scab is an economically devastating plant disease, not only because it causes significant reduction in seed yields and quality, but also because infested seeds are often contaminated with trichothecene and estrogenic mycotoxins that pose a serious threat to animal health and food safety. To test whether the primary etiological agent of scab, the fungus Fusarium graminearum, is panmictic throughout its range, allelic genealogies were constructed from six single-copy nuclear genes from strains selected to represent the global genetic diversity of this pathogen. Excluding one hybrid strain, all six genealogies recovered the same seven biogeographically structured lineages, suggesting that they represent phylogenetically distinct species among which gene flow has been very limited during their evolutionary history. Parsimony analysis of the combined data set comprising 7,120 aligned nucleotide characters resolved most relationships among the seven lineages of the F. graminearum clade and related fusaria included in the study. Phylogenetic evidence is also presented for introgressive hybridization and intragenic recombination among lineages of the F. graminearum clade in nature.

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Section: Discussioncontrasting

confidence: 69%

Section: Methodsmentioning

confidence: 99%

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Gene genealogies reveal global phylogeographic structure and reproductive isolation among lineages of Fusarium graminearum , the fungus causing wheat scab

O’Donnell

Kistler

Tacke

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

759

580

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“…These two types of Fusarium strains (producers and nonproducers) can be distinguished on the basis of DNA polymorphism in the ␤-tubulin gene (43) as well as in the large ribosomal subunit or the internal transcribed spacer (21,37,43).…”

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confidence: 99%

Identification by PCR of Fusarium culmorum Strains Producing Large and Small Amounts of Deoxynivalenol

Bakan

Giraud-Delville

Pinson

et al. 2002

Appl Environ Microbiol

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Thirty deoxynivalenol-producing F. culmorum strains, isolated from wheat grains, were incubated in vitro and analyzed for trichothecene production. Seventeen strains produced more than 1 ppm of deoxynivalenol and acetyldeoxynivalenol and were considered high-deoxynivalenol-producing strains, whereas 13 F. culmorum strains produced less than 0.07 ppm of trichothecenes and were considered low-deoxynivalenol-producing strains. For all strains, a 550-base portion of the trichodiene synthase gene (tri5) was amplified and sequenced. According to the tri5 data, the F. culmorum strains tested clustered into two groups that correlated with in vitro deoxynivalenol production. For three high-producing and three low-producing F. culmorum strains, the tri5-tri6 intergenic region was then sequenced, which confirmed the two separate clusters within the F. culmorum strains. According to the tri5-tri6 sequence data, specific PCR primers were designed to allow differentiation of high-producing from low-producing F. culmorum strains.Trichothecenes, including deoxynivalenol, acetyldeoxynivalenol, nivalenol, and fusarenone X, are sesquiterpene toxins produced by Fusarium species, including Fusarium culmorum, which are common fungal contaminants of cereals. Trichothecenes can be found naturally worldwide on cereals (1,9,18,27,38,45,48,54,55,59), and the consumption of these toxins is a potential problem for humans and farm animals (14, 47).It has been established that some Fusarium species, including F. graminearum and F culmorum, are able to produce B trichothecenes, such as deoxynivalenol and acetyldeoxynivalenol, while other species are not (31). These two types of Fusarium strains (producers and nonproducers) can be distinguished on the basis of DNA polymorphism in the ␤-tubulin gene (43) as well as in the large ribosomal subunit or the internal transcribed spacer (21,37,43).According to their trichothecene production, some Fusarium species, such as F graminearum, have been divided into two chemotypes: (i) the nivalenol chemotype, which includes isolates producing nivalenol and fusarenone X, and (ii) the deoxynivalenol chemotype, which includes isolates producing deoxynivalenol and acetyldeoxynivalenol (26,53). Similar observations have been made for F. culmorum strains (28, 39).In addition, it has been demonstrated that, within the same species and in the same culture conditions, toxin production by Fusarium strain may vary sharply; some strains produce large amounts of trichothecenes, whereas others produce small or undetectable amounts of trichothecenes (3,5,19,28,30,35,36,39,53,57). Until now, no method except in vitro culture has been available to distinguish high-producing from low-producing Fusarium strains.Several genes involved in the biosynthesis of trichothecenes have been described, most of them localized in a gene cluster. The tri5 gene encodes the trichodiene synthase, which catalyzes the first step in the biosynthesis of trichothecenes. The nucleotide sequence of the tri5 gene has been characterized in several Fusa...

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“…In filamentous fungi, mutations which confer selective advantages frequently have pleiotropic effects which cause a change in morphology (Forss et al, 1974;Withers et al, 1994). For example, when grown at a high dilution rate in glucose-limited chemostat culture, highly branched mutants of Fusarium venenatum A3/5 (formerly called F. graminearum A3/5;O'Donnell et al, 1998;Yoder and Christianson, 1998) come to dominate the culture, although it is not the changed morphology of these mutants which is responsible for their selective advantage .…”

Section: Introductionmentioning

confidence: 98%

Evolution of a recombinant (gucoamylase‐producing) strain of Fusarium venenatum A3/5 in chemostat culture

Wiebe

Robson

Shuster

et al. 2001

Biotech & Bioengineering

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Fusarium venenatum JeRS 325 is a transformant of strain A3/5 which produces Aspergillus niger glucoamylase (GAM) under the control of a Fusarium oxysporum trypsin-like protease promoter. The evolution of JeRS 325 was studied in glucose-limited chemostat cultures grown on NaNO3 or (NH4)2SO4 as the nitrogen source. Thirteen mutants which were more highly branched and four mutants which were more sparsely branched than the parental strain were isolated from the NaNO3 chemostat. The highly branched mutants detected in this chemostat did not displace the sparsely branched population. The mutants isolated from the NaNO3 chemostat complemented representative strains previously isolated from glucose-limited chemostat cultures of F. venenatum A3/5 grown on (NH4)2SO4, but showed little complementation between themselves. By contrast, a highly branched mutant isolated from the (NH4)2SO4 chemostat culture displaced the sparsely branched mycelial population. None of the mutants isolated from the NaNO3 or (NH4)2SO4 chemostats produced as much GAM as JeRS 325. Southern blot analysis showed that all except one mutant had lost copies of both the glucoamylase and the acetamidase (the selectable marker) genes. However, specific GAM production was not necessarily correlated with the extent of glaA gene loss observed. Further, 10 of the mutants had lost the ability to grow on acetamide as the sole nitrogen source, although they retained copies of the amdS gene. In competition studies, mutants which could not utilize acetamide displaced mutants which could. The presence of foreign DNA in JeRS 325 resulted in a reduced specific growth rate (compared to A3/5), but the presence of the foreign DNA did not prevent the evolution of the strain or the isolation of mutants which had improved growth rates.

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Molecular Phylogenetic, Morphological, and Mycotoxin Data Support Reidentification of the Quorn Mycoprotein Fungus asFusarium venenatum

Cited by 124 publications

References 20 publications

Gene genealogies reveal global phylogeographic structure and reproductive isolation among lineages of Fusarium graminearum , the fungus causing wheat scab

Gene genealogies reveal global phylogeographic structure and reproductive isolation among lineages of Fusarium graminearum , the fungus causing wheat scab

Identification by PCR of Fusarium culmorum Strains Producing Large and Small Amounts of Deoxynivalenol

Evolution of a recombinant (gucoamylase‐producing) strain of Fusarium venenatum A3/5 in chemostat culture

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