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US scientists have identified a gene from wild wheat that could increase
protein and micronutrient content of its cultivated cousin by 10 to 15
per cent, and could soon be used in food products with enhanced
nutritional value, November 2006 by Stephen Daniells.

?The reintroduction of the functional gene from the wild species into
commercial wheat varieties has the potential to increase the nutritional
value of a large proportion of our current cultivated wheat varieties,"
said lead researcher Professor Jorge Dubcovsky from the University of
California, Davis.

Over two billion people are reported to be deficient in zinc and iron,
and more than 160 million children under the age of five lack an
adequate protein supply, according to the World Health Organization.

The development and commercialization of this nutrient-rich wheat could
therefore lead to a range of functional bakery with enhanced nutritional
profiles.

The focus of the study is the gene GPC-B1, so-called for its effect on
Grain Protein Content, found to be non-functional in all the cultivated
pasta and bread wheat varieties analyzed by the researchers. This
suggested that the functionality of the gene was lost during the
domestication of wheat.

To test if the gene is responsible for accelerating grain maturity and
increasing protein and micronutrient content, the researchers used a
technique called RNA interference to create GM wheat lines with
decreased levels of the GPC gene.

The researchers report in the new issue of Science that the transgenic
experimental plants had significantly reduced levels of protein (30 per
cent), zinc (36 per cent), and iron (38 per cent), compared to the
non-transgenic controls.

"The results were spectacular," said Dubcovsky. "The grains from the
genetically modified plants matured several weeks later than the control
plants and showed 30 percent less grain protein, zinc and iron, without
differences in grain size. This experiment confirmed that this single
gene was responsible for all these changes."

Having shown that gene was behind the accelerated maturing and increased
protein, zinc and iron content, Dubcovsky and his collaborators in the
Wheat Coordinated Agricultural Project are now racing to introduce the
GPC-B1 gene into U.S. wheat varieties using a rapid-breeding technique
called Marker Assisted Selection.

The new varieties, bred by conventional rather than transgenic methods,
used wild emmer wheat (Triticum turgidum ssp. dicoccoides), ancestor of
cultivated pasta wheat (T. turgidum ssp. durum).

Several breeding programs are reported to have already used the GPC-B1
gene to develop elite breeding lines, which are close to being released
as new wheat varieties.

Such varieties are now being tested by breeders in multiple environments
to determine if the introduction of GPC-B1 has any negative impacts on
factors such as yield and quality, and the researchers hope that these
will soon translate into food products with enhanced nutritional value.

And concerns associated with transgenic crops are not valid with the new
wheat variety, because: ?The resulting varieties are not genetically
modified organisms, which will likely speed their commercial adoption,?
said a statement from the University of California, Davis.

"Wheat is one of the world's major crops, providing approximately
one-fifth of all calories consumed by humans, therefore, even small
increases in wheat's nutritional value may help decrease deficiencies in
protein and key micronutrients," said Dubcovsky.

Enhancement of the nutritional content of plants is gaining ever
increasing scientific attention, with a number of traditionally
cross-bred and genetically modified plants and crops coming to light
considered to offer human health benefits, including zeaxanthin to
potato tubers, and the omega-3 fatty acid, eicosapentaeoic acid (EPA),
to soybeans and brassica, and stearidonic acid (SDA) in canola crops.

Source: Science, 24 November 2006, Volume 314, pp. 1298-1301, ?A NAC
gene regulating senescence improves grain protein, zinc, and iron
content in wheat?, Authors: C. Uauy, A. Distelfeld, T. Fahima, A.
Blechl, J. Dubcovsky

www.checkbiotech.org

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