This review of Fusarium ear blight (scab) of small grain cereals has shown that up to 17 causal organisms have been associated with the disease, which occurs in most cereal-growing areas of the world. The most common species were Fusarium graminearum (Gibberella zeae), F. culmorum, F, avenaceum (G, avenacea), F, poae and Microdochium nivale (Monographella nivalis). The disease was recorded most frequently under hot, wet climatic conditions where significant yield losses and mycotoxin accumulation in grain were reported. Possible sources of inoculum were reported as crop debris, alternative hosts and Fusarium seedling blight and foot rot of cereals. The mode of dispiersal of inoculum to ears remains unclear, but contaminated arthropod vectors, systemic fungal growth through plants, and wind and rain-splash dispersal of spores have been proposed. Infection of wheat ears was shown to occur mainly during anthesis, and it has been demonstrated that fungal growth stimulants may be present in anthers. Despite the importance of the disease, particularly during epidemic years, control methods are limited. Much effort has gone into breeding resistant wheat varieties and into improving our understanding of the possible mechanisms and genetic basis of resistance, with only moderate success. There are also surprisingly few reports of successful fungicidal or biological control of the disease in the field.

Fusarium ear blight (scab) in small grain cereals—a review

Review on the toxicity, occurrence, metabolism, detoxification, regulations and intake of zearalenone: an oestrogenic mycotoxin.

Natural products to drugs: natural product derived compounds in clinical trials

Trichothecene mycotoxins are a group of structurally similar fungal metabolites that are capable of producing a wide range of toxic effects. Deoxynivalenol (DON, vomitoxin), a trichothecene, is prevalent worldwide in crops used for food and feed production, including in Canada and the United States. Although DON is one of the least acutely toxic trichothecenes, it should be treated as an important food safety issue because it is a very common contaminant of grain. This review focuses on the ability of DON to induce toxicologic and immunotoxic effects in a variety of cell systems and animal species. At the cellular level, the main toxic effect is inhibition of protein synthesis via binding to the ribosome. In animals, moderate to low ingestion of toxin can cause a number of as yet poorly defined effects associated with reduced performance and immune function. The main overt effect at low dietary concentrations appears to be a reduction in food consumption (anorexia), while higher doses induce vomiting (emesis). DON is known to alter brain neurochemicals. The serotoninergic system appears to play a role in mediation of the feeding behavior and emetic response. Animals fed low to moderate doses are able to recover from initial weight losses, while higher doses induce more long-term changes in feeding behavior. At low dosages of DON, hematological, clinical, and immunological changes are also transitory and decrease as compensatory/adaptation mechanisms are established. Swine are more sensitive to DON than mice, poultry, and ruminants, in part because of differences in metabolism of DON, with males being more sensitive than females. The capacity of DON to alter normal immune function has been of particular interest. There is extensive evidence that DON can be immunosuppressive or immunostimulatory, depending upon the dose and duration of exposure. While immunosuppression can be explained by the inhibition of translation, immunostimulation can be related to interference with normal regulatory mechanisms. In vivo, DON suppresses normal immune response to pathogens and simultaneously induces autoimmune-like effects which are similar to human immunoglobulin A (IgA) nephropathy. Other effects include superinduction of cytokine production by T helper cells (in vitro) and activation of macrophages and T cells to produce a proinflammatory cytokine wave that is analogous to that found in lipopolysaccharide-induced shock (in vivo). To what extent the elevation of cytokines contributes to metabolic effects such as decreased feed intake remains to be established. Although these effects have been largely characterized in the mouse, several investigations with DON suggest that immunotoxic effects are also likely in domestic animals. Further toxicology studies and an assessment of the potential of DON to be an etiologic agent in human disease are warranted.

Toxicology of deoxynivalenol (vomitoxin).

(1982). Epidemiology of wheat head blight and maize ear rot caused by Fusarium graminearum. Canadian Journal of Plant Pathology: Vol. 4, No. 2, pp. 195-209.

Epidemiology of wheat head blight and maize ear rot caused by Fusarium graminearum

A method has been developed for the production of aflatoxin by growing Aspergillus flavus strain NRRL 2999 on the solid substrate rice. Optimal yields, more than 1 mg of aflatoxin B(1) per g of starting material, were obtained in 5 days at 28 C. A crude product containing aflatoxins was isolated by chloroform extraction and precipitation with hexane from concentrated solutions. The crude product consisted of 50% aflatoxin in the following ratio: B(1)-B(2)-G(1)-G(2), 100:0.15:0.22:0.02. Aflatoxin B(1) was separated from almost all the impurities and from the other aflatoxins by chromatography on silica gel with 1% ethyl alcohol in chloroform. Analytically pure aflatoxin B(1) was recrystallized from chloroform-hexane mixtures.

Production of aflatoxin on rice.

To determine whether ochratoxin is produced by species of Aspergillus other than Asp. ochraceus, 44 strains representative of the 9 spp. composing the Asp. ochraceus group were grown on both pearled wheat and cracked corn in duplicate shaken flasks at 28°C for 5 days. Rice was a poor substrate for ochratoxin production. Moulded substrates were extracted with acetonitrile-water; partially purified extracts were assayed for ochratoxins by TLC. All positive samples were confirmed by solubility in sodium bicarbonate and preparation of methyl esters. Ochratoxins A and B were found in some strains of Asp. sulphureus, Asp. sclerotiorum, Asp. alliaceus, Asp. melleus, Asp. ochraceus, Asp. ostianus, and Asp. petrakii. No ochratoxin was produced by the one strain of Asp. elegans or any of 6 strains of Asp. auricomus. 5 of 9 strains of Asp. sclerotiorum and 5 of 11 strains of Asp. ochraceus were negative. All 7 strains of Asp. alliaceus were positive, but one was at a very low level. Generally, yields of ochratoxin were higher in wheat than in corn. Occasionally, as much ochratoxin B was produced as A. Highest yields of ochratoxins A and B were obtained from respective strains of Asp. ochraceus NRRL 3174 and NRRL 3519. Some strains of most species of the Asp. ochraceus group produce this mycotoxin as a secondary metabolite.

https://www.jstor.org/stable/info/3757871

Aspergilli as ochratoxin producers.

Ochratoxin A was detected as a natural contaminant for the first time It was present in a corn sample Images

Ochratoxin A: Occurrence as Natural Contaminant of a Corn Sample

An experiment was designed to determine whether certain fungi commonly isolated from maize at harvest can affect aflatoxin development when inoculated with Aspergillus flavus (NRRL 6412) onto individual sterilized maize kernels (incubation 8 days at 28 deg C). No aflatoxins were detected when A. niger (NRRL 6411) or Trichoderma viride (NRRL 6418) were paired with A. flavus. Aflatoxin contamination was substantial (mean value for B1 ranging from 676 p.p.b. to 3765 p.p.b.) in 11 other simultaneous pairings. When inoculation with A. flavus followed by 5 days that of the other test fungi, aflatoxin was detected only in pairings with Candida guilliermondii (B1, 16 p.p.b.; B2, 1 p.p.b.). However A. flavus invaded a number of the other preinoculated kernels in this series, as evidenced by its abundant sporulation on kernel surfaces and/or the formation of a bright greenish-yellow (BGY) fluorescence in kernel tissues examined under black light (365 nm). The status of individual fungal colonists as interference competitors and the order in which spp. colonize a kernel (i.e. prior to, or simultaneous with, the introduction of A. flavus), are examined as factors contributing to variation in aflatoxin levels among field samples.

/pdf/interference-competition-and-aflatoxin-levels-in-corn-2bmfpgrbxv.pdf

Interference competition and aflatoxin levels in corn.

Samples of airborne dust generated during the handling' of aflatoxin-contaminated corn were collected and analyzed to assess potential exposures of farmers and other agricultural workers to these mycotoxins. Using high volume total dust samplers and a high volume Andersen sampler, downwind dust samples were collected on glass fiber filters when contaminated corn was transferred by augers from a storage bin into a wagon and back into the storage bin. The aflatoxin B1 content of the 15 dust samples ranged from 12.5 to 204.3 ppb, with an average of 138 ppb; the aflatoxin B2 content ranged from 1.1 to 41.6 ppb, with an average of 24.6 ppb. The B1 and B2 levels of contamination in the bulk corn were 223.9 and 17.5 ppb, respectively. The gravimetric dust concentration in the air ranged from 7 mg/m3 to 417 mg/m3. The samples taken with an Andersen sampler indicate the dust is relatively coarse with only approximately 17% less than 7 µm. An analysis of the dust from each stage showed higher levels of aflatoxins i...

Odette L. Shotwell

Papers

Production of aflatoxin on rice.

Aspergilli as ochratoxin producers.

Ochratoxin A: Occurrence as Natural Contaminant of a Corn Sample

Interference competition and aflatoxin levels in corn.

Measurements of airborne aflatoxins during the handling of contaminated corn