Mycotoxins:Gibberella zeae

John Carlo O. MacujaJackielyn B. Ocbina

III-BSCT

Gibberella zeae

• Also known as Fusarium graminearum• Kingdom: Fungi• Phylum: Ascomycota• Class: Sordariomycetes• Subclass: Hypocreomycetidae• Order:Hypocreales• Family:Nectriaceae

Gibberella zeae

• This ascomycete fungus is the causal agent of head blight of wheat

• It has caused an estimated several billion dollars worth of damage in the US alone over the past decade.

• In head blight of wheat, newly emerging wheat heads (the fruits, which contain the seeds, the part that we eat) are infected by forcibly discharged, airborne ascospores released by G. zeae .

• The spore germinates on a wheat kernel, penetrates, and grows down through the stalk.

• Once a certain fungal mass is reached, fruiting structures penetrate though the wheat's stomates (the breathing apparatus on its leaves).

• These fruiting structures may be either asexual or sexual

Fusarium head blight

Mycotoxins

• deoxynivalenol• zearalenone

deoxynivalenol

• Also known as Vomitoxin• a type B trichothecene, an epoxy-

sesquiterpenoid.• This mycotoxin occurs predominantly in grains

such as wheat, barley, oats, rye, and maize.

vomitoxin

• Response to vomitoxin appears to occur through the central nervous system.

• Vomitoxin belongs to a class of mycotoxins (tricothecenes) which are strong inhibitors of protein synthesis.

• Exposure to vomitoxin causes the brain to increase its uptake of the amino acid tryptophan and, in turn, its synthesis of serotonin.

• Increased levels of serotonin are believed to be responsible for the anorexic effects of DON and other tricothecenes.

• Human foods: Vomitoxin is not a known carcinogen as with aflatoxin. Large amounts of grain with vomitoxin would have to be consumed to pose a health risk to humans.

• The U.S. Food and Drug Administration has established a level of 1 ppm (parts per million) restriction of vomitoxin.

• Companion animals: Dogs and cats are restricted to 5 ppm and of grain.

• Livestock and farm animals: In animals and livestock, vomitoxin causes a refusal to feed and lack of weight gain when fed above advised levels. Restrictions are set at 10 ppm for poultry and cattle.

Zearalenone

• Zearalenone is the primary toxin, causing infertility, abortion and other breeding problems in swine.

• The main concern is that zearalenone is a naturally occurring estrogen

• It causes hormonal effects in animals such as the pig