Aflatoxins, fumonisins, and trichothecenes: a convergence of knowledge

Woloshuk, Charles P.; Shim, Won‐Bo

doi:10.1111/1574-6976.12009

Cited by 150 publications

(79 citation statements)

References 148 publications

(341 reference statements)

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“…produce toxic secondary metabolites, such as trichothecenes, fumonisins (33), and fusaric acid (FA) (34). These mycotoxins can be produced by the fungus in infected plant tissues, thereby contaminating agricultural products, rendering them unacceptable for food or feed.…”

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confidence: 99%

An Interspecies Signaling System Mediated by Fusaric Acid Has Parallel Effects on Antifungal Metabolite Production by Pseudomonas protegens Strain Pf-5 and Antibiosis of Fusarium spp

Quecine

Kidarsa

Goebel

et al. 2016

Appl Environ Microbiol

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dPseudomonas protegens strain Pf-5 is a rhizosphere bacterium that suppresses soilborne plant diseases and produces at least seven different secondary metabolites with antifungal properties. We derived mutants of Pf-5 with single and multiple mutations in biosynthesis genes for seven antifungal metabolites: 2,4-diacetylphoroglucinol (DAPG), pyrrolnitrin, pyoluteorin, hydrogen cyanide, rhizoxin, orfamide A, and toxoflavin. These mutants were tested for inhibition of the pathogens Fusarium verticillioides and Fusarium oxysporum f. sp. pisi. Rhizoxin, pyrrolnitrin, and DAPG were found to be primarily responsible for fungal antagonism by Pf-5. Previously, other workers showed that the mycotoxin fusaric acid, which is produced by many Fusarium species, including F. verticillioides, inhibited the production of DAPG by Pseudomonas spp. In this study, amendment of culture media with fusaric acid decreased DAPG production, increased pyoluteorin production, and had no consistent influence on pyrrolnitrin or orfamide A production by Pf-5. Fusaric acid also altered the transcription of biosynthetic genes, indicating that the mycotoxin influenced antibiotic production by Pf-5 at the transcriptional level. Addition of fusaric acid to the culture medium reduced antibiosis of F. verticillioides by Pf-5 and derivative strains that produce DAPG but had no effect on antibiosis by Pf-5 derivatives that suppressed F. verticillioides due to pyrrolnitrin or rhizoxin production. Our results demonstrated the importance of three compounds, rhizoxin, pyrrolnitrin, and DAPG, in suppression of Fusarium spp. by Pf-5 and confirmed that an interspecies signaling system mediated by fusaric acid had parallel effects on antifungal metabolite production and antibiosis by the bacterial biological control organism. Pseudomonas is a heterogeneous genus of Gammaproteobacteria composed of species with diverse ecological roles; certain strains are members of the plant microbiome contributing to plant growth and health. Our studies focus on the soil bacterium Pseudomonas protegens Pf-5, which is known for its capacity to suppress plant diseases and produce a large spectrum of metabolites with antibiotic activity (1, 2). The antibiotics produced by Pf-5 include pyrrolnitrin (3), pyoluteorin (4), analogs of rhizoxin (5, 6), hydrogen cyanide (7), 2,4-diacetylphloroglucinol (DAPG) (8), monoacetylphloroglucinol (MAPG) (9) (an intermediate in the DAPG biosynthetic pathway [10,11]), the lipopeptide orfamide A (12), and toxoflavin (13). The antibiotics produced by Pf-5 have distinct but overlapping activity spectra, and it is likely that multiple compounds contribute to the interactions of Pf-5 with target plant pathogens that result in disease suppression. Commonly, the role of an antibiotic in biological control is assessed by comparing the level of disease suppression provided by a wild-type strain versus an antibiotic-deficient mutant (14). For strain Pf-5, however, this approach has not been highly successful in providing evidence for the roles of antibioti...

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An Interspecies Signaling System Mediated by Fusaric Acid Has Parallel Effects on Antifungal Metabolite Production by Pseudomonas protegens Strain Pf-5 and Antibiosis of Fusarium spp

Quecine

Kidarsa

Goebel

et al. 2016

Appl Environ Microbiol

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“…Deciphering the molecular genetic basis of mycotoxin production in fungi will improve our understanding of its genetic regulation and facilitate the identification of potential mycotoxin-producing fungi in the environment (7,8). There has been considerable interest in developing PCR-based diagnosis methods for detection of mycotoxin-producing fungi in agricultural commodities and in food and feed (9).…”

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SnPKS19 Encodes the Polyketide Synthase for Alternariol Mycotoxin Biosynthesis in the Wheat Pathogen Parastagonospora nodorum

Chooi

Muria-Gonzalez

Mead

et al. 2015

Appl Environ Microbiol

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b Alternariol (AOH) is an important mycotoxin from the Alternaria fungi. AOH was detected for the first time in the wheat pathogen Parastagonospora nodorum in a recent study. Here, we exploited reverse genetics to demonstrate that SNOG_15829 (SnPKS19), a close homolog of Penicillium aethiopicum norlichexanthone (NLX) synthase gene gsfA, is required for AOH production. We further validate that SnPKS19 is solely responsible for AOH production by heterologous expression in Aspergillus nidulans. The expression profile of SnPKS19 based on previous P. nodorum microarray data correlated with the presence of AOH in vitro and its absence in planta. Subsequent characterization of the ⌬SnPKS19 mutants showed that SnPKS19 and AOH are not involved in virulence and oxidative stress tolerance. Identification and characterization of the P. nodorum SnPKS19 cast light on a possible alternative AOH synthase gene in Alternaria alternata and allowed us to survey the distribution of AOH synthase genes in other fungal genomes. We further demonstrate that phylogenetic analysis could be used to differentiate between AOH synthases and the closely related NLX synthases. This study provides the basis for studying the genetic regulation of AOH production and for development of molecular diagnostic methods for detecting AOH-producing fungi in the future.

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“…The genes for aflatoxin biosynthesis in Aspergillus, fumonisin and trichothecene biosynthesis in Fusarium, and fumonisin production in Aspergillus niger and other black Aspergilli are clustered (Woloshuk and Shim, 2012). This may facilitate the coordinated expression and regulation of these genes, and, if correct, raises questions about the minimum number of genes that comprise a cluster and whether a single gene module comprising two divergently transcribed genes represents the earliest stages of functional innovation and the birth of clusters.…”

Section: Mycology and Fungal Genomicsmentioning

confidence: 99%

Mycotoxins that affect the North American agri-food sector: state of the art and directions for the future

Miller

Schaafsma

Bhatnagar

et al. 2014

WMJ

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This paper summarises workshop discussions at the 5 th international MYCORED meeting in Ottawa, Canada ( June 2012) with over 200 participants representing academics, government and industry scientists, government officials and farming organisations (present in roughly equal proportions) from 27 countries. Workshops centred on how mycotoxins in food and feed affect value chains and trade in the region covered by the North American Free Trade Agreement. Crops are contaminated by one or more of five important mycotoxins in parts of Canada and the United States every year, and when contaminated food and feed are consumed in amounts above tolerable limits, human and animal health are at risk. Economic loss from such contamination includes reduced crop yield, grain quality, animal productivity and loss of domestic and export markets. A systematic effort by grain producers, primary, transfer, and terminal elevators, millers and food and feed processers is required to manage these contaminants along the value chain. Workshops discussed lessons learned from investments in plant genetics, fungal genomics, toxicology, analytical and sampling science, management strategies along the food and feed value chains and methods to ameliorate the effects of toxins in grain on animal production and on reducing the impact of mycotoxins on population health in developing countries. These discussions were used to develop a set of priorities and recommendations.

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Aflatoxins, fumonisins, and trichothecenes: a convergence of knowledge

Cited by 150 publications

References 148 publications

An Interspecies Signaling System Mediated by Fusaric Acid Has Parallel Effects on Antifungal Metabolite Production by Pseudomonas protegens Strain Pf-5 and Antibiosis of Fusarium spp

An Interspecies Signaling System Mediated by Fusaric Acid Has Parallel Effects on Antifungal Metabolite Production by Pseudomonas protegens Strain Pf-5 and Antibiosis of Fusarium spp

SnPKS19 Encodes the Polyketide Synthase for Alternariol Mycotoxin Biosynthesis in the Wheat Pathogen Parastagonospora nodorum

Mycotoxins that affect the North American agri-food sector: state of the art and directions for the future

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