www.czu.cz ; www.raupp.info

CIMMYT took a historic step in March 2004 by planting a small trial of
genetically engineered wheat in its screenhouse at headquarters in El Batan,
Mexico. It was the first time that transgenic wheat has been planted in
Mexico under field-like conditions, and encouraging results have spurred
plans for a more extensive follow-up trial, October 2004.

Striving for Drought-Tolerant Wheat

Researchers used genetic engineering to insert a gene from Arabidopsis
thaliana, a relative of wild mustard, into wheat. The gene, DREB1A, was
provided by the Japan International Research Center for Agricultural
Sciences, and has been shown to confer tolerance to drought, low
temperature, and salinity in its natural host. The small trial completed
this year was conducted in full accordance with Mexican and CIMMYT biosafety
procedures, and represents a critical step toward developing
drought-tolerant wheat varieties by allowing scientists to see how the
DREB1A-expressing wheat responds under more natural conditions.

?When a plant is exposed to drought, there can be moisture stress, but there
can also be heat or soil micro-element deficiencies or toxicities.? Because
there are so many stresses, it is important to evaluate a potential solution
under a variety of environments. Moreover, scientists are discovering that
plants react to numerous stresses, especially to water deficiency and high
levels of salt, in complex ways.

Encouraging and Consistent Results

Looking at the trial results, Pellegrineschi and colleagues were encouraged
when they observed a more normal, non-stressed phenotype in the transgenic
lines under drought conditions. Near the trial?s end, the non-DREB control
wheat was dry, yellow, and shriveled, while the DREB wheat was still green
and thriving. Pellegrineschi was surprised that a single gene could bring
about such a visible response.

Pellegrineschi says the results of this trial, which is part of CIMMYT?s
joint work with the Australian Cooperative Research Centre for Molecular
Plant Breeding, are compatible with previous observations from small pots in
the biosafety greenhouse. Many of the measured traits correlated with the
improved performance of transgenic lines under water stress. However, the
results need to be verified in a larger field trial with selected transgenic
lines.

Taking Precautions

This is the first time that a food crop carrying the DREB1A gene has
advanced to this level of testing. The Mexican government, which had
announced a moratorium on planting transgenic maize under field conditions
in 1998, approved the trial in December 2003.

CIMMYT followed strict biosafety procedures and worked closely with the
government of Mexico in planning, conducting, and monitoring the trial.
Access to the screenhouse was restricted. The researchers covered all plant
flowers with bags and did not allow other wheat plants to grow within 10
meters of the trial, even though it is unlikely that self-pollinating wheat
plants would cross with each other. After the trial, all plant materials
except the harvested seed were destroyed.

What Next?

?This was the first trial transgenic wheat trial after the government
removed the moratorium on growing transgenic varieties under field
conditions, so we were very conservative in our request to the Mexican
authorities for approval of the initial trial,? says Pellegrineschi. ?Now
that we have had some success, we will submit a request for a larger trial.?

Pending approval from the Mexican authorities, researchers are ready to
begin a second trial, which will evaluate the best performing lines from the
first trial more closely. In response to lessons learned from the first
trial, the researchers are going to use a larger plot, have more
replications, and restrict walking and the resultant soil compaction in the
plots.

Five years ago, many people thought it was unrealistic that a single gene
could improve a complex trait such as drought tolerance. With the right
approaches, including the investment in proper field trials, Pellegrineschi
believes that it will be possible to produce lines containing effective
transgenes within five years.

Why Genetic Engineering?

With genetic engineering, useful genes for traits of interest can be
transferred across species. DNA can be directly inserted into individual
plant cells. The genetically altered tissue can be regenerated into complete
plants and later transferred through conventional breeding into entire lines
and varieties. This approach may also applied to rapidly and efficiently
transfer traits within species for either research or development purposes.
In both instances, CIMMYT remains committed to generating end-products that
carry only the gene(s) of interest?that is, the undesired genes (marker
genes) have been removed through conventional breeding.

Genetic engineering could increase the productivity and profitability of
farming through reduced input use (lowering costs), added pest or disease
resistance, and crops with better nutritional content or storage
characteristics. Also, genetic engineering may solve problems that
conventional breeding methods cannot. Nutritionally fortified crop varieties
could be especially valuable in developing countries where millions of
people suffer from dietary deficiencies.

Genetic engineering could become an important tool for introducing
beneficial traits into maize and wheat. Efforts such as the DREB wheat field
trail will allow our scientists to use a range of genes for the benefit of
farmers and to pass on the products of cutting-edge technology to research
partners in developing countries.

[www.cimmyt.org]

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