Articles de revues : « Trichothecene »

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Boddu, Jayanand, Seungho Cho et Gary J. Muehlbauer. « Transcriptome Analysis of Trichothecene-Induced Gene Expression in Barley ». Molecular Plant-Microbe Interactions® 20, n^o 11 (novembre 2007) : 1364–75. http://dx.doi.org/10.1094/mpmi-20-11-1364.

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Fusarium head blight, caused primarily by Fusarium graminearum, is a major disease problem on barley (Hordeum vulgare L.). Trichothecene mycotoxins produced by the fungus during infection increase the aggressiveness of the fungus and promote infection in wheat (Triticum aestivum L.). Loss-of-function mutations in the TRI5 gene in F. graminearum result in the inability to synthesize trichothecenes and in reduced virulence on wheat. We examined the impact of pathogen-derived trichothecenes on virulence and the transcriptional differences in barley spikes infected with a trichothecene-producing wild-type strain and a loss-of-function tri5 trichothecene nonproducing mutant. Disease severity, fungal biomass, and floret necrosis and bleaching were reduced in spikes inoculated with the tri5 mutant strain compared with the wild-type strain, indicating that the inability to synthesize trichothecenes results in reduced virulence in barley. We detected 63 transcripts that were induced during trichothecene accumulation, including genes encoding putative trichothecene detoxification and transport proteins, ubiquitination-related proteins, programmed cell death-related proteins, transcription factors, and cytochrome P450s. We also detected 414 gene transcripts that were designated as basal defense response genes largely independent of trichothecene accumulation. Our results show that barley exhibits a specific response to trichothecene accumulation that can be separated from the basal defense response. We propose that barley responds to trichothecene accumulation by inducing at least two general responses. One response is the induction of genes encoding trichothecene detoxification and transport activities that may reduce the impact of trichothecenes. The other response is to induce genes encoding proteins associated with ubiquitination and cell death which may promote successful establishment of the disease.

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Nishiuchi, Takumi, Daisuke Masuda, Hideo Nakashita, Kazuya Ichimura, Kazuo Shinozaki, Shigeo Yoshida, Makoto Kimura, Isamu Yamaguchi et Kazuo Yamaguchi. « Fusarium Phytotoxin Trichothecenes Have an Elicitor-Like Activity in Arabidopsis thaliana, but the Activity Differed Significantly Among Their Molecular Species ». Molecular Plant-Microbe Interactions® 19, n^o 5 (mai 2006) : 512–20. http://dx.doi.org/10.1094/mpmi-19-0512.

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Phytopathogenic fungi such as Fusarium spp. synthesize trichothecene family phytotoxins. Although the type B trichothecene, deoxynivalenol (DON), is thought to be a virulence factor allowing infection of plants by their trichothecene-producing Fusarium spp., little is known about effects of trichothecenes on the defense response in host plants. Therefore, in this article, we investigated these effects of various trichothecenes in Fusarium-susceptible Arabidopsis thaliana. Necrotic lesions were observed in Arabidopsis leaves infiltrated by 1 μM type A trichothecenes such as T-2 toxin. Trichothecene-induced lesions exhibited dead cells, callose deposition, generation of hydrogen peroxide, and accumulation of salicylic acids. Moreover, infiltration by trichothecenes caused rapid and prolonged activation of two mitogen-activated protein kinases and induced expression of both PR-1 and PDF1.2 genes. Thus, type A trichothecenes trigger the cell death by activation of an elicitor-like signaling pathway in Arabidopsis. Although DON did not have such an activity even at 10 μM, translational inhibition by DON was observed at concentrations above 5 μM. These results suggested that DON is capable of inhibiting translation in Arabidopsis cells without induction of the elicitor-like signaling pathway.

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Polak-Śliwińska, Magdalena, et Beata Paszczyk. « Trichothecenes in Food and Feed, Relevance to Human and Animal Health and Methods of Detection : A Systematic Review ». Molecules 26, n^o 2 (16 janvier 2021) : 454. http://dx.doi.org/10.3390/molecules26020454.

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Trichothecene mycotoxins are sesquiterpenoid compounds primarily produced by fungi in taxonomical genera such as Fusarium, Myrothecium, Stachybotrys, Trichothecium, and others, under specific climatic conditions on a worldwide basis. Fusarium mold is a major plant pathogen and produces a number of trichothecene mycotoxins including deoxynivalenol (or vomitoxin), nivalenol, diacetoxyscirpenol, and T-2 toxin, HT-2 toxin. Monogastrics are sensitive to vomitoxin, while poultry and ruminants appear to be less sensitive to some trichothecenes through microbial metabolism of trichothecenes in the gastrointestinal tract. Trichothecene mycotoxins occur worldwide however both total concentrations and the particular mix of toxins present vary with environmental conditions. Proper agricultural practices such as avoiding late harvests, removing overwintered stubble from fields, and avoiding a corn/wheat rotation that favors Fusarium growth in residue can reduce trichothecene contamination of grains. Due to the vague nature of toxic effects attributed to low concentrations of trichothecenes, a solid link between low level exposure and a specific trichothecene is difficult to establish. Multiple factors, such as nutrition, management, and environmental conditions impact animal health and need to be evaluated with the knowledge of the mycotoxin and concentrations known to cause adverse health effects. Future research evaluating the impact of low-level exposure on livestock may clarify the potential impact on immunity. Trichothecenes are rapidly excreted from animals, and residues in edible tissues, milk, or eggs are likely negligible. In chronic exposures to trichothecenes, once the contaminated feed is removed and exposure stopped, animals generally have an excellent prognosis for recovery. This review shows the occurrence of trichothecenes in food and feed in 2011–2020 and their toxic effects and provides a summary of the discussions on the potential public health concerns specifically related to trichothecenes residues in foods associated with the exposure of farm animals to mycotoxin-contaminated feeds and impact to human health. Moreover, the article discusses the methods of their detection.

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Foroud, Nora A., Danica Baines, Tatiana Y. Gagkaeva, Nehal Thakor, Ana Badea, Barbara Steiner, Maria Bürstmayr et Hermann Bürstmayr. « Trichothecenes in Cereal Grains – An Update ». Toxins 11, n^o 11 (31 octobre 2019) : 634. http://dx.doi.org/10.3390/toxins11110634.

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Trichothecenes are sesquiterpenoid mycotoxins produced by fungi from the order Hypocreales, including members of the Fusarium genus that infect cereal grain crops. Different trichothecene-producing Fusarium species and strains have different trichothecene chemotypes belonging to the Type A and B class. These fungi cause a disease of small grain cereals, called Fusarium head blight, and their toxins contaminate host tissues. As potent inhibitors of eukaryotic protein synthesis, trichothecenes pose a health risk to human and animal consumers of infected cereal grains. In 2009, Foroud and Eudes published a review of trichothecenes in cereal grains for human consumption. As an update to this review, the work herein provides a comprehensive and multi-disciplinary review of the Fusarium trichothecenes covering topics in chemistry and biochemistry, pathogen biology, trichothecene toxicity, molecular mechanisms of resistance or detoxification, genetics of resistance and breeding strategies to reduce their contamination of wheat and barley.

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Bycroft, Barrie W., Nigel C. P. Baldwin, Paul M. Dewick, David C. Marsh et John Gilbert. « Trichothecene Mycotoxins from Fusarium culmorum Cultures ». Zeitschrift für Naturforschung C 42, n^o 9-10 (1 octobre 1987) : 1043–49. http://dx.doi.org/10.1515/znc-1987-9-1007.

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Chemical analysis of the culture filtrates of Fusarium culmorum CMI 14764 has demonstrated the presence of seven trichothecene mycotoxins. Major metabolites are 3-acetyldeoxynivalenol and 7α,8α-dihydroxycalonectrin. with 3,15-diacetyldeoxynivalenol, deoxynivalenol. calonectrin, isotrichodermin and 12,13-epoxytrichothec-9-ene (EPT) as minor products. The occurrence of the rarely encountered unsubstituted trichothecene EPT is significant in that this compound may function as a common intermediate in the biosynthetic pathways to all natural trichothecenes. The structures of the known trichothecenes isolated from F. culmorum suggest a route in which EPT is sequentially oxygenated to the more complex deoxynivalenol derivatives.

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Meek, Isaac B., Andrew W. Peplow, Charles Ake,, T. D. Phillips et Marian N. Beremand. « Tri1 Encodes the Cytochrome P450 Monooxygenase for C-8 Hydroxylation during Trichothecene Biosynthesis in Fusarium sporotrichioides and Resides Upstream of Another New Tri Gene ». Applied and Environmental Microbiology 69, n^o 3 (mars 2003) : 1607–13. http://dx.doi.org/10.1128/aem.69.3.1607-1613.2003.

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ABSTRACT Many Fusarium species produce one or more agriculturally important trichothecene mycotoxins, and the relative level of toxicity of these compounds is determined by the pattern of oxygenations and acetylations or esterifications on the core trichothecene structure. Previous studies with UV-induced Fusarium sporotrichioides NRRL 3299 trichothecene mutants defined the Tri1 gene and demonstrated that it was required for addition of the oxygen at the C-8 position during trichothecene biosynthesis. We have cloned and characterized the Tri1 gene from NRRL 3299 and found that it encodes a cytochrome P450 monooxygenase. The disruption of Tri1 blocks production of C-8-oxygenated trichothecenes and leads to the accumulation of 4,15-diacetoxyscirpenol, the same phenotype observed in the tri1 UV-induced mutants MB1716 and MB1370. The Tri1 disruptants and the tri1 UV-induced mutants do not complement one another when coinoculated, and the Tri1 gene sequence restores T-2 toxin production in both MB1716 and MB1370. The DNA sequence flanking Tri1 contains another new Tri gene. Thus, Tri1 encodes a C-8 hydroxylase and is located either in a new distal portion of the trichothecene gene cluster or in a second separate trichothecene gene cluster.

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SNYDER, A. PETER. « Qualitative, Quantitative and Technological Aspects of the Trichothecene Mycotoxins ». Journal of Food Protection 49, n^o 7 (1 juillet 1986) : 544–69. http://dx.doi.org/10.4315/0362-028x-49.7.544.

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Trichothecene mycotoxins pose a natural threat to plants, foodstuffs, animals and humans. Recently, strong implications regarding artificially induced trichothecene threats to humans in various parts of the world have come to the attention of the general public. This has spawned renewed interest and scientific research into the various properties of the toxins. The trichothecenes display orders of magnitude differences in toxicity levels depending upon the test subject and mode of administration. Potentially more sensitive and specific analytical characterization techniques and convenient, milder and faster organic decontamination reaction schemes exist in comparison to established methods. This review attempts to supply a concise information source as an aid to investigators faced with problems of trichothecene detection, analysis, and decontamination.

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Engler, Kathryn H., Raymond D. Coker et Ivor H. Evans. « A Colorimetric Technique for Detecting Trichothecenes and Assessing Relative Potencies ». Applied and Environmental Microbiology 65, n^o 5 (1 mai 1999) : 1854–57. http://dx.doi.org/10.1128/aem.65.5.1854-1857.1999.

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ABSTRACT We tested a novel colorimetric toxicity test, based on inhibition of β-galactosidase activity in the yeastKluyveromyces marxianus, for sensitivity to a range of mycotoxins. A variety of trichothecene mycotoxins could be detected. The order of toxicity established with this bioassay was verrucarin A > roridin A > T-2 toxin > diacetoxyscirpenol > HT-2 toxin > acetyl T-2 toxin > neosolaniol > fusarenon X > T-2 triol > scirpentriol > nivalenol > deoxynivalenol > T-2 tetraol. The sensitivity of detection was high, with the most potent trichothecene tested, verrucarin A, having a 50% effective concentration (concentration of toxin causing 50% inhibition) of 2 ng/ml. Other mycotoxins (cyclopiazonic acid, fumonisin B1, ochratoxin A, patulin, sterigmatocystin, tenuazonic acid, and zearalenone) could not be detected at up to 10 μg/ml, nor could aflatoxins B1 and M1 be detected at concentrations up to 25 μg/ml. This test should be useful for trichothecene detection and for studies of relevant interactions—both between trichothecenes themselves and between trichothecenes and other food constituents.

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Zhu, Muzi, Youfei Cen, Wei Ye, Saini Li et Weimin Zhang. « Recent Advances on Macrocyclic Trichothecenes, Their Bioactivities and Biosynthetic Pathway ». Toxins 12, n^o 6 (23 juin 2020) : 417. http://dx.doi.org/10.3390/toxins12060417.

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Macrocyclic trichothecenes are an important group of trichothecenes bearing a large ring. Despite the fact that many of trichothecenes are of concern in agriculture, food contamination, health care and building protection, the macrocyclic ones are becoming the research hotspot because of their diversity in structure and biologic activity. Several researchers have declared that macrocyclic trichothecenes have great potential to be developed as antitumor agents, due to the plenty of their compounds and bioactivities. In this review we summarize the newly discovered macrocyclic trichothecenes and their bioactivities over the last decade, as well as identifications of genes tri17 and tri18 involved in the trichothecene biosynthesis and putative biosynthetic pathway. According to the search results in database and phylogenetic trees generated in the review, the species of the genera Podostroma and Monosporascus would probably be great sources for producing macrocyclic trichothecenes. Moreover, we propose that the macrocyclic trichothecene roridin E could be formed via acylation or esterification of the long side chain linked with C-4 to the hydroxyl group at C-15, and vice versa. More assays and evidences are needed to support this hypothesis, which would promote the verification of the proposed pathway.

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Tanaka, Nozomu, Ryo Takushima, Akira Tanaka, Ayaki Okada, Kosuke Matsui, Kazuyuki Maeda, Shunichi Aikawa, Makoto Kimura et Naoko Takahashi-Ando. « Reduced Toxicity of Trichothecenes, Isotrichodermol, and Deoxynivalenol, by Transgenic Expression of the Tri101 3-O-Acetyltransferase Gene in Cultured Mammalian FM3A Cells ». Toxins 11, n^o 11 (10 novembre 2019) : 654. http://dx.doi.org/10.3390/toxins11110654.

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In trichothecene-producing fusaria, isotrichodermol (ITDol) is the first intermediate with a trichothecene skeleton. In the biosynthetic pathway of trichothecene, a 3-O-acetyltransferase, encoded by Tri101, acetylates ITDol to a less-toxic intermediate, isotrichodermin (ITD). Although trichothecene resistance has been conferred to microbes and plants transformed with Tri101, there are no reports of resistance in cultured mammalian cells. In this study, we found that a 3-O-acetyl group of trichothecenes is liable to hydrolysis by esterases in fetal bovine serum and FM3A cells. We transfected the cells with Tri101 under the control of the MMTV-LTR promoter and obtained a cell line G3 with the highest level of C-3 acetylase activity. While the wild-type FM3A cells hardly grew in the medium containing 0.40 μM ITDol, many G3 cells survived at this concentration. The IC50 values of ITDol and ITD in G3 cells were 1.0 and 9.6 μM, respectively, which were higher than the values of 0.23 and 3.0 μM in the wild-type FM3A cells. A similar, but more modest, tendency was observed in deoxynivalenol and 3-acetyldeoxynivalenol. Our findings indicate that the expression of Tri101 conferred trichothecene resistance in cultured mammalian cells.

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Harris, L. J., A. E. Desjardins, R. D. Plattner, P. Nicholson, G. Butler, J. C. Young, G. Weston, R. H. Proctor et T. M. Hohn. « Possible Role of Trichothecene Mycotoxins in Virulence of Fusarium graminearum on Maize ». Plant Disease 83, n^o 10 (octobre 1999) : 954–60. http://dx.doi.org/10.1094/pdis.1999.83.10.954.

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Trichothecene-producing and -nonproducing Fusarium graminearum strains were tested for their ability to cause Gibberella ear rot in field trials at two locations—Ottawa, Ontario, and Peoria, Illinois—in 1996. Maize ears were inoculated with wild-type or transgenic F. graminearum strains in which the trichothecene biosynthetic pathway had been disabled by the specific disruption of the trichodiene synthase gene and with a derivative revertant strain in which trichothecene production had been restored through recombination. A silk channel inoculation method was employed at both locations. In addition, a kernel puncture inoculation method was used at the Ontario location. Harvested maize ears were analyzed for visual disease severity, grain yield, deoxynivalenol (DON) concentration, and fungal biomass by quantitative polymerase chain reaction (PCR) and/or ergosterol quantitation. There was a significant correlation (r= 0.86) between data obtained from the two different methods of quantifying fungal biomass. The trichothecene-nonproducing strains were still pathogenic but appeared less virulent on maize than the trichothecene-producing progenitor and revertant strains, as assayed by most parameters. This suggests that the trichothecenes may act as virulence factors to enhance the spread of F. graminearum on maize.

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Weaver, M., R. Hoagland, C. Boyette et R. Zablotowicz. « Macrocyclic trichothecene production and sporulation by a biological control strain of Myrothecium verrucaria is regulated by cultural conditions ». World Mycotoxin Journal 2, n^o 1 (1 février 2009) : 35–43. http://dx.doi.org/10.3920/wmj2008.1026.

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Myrothecium verrucaria is a pathogen of several invasive weed species, including kudzu, and is currently being evaluated for use as a bioherbicide. However, the fungus also produces macrocyclic trichothecene mycotoxins. The safety of this biological control agent during production and handling would be improved if an inoculum could be produced without concomitant accumulation of macrocyclic trichothecenes. Sporulation and trichothecene production by M. verrucaria was evaluated on standard potato dextrose agar (PDA) and a series of complex and defined media. Sporulation on PDA and on agar media with nitrogen as ammonium nitrate or potassium nitrate was more than ten-fold greater then sporulation on the medium with ammonium sulphate as the nitrogen source. Accumulation of macrocyclic trichothecenes was strongly affected by the media composition, with higher levels often associated with higher carbon content in the media. Overall, incubation in continuous darkness resulted in higher macrocyclic trichothecene concentrations. Results support the hypothesis that accumulation of macrocyclic trichothecenes by this fungus can be altered by manipulating carbon and nitrogen sources. Furthermore, the biosynthesis of these mycotoxins may be independent of sporulation, demonstrating that the bioherbicide can be readily produced on solid substrates while simultaneously yielding conidia that are less threatening to worker safety. A more detailed implementation of the concepts demonstrated in this study will facilitate the safe and economical production of this bioherbicide.

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Ilgen, Peter, Birgit Hadeler, Frank J. Maier et Wilhelm Schäfer. « Developing Kernel and Rachis Node Induce the Trichothecene Pathway of Fusarium graminearum During Wheat Head Infection ». Molecular Plant-Microbe Interactions® 22, n^o 8 (août 2009) : 899–908. http://dx.doi.org/10.1094/mpmi-22-8-0899.

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The fungal pathogen Fusarium graminearum is the most common agent of Fusarium head blight (FHB) in small grain cereals and cob rot of maize. The threat posed by this fungus is due to a decrease in yield and, additionally, mycotoxin contamination of the harvested cereals. Among the mycotoxins, trichothecenes influence virulence of F. graminearum in a highly complex manner that is strongly host- as well as chemotype-specific. The factors inducing mycotoxin production during plant infection are still unknown. To evaluate the induction of the trichothecene pathway, the green fluorescence protein (GFP) gene was fused to the promoter of the TRI5 gene coding for the trichodiene synthase and integrated into the genome by homologous integration. The resulting mutant contains a fully functional TRI5 gene ensuring virulence on wheat and exhibits GFP driven by the endogenous TRI5 promoter. We are now able to monitor the induction of trichothecenes under real-time conditions. To localize the fungus in the plant tissue, the dsRed gene was integrated under constitutive control of the glycerol-3-phosphate dehydrogenase (gpdA) promoter. We are now able to show that, first, induction of GFP as well as trichothecene production in the reporter strain reflects TRI5 induction and trichothecene production in the wild type; second, expression of TRI5 is inducible during growth in culture; and, third, trichothecene production is not uniformly induced during the onset of infection but is tissue specific during fungal infection of wheat.

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Froquet, R., Y. Sibiril et D. Parent-Massin. « Trichothecene toxicity on human megakaryocyte progenitors (CFU-MK) ». Human & ; Experimental Toxicology 20, n^o 2 (février 2001) : 84–89. http://dx.doi.org/10.1191/096032701677428611.

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Trichothecenes are mycotoxins produced by various species of fungi, which can occur on various agricultural products. Among these compounds, T-2 toxin, HT-2 toxin, diacetoxyscirpenol (DAS) and deoxynivalenol (DON) are the most naturally encountered and the most potent trichothecenes. Consumption of trichothecene contaminated foods by farm animals and humans leads to mycotoxicosis. Trichothecenes are known to induce haematological disorders such as neutropenia, aplastic anemia and thrombocytopenia in humans and animals. Four trichothecenes, T-2 toxin, HT-2 toxin, DAS and DON have been tested on human platelet progenitors (CFU-MK) using a culture model of CFU-MK optimized for toxicological studies. Trichothecenes cause, at low concentrations, cytotoxic effects in megakaryocyte progenitors, which could induce thrombocytopenia. Sensitivity of human CFU-MK is compared to respective sensitivities of human red blood cell progenitors (BFU-E) and white blood cell progenitors (CF-U-GM) that were described in previous works.

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Wipfler, McCormick, Proctor, Teresi, Hao, Ward, Alexander et Vaughan. « Synergistic Phytotoxic Effects of Culmorin and Trichothecene Mycotoxins ». Toxins 11, n^o 10 (20 septembre 2019) : 555. http://dx.doi.org/10.3390/toxins11100555.

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Species of the fungus Fusarium cause Fusarium head blight (FHB) of cereal crops and contaminate grain with sesquiterpenoid mycotoxins, including culmorin (CUL) and trichothecenes. While the phytotoxicity of trichothecenes, such as deoxynivalenol (DON), and their role in virulence are well characterized, less is known about the phytotoxicity of CUL and its role in the development of FHB. Herein, we evaluated the phytotoxic effects of purified CUL and CUL-trichothecene mixtures using Chlamydomonas reinhardtii growth and Triticum aestivum (wheat) root elongation assays. By itself, CUL did not affect growth in either system. However, mixtures of CUL with DON, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, or NX-3, but not with nivalenol, inhibited growth in a synergistic manner. Synergistic phytotoxic effects of CUL and DON were also observed on multiple plant varieties and species. The severity of wheat FHB caused by 15 isolates of Fusarium graminearum was negatively correlated with the CUL/DON ratio, but positively correlated with the sum of both CUL and DON. Additionally, during the first week of infection, CUL biosynthetic genes were more highly expressed than the TRI5 trichothecene biosynthetic gene. Furthermore, genomic analysis of Fusarium species revealed that CUL and trichothecene biosynthetic genes consistently co-occur among species closely related to F. graminearum.

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Zhou, T., J. He et J. Gong. « Microbial transformation of trichothecene mycotoxins ». World Mycotoxin Journal 1, n^o 1 (1 février 2008) : 23–30. http://dx.doi.org/10.3920/wmj2008.x003.

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Trichothecene mycotoxins produced by the Fusarium genus are highly toxic to humans and animals. They are commonly found in cereals worldwide, which is not only a concern for food safety, but also highly relevant to the livestock industry. Controlling trichothecenes in food and feed has been a challenge since the toxins are markedly stable under different environmental conditions. Thermal processing is usually ineffective, and chemical treatments generally are expensive and often result in side effects. Previous studies on innovative biological approaches, such as the use of microorganisms and enzymes, to convert the toxins into non or less toxic compounds have shown promise. This review will briefly describe the chemical structures and toxicity of trichothecenes, and examine the microorganisms, including both bacteria and fungi, from various natural sources that are able to detoxify the toxins as either mixed cultures or a pure culture of single isolates. Finally, challenges and innovative strategies in the development of technology to detoxify trichothecenes by microorganisms are described.

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Brasel, T. L., J. M. Martin, C. G. Carriker, S. C. Wilson et D. C. Straus. « Detection of Airborne Stachybotrys chartarum Macrocyclic Trichothecene Mycotoxins in the Indoor Environment ». Applied and Environmental Microbiology 71, n^o 11 (novembre 2005) : 7376–88. http://dx.doi.org/10.1128/aem.71.11.7376-7388.2005.

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ABSTRACT The existence of airborne mycotoxins in mold-contaminated buildings has long been hypothesized to be a potential occupant health risk. However, little work has been done to demonstrate the presence of these compounds in such environments. The presence of airborne macrocyclic trichothecene mycotoxins in indoor environments with known Stachybotrys chartarum contamination was therefore investigated. In seven buildings, air was collected using a high-volume liquid impaction bioaerosol sampler (SpinCon PAS 450-10) under static or disturbed conditions. An additional building was sampled using an Andersen GPS-1 PUF sampler modified to separate and collect particulates smaller than conidia. Four control buildings (i.e., no detectable S. chartarum growth or history of water damage) and outdoor air were also tested. Samples were analyzed using a macrocyclic trichothecene-specific enzyme-linked immunosorbent assay (ELISA). ELISA specificity was tested using phosphate-buffered saline extracts of the fungal genera Aspergillus, Chaetomium, Cladosporium, Fusarium, Memnoniella, Penicillium, Rhizopus, and Trichoderma, five Stachybotrys strains, and the indoor air allergens Can f 1, Der p 1, and Fel d 1. For test buildings, the results showed that detectable toxin concentrations increased with the sampling time and short periods of air disturbance. Trichothecene values ranged from <10 to >1,300 pg/m3 of sampled air. The control environments demonstrated statistically significantly (P < 0.001) lower levels of airborne trichothecenes. ELISA specificity experiments demonstrated a high specificity for the trichothecene-producing strain of S. chartarum. Our data indicate that airborne macrocyclic trichothecenes can exist in Stachybotrys-contaminated buildings, and this should be taken into consideration in future indoor air quality investigations.

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Elhouiti, Fatiha, Djilali Tahri, Mohamed Ouinten et Mohamed Yousfi. « In silico assessment of Rhanterium adpressum sesquiterpenes inhibitory effect on 3 and 15-O-trichothecene acetyltransferases ». Nova Biotechnologica et chimica 19, n^o 1 (30 juin 2020) : 30–36. http://dx.doi.org/10.36547/nbc.v19i1.575.

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Essential oils (EO) from leaves and flowers of Rhanterium adpressum have shown to inhibit the mycelial growth and type B trichothecenes production. The four strains of Fusarium culmorum and Fusarium graminearum were inhibited with 0.25 μL.mL-1 of each oil. The inhibitory activity of 11 sesquiterpenes identified in these oils was here examined in silico against two key enzymes in the biosynthesis pathway of trichotecenes namely: 15-O-trichothecene acetyltransferase and 3-O-trichothecene acetyltransferase. In sesquiterpene composition, T-Muurolol and α-Eudesmol have the highest percentages ranging from 1.4 to 2.75 %. Three-dimensional structures of these two enzymes were modeled using SWISS-MODEL with GMQE = 0.93 and QMEAN = -0.45 for 3-O-trichothecene acetyltransferase and GMQE = 0.93, QMEAN = -0.58 for 15-O-trichothecene acetyltransferase. By the results of docking, T-Muurolol and α-Eudesmol showed high affinity compared to 15-Decalonectrin and Deoxynivalenol. These molecules are all sesquiterpenes with no major conformational difference with an RMSD of 3.7 Å and 3.5 Å between 15-decalonectrin and α-Eudesmol, T-Muurolol respectively. The results of docking prove the inhibitory effect of R. adpressum EO sesquiterpenes on the enzymes of mycotoxins biosynthesis pathway of F. culmorum and F. graminearum.

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Chen, Lifeng, Susan P. McCormick et Thomas M. Hohn. « Altered Regulation of 15-Acetyldeoxynivalenol Production in Fusarium graminearum ». Applied and Environmental Microbiology 66, n^o 5 (1 mai 2000) : 2062–65. http://dx.doi.org/10.1128/aem.66.5.2062-2065.2000.

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ABSTRACT Most Fusarium graminearum isolates produce low or undetectable levels of trichothecenes in liquid shake cultures, making it difficult to perform biochemical studies of trichothecene biosynthesis. To develop strains with higher levels of trichothecene production under liquid shake conditions we transformed F. graminearum with both a reporter gene containing a homologous trichothecene pathway gene promoter (TRI5) and a gene encoding a heterologous trichothecene pathway transcription factor (TRI6). The TRI5 and TRI6 genes are part of the trichothecene pathway gene clusters of both Fusarium sporotrichioides and F. graminearum. These genes encode trichodiene synthase (encoded by TRI5), the first enzyme in the trichothecene pathway, and a transcription factor (encoded by TRI6) required for pathway gene expression. Transformation of F. graminearum with plasmids containing either an F. graminearum TRI5 promoter fragment (FGTRI5P ) or FGTRI5P coupled with the β-d-glucuronidase (GUS) reporter gene resulted in the identification of several transformants capable of producing 45 to 200 mg of 15-acetyldeoxynivalenol (15-ADON)/liter in liquid shake culture after 7 days. Increased 15-ADON production was only observed in transformants where plasmid integration occurred through the FGTRI5P sequence and was not accompanied by increased GUS expression. 15-ADON production was further increased in liquid culture up to 1,200 mg/liter following introduction of the F. sporotrichioides TRI6 gene (FSTRI16) into F. graminearum. The effects of FSTRI6 on 15-ADON production also depended on plasmid integration via homologous recombination of the FGTRI5P fragment and resulted in a 100-fold increase in GUS expression. High-level production of 15-ADON in liquid shake cultures provides a convenient method for large-scale trichothecene preparation. The results suggest that targeting transformation vector integration toFGTRI5P alters pathway gene expression and are consistent with the proposed conservation of TRI6 function betweenFusarium species.

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Eudes, F., A. Comeau, S. Rioux et J. Collin. « Trichothecene-mediated in vitro selection in wheat for reduced mycotoxin accumulation caused by Fusarium graminearum ». Canadian Journal of Plant Science 88, n^o 6 (1 novembre 2008) : 1115–25. http://dx.doi.org/10.4141/cjps08060.

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Trichothecene, a factor of aggressiveness of Fusarium graminearum in wheat fusarium head blight (FHB), was evaluated in an anther co-culture assay for the regeneration of doubled haploid (DH) lines with reduced mycotoxin accumulation. A Fusarium graminearum culture filtrate and a defined mixture of purified trichothecenes were compared with a control treatment in two F1-derived microspores populations. Frontana and Katepwa were the FHB resistant and intermediate resistant sources, respectively, and the cultivar Norseman was the FHB susceptible parent. A preliminary evaluation of the subpopulations of DH lines, using the point inoculation method in the greenhouse, showed selection effects for FHB resistance in the trichothecene co-cultured Frontana/Norseman subpopulation only. Three years of field evaluation using the spray inoculation method revealed that the DH subpopulation from the F1 hybrid Frontana/Norseman co-culture in the presence of trichothecenes accumulated consistently less deoxynivalenol (DON) in the grain than the control subpopulation. The FHB symptoms were also significantly reduced for 1 yr (2001) in the same subpopulation. This subpopulation showed increased test weight, plant height and a 1.1-d delay in heading date when compared with the control subpopulation, under disease pressure. A trichothecene co-cultured DH subpopulation from Katepwa/Norseman also had a significantly lower DON content for 1 yr. Key words: Androgenesis, disease resistance, Gibberella zeae, mycotoxin, Triticum aestivum, wheat scab

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Kimura, Makoto, Takeshi Tokai, Gentaro Matsumoto, Makoto Fujimura, Hiroshi Hamamoto, Katsuyoshi Yoneyama, Takehiko Shibata et Isamu Yamaguchi. « Trichothecene Nonproducer Gibberella Species Have Both Functional and Nonfunctional 3-O-Acetyltransferase Genes ». Genetics 163, n^o 2 (1 février 2003) : 677–84. http://dx.doi.org/10.1093/genetics/163.2.677.

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Abstract The trichothecene 3-O-acetyltransferase gene (FgTri101) required for trichothecene production by Fusarium graminearum is located between the phosphate permease gene (pho5) and the UTP-ammonia ligase gene (ura7). We have cloned and sequenced the pho5-to-ura7 regions from three trichothecene nonproducing Fusarium (i.e., F. oxysporum, F. moniliforme, and Fusarium species IFO 7772) that belong to the teleomorph genus Gibberella. BLASTX analysis of these sequences revealed portions of predicted polypeptides with high similarities to the TRI101 polypeptide. While FspTri101 (Fusarium species Tri101) coded for a functional 3-O-acetyltransferase, FoTri101 (F. oxysporum Tri101) and FmTri101 (F. moniliforme Tri101) were pseudogenes. Nevertheless, F. oxysporum and F. moniliforme were able to acetylate C-3 of trichothecenes, indicating that these nonproducers possess another as yet unidentified 3-O-acetyltransferase gene. By means of cDNA expression cloning using fission yeast, we isolated the responsible FoTri201 gene from F. oxysporum; on the basis of this sequence, FmTri201 has been cloned from F. moniliforme by PCR techniques. Both Tri201 showed only a limited level of nucleotide sequence similarity to FgTri101 and FspTri101. The existence of Tri101 in a trichothecene nonproducer suggests that this gene existed in the fungal genome before the divergence of producers from nonproducers in the evolution of Fusarium species.

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McCormick, Susan P., Nancy J. Alexander, Susan E. Trapp et Thomas M. Hohn. « Disruption of TRI101, the Gene Encoding Trichothecene 3-O-Acetyltransferase, fromFusarium sporotrichioides ». Applied and Environmental Microbiology 65, n^o 12 (1 décembre 1999) : 5252–56. http://dx.doi.org/10.1128/aem.65.12.5252-5256.1999.

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ABSTRACT We screened a Fusarium sporotrichioides NRRL 3299 cDNA expression library in a toxin-sensitive Saccharomyces cerevisiae strain lacking a functional PDR5 gene. Fourteen yeast transformants were identified as resistant to the trichothecene 4,15-diacetoxyscirpenol, and each carried a cDNA encoding the trichothecene 3-O-acetyltransferase that is theF. sporotrichioides homolog of the Fusarium graminearum TRI101 gene. Mutants of F. sporotrichioides NRRL 3299 produced by disruption ofTRI101 were altered in their abilities to synthesize T-2 toxin and accumulated isotrichodermol and small amounts of 3,15-didecalonectrin and 3-decalonectrin, trichothecenes that are not observed in cultures of the parent strain. Our results indicate that TRI101 converts isotrichodermol to isotrichodermin and is required for the biosynthesis of T-2 toxin.

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Lakornwong, Waranya, Kwanjai Kanokmedhakul, Kasem Soytong, Arm Unartngam, Sarawut Tontapha, Vittaya Amornkitbamrung et Somdej Kanokmedhakul. « Types A and D Trichothecene Mycotoxins from the Fungus Myrothecium roridum ». Planta Medica 85, n^o 09/10 (26 avril 2019) : 774–80. http://dx.doi.org/10.1055/a-0895-5753.

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AbstractChromatographic separation of extracts from the fungal biomass of a plant pathogenic fungus, Myrothecium roridum, yielded 8 trichothecene toxins including 6 type D trichothecenes (1–6) and 2 type A trichothecenes (7–8). 6′,12′-Epoxymyrotoxin A (1) and 7′-hydroxymytoxin B (2) were new macrocyclic trichothecenes, while the other trichothecenes were identified as myrotoxin B (3), myrotoxin D hydrate (4), 2′,3′-epoxymyrothecine A (5), miotoxin A (6), and 2 trichothecenes lacking the macrocyclic lactone system, roridin L-2 (7) and trichoverritone (8). The structures of these mycotoxins were characterized using spectroscopic methods. The absolute configurations of 1 and 2 were determined by NOESY and a comparison of their experimental and calculated ECD spectra. Most of these mycotoxins (1–4 and 6) exhibited highly potent antimalarial activity against Plasmodium falciparum. They also showed strong cytotoxicity towards KB and NCI-H187 cell lines (IC50 0.60 – 112.28 nM), as well as the Vero cell line (IC50 1.50 – 46.51 nM).

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Suman, M., A. Manzitti et D. Catellani. « A design of experiments approach to studying deoxynivalenol and deoxynivalenol-3-glucoside evolution throughout industrial production of wholegrain crackers exploiting LC-MS/MS techniques ». World Mycotoxin Journal 5, n^o 3 (1 août 2012) : 241–49. http://dx.doi.org/10.3920/wmj2012.1422.

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Fusarium mycotoxins represent a significant problem in the cereal supply chain, with wheat, maize and barley being the main contaminated crops. Among the Fusarium toxins, the trichothecene deoxynivalenol (DON) is considered to be the most important contaminant in wheat due to its widespread occurrence. To protect consumers from unacceptably high trichothecene intakes in their diets, many countries have set maximum trichothecene levels for cereals and related food commodities. Relatively few studies have considered the loss of trichothecenes during industrial processing and focused on how processing steps may influence their degradation or modification. The aim of the present study is to verify how the DON and deoxynivalenol-3-glucoside (DON-3G) concentration in wholegrain crackers can be influenced by changes to the technological parameters employed during the fermentation and baking steps, starting with naturally contaminated bran, using a pilot-scale plant and exploiting the power of the Design of Experiments (DoE) approach. The DON results were then used to generate a preliminary predictive model, suggesting that the baking step represents the most important phase in minimising the native toxin level in crackers.

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Köck, Johannes, Christoph Gottschalk, Sebastian Ulrich, Karin Schwaiger, Manfred Gareis et Ludwig Niessen. « Rapid and selective detection of macrocyclic trichothecene producing Stachybotrys chartarum strains by loop-mediated isothermal amplification (LAMP) ». Analytical and Bioanalytical Chemistry 413, n^o 19 (15 juin 2021) : 4801–13. http://dx.doi.org/10.1007/s00216-021-03436-y.

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AbstractCytotoxic macrocyclic trichothecenes such as satratoxins are produced by chemotype S strains of Stachybotrys chartarum. Diseases such as stachybotryotoxicosis in animals and the sick building syndrome as a multifactorial disease complex in humans have been associated with this mold and its toxins. Less toxic non-chemotype S strains of S. chartarum are morphologically indistinguishable from chemotype S strains, which results in uncertainties in hazard characterization of isolates. To selectively identify macrocyclic trichothecene producing S. chartarum isolates, a set of sat14 gene-specific primers was designed and applied in a loop-mediated isothermal amplification (LAMP) assay using neutral red for visual signal detection. The assay was highly specific for S. chartarum strains of the macrocyclic trichothecene producing chemotype and showed no cross-reaction with non-macrocyclic trichothecene producing S. chartarum strains or 152 strains of 131 other fungal species. The assay’s detection limit was 0.635 pg/rxn (picogram per reaction) with a reaction time of 60 min. Its high specificity and sensitivity as well as the cost-saving properties make the new assay an interesting and powerful diagnostic tool for easy and rapid testing.

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Girotti, J. R., I. Malbrán, G. A. Lori et M. P. Juárez. « Early detection of toxigenic Fusarium graminearum in wheat ». World Mycotoxin Journal 5, n^o 2 (1 mai 2012) : 143–52. http://dx.doi.org/10.3920/wmj2011.1348.

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Fusarium graminearum (Schwabe) contaminates agricultural crops and commodities with trichothecenes, mostly deoxynivalenol and its acetyl-derivatives. Current techniques available to detect final mycotoxin contamination products usually require an extended time lag between sampling and the corresponding report, and include different clean-up steps and eventually derivatisation. This study was aimed to develop a methodology to detect toxigenic F. graminearum prior to mycotoxin production. Headspace solid-phase microextraction coupled to capillary gas chromatography is shown to be useful to predict the potential of trichothecene mycotoxin formation by detecting the presence of F. graminearum at early stages of fungal growth in wheat cultivars, based on the detection of trichodiene (TRI), the volatile intermediate of trichothecenes. We showed that TRI is a useful marker to detect toxigenic Fusarium in wheat spikes from live plants, regardless of the actual development of Fusarium head blight (FHB). This is the first predictive methodology for FHB and trichothecene occurrence in field-collected samples. It might be a useful tool to help to prevent the risk of mycotoxin contamination.

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Delgado, Javier A., Paul B. Schwarz, James Gillespie, Viviana V. Rivera-Varas et Gary A. Secor. « Trichothecene Mycotoxins Associated with Potato Dry Rot Caused by Fusarium graminearum ». Phytopathology® 100, n^o 3 (mars 2010) : 290–96. http://dx.doi.org/10.1094/phyto-100-3-0290.

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Fusarium graminearum, a known producer of trichothecene mycotoxins in cereal hosts, has been recently documented as a cause of dry rot of potato tubers in the United States. Due to the uncertainty of trichothecene production in these tubers, a study was conducted to determine the accumulation and diffusion of trichothecenes in potato tubers affected with dry rot caused by F. graminearum. Potato tubers of cv. Russet Burbank were inoculated with 14 F. graminearum isolates from potato, sugar beet, and wheat and incubated at 10 to 12°C for 5 weeks to determine accumulation of trichothecenes in potato tubers during storage. Twelve of the isolates were classified as deoxynivalenol (DON) genotype and two isolates were as nivalenol (NIV) genotype. Trichothecenes were detected only in rotted tissue. DON was detected in all F. graminearum DON genotype isolates up to 39.68 μg/ml in rotted potato tissue. Similarly, both NIV genotype isolates accumulated NIV in rotted potato tissue up to 18.28 μg/ml. Interestingly, isolates classified as genotype DON accumulated both DON and NIV in the dry rot lesion. Potato tubers were then inoculated with two isolates of F. graminearum chemotype DON and incubated up to 7 weeks at 10 to 12°C and assayed for DON diffusion. F. graminearum was recovered from >53% of the isolations from inoculated tubers at 3 cm distal to the rotted tissue after 7 weeks of incubation but DON was not detected in the surrounding tissue. Based in this data, the accumulation of trichothecenes in the asymptomatic tissue surrounding dry rot lesions caused by F. graminearum is minimal in cv. Russet Burbank potato tubers stored for 7 weeks at customary processing storage temperatures.

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Smith, T. K. « The use of trichothecene-contaminated grains in feeds ». Canadian Journal of Physiology and Pharmacology 68, n^o 7 (1 juillet 1990) : 1000–1003. http://dx.doi.org/10.1139/y90-152.

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A review is presented describing the relative efficiencies of the various technologies that have been proposed to permit incorporation of mycotoxin-contaminated grains into animal diets without adversely influencing growth rate or resulting in hazardous residues in edible animal tissues. When the degree of contamination is modest, it may be possible to dilute the contaminated materials with uncontaminated grain to lower the concentration of trichothecenes below the threshold of significant biological activity. A less useful alternative to dilution is the other mechanical approach of milling to remove the most heavily contaminated fractions of the grain. Chemical destruction of trichothecenes is also a possibility. An example is the use of sodium bisulfite treatment to destroy deoxynivalenol in contaminated corn. Such treatments may, however, reduce palatability and nutritional value. When the biochemical mechanism of trichothecene toxicity is known, in vivo therapeutic treatments may be possible. It has been shown, for example, that T-2 toxin-induced changes in brain prostaglandin production can be overcome by treatment with dexamethasone resulting in increased survival. A similar effect was seen using the selective platelet activating factor antagonist BN 52021. Another approach is the use of dietary treatments to either promote in vivo detoxification of mycotoxins or to reduce absorption from the digestive tract with the aid of nonnutritive binding agents.Key words: trichothecene, Fusarium, mycotoxin, utilization, feed.

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Gardiner, Stephanie A., Jayanand Boddu, Franz Berthiller, Christian Hametner, Robert M. Stupar, Gerhard Adam et Gary J. Muehlbauer. « Transcriptome Analysis of the Barley–Deoxynivalenol Interaction : Evidence for a Role of Glutathione in Deoxynivalenol Detoxification ». Molecular Plant-Microbe Interactions® 23, n^o 7 (juillet 2010) : 962–76. http://dx.doi.org/10.1094/mpmi-23-7-0962.

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Trichothecenes are a major group of toxins produced by phytopathogenic fungi, including Fusarium graminearum. Trichothecenes inhibit protein synthesis in eukaryotic cells and are toxicologically relevant mycotoxins for humans and animals. Because they promote plant disease, the role of host responses to trichothecene accumulation is considered to be an important aspect of plant defense and resistance to fungal infection. Our overall objective was to examine the barley response to application of the type B trichothecene deoxynivalenol (DON). We found that DON is diluted by movement from the application site to acropetal and basipetal florets. A susceptible barley genotype converted DON to DON-3-O-glucoside, indicating that UDP-glucosyltransferases capable of detoxifying DON must exist in barley. RNA profiling of DON-treated barley spikes revealed strong upregulation of gene transcripts encoding ABC transporters, UDP-glucosyltransferases, cytochrome P450s, and glutathione-S-transferases. We noted that transcripts encoding cysteine synthases were dramatically induced by DON, and that toxin-sensitive yeast on glutathione- or cysteine-supplemented media or carrying a gene that encodes a cysteine biosynthetic enzyme exhibit DON resistance, suggesting that preventing glutathione depletion by increasing cysteine supply could play a role in ameliorating the impact of DON. Evidence for nonenzymatic formation of DON-glutathione adducts in vitro was found using both liquid chromatography–mass spectrometry and nuclear magnetic resonance analysis, indicating that the formation of DON-glutathione conjugates in vivo may reduce the impact of trichothecenes. Our results indicate that barley exhibits multiple defense mechanisms against trichothecenes.

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Hao, Guixia, Susan McCormick, Helene Tiley et Thomas Usgaard. « Detoxification and Excretion of Trichothecenes in Transgenic Arabidopsis thaliana Expressing Fusarium graminearum Trichothecene 3-O-acetyltransferase ». Toxins 13, n^o 5 (29 avril 2021) : 320. http://dx.doi.org/10.3390/toxins13050320.

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Fusarium graminearum, the causal agent of Fusarium head blight (FHB), produces trichothecenes including deoxynivalenol (DON), nivalenol (NIV), and 3,7,15-trihydroxy-12,13-epoxytrichothec-9-ene (NX-3). These toxins contaminate grains and cause profound health problems in humans and animals. To explore exploiting a fungal self-protection mechanism in plants, we examined the ability of F. graminearum trichothecene 3-O-acetyltransferase (FgTri101) to detoxify several key trichothecenes produced by F. graminearum: DON, 15-ADON, NX-3, and NIV. FgTri101 was cloned from F. graminearum and expressed in Arabidopsis plants. We compared the phytotoxic effects of purified DON, NIV, and NX-3 on the root growth of transgenic Arabidopsis expressing FgTri101. Compared to wild type and GUS controls, FgTri101 transgenic Arabidopsis plants displayed significantly longer root length on media containing DON and NX-3. Furthermore, we confirmed that the FgTri101 transgenic plants acetylated DON to 3-ADON, 15-ADON to 3,15-diADON, and NX-3 to NX-2, but did not acetylate NIV. Approximately 90% of the converted toxins were excreted into the media. Our study indicates that transgenic Arabidopsis expressing FgTri101 can provide plant protection by detoxifying trichothecenes and excreting the acetylated toxins out of plant cells. Characterization of plant transporters involved in trichothecene efflux will provide novel targets to reduce FHB and mycotoxin contamination in economically important plant crops.

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Koshinsky, Heather A., Patrick J. Hannan et George G. Khachatourians. « HT-2 toxin, roridin A, T-2 toxin, and verrucarin A mycotoxins inhibit carbon dioxide production by Kluyveromyces marxianus ». Canadian Journal of Microbiology 37, n^o 12 (1 décembre 1991) : 933–38. http://dx.doi.org/10.1139/m91-161.

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The effects of four trichothecene mycotoxins on carbon dioxide production by a yeast, Kluyveromyces marxianus, were examined. Carbon dioxide release rate was inhibited by 10% in less than 25 min or 50% in less than 65 min by 0.0625, 0.125, 1.25, and 12.5 μg/mL of verrucarin A, roridin A, T-2 toxin, and HT-2 toxin, respectively. Lower concentrations did not affect carbon dioxide release rate within 160 min. Individually, neither 0.625 μg/mL T-2 toxin nor 0.000125 μg/mL roridin A alters carbon dioxide production. When combined at these concentrations, the two trichothecenes interact synergistically to inhibit carbon dioxide release rate by 50% within 60 min. In the case of grains contaminated with mycotoxin mixtures this synergistic interaction may raise concerns about safe-exposure conditions. Key words: carbon dioxide, Kluyveromyces marxianus, synergism, trichothecene mycotoxins.

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Villafana, Ria T., Amanda C. Ramdass et Sephra N. Rampersad. « TRI Genotyping and Chemotyping : A Balance of Power ». Toxins 12, n^o 2 (21 janvier 2020) : 64. http://dx.doi.org/10.3390/toxins12020064.

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Fusarium is among the top 10 most economically important plant pathogens in the world. Trichothecenes are the principal mycotoxins produced as secondary metabolites by select species of Fusarium and cause acute and chronic toxicity in animals and humans upon exposure either through consumption and/or contact. There are over 100 trichothecene metabolites and they can occur in a wide range of commodities that form food and feed products. This review discusses strategies to mitigate the risk of mycotoxin production and exposure by examining the Fusarium-trichothecene model. Fundamental to mitigation of risk is knowing the identity of the pathogen. As such, a comparison of current, recommended molecular approaches for sequence-based identification of Fusaria is presented, followed by an analysis of the rationale and methods of trichothecene (TRI) genotyping and chemotyping. This type of information confirms the source and nature of risk. While both are powerful tools for informing regulatory decisions, an assessment of the causes of incongruence between TRI genotyping and chemotyping data must be made. Reconciliation of this discordance will map the way forward in terms of optimization of molecular approaches, which includes data validation and sharing in the form of accessible repositories of genomic data and browsers for querying such data.

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Khachatourians, George G. « Metabolic effects of trichothecene T-2 toxin ». Canadian Journal of Physiology and Pharmacology 68, n^o 7 (1 juillet 1990) : 1004–8. http://dx.doi.org/10.1139/y90-153.

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Cereals and other agricultural products contaminated with trichothecene mycotoxins are unfit for consumption. Until recently, the metabolic effects of T-2 toxin (T-2) were thought to reside in its ability to inhibit protein synthesis. It is now clear that trichothecenes have multiple effects, including inhibition of DNA, RNA, and protein synthesis in several cellular systems, inhibition of in vitro protein synthesis, inhibition of mitochondrial functions, effects on cell division, normal cell shape, and hemolysis of erythrocytes. It is argued that these effects are pleiotropic responses of the cell's biosynthetic network to protein synthesis inhibition. However, in studies with erythrocytes, which lack nuclei and protein synthesis, changes in cell shape and lytic response towards T-2 are observed. Susceptibility to lysis is species dependent and correlates with the presence of phosphatidylcholine. Owing to their amphipathic nature, T-2 and other trichothecenes could exert their cytotoxicity by acting on cell membranes. As for cell energetics, T-2 inhibits the mitochondrial electron transport system, with succinic dehydrogenase as one site of action. Although initial investigations of the metabolic effects of T-2 mediated cytotoxicity suggested the inhibition of protein synthesis as the principal site of action, current thought suggests that the effects of trichothecenes are much more diverse.Key words: T-2 toxin, erythrocyte deformability, membrane lipids, yeast, anaesthetics.

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Kulik, Tomasz, Kessy Abarenkov, Maciej Buśko, Katarzyna Bilska, Anne D. van Diepeningen, Anna Ostrowska-Kołodziejczak, Katarzyna Krawczyk et al. « ToxGen : an improved reference database for the identification of type B-trichothecene genotypes inFusarium ». PeerJ 5 (15 février 2017) : e2992. http://dx.doi.org/10.7717/peerj.2992.

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Type B trichothecenes, which pose a serious hazard to consumer health, occur worldwide in grains. These mycotoxins are produced mainly by three different trichothecene genotypes/chemotypes: 3ADON (3-acetyldeoxynivalenol), 15ADON (15-acetyldeoxynivalenol) and NIV (nivalenol), named after these three major mycotoxin compounds. Correct identification of these genotypes is elementary for all studies relating to population surveys, fungal ecology and mycotoxicology. Trichothecene producers exhibit enormous strain-dependent chemical diversity, which may result in variation in levels of the genotype’s determining toxin and in the production of low to high amounts of atypical compounds. New high-throughput DNA-sequencing technologies promise to boost the diagnostics of mycotoxin genotypes. However, this requires a reference database containing a satisfactory taxonomic sampling of sequences showing high correlation to actually produced chemotypes. We believe that one of the most pressing current challenges of such a database is the linking of molecular identification with chemical diversity of the strains, as well as other metadata. In this study, we use the Tri12 gene involved in mycotoxin biosynthesis for identification of Tri genotypes through sequence comparison. Tri12 sequences from a range of geographically diverse fungal strains comprising 22Fusariumspecies were stored in the ToxGen database, which covers descriptive and up-to-date annotations such as indication on Tri genotype and chemotype of the strains, chemical diversity, information on trichothecene-inducing host, substrate or media, geographical locality, and most recent taxonomic affiliations. The present initiative bridges the gap between the demands of comprehensive studies on trichothecene producers and the existing nucleotide sequence databases, which lack toxicological and other auxiliary data. We invite researchers working in the fields of fungal taxonomy, epidemiology and mycotoxicology to join the freely available annotation effort.

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Villafana, Ria, Amanda Ramdass et Sephra Rampersad. « Selection of Fusarium Trichothecene Toxin Genes for Molecular Detection Depends on TRI Gene Cluster Organization and Gene Function ». Toxins 11, n^o 1 (14 janvier 2019) : 36. http://dx.doi.org/10.3390/toxins11010036.

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Food security is a global concern. Fusarium are among the most economically important fungal pathogens because they are ubiquitous, disease management remains a challenge, they produce mycotoxins that affect food and feed safety, and trichothecene mycotoxin production can increase the pathogenicity of some Fusarium species depending on the host species. Although trichothecenes may differ in structure by their patterns of hydroxylation or acetylation, these small changes have a significant impact on toxicity and the biological activity of these compounds. Therefore, detecting and identifying which chemotype is present in a given population are important to predicting the specific toxins that may be produced and, therefore, to evaluating the risk of exposure. Due to the challenges of inducing trichothecene production by Fusarium isolates in vitro for subsequent chemical analysis, PCR assays using gene-specific primers, either singly or in combination, designed against specific genes of the trichothecene gene cluster of multiple species of Fusarium have been developed. The establishment of TRI genotypes that potentially correspond to a specific chemotype requires examination of an information and knowledge pipeline whose critical aspects in sequential order are: (i) understanding the TRI gene cluster organization which differs according to Fusarium species under study; (ii) knowledge of the re-arrangements to the core TRI gene cluster over evolutionary time, which also differs according to Fusarium species; (iii) the functions of the TRI genes in the biosynthesis of trichothecene analogs; and (iv) based on (i)–(iii), selection of appropriate target TRI gene(s) for primer design in PCR amplification for the Fusarium species under study. This review, therefore, explains this pipeline and its connection to utilizing TRI genotypes as a possible proxy to chemotype designation.

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Kuhnem, Paulo R., Emerson M. Del Ponte, Yanhong Dong et Gary C. Bergstrom. « Fusarium graminearum Isolates from Wheat and Maize in New York Show Similar Range of Aggressiveness and Toxigenicity in Cross-Species Pathogenicity Tests ». Phytopathology® 105, n^o 4 (avril 2015) : 441–48. http://dx.doi.org/10.1094/phyto-07-14-0208-r.

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This study aimed to assess whether pathogenic Fusarium graminearum isolates from wheat and maize were more aggressive on their host of origin and whether aggressiveness was influenced further by B-trichothecene chemotype. Fifteen isolates were selected from a contemporary collection of isolates surveyed in New York in 2011 to 2012 to represent diversity of host of origin and chemotype. Three pathogenicity assays were used to evaluate and compare these isolates. Fusarium head blight (FHB) severity and trichothecene production in wheat, and maize seedling blight were evaluated in greenhouse inoculation experiments, and Gibberella ear rot (GER) severity and trichothecene production were evaluated in maize ears inoculated in the field. Our results showed among F. graminearum isolates a wide variation in aggressiveness and mycotoxin production toward wheat and maize and these isolates could not be structured by their host of origin or by chemotype. Moreover, aggressiveness rank order changed according to the host/organ evaluated. This indicates that relative susceptibility at the seedling stage may not predict susceptibility of ears. Significant correlations were observed of total trichothecenes (deoxynivalenol [DON] and its acetylated derivatives) produced with FHB and GER severity on wheat and maize, respectively. One isolate did not produce DON or ADON in wheat or maize kernels, yet was aggressive on both hosts. Nine of the fifteen isolates produced small amounts of zearalenone (ZON) in maize kernels, but not in wheat kernels, and ZON level was not correlated with GER severity. F. graminearum isolates from New York showed wide variation in aggressiveness and mycotoxin production toward susceptible wheat and maize. Neither host of origin nor trichothecene chemotype appeared to structure the populations we sampled.

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McCormick, Susan P., et Nancy J. Alexander. « Myrothecium roridum Tri4 encodes a multifunctional oxygenase required for three oxygenation steps ». Canadian Journal of Microbiology 53, n^o 5 (mai 2007) : 572–79. http://dx.doi.org/10.1139/w07-025.

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The biosyntheses of both macrocyclic trichothecenes in Myrothecium roridum and simple trichothecenes in Fusarium species begin with the cyclization of farnesyl pyrophosphate to form the sesquiterpene hydrocarbon trichodiene. A previous study showed that Myrothecium has a cluster of 3 genes that are homologous with Fusarium trichothecene genes: Tri4, a P450 oxygenase; Tri5, the sesquiterpene cyclase; and Tri6, a zinc-finger regulatory gene. Fusarium graminearum Tri4 (FgTri4) and M. roridum MrTri4 (MrTri4) have 66.9% identity. In this study, MrTri4 was expressed in Fusarium verticillioides . Liquid cultures of transformant strains expressing MrTri4 converted exogenous trichodiene to isotrichodiol, indicating that MrTri4 controls 3 oxygenation steps and that the product of MrTRI4 is isotrichodiol.

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Hartman, Glen L., Susan P. McCormick et Kerry O’Donnell. « Trichothecene-Producing Fusarium Species Isolated from Soybean Roots in Ethiopia and Ghana and their Pathogenicity on Soybean ». Plant Disease 103, n^o 8 (août 2019) : 2070–75. http://dx.doi.org/10.1094/pdis-12-18-2286-re.

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Numerous pathogen surveys have reported that diverse Fusarium spp. threaten soybean production in North and South America. However, little research has been conducted to characterize Fusarium pathogens of soybean in sub-Saharan Africa. Our objectives were to (i) identify Fusarium spp. isolated from discolored root segments of soybean grown in Ethiopia and Ghana using DNA sequence data, (ii) determine whether isolates nested in the Fusarium incarnatum-equiseti and F. sambucinum species complexes (FIESC and FSAMSC, respectively) produced trichothecene mycotoxins in vitro, and (iii) test these isolates for pathogenicity on soybean. Molecular phylogenetic analyses revealed that the trichothecene mycotoxin-producing isolates comprised three undescribed species within the FIESC and FSAMSC. Mycotoxin type B trichothecene 4,15-diacetylnivalenol or T-2 toxin and related type A neosolaniol trichothecenes were produced by 18 of the 21 isolates. Of the 12 isolates from Ethiopia and Ghana tested for their impact on seed germination, 5, comprising two undescribed phylospecies (i.e., Fusarium sp. number 3 and Fusarium sp. FIESC 2,) completely inhibited germination, whereas 4 caused no reduction in germination. Root lesions induced by all 12 isolates were greater than the uninoculated negative control. Additional variation among the isolates was reflected in differences (α = 0.05) in lesion lengths, which ranged from 34 to 67% of total root length. This is the first report characterizing FIESC and FSAMSC isolates from soybean roots in Ethiopia and Ghana.

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Brasel, T. L., D. R. Douglas, S. C. Wilson et D. C. Straus. « Detection of Airborne Stachybotrys chartarum Macrocyclic Trichothecene Mycotoxins on Particulates Smaller than Conidia ». Applied and Environmental Microbiology 71, n^o 1 (janvier 2005) : 114–22. http://dx.doi.org/10.1128/aem.71.1.114-122.2005.

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ABSTRACT Highly respirable particles (diameter, <1 μm) constitute the majority of particulate matter found in indoor air. It is hypothesized that these particles serve as carriers for toxic compounds, specifically the compounds produced by molds in water-damaged buildings. The presence of airborne Stachybotrys chartarum trichothecene mycotoxins on particles smaller than conidia (e.g., fungal fragments) was therefore investigated. Cellulose ceiling tiles with confluent Stachybotrys growth were placed in gas-drying containers through which filtered air was passed. Exiting particulates were collected by using a series of polycarbonate membrane filters with decreasing pore sizes. Scanning electron microscopy was employed to determine the presence of conidia on the filters. A competitive enzyme-linked immunosorbent assay (ELISA) specific for macrocyclic trichothecenes was used to analyze filter extracts. Cross-reactivity to various mycotoxins was examined to confirm the specificity. Statistically significant (P < 0.05) ELISA binding was observed primarily for macrocyclic trichothecenes at concentrations of 50 and 5 ng/ml and 500 pg/ml (58.4 to 83.5% inhibition). Of the remaining toxins tested, only verrucarol and diacetylverrucarol (nonmacrocyclic trichothecenes) demonstrated significant binding (18.2 and 51.7% inhibition, respectively) and then only at high concentrations. The results showed that extracts from conidium-free filters demonstrated statistically significant (P < 0.05) antibody binding that increased with sampling time (38.4 to 71.9% inhibition, representing a range of 0.5 to 4.0 ng/ml). High-performance liquid chromatography analysis suggested the presence of satratoxin H in conidium-free filter extracts. These data show that S. chartarum trichothecene mycotoxins can become airborne in association with intact conidia or smaller particles. These findings may have important implications for indoor air quality assessment.

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Tokai, Takeshi, Makoto Fujimura, Hirokazu Inoue, Takayuki Aoki, Kunihiro Ohta, Takehiko Shibata, Isamu Yamaguchi et Makoto Kimura. « Concordant evolution of trichothecene 3-O-acetyltransferase and an rDNA species phylogeny of trichothecene-producing and non-producing fusaria and other ascomycetous fungi ». Microbiology 151, n^o 2 (1 février 2005) : 509–19. http://dx.doi.org/10.1099/mic.0.27435-0.

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The cereal pathogen Fusarium graminearum species complex (e.g. Fusarium asiaticum, previously referred to as F. graminearum lineage 6) produces the mycotoxin trichothecene in infected grains. The fungus has a gene for self-defence, Tri101, which is responsible for 3-O-acetylation of the trichothecene skeleton in the biosynthetic pathway. Recently, trichothecene non-producers Fusarium oxysporum and Fusarium fujikuroi (teleomorph Gibberella fujikuroi) were shown to have both functional (Tri201) and non-functional (pseudo-Tri101) trichothecene 3-O-acetyltransferase genes in their genome. To gain insight into the evolution of the trichothecene genes in Gibberella species, the authors examined whether or not other (pseudo-)biosynthesis-related genes are found near Tri201. However, sequence analysis of a 12 kb region containing Tri201 did not result in identification of additional trichothecene (pseudo-)genes in F. oxysporum. In a further attempt to find other trichothecene (pseudo-)genes from the non-producer, the authors examined whether or not the non-trichothecene genes flanking the ends of the core trichothecene gene cluster (i.e. the Tri5 cluster) comprise a region of synteny in Gibberella species. However, it was not possible to isolate trichothecene (pseudo-)genes from F. oxysporum (in addition to the previously identified pseudo-Tri101), because synteny was not observed for this region in F. asiaticum and F. oxysporum. In contrast to this unsuccessful identification of additional trichothecene (pseudo-)genes in the non-producer, a functional trichothecene 3-O-acetyltransferase gene could be identified in fusaria other than Gibberella: Fusarium decemcellulare and Fusarium solani; and in an ascomycete from a different fungal genus, Magnaporthe grisea. Together with the recent functional identification of Saccharomyces cerevisiae ScAYT1, these results are suggestive of a different evolutionary origin for the trichothecene 3-O-acetyltransferase gene from other biosynthesis pathway genes. The phylogeny of the 3-O-acetyltransferase was mostly concordant with the rDNA species phylogeny of these ascomycetous fungi.

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Wong, L. S. L., D. Abramson, A. Tekauz, D. Leisle et R. I. H. McKenzie. « Pathogenicity and mycotoxin production of Fusarium species causing head blight in wheat cultivars varying in resistance ». Canadian Journal of Plant Science 75, n^o 1 (1 janvier 1995) : 261–67. http://dx.doi.org/10.4141/cjps95-047.

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Fusarium head blight (FHB) of wheat has recently become more prevalent in Manitoba, Canada. The objectives of this study were to assess the pathogenicity of Fusarium species isolated from infected wheat spikes, determine their potential to produce trichothecene mycotoxins and evaluate wheat cultivars for resistance to these Fusarium species. This information is a prerequisite to the development of cultivars with effective resistance to FHB in Manitoba. Eight Chinese and three Canadian wheat cultivars were evaluated against individual strains of seven Fusarium species singly in the field. Severity of FHB was measured as percentage of discolored peduncles and percentage of tombstone kernels. On this basis, Fusarium culmorum and F. graminearum were highly pathogenic, F. sporotrichioides had intermediate pathogenicity, and the other species were weakly pathogenic. For F. culmorum and F. graminearum, FHB severity correlated positively with kernel weight reduction and recovery of Fusarium species from the seed and correlated negatively with seed germination. Fusarium species varied in their ability to produce trichothecenes in infected wheat spikes. Wheat inoculated with F. poae contained both type A and B trichothecenes, while that inoculated with F. culmorum and F. graminearum produced type B only. Wheat inoculated with F. sporotrichioides contained type A trichothecenes, while that inoculated with F. avenaceum contained no detectable trichothecenes. Concentration of DON correlated positively with percentage of tombstone kernels in F. culmorum and F. graminearum, and that of HT-2 toxin correlated positively with percentage tombstone kernels in F. sporotrichioides. Biggar, Katepwa and Sceptre wheats were susceptible to F. culmorum and F. graminearum. High levels of resistance, expressed as low FHB severity combined with low trichothecene production, were found in several Chinese cultivars. These traits could be incorporated in adapted cultivars and be monitored by use of artificial inoculation. Key words:Fusarium culmorum, Fusarium graminearum, fusarium head blight, mycotoxins, resistance, wheat

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Edwards, S. G., S. R. Pirgozliev, M. C. Hare et P. Jenkinson. « Quantification of Trichothecene-ProducingFusarium Species in Harvested Grain by Competitive PCR To Determine Efficacies of Fungicides against Fusarium Head Blight of Winter Wheat ». Applied and Environmental Microbiology 67, n^o 4 (1 avril 2001) : 1575–80. http://dx.doi.org/10.1128/aem.67.4.1575-1580.2001.

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ABSTRACT We developed a PCR-based assay to quantify trichothecene-producingFusarium based on primers derived from the trichodiene synthase gene (Tri5). The primers were tested against a range of fusarium head blight (FHB) (also known as scab) pathogens and found to amplify specifically a 260-bp product from 25 isolates belonging to six trichothecene-producing Fusariumspecies. Amounts of the trichothecene-producing Fusariumand the trichothecene mycotoxin deoxynivalenol (DON) in harvested grain from a field trial designed to test the efficacies of the fungicides metconazole, azoxystrobin, and tebuconazole to control FHB were quantified. No correlation was found between FHB severity and DON in harvested grain, but a good correlation existed between the amount of trichothecene-producing Fusarium and DON present within grain. Azoxystrobin did not affect levels of trichothecene-producingFusarium compared with those of untreated controls. Metconazole and tebuconazole significantly reduced the amount of trichothecene-producing Fusarium in harvested grain. We hypothesize that the fungicides affected the relationship between FHB severity and the amount of DON in harvested grain by altering the proportion of trichothecene-producing Fusarium within the FHB disease complex and not by altering the rate of DON production. The Tri5 quantitative PCR assay will aid research directed towards reducing amounts of trichothecene mycotoxins in food and animal feed.

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Wu, Qinghua, Kamil Kuca, Eugenie Nepovimova et Wenda Wu. « Type A Trichothecene Diacetoxyscirpenol-Induced Emesis Corresponds to Secretion of Peptide YY and Serotonin in Mink ». Toxins 12, n^o 6 (25 juin 2020) : 419. http://dx.doi.org/10.3390/toxins12060419.

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The trichothecene mycotoxins contaminate cereal grains and have been related to alimentary toxicosis resulted in emetic response. This family of mycotoxins comprises type A to D groups of toxic sesquiterpene chemicals. Diacetoxyscirpenol (DAS), one of the most toxic type A trichothecenes, is considered to be a potential risk for human and animal health by the European Food Safety Authority. Other type A trichothecenes, T-2 toxin and HT-2 toxin, as well as type B trichothecene deoxynivalenol (DON), have been previously demonstrated to induce emetic response in the mink, and this response has been associated with the plasma elevation of neurotransmitters peptide YY (PYY) and serotonin (5-hydroxytryptamine, 5-HT). However, it is found that not all the type A and type B trichothecenes have the capacity to induce PYY and 5-HT. It is necessary to identify the roles of these two emetogenic mediators on DAS-induced emesis. The goal of this study was to determine the emetic effect of DAS and relate this effect to PYY and 5-HT, using a mink bioassay. Briefly, minks were fasted one day before experiment and given DAS by intraperitoneally and orally dosing on the experiment day. Then, emetic episodes were calculated and blood collection was employed for PYY and 5-HT test. DAS elicited robust emetic responses that corresponded to upraised PYY and 5-HT. Blocking the neuropeptide Y2 receptor (NPY2R) diminished emesis induction by PYY and DAS. The serotonin 3 receptor (5-HT3R) inhibitor granisetron totally restrained the induction of emesis by serotonin and DAS. In conclusion, our findings demonstrate that PYY and 5-HT have critical roles in DAS-induced emetic response.

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McCormick, Susan P., Nancy J. Alexander et Robert H. Proctor. « Fusarium Tri4encodes a multifunctional oxygenase required for trichothecene biosynthesis ». Canadian Journal of Microbiology 52, n^o 7 (1 juillet 2006) : 636–42. http://dx.doi.org/10.1139/w06-011.

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Fusarium graminearum and Fusarium sporotrichioides produce the trichothecene mycotoxins 15-acetyldeoxynivalenol and T-2 toxin, respectively. In both species, disruption of the P450 monooxygenase-encoding gene, Tri4, blocks production of the mycotoxins and leads to the accumulation of the trichothecene precursor trichodiene. To further characterize its function, the F. graminearum Tri4 (FgTri4) was heterologously expressed in the trichothecene-nonproducing species Fusarium verticillioides. Transgenic F. verticillioides carrying the FgTri4 converted exogenous trichodiene to the trichothecene biosynthetic intermediates isotrichodermin and trichothecene. Conversion of trichodiene to isotrichodermin requires seven biochemical steps. The fifth and sixth steps can occur nonenzymatically. Precursor feeding studies done in the current study indicate that wild-type F. verticillioides has the enzymatic activity necessary to carry out the seventh step, the C-3 acetylation of isotrichodermol to form isotrichodermin. Together, the results of this study indicate that the Tri4 protein catalyzes the remaining four steps and is therefore a multifunctional monooxygenase required for trichothecene biosynthesis.Key words: trichothecene, P450 oxygenase, trichodiene, Tri101, Tri4, multifunctional oxygenase, monooxygenase.

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Atanasova-Penichon, Vessela, Sebastien Pons, Laetitia Pinson-Gadais, Adeline Picot, Gisèle Marchegay, Marie-Noelle Bonnin-Verdal, Christine Ducos et al. « Chlorogenic Acid and Maize Ear Rot Resistance : A Dynamic Study Investigating Fusarium graminearum Development, Deoxynivalenol Production, and Phenolic Acid Accumulation ». Molecular Plant-Microbe Interactions® 25, n^o 12 (décembre 2012) : 1605–16. http://dx.doi.org/10.1094/mpmi-06-12-0153-r.

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Fusarium graminearum is the causal agent of Gibberella ear rot and produces trichothecene mycotoxins. Basic questions remain unanswered regarding the kernel stages associated with trichothecene biosynthesis and the kernel metabolites potentially involved in the regulation of trichothecene production in planta. In a two-year field study, F. graminearum growth, trichothecene accumulation, and phenolic acid composition were monitored in developing maize kernels of a susceptible and a moderately resistant variety using quantitative polymerase chain reaction and liquid chromatography coupled with photodiode array or mass spectrometry detection. Infection started as early as the blister stage and proceeded slowly until the dough stage. Then, a peak of trichothecene accumulation occurred and infection progressed exponentially until the final harvest time. Both F. graminearum growth and trichothecene production were drastically reduced in the moderately resistant variety. We found that chlorogenic acid is more abundant in the moderately resistant variety, with levels spiking in the earliest kernel stages induced by Fusarium infection. This is the first report that precisely describes the kernel stage associated with the initiation of trichothecene production and provides in planta evidence that chlorogenic acid may play a role in maize resistance to Gibberella ear rot and trichothecene accumulation.

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Hajšlová, J., K. Lancová, M. Sehnalová, A. Krplová, M. Zachariášová, H. Moravcová, J. Nedělník, J. Marková et J. Ehrenbergerová. « Occurrence of trichothecene mycotoxins in cereals harvested in the Czech Republic ». Czech Journal of Food Sciences 25, No. 6 (7 janvier 2008) : 339–50. http://dx.doi.org/10.17221/745-cjfs.

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A large-scale survey of the natural occurrence of trichothecene mycotoxins in major cereals harvested in the Czech Republic was conducted during the years 1999–2001. In total, 198 cereal samples representing various wheat, barley, and rye cultivars were examined for deoxynivalenol (DON) using gas chromatography with electron capture detector (GC-ECD). Four years later, in 2005, the list of target analytes was fairly extended, 65 wheat and barley samples were analysed for seven trichothecene mycotoxins – deoxynivalenol (DON), nivalenol (NIV), fusarenon-X (Fus-X), 15-acetyldeoxynivalenol and 3-acetyldeoxynivalenol (ADONs), HT-2 toxin (HT-2). and T-2 toxin (T-2) by high performance liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Trichothecenes represented mainly by DON were detected in almost all grain samples, its mean levels were the highest in the year 1999 which was characterised by very humid conditions during the growing season. The maximum concentration set in Commission Regulation EC (No. 856/2005) for DON (1250 µg/kg) in unprocessed cereals was exceeded only in two of all the samples analysed.

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Krnjaja, Vesna, Slavica Stanković, Ana Obradović, Tanja Petrović, Violeta Mandić, Zorica Bijelić et Manja Božić. « Trichothecene Genotypes of Fusarium graminearum Populations Isolated from Winter Wheat Crops in Serbia ». Toxins 10, n^o 11 (8 novembre 2018) : 460. http://dx.doi.org/10.3390/toxins10110460.

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Fusarium graminearum as the main causal agent of Fusarium head blight (FHB) and its ability to produce trichothecenes was investigated by molecular techniques. A total of 37 strains isolated from the wheat, harvested in Serbia in 2005, 2008 and 2015, and previously designated by morphological observation as F. graminearum, were used for trichothecene genotypes characterization. The strains were identified using the species-specific primer set FG16R/FG16F while genotypic characterization was done using specific TRI13 and TRI3 sequences of the trichothecene gene clusters. The PCR assays identified all strains as species of F. graminearum sensu stricto with the DON/15-ADON genotype. The quantification of the mycotoxin (DON) was performed using the biochemical assay. The high levels of DON (>20,000 µg kg−1) were recorded in all of the strains from 2005, four strains from 2008 and two strains from 2015. Weather data of the investigated seasons, showed that the optimal temperature, frequent rains and high relative humidity (RH) was very favourable for the development of F. graminearum, affecting the DON biosynthesis.

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McCormick, Susan P., Nancy J. Alexander et Robert H. Proctor. « Heterologous expression of two trichothecene P450 genes inFusarium verticillioides ». Canadian Journal of Microbiology 52, n^o 3 (1 mars 2006) : 220–26. http://dx.doi.org/10.1139/w05-124.

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Fusarium graminearum Z-3639 and F. sporotrichioides NRRL3299 produce the trichothecene mycotoxins 15-acetyldeoxynivalenol and T-2 toxin, respectively. These toxins differ in oxygenation at C-4, C-7, and C-8. In F. sporotrichioides, Tri1 (FsTri1) controls C-8 hydroxylation. To determine the function of an apparent F. graminearum Tri1 (FgTri1) homolog, both FsTri1 and FgTri1 genes were heterologously expressed in the trichothecene-nonproducing species F. verticillioides by fusing the Tri1 coding regions to the promoter of the fumonisin biosynthetic gene FUM8. FsTri1 and FgTri1 have been partially characterized by disruption analysis, and the results from these analyses suggest that FsTri1 most likely has a single function but that FgTri1 may have two functions. Transgenic F. verticillioides carrying the FsTri1 (FvF8FsTri1) converted exogenous isotrichodermin and calonectrin to 8-hydroxyisotrichodermin and 8-hydroxycalonectrin, respectively. Transgenic F. verticillioides carrying FgTri1 (FvF8FgTri1) converted isotrichodermin to a mixture of 7-hydroxyisotrichodermin and 8-hydroxyisotrichodermin but converted calonectrin to a mixture of 7-hydroxycalonectrin, 8-hydroxycalonectrin, and 3,15-diacetyldeoxynivalenol. A fourth compound, 7,8-dihydroxycalonectrin, was identified in large-scale F. verticillioides FvF8FgTri1 cultures fed isotrichodermin. Our results indicate that FgTri1 controls both C-7 and C-8 hydroxylation but that FsTri1 controls only C-8 hydroxylation. Our studies also demonstrate that F. verticillioides can metabolize some trichothecenes by adding an acetyl group to C-3 or by removing acetyl groups from C-4 or C-15. In addition, wild-type F. verticillioides can convert 7,8-dihydroxycalonectrin to 3,15-diacetyldeoxynivalenol.Key words: trichothecene, P450 oxygenase, 15-acetyldeoxynivalenol, heterologous expression.

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Savard, Marc E., Barbara A. Blackwell et Roy Greenhalgh. « An 1H nuclear magnetic resonance study of derivatives of 3-hydroxy-12,13-epoxytrichothec-9-enes ». Canadian Journal of Chemistry 65, n^o 9 (1 septembre 1987) : 2254–62. http://dx.doi.org/10.1139/v87-376.

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The 250-MHz 1H nuclear magnetic resonance spectra of 36 natural and synthetic trichothecenes have been analyzed and the chemical shifts as well as the vicinal and long-range coupling constants determined. Knowledge of the 16-CH3 chemical shift enables the substitution pattern of the A ring to be defined. Similarly, oxygenation in the C ring results in easily identifiable resonances. The J2,3 and J3,4 values define the configuration of substituents at C-3 and C-4, while the configuration at C-7 and C-8 can be defined by the J7,8, J7α,11, and J7β,15 values. The trichothecene ring system adopts the most stable A-half-chair, B-chair conformation in solution. The correlations obtained allow easy structural determination of unknown trichothecenes.

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Rio, B., S. Lautraite et D. Parent-Massin. « In vitro toxicity of trichothecenes on human erythroblastic progenitors ». Human & ; Experimental Toxicology 16, n^o 11 (novembre 1997) : 673–79. http://dx.doi.org/10.1177/096032719701601108.

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Trichothecenes are mycotoxins produced by various species of fungi which can occur on various agricultural products. Among these compounds, T-2 toxin, HT-2 toxin, diacetoxyscirpenol (DAS) and deoxynivalenol (DON) are the most naturally encountered and potent trichothe cenes. Consumption of trichothecene contaminated foods by farm animals and humans leads to mycotoxicoses. Trichothecenes are known to induce haematologic dis orders such as neutropenia, thrombopenia, and aplastic anemia in human and animals. The aim of our investigations is to explore the effects of trichothecenes on the haematopoietic progenitors. The four trichothecenes previously demonstrated to be strongly cytotoxic for human CFU-GM have been tested on human BFU-E. For this purpose, a culture model of human erythroblastic progenitors (BFU-E) optimized for toxicological studies was used to determine the effects of T-2, HT-2, diacetoxyscirpenol (DAS) and deoxynivalenol (DON) on red blood cell precursor proliferation and differentiation. Results showed that human BFU-E are as sensitive to trichothecenes as human CFU-GM, except for DON, in the range of concentrations tested. Differentiation of erythroblastic progenitors could be perturbed by these mycotoxins. Human erythroblastic progenitors are also a target of trichothecenes.

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