Fusarium, which is common soil phytopathogenic
fungi, to produce a number of different mycotoxins
of the class of trichothecenes and fumonisins in stored
food grains. Trichothecenes are a group of more than 40
compounds found commonly in grains. Trichothecenes
are classified as macrocylic or nonmacrocyclic,
depending on the presence or absence of a macrocylic
ester. The most toxic nonmacrocyclic compounds are
T-2toxin, Deoxynivalenol and fumonisins. Most of these
are biological weapon toxins. These can be absorbed
through intact skin causing systemic toxicity. Clinical
symptoms may be present within seconds of exposure.
Trichothecenes inhibits production of proteins and
nucleic acids and also stimulates lipid peroxidation.
Once the toxin crosses the plasma membrane barrier,
interacts with a number of targets, including ribosomes
and mitochondria and then inhibits electron transport
activity contributing to cellular cytotoxicity.
In the present study, an attempt was made to develop
a multiplex PCR for the rapid detection of the genes
involved in toxin metabolic pathway viz., tri5, tri6 and
fum1, fum13 for trichothecene and fumonisin producing
organisms respectively and rDNA gene for the specific
detection of Fusarium genus as a internal control. The
primers were designed for the individual mentioned
genes to obtain adequate spatial product amplification
for a clear resolution on agarose gel elctrophoresis.
The mPCR assay was standardized with the DNA
extracted from pure cultures of toxigenic Fusarium
strains obtained from culture collection centers, India.
A total of 100 food samples comprising Paddy, corn
and fingermillet collected from southern parts of India,
were analyzed by seed blot fungal isolation method,
from which 85 Fusarium strains could be isolated. From
among the isolated strains, 15 were showed positive
signal for fumonisin metabolic pathway genes, 35 were
trichothecene positive producing strains and rest stayed
as negative for multiplex PCR assay. The PCR positive
strains were cross checked by the HPTLC chemical
analysis (CAMAG. Anchrome) for the presence of the
toxin and this provided identical results.
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