The Experts below are selected from a list of 3189 Experts worldwide ranked by ideXlab platform
Susan P. Mccormick - One of the best experts on this subject based on the ideXlab platform.
-
evolution of structural diversity of Trichothecenes a family of toxins produced by plant pathogenic and entomopathogenic fungi
PLOS Pathogens, 2018Co-Authors: Robert H. Proctor, Laura Lindo, Susan P. Mccormick, Rosa E. Cardoza, Daren W. Brown, Hyeseon Kim, April M Stanley, Amy C Kelly, Theresa Lee, Martha M VaughanAbstract:Trichothecenes are a family of terpenoid toxins produced by multiple genera of fungi, including plant and insect pathogens. Some Trichothecenes produced by the fungus Fusarium are among the mycotoxins of greatest concern to food and feed safety because of their toxicity and frequent occurrence in cereal crops, and Trichothecene production contributes to pathogenesis of some Fusarium species on plants. Collectively, fungi produce over 150 Trichothecene analogs: i.e., molecules that share the same core structure but differ in patterns of substituents attached to the core structure. Here, we carried out genomic, phylogenetic, gene-function, and analytical chemistry studies of strains from nine fungal genera to identify genetic variation responsible for Trichothecene structural diversity and to gain insight into evolutionary processes that have contributed to the variation. The results indicate that structural diversity has resulted from gain, loss, and functional changes of Trichothecene biosynthetic (TRI) genes. The results also indicate that the presence of some substituents has arisen independently in different fungi by gain of different genes with the same function. Variation in TRI gene duplication and number of TRI loci was also observed among the fungi examined, but there was no evidence that such genetic differences have contributed to Trichothecene structural variation. We also inferred ancestral states of the TRI cluster and Trichothecene biosynthetic pathway, and proposed scenarios for changes in Trichothecene structures during divergence of TRI cluster homologs. Together, our findings provide insight into evolutionary processes responsible for structural diversification of toxins produced by pathogenic fungi.
-
Requirement of Two Acyltransferases for 4‑O‑Acylation during Biosynthesis of Harzianum A, an Antifungal Trichothecene Produced by Trichoderma arundinaceum
2018Co-Authors: Laura Lindo, Mark Busman, Nancy J Alexander, Robert H. Proctor, Susan P. Mccormick, Rosa E. Cardoza, Santiago GutiérrezAbstract:Trichothecenes are sesquiterpenoid toxins produced by multiple fungi, including plant pathogens, entomopathogens, and saprotrophs. Most of these fungi have the acyltransferase-encoding gene tri18. Even though its function has not been determined, tri18 is predicted to be involved in Trichothecene biosynthesis because of its pattern of expression and its location near other Trichothecene biosynthetic genes. Here, molecular genetic, precursor feeding, and analytical chemistry experiments indicate that in the saprotroph Trichoderma arundinaceum the tri18-encoded acyltransferase (TRI18) and a previously characterized acyltransferase (TRI3) are required for conversion of the Trichothecene biosynthetic intermediate trichodermol to harzianum A, an antifungal Trichothecene analog with an octa-2,4,6-trienedioyl acyl group. On the basis of the results, we propose that TRI3 catalyzes Trichothecene 4-O-acetylation, and subsequently, TRI18 catalyzes replacement of the resulting acetyl group with octa-2,4,6-trienedioyl to form harzianum A. Thus, the findings provide evidence for a previously unrecognized two-step acylation process during Trichothecene biosynthesis in T. arundinaceum and possibly other fungi
-
Variation in Type A Trichothecene Production and Trichothecene Biosynthetic Genes in Fusarium goolgardi from Natural Ecosystems of Australia
MDPI AG, 2015Co-Authors: Liliana O. Rocha, Robert H. Proctor, Susan P. Mccormick, Matthew H. Laurence, Brett A. Summerell, Edward C. Y. LiewAbstract:Fusarium goolgardi, isolated from the grass tree Xanthorrhoea glauca in natural ecosystems of Australia, is closely related to fusaria that produce a subgroup of Trichothecene (type A) mycotoxins that lack a carbonyl group at carbon atom 8 (C-8). Mass spectrometric analysis revealed that F. goolgardi isolates produce type A Trichothecenes, but exhibited one of two chemotypes. Some isolates (50%) produced multiple type A Trichothecenes, including 4,15-diacetoxyscirpenol (DAS), neosolaniol (NEO), 8-acetylneosolaniol (Ac-NEO) and T-2 toxin (DAS-NEO-T2 chemotype). Other isolates (50%) produced only DAS (DAS chemotype). In the phylogenies inferred from DNA sequences of genes encoding the RNA polymerase II largest (RPB1) and second largest (RPB2) subunits as well as the Trichothecene biosynthetic genes (TRI), F. goolgardi isolates were resolved as a monophyletic clade, distinct from other type A Trichothecene-producing species. However, the relationships of F. goolgardi to the other species varied depending on whether phylogenies were inferred from RPB1 and RPB2, the 12-gene TRI cluster, the two-gene TRI1-TRI16 locus, or the single-gene TRI101 locus. Phylogenies based on different TRI loci resolved isolates with different chemotypes into distinct clades, even though only the TRI1-TRI16 locus is responsible for structural variation at C-8. Sequence analysis indicated that TRI1 and TRI16 are functional in F. goolgardi isolates with the DAS-NEO-T2 chemotype, but non-functional in isolates with DAS chemotype due to the presence of premature stop codons caused by a point mutation
-
Trichothecene triangle toxins genes and plant disease
2013Co-Authors: Susan P. Mccormick, Nancy J Alexander, Robert H. ProctorAbstract:Trichothecenes are a family of sesquiterpene epoxides that inhibit eukaryotic protein synthesis. These mycotoxins are produced in Fusarium-infested grains such as corn, wheat, and barley, and ingestion of contaminated grain can result in a variety of symptoms including diarrhea, hemorrhaging, and feed refusal. Biochemical and genetic investigations have characterized the genes controlling Trichothecene biosynthesis. In Fusarium, Trichothecene genes have been mapped to three loci including a 26-kb cluster of 12 genes. Production of Trichothecenes by Fusarium graminearum has been shown to be an important virulence factor in wheat head blight. Strains of F. graminearum have been categorized into three different chemotypes, nivalenol (NIV), 3-acetyldeoxynivalenol (3ADON), and 15-acetyldeoxynivalenol (15ADON), based on polymorphisms observed in PCR assays. Although 15ADON-producing strains predominate in North America, there has been a recent emergence of 3ADON- and NIV-producing strains. The genetic basis for these chemotypes has been elucidated with sequence analysis, genetic engineering, and heterologous expression of Trichothecene biosynthetic genes.
-
Trichothecene mycotoxins inhibit mitochondrial translation implication for the mechanism of toxicity
Toxins, 2011Co-Authors: Mohamed Anwar Binumer, Susan P. Mccormick, John E Mclaughlin, Debaleena Basu, Nilgun E TumerAbstract:Fusarium head blight (FHB) reduces crop yield and results in contamination of grains with Trichothecene mycotoxins. We previously showed that mitochondria play a critical role in the toxicity of a type B Trichothecene. Here, we investigated the direct effects of type A and type B Trichothecenes on mitochondrial translation and membrane integrity in Saccharomyces cerevisiae. Sensitivity to Trichothecenes increased when functional mitochondria were required for growth, and Trichothecenes inhibited mitochondrial translation at concentrations, which did not inhibit total translation. In organello translation in isolated mitochondria was inhibited by type A and B Trichothecenes, demonstrating that these toxins have a direct effect on mitochondrial translation. In intact yeast cells Trichothecenes showed dose-dependent inhibition of mitochondrial membrane potential and reactive oxygen species, but only at doses higher than those affecting mitochondrial translation. These results demonstrate that inhibition of mitochondrial translation is a primary target of Trichothecenes and is not secondary to the disruption of mitochondrial membranes.
Thomas M. Hohn - One of the best experts on this subject based on the ideXlab platform.
-
Disruption of TRI101, the gene encoding Trichothecene 3-O-acetyltransferase, from Fusarium sporotrichioides.
Applied and environmental microbiology, 1999Co-Authors: Susan P. Mccormick, Nancy J Alexander, Susan E. Trapp, Thomas M. HohnAbstract: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 the F. sporotrichioides homolog of the Fusarium graminearum TRI101 gene. Mutants of F. sporotrichioides NRRL 3299 produced by disruption of TRI101 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.
-
possible role of Trichothecene mycotoxins in virulence of fusarium graminearum on maize
Plant Disease, 1999Co-Authors: Linda J Harris, Ronald D. Plattner, Robert H. Proctor, Anne E. Desjardins, P Nicholson, G Butler, J C Young, G Weston, Thomas M. HohnAbstract: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.
-
possible role of Trichothecene mycotoxins in virulence of fusarium graminearum on maize
Plant Disease, 1999Co-Authors: Linda J Harris, Ronald D. Plattner, Robert H. Proctor, Anne E. Desjardins, P Nicholson, G Butler, J C Young, G Weston, Thomas M. HohnAbstract:Harris, L. J., Desjardins, A. E., Plattner, R. D., Nicholson, P., Butler, G., Young, J. c., Weston, G., Proctor, R. H., and Hohn, T. M. 1999. Possible role of Trichothecene mycotoxins in virulence of Fusarium graminearum on maize. Plant Dis. 83:954-960. 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 inocu lation 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 sever ity, grain yield, deoxynivalenol (DON) concentration, and fungal biomass by quantitative poly merase 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.
-
characterization of the gene cluster for biosynthesis of macrocyclic Trichothecenes in myrothecium roridum
Molecular Genetics and Genomics, 1998Co-Authors: S C Trapp, Susan P. Mccormick, Thomas M. Hohn, B B JarvisAbstract:Macrocyclic Trichothecenes are toxic sesquiterpenoids that are produced by certain fungi and plants. The unique structural features of macrocyclic Trichothecenes result in increased toxicity relative to other Trichothecene structural types. Here we report the sequences and relative locations of the MRTRI5, MRTRI6, and MRTRI4 genes in the biosynthetic pathway for macrocyclic Trichothecenes in Myrothecium roridum. The deduced sequences of the products of MRTRI5 and MRTRI4 display overall identities of 75 and 63%, respectively, with the corresponding proteins in Fusarium sporotrichioides. Based on sequence comparisons, MRTRI5 encodes the enzyme trichodiene synthase, which has been shown to catalyze the first step in the Trichothecene pathways of Fusarium and Trichothecium species. MRTRI6 encodes a transcription factor (392 amino acids) required for pathway gene expression, and the predicted MRTRI4 product (533 amino acids) is a cytochrome P450 monooxygenase responsible for the initial oxygenation step in the pathway. The sizes of the predicted products of MRTRI5 and MRTRI4 show good agreement with their apparent counterparts in the Fusarium pathway; however, the protein specified by MRTRI6 is almost twice the size of its putative homolog in F. sporotrichioides. Only the C-terminal 124 residues of MRTRI6, containing the proposed Cys2His2 zinc finger motifs, show significant similarity (65% identity) to the TRI6 sequence in F. sporotrichioides. MRTRI4 can successfully complement a TRI4-mutant in F. sporotrichioides, although the resulting Trichothecene profile differed from that observed in wild-type strains. Complemented mutants accumulated low levels of T-2 toxin, in addition to sambucinol, deoxysambucinol, and the pathway intermediates Trichothecene and isotrichodiol. Mapping data indicate that the genes of the macrocyclic Trichothecene pathway in M. roridum are clustered, but that their organization and orientation differ markedly from those of the Trichothecene gene cluster found in F. sporotrichioides. These results show that the biosynthetic pathways for macrocyclic Trichothecenes are closely related to other Trichothecene pathways and that the evolution of gene clusters for the biosynthesis of natural products in fungi can involve significant rearrangements.
-
restoration of wild type virulence to tri5 disruption mutants of gibberella zeae via gene reversion and mutant complementation
Microbiology, 1997Co-Authors: Robert H. Proctor, Thomas M. Hohn, Susan P. MccormickAbstract:Summary: Gibberella zeae is a pathogen of small grain crops and produces Trichothecene mycotoxins in infected host tissue. The role of Trichothecenes in the virulence of G. zeae was previously investigated using Trichothecene-non-producing mutants that were generated via transformation-mediated disruption of a gene (Tri5) that encodes the first enzyme in the Trichothecene biosynthetic pathway. The mutants were less virulent on some hosts than the wild-type strain from which they were derived. Here, we used two approaches to determine whether the reduced virulence of mutants was due specifically to Tri5 disruption or to non-target effects caused by the transformation process. First, we generated a revertant from a Tri5 disruption mutant by allowing the mutant to pass through the sexual phase of its life cycle. In approximately 2% of the resulting progeny the disrupted Tri5 had reverted to wild-type; however, only one of three revertant progeny also regained the ability to produce Trichothecenes. In the second approach, we complemented the Tri5 mutation in a disruption mutant by transforming the mutant with a plasmid carrying a functional copy of Tri5. In all transformants examined, the ability to produce Trichothecenes was restored. The restoration of Trichothecene production in the revertant progeny and in the complemented mutant was accompanied by restoration of wild-type or near wild-type levels of virulence on wheat seedlings (cultivar Wheaton). The results indicate that the reduced virulence of the mutants was caused by disruption of Tri5 rather than non-target effects resulting from the transformation process. The results also provide further evidence that Trichothecenes contribute to the virulence of plant-pathogenic fungi.
Robert H. Proctor - One of the best experts on this subject based on the ideXlab platform.
-
evolution of structural diversity of Trichothecenes a family of toxins produced by plant pathogenic and entomopathogenic fungi
PLOS Pathogens, 2018Co-Authors: Robert H. Proctor, Laura Lindo, Susan P. Mccormick, Rosa E. Cardoza, Daren W. Brown, Hyeseon Kim, April M Stanley, Amy C Kelly, Theresa Lee, Martha M VaughanAbstract:Trichothecenes are a family of terpenoid toxins produced by multiple genera of fungi, including plant and insect pathogens. Some Trichothecenes produced by the fungus Fusarium are among the mycotoxins of greatest concern to food and feed safety because of their toxicity and frequent occurrence in cereal crops, and Trichothecene production contributes to pathogenesis of some Fusarium species on plants. Collectively, fungi produce over 150 Trichothecene analogs: i.e., molecules that share the same core structure but differ in patterns of substituents attached to the core structure. Here, we carried out genomic, phylogenetic, gene-function, and analytical chemistry studies of strains from nine fungal genera to identify genetic variation responsible for Trichothecene structural diversity and to gain insight into evolutionary processes that have contributed to the variation. The results indicate that structural diversity has resulted from gain, loss, and functional changes of Trichothecene biosynthetic (TRI) genes. The results also indicate that the presence of some substituents has arisen independently in different fungi by gain of different genes with the same function. Variation in TRI gene duplication and number of TRI loci was also observed among the fungi examined, but there was no evidence that such genetic differences have contributed to Trichothecene structural variation. We also inferred ancestral states of the TRI cluster and Trichothecene biosynthetic pathway, and proposed scenarios for changes in Trichothecene structures during divergence of TRI cluster homologs. Together, our findings provide insight into evolutionary processes responsible for structural diversification of toxins produced by pathogenic fungi.
-
Requirement of Two Acyltransferases for 4‑O‑Acylation during Biosynthesis of Harzianum A, an Antifungal Trichothecene Produced by Trichoderma arundinaceum
2018Co-Authors: Laura Lindo, Mark Busman, Nancy J Alexander, Robert H. Proctor, Susan P. Mccormick, Rosa E. Cardoza, Santiago GutiérrezAbstract:Trichothecenes are sesquiterpenoid toxins produced by multiple fungi, including plant pathogens, entomopathogens, and saprotrophs. Most of these fungi have the acyltransferase-encoding gene tri18. Even though its function has not been determined, tri18 is predicted to be involved in Trichothecene biosynthesis because of its pattern of expression and its location near other Trichothecene biosynthetic genes. Here, molecular genetic, precursor feeding, and analytical chemistry experiments indicate that in the saprotroph Trichoderma arundinaceum the tri18-encoded acyltransferase (TRI18) and a previously characterized acyltransferase (TRI3) are required for conversion of the Trichothecene biosynthetic intermediate trichodermol to harzianum A, an antifungal Trichothecene analog with an octa-2,4,6-trienedioyl acyl group. On the basis of the results, we propose that TRI3 catalyzes Trichothecene 4-O-acetylation, and subsequently, TRI18 catalyzes replacement of the resulting acetyl group with octa-2,4,6-trienedioyl to form harzianum A. Thus, the findings provide evidence for a previously unrecognized two-step acylation process during Trichothecene biosynthesis in T. arundinaceum and possibly other fungi
-
Variation in Type A Trichothecene Production and Trichothecene Biosynthetic Genes in Fusarium goolgardi from Natural Ecosystems of Australia
MDPI AG, 2015Co-Authors: Liliana O. Rocha, Robert H. Proctor, Susan P. Mccormick, Matthew H. Laurence, Brett A. Summerell, Edward C. Y. LiewAbstract:Fusarium goolgardi, isolated from the grass tree Xanthorrhoea glauca in natural ecosystems of Australia, is closely related to fusaria that produce a subgroup of Trichothecene (type A) mycotoxins that lack a carbonyl group at carbon atom 8 (C-8). Mass spectrometric analysis revealed that F. goolgardi isolates produce type A Trichothecenes, but exhibited one of two chemotypes. Some isolates (50%) produced multiple type A Trichothecenes, including 4,15-diacetoxyscirpenol (DAS), neosolaniol (NEO), 8-acetylneosolaniol (Ac-NEO) and T-2 toxin (DAS-NEO-T2 chemotype). Other isolates (50%) produced only DAS (DAS chemotype). In the phylogenies inferred from DNA sequences of genes encoding the RNA polymerase II largest (RPB1) and second largest (RPB2) subunits as well as the Trichothecene biosynthetic genes (TRI), F. goolgardi isolates were resolved as a monophyletic clade, distinct from other type A Trichothecene-producing species. However, the relationships of F. goolgardi to the other species varied depending on whether phylogenies were inferred from RPB1 and RPB2, the 12-gene TRI cluster, the two-gene TRI1-TRI16 locus, or the single-gene TRI101 locus. Phylogenies based on different TRI loci resolved isolates with different chemotypes into distinct clades, even though only the TRI1-TRI16 locus is responsible for structural variation at C-8. Sequence analysis indicated that TRI1 and TRI16 are functional in F. goolgardi isolates with the DAS-NEO-T2 chemotype, but non-functional in isolates with DAS chemotype due to the presence of premature stop codons caused by a point mutation
-
Trichothecene triangle toxins genes and plant disease
2013Co-Authors: Susan P. Mccormick, Nancy J Alexander, Robert H. ProctorAbstract:Trichothecenes are a family of sesquiterpene epoxides that inhibit eukaryotic protein synthesis. These mycotoxins are produced in Fusarium-infested grains such as corn, wheat, and barley, and ingestion of contaminated grain can result in a variety of symptoms including diarrhea, hemorrhaging, and feed refusal. Biochemical and genetic investigations have characterized the genes controlling Trichothecene biosynthesis. In Fusarium, Trichothecene genes have been mapped to three loci including a 26-kb cluster of 12 genes. Production of Trichothecenes by Fusarium graminearum has been shown to be an important virulence factor in wheat head blight. Strains of F. graminearum have been categorized into three different chemotypes, nivalenol (NIV), 3-acetyldeoxynivalenol (3ADON), and 15-acetyldeoxynivalenol (15ADON), based on polymorphisms observed in PCR assays. Although 15ADON-producing strains predominate in North America, there has been a recent emergence of 3ADON- and NIV-producing strains. The genetic basis for these chemotypes has been elucidated with sequence analysis, genetic engineering, and heterologous expression of Trichothecene biosynthetic genes.
-
identification of loci and functional characterization of Trichothecene biosynthesis genes in filamentous fungi of the genus trichoderma
Applied and Environmental Microbiology, 2011Co-Authors: Rosa E. Cardoza, Nancy J Alexander, Robert H. Proctor, Susan P. Mccormick, Monica G Malmierca, M R Hermosa, Anamariela Tijerino, Angel Rumbero, Enrique Monte, Santiago GutierrezAbstract:Trichothecenes are mycotoxins produced by Trichoderma, Fusarium, and at least four other genera in the fungal order Hypocreales. Fusarium has a Trichothecene biosynthetic gene (TRI) cluster that encodes transport and regulatory proteins as well as most enzymes required for the formation of the mycotoxins. However, little is known about Trichothecene biosynthesis in the other genera. Here, we identify and characterize TRI gene orthologues (tri) in Trichoderma arundinaceum and Trichoderma brevicompactum. Our results indicate that both Trichoderma species have a tri cluster that consists of orthologues of seven genes present in the Fusarium TRI cluster. Organization of genes in the cluster is the same in the two Trichoderma species but differs from the organization in Fusarium. Sequence and functional analysis revealed that the gene (tri5) responsible for the first committed step in Trichothecene biosynthesis is located outside the cluster in both Trichoderma species rather than inside the cluster as it is in Fusarium. Heterologous expression analysis revealed that two T. arundinaceum cluster genes (tri4 and tri11) differ in function from their Fusarium orthologues. The Tatri4-encoded enzyme catalyzes only three of the four oxygenation reactions catalyzed by the orthologous enzyme in Fusarium. The Tatri11-encoded enzyme catalyzes a completely different reaction (Trichothecene C-4 hydroxylation) than the Fusarium orthologue (Trichothecene C-15 hydroxylation). The results of this study indicate that although some characteristics of the tri/TRI cluster have been conserved during evolution of Trichoderma and Fusarium, the cluster has undergone marked changes, including gene loss and/or gain, gene rearrangement, and divergence of gene function.
Anne E. Desjardins - One of the best experts on this subject based on the ideXlab platform.
-
structure activity relationships of Trichothecene toxins in an arabidopsis thaliana leaf assay
Journal of Agricultural and Food Chemistry, 2007Co-Authors: Anne E. Desjardins, Susan P. Mccormick, Michael AppellAbstract:Many Fusarium species produce Trichothecenes, sesquiterpene epoxides that differ in patterns of oxygenation and esterification at carbon positions C-3, C-4, C-7, C-8, and C-15. For the first comprehensive and quantitative comparison of the effects of oxygenation and esterification on Trichothecene phytotoxicity, we tested 24 precursors, intermediates, and end products of the Trichothecene biosynthetic pathway in an Arabidopsis thaliana detached leaf assay. At 100 μM, the highest concentration tested, only the Trichothecene precursor trichodiene was nontoxic. Among Trichothecenes, toxicity varied more than 200-fold. Oxygenation at C-4, C-8, C-7/8, or C-15 was, on average, as likely to decrease as to increase toxicity. Esterification at C-4, C-8, or C-15 generally increased toxicity. Esterification at C-3 increased toxicity in one case and decreased toxicity in three of eight cases tested. Thus, the increase in structural complexity along the Trichothecene biosynthetic pathway in Fusarium is not necessarily...
-
A Genetic and Biochemical Approach to Study Trichothecene Diversity in Fusarium sporotrichioides and Fusarium graminearum
Fungal genetics and biology : FG & B, 2001Co-Authors: Daren W. Brown, Nancy J Alexander, Robert H. Proctor, Susan P. Mccormick, Anne E. DesjardinsAbstract:The Trichothecenes T-2 toxin and deoxynivalenol (DON) are natural fungal products that are toxic to both animals and plants. Their importance in the pathogenicity of Fusarium spp. on crop plants has inspired efforts to understand the genetic and biochemical mechanisms leading to Trichothecene synthesis. In order to better understand T-2 toxin biosynthesis by Fusarium sporotrichioides and DON biosynthesis by F. graminearum, we compared the nucleotide sequence of the 23-kb core Trichothecene gene cluster from each organism. This comparative genetic analysis allowed us to predict proteins encoded by two Trichothecene genes, TRI9 and TRI10, that had not previously been described from either Fusarium species. Differences in gene structure also were correlated with differences in the types of Trichothecenes that the two species produce. Gene disruption experiments showed that F. sporotrichioides TRI7 (FsTRI7) is required for acetylation of the oxygen on C-4 of T-2 toxin. Sequence analysis indicated that F. graminearum TRI7 (FgTRI7) is nonfunctional. This is consistent with the fact that the FgTRI7 product is not required for DON synthesis in F. graminearum because C-4 is not oxygenated.
-
analysis of aberrant virulence of gibberella zeae following transformation mediated complementation of a Trichothecene deficient tri5 mutant
Microbiology, 2000Co-Authors: Anne E. Desjardins, Ronald D. Plattner, Guihua Bai, Robert H. ProctorAbstract:Gibberella zeae causes wheat ear blight and produces Trichothecene toxins in infected grain. In previous studies, Trichothecene production in this fungus was disabled by specific disruption of the trichodiene synthase gene (Tri5) and was restored by two methods: gene reversion and transformation-mediated mutant complementation. In previous field tests of wheat ear blight, Trichothecene-nonproducing mutants were less virulent than the wild-type progenitor strain from which they were derived. Trichothecene-producing revertants also were restored to wild-type levels of virulence. In contrast, in the field test of wheat ear blight reported here, Trichothecene-producing strains obtained by Tri5 mutant complementation were not restored to wild-type levels of virulence. The complemented mutants showed a slightly reduced radial growth compared to the wild-type strain, but otherwise appeared normal in morphology, pigmentation and sexual fertility. Genetic analysis indicated that the aberrant virulence of a complemented mutant was likely due to non-target effects that occurred during the process of transforming the Trichothecene-nonproducing mutant with Tri5. These results confirm previous findings that Trichothecenes contribute to the virulence of G. zeae, but also demonstrate that manipulating this fungus in the laboratory may cause it to undergo subtle changes that reduce its virulence.
-
possible role of Trichothecene mycotoxins in virulence of fusarium graminearum on maize
Plant Disease, 1999Co-Authors: Linda J Harris, Ronald D. Plattner, Robert H. Proctor, Anne E. Desjardins, P Nicholson, G Butler, J C Young, G Weston, Thomas M. HohnAbstract: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.
-
possible role of Trichothecene mycotoxins in virulence of fusarium graminearum on maize
Plant Disease, 1999Co-Authors: Linda J Harris, Ronald D. Plattner, Robert H. Proctor, Anne E. Desjardins, P Nicholson, G Butler, J C Young, G Weston, Thomas M. HohnAbstract:Harris, L. J., Desjardins, A. E., Plattner, R. D., Nicholson, P., Butler, G., Young, J. c., Weston, G., Proctor, R. H., and Hohn, T. M. 1999. Possible role of Trichothecene mycotoxins in virulence of Fusarium graminearum on maize. Plant Dis. 83:954-960. 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 inocu lation 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 sever ity, grain yield, deoxynivalenol (DON) concentration, and fungal biomass by quantitative poly merase 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.
Maurizio Vurro - One of the best experts on this subject based on the ideXlab platform.
-
metabolites inhibiting germination of orobanche ramosa seeds produced by myrothecium verrucaria and fusarium compactum
Journal of Agricultural and Food Chemistry, 2005Co-Authors: Anna Andolfi, Angela Boari, Antonio Evidente, Maurizio VurroAbstract:Myrothecium verrucaria and Fusarium compactum were isolated from diseased Orobanche ramosa plants collected in southern Italy to find potential biocontrol agents of this parasitic weed. Both fungi grown in liquid culture produced metabolites that inhibited the germination of O. ramosa seeds at 1−10 μM. Eight metabolites were isolated from M. verrucaria culture extracts. The main metabolite was identified as verrucarin E, a disubstituted pyrrole not belonging to the Trichothecene group. Seven compounds were identified by spectroscopic methods as macrocyclic Trichothecenes, namely, verrucarins A, B, M, and L acetate, roridin A, isotrichoverrin B, and trichoverrol B. The main metabolite produced by F. compactum was neosoloaniol monoacetate, a Trichothecene. All the Trichothecenes proved to be potent inhibitors of O. ramosa seed germination and possess strong zootoxic activity when assayed on Artemia salina brine shrimps. Verrucarin E is inactive on both seed germination and zootoxic assay. Keywords: Orobanch...
-
metabolites inhibiting germination of orobanche ramosa seeds produced by myrothecium verrucaria and fusarium compactum
Journal of Agricultural and Food Chemistry, 2005Co-Authors: Anna Andolfi, Angela Boari, Antonio Evidente, Maurizio VurroAbstract:Myrothecium verrucaria and Fusarium compactum were isolated from diseased Orobanche ramosa plants collected in southern Italy to find potential biocontrol agents of this parasitic weed. Both fungi grown in liquid culture produced metabolites that inhibited the germination of O. ramosa seeds at 1−10 μM. Eight metabolites were isolated from M. verrucaria culture extracts. The main metabolite was identified as verrucarin E, a disubstituted pyrrole not belonging to the Trichothecene group. Seven compounds were identified by spectroscopic methods as macrocyclic Trichothecenes, namely, verrucarins A, B, M, and L acetate, roridin A, isotrichoverrin B, and trichoverrol B. The main metabolite produced by F. compactum was neosoloaniol monoacetate, a Trichothecene. All the Trichothecenes proved to be potent inhibitors of O. ramosa seed germination and possess strong zootoxic activity when assayed on Artemia salina brine shrimps. Verrucarin E is inactive on both seed germination and zootoxic assay. Keywords: Orobanch...
-
Metabolites inhibiting germination of Orobanche ramosa seeds produced by Myrothecium verrucaria and Fusarium compactum
American Chemical Society:1155 Sixteenth Street Northwest:Washington DC 20036:(800)227-5558 EMAIL: service@acs.org INTERNET: http: www.pubs.acs.org Fa, 2005Co-Authors: Anna Andolfi, Angela Boari, Antonio Evidente, Maurizio VurroAbstract:Myrothecium verrucaria and Fusarium compactum were isolated from diseased Orobanche ramosa plants collected in southern Italy to find potential biocontrol agents of this parasitic weed. Both fungi grown in liq. culture produced metabolites that inhibited the germination of O. ramosa seeds at 1-10 M. Eight metabolites were isolated from M. verrucaria culture exts. The main metabolite was identified as verrucarin E, a disubstituted pyrrole not belonging to the Trichothecene group. Seven compds. were identified by spectroscopic methods as macrocyclic Trichothecenes, namely, verrucarins A, B, M, and L acetate, roridin A, isotrichoverrin B, and trichoverrol B. The main metabolite produced by F. compactum was neosoloaniol monoacetate, a Trichothecene. All the Trichothecenes proved to be potent inhibitors of O. ramosa seed germination and possess strong zootoxic activity when assayed on Artemia salina brine shrimps. Verrucarin E is inactive on both seed germination and zootoxic assay
