www.czu.cz ; www.raupp.info
Bt maize and reduced mycotoxins provoced lots of comments and additions,
which are summarized here, including an enhanced bibliography, it grew from
500 to nealry 1000 references. Thanks to all the contributors.
See the previous Berne Debate about maize and mycotoxins under:
Correction: Ustilago maydis, Corn Smut in the US, Huitlacoche in Mexico are
not containing toxic fumonisins.
Huitlacoche (or cuitlacoche) and fumonisins are not related. I was not able
to find a single bibliographical record where any of the mycotoxins in
question was related to Ustilago maydis,
but there is a lot of misleading information on the internet, see for
"Corn smut in the US a disease, in Mexico its a delicacy", but this does not
mean, that the US consider corn smut as a disease because its toxic, only
because there is no real market to sell the infected cobs which they sell in
Mexico for a much higher prize (recently efforts in this direction have been
made in the States).
Huitlacoche (or as a variant cuitlacoche) is caused by a fungus with the
name of Ustilago maydis, its a basidiomycete Ustilaginales, Ustilaginaceae,
the Genus Ustilago (Persoon) Roussel 1806
From the Ustilago maydis database located and maintained at the Broad
Institute at the MIT.
Ustilago maydis, the causal agent of corn smut disease, has been used for
over 100 years as a model system for studying genetics and pathogen-host
interactions. Recently, the fungus has emerged as an excellent experimental
model for the molecular genetic analysis of phytopathogenesis, particularly
in the characterization of infection-specific morphogenesis in response to
signals from host plants.
Corn Ear Rot: a multitude of fungal infects of corn
When evaluating an ear rot problem, remember, certain ear rots are a warning
sign to suspect toxins, but ear rots do not always lead to toxin problems.
Many fungi are not known to produce toxins. Even those that can produce
toxins do not always do so.
important Ear Rots:
(the complete index of plant diseases
Fusarium verticilloides (synonym F. monififorme),
Fusarium verticilloides is an important mycotoxigenic fungus and is found
wherever maize, its primary host, is cultivated. F. verticilloides, like
most Fusarium species, produces the mycotoxin fusaric acid.
Aspergillus ear rot and storage mold. Aspergillus flavus and A. parasiticus
can produce aflatoxins. They are generally known as storage fungi, but they
can also cause ear rots in the field. Aspergillus is a gray-green, powdery
mold. In Iowa, Aspergillus is much more common in hot, dry years. It can
grow at temperatures higher than 90? F, and grain moisture content as low as
15 percent. The fungus can be detected in corn because it produces compounds
that are fluorescent under black light, but this does not directly detect
the presence of aflatoxins.
Cladosporium ear rot. Cladosporium herbarum and other species often infect
kernels damaged by insects, hail, or frost. This fungus appears gray to
black or very dark green, and can have a powdery appearance. It also causes
black streaks in the kernels. This disease can be fairly common but usually
does not cause extensive damage to the ears.
Diplodia ear rot. This fungus initially appears as a white mold beginning at
the base of the ear. The mold and the kernels then turn a grayish brown
color and rot the entire ear. Diplodia ear rot occurs most often in fields
under reduced tillage where corn follows corn.
Gibberella ear rot is caused by the fungus Gibberella zeae, also known as
Fusarium graminearum. It can be identified most readily by the red or pink
color of the mold. In some cases, the color appears white. It usually begins
at the tip of the ear. Gibberella will sometimes rot the entire ear.
Gibberella ear rot infections occur more commonly when the weather is cool
and wet after silking and through the late summer. Gibberella can produce
vomitoxin and zearalenone.
Informativ webpages with lots of links:
just one example on fumonisins:
Fumonisins are toxins produced by Fusarium species that grow on several
agricultural commodities, mainly corn, in the field or during storage. The
disease, Fusarium kernel rot of corn, is caused by Fusarium verticillioides
and F. proliferatum, common producers of fumonisin.
More than ten chemical forms of fumonisins have been isolated, of which FB1
is the most prevalent in contaminated corn and is believed to be the most
Fusarium is also important in human medicine
So far the story (the previous debate infos not repeated here) about the Bt
crops reducing mycotoxin contents.
A much wider, excellently documented perspective is given in
Gressel, J., Hanafi, A., Head, G., Marasas, W., Obilana, B., Ochanda, J.,
Souissi, T., & Tzotzos, G. (2004)
Major heretofore intractable biotic constraints to African food security
that may be amenable to novel biotechnological solutions. Crop Protection,
23, 8, pp 661-689
see my comments in:
It should be noted that in developing countries the mycotoxin problems are
serious due to infections in the field, but also due to the serious problems
of post harvest diseases.
and finally a link to the enhanced, nearly doubled bibliography, it contains
mycotoxin papers related to agriculture.
Bibliography extracted from the Web of Science 27. August 2004,
keywords maize, mycotoxin, fumonisin, transgenic, enhanced with lots of
references and cross references from correspondence with Debate
Klaus Ammann: email@example.com
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