www.checkbiotech.org ; www.raupp.info ; www.czu.cz

About 100 km north of Durban, South Africa, in a greenhouse chamber no
larger than a walk-in closet, Frederik Kloppers clips a slender vial to a
baby maize plant's new leaf. Inside the tube sits an insect with a
potentially deadly bite, at least deadly to corn, January 2007 by Gunjan
Sinha.

This African leafhopper (Cicadulina mbila) carries maize streak virus, a
scourge endemic to sub-Saharan Africa that devastates fields. Kloppers, a
plant pathologist and technical manager at Pannar Seeds in Greytown, South
Africa, gathers a dozen more tubes from the insect house and clips them to
additional plants. Tomorrow, after the bugs have eaten their fill, he'll
remove the tubes and then wait.

The fruit of more than a dozen years of effort, these maize plants have been
genetically altered to resist infection by the virus. In greenhouse studies
so far, the plant is highly resistant. If it proves equally hardy in field
trials scheduled to begin in late 2007, it would be a milestone: the
first-ever genetically modified (GM) crop developed by Africans for Africa.

But Kloppers and the plant's inventors, microbiologist Jennifer Thomson,
virologist Edward Rybicki, and collaborators at the University of Cape Town
(UCT), have much larger goals in mind. In a region where chronic hunger is
the norm, GM maize could help alleviate grain shortages and potentially even
boost economic development, says Thomson. And because plans call for selling
the seed to small-scale and subsistence farmers for minimal profit, the
inventors also hope it will help burnish the dim reputation of GM
technology.

None of that is assured, Thomson and Rybicki concede. The plant could still
fail in the field, as other African GM crop varieties such as sweet potato
and cassava have done. The failures not only have disappointed the
technology's advocates, but they've also fanned the flames of anti-GM
sentiment. Although South Africa is one of the few African countries to
permit farmers to plant GM crops within its borders, naysayers there, who
still have substantial clout, have condemned the technology as a mere
moneymaking tool for Western companies. Moreover, they remain unconvinced
that homegrown efforts such as UCT's maize will succeed. Another failure
would give anti-GM groups even more ammunition. The stakes are high, and the
UCT scientists are treading carefully.

The problem
Maize is not native to Africa. It likely sailed across the Atlantic from the
New World as cargo during the early 1500s, according to historian James
McCann of Boston University. Maize flourished and displaced other native
crops during the 20th century because it grows in only a few months and
requires relatively little labor--one pass of the plow instead of the three
or four necessary for crops such as sorghum and millet. In sub-Saharan
Africa, maize has become the staple food; it makes up more than 50% of
calories in local diets. In Malawi alone, maize occupies 90% of cultivated
land and accounts for 54% of Malawians' caloric intake.

Maize streak virus is likely homegrown, say scientists. It lives in native
grasses. At some point, the virus adapted itself to maize and is now able to
jump between grasses and corn through the bite of an infected leafhopper,
which itself isn't sickened by the virus.

Like any other infection, the wrath of maize streak waxes and wanes with
different environmental conditions. Some years, crop losses are minimal. But
in bad years, such as 2006, it can wipe out from 5% to 100% of a farmer's
maize crop.

For the past 25 years, African crop scientists have been trying to breed
resistant maize by crossing plants that carry some degree of natural
resistance. But the task has not been wholly successful. The trait is
conferred by several genes on different chromosomes and isn't consistently
transmitted to the next generation. "It's not quite clear how resistance
genes are inherited," says Kloppers of Pannar Seeds. Moreover, traditionally
bred varieties do not completely resist the virus, Kloppers explains. Many
tolerate an infection but still produce stunted or deformed cobs.

A solution
In 1988, when Thomson took over as head of microbiology at UCT, GM
technology seemed a perfect solution. Rybicki's plant virology group there
was already intensively studying the virus. Perhaps they could engineer a
way to stop it in its tracks?

The design seemed simple enough: The team studied the proteins necessary for
the virus to replicate. If they inserted a mutated viral gene into the
plant, which in turn expressed a mutated protein necessary for the virus to
replicate at very high levels, it could beat out the virus's normal protein
and immobilize the virus, they reasoned.

But getting the genes in proved tough, Thomson says. The UCT team first
tried infecting maize with a widely used vector, Agrobacterium tumefaciens,
carrying the genes, but to no avail. Ultimately, they successfully shot DNA
into the plant using a gene gun. The GM maize plant carries a mutated form
of a gene from the maize streak virus and two additional regulatory genes,
one derived from maize itself and another from Agrobacterium.

Into the field
That was 6 years ago. Since then, the UCT scientists have been working
closely with Kloppers at Pannar Seeds to test the plant's hardiness against
infection. Kloppers has bred a previous version of the plant that carried an
antibiotic-resistance gene through four generations. So far, it resists
infection consistently. Moreover, the trait appears to be inherited in a
dominant fashion.

Kloppers is repeating the experiment with a new group of plants that,
because of environmental safety concerns, no longer carry an
antibiotic-resistance gene. He expects to carry on crossing and checking
inheritance and resistance through the next few months. Provided there are
no major setbacks, he expects to apply for field trials during the latter
part of this year.

Field trials are crucial to assess environmental and health risks, says
Dionne Shepherd, a UCT postdoc who has been working on the project for the
past 10 years. The scientists plan to examine whether the crop affects soil
microorganisms and also whether it affects insects that feed on it. Other
studies will also ensure that the added protein is indeed digestible and not
an allergen.

If all goes well, the resistant maize will be the first GM crop to be
field-tested in South Africa; to date, all GM crops planted in the country
have been developed and tested elsewhere. The government is now developing
its own expertise to evaluate environmental and human safety, says Shepherd,
and because "UCT's maize is the most advanced locally produced GM product,
they want to use our plant as a guinea pig," she adds.

To avoid the pitfalls that have beset other African GM crop varieties, the
UCT scientists and Pannar have been working with regulators all along. At
stake, they say, is not only their crop's fate, but also the technology's
reputation.

A few years ago, Kenyan scientist Florence Wambugu, who was trained and
supported by Monsanto, developed a sweet potato plant resistant to the
feathery mottle virus. But when scientists field-tested the crop,
traditionally bred resistant varieties outperformed it. Other efforts have
also stumbled during field tests. Just a few months ago, scientists at the
nonprofit Donald Danforth Plant Science Center in St. Louis, Missouri,
announced that cassava plants genetically modified to resist cassava mosaic
disease lost the trait after a few generations.

Both setbacks have fueled ongoing skepticism about GM technology. "All this
talk about the technology's benefit for Africa is just a lot of PR hype to
garner funding," says Mariam Mayet of the African Centre for Biosafety, an
anti-GM lobby group in Richmond, South Africa. Most of the GM crops in the
world are grown for animal feed or go toward food aid, Mayet says. "The
benefit mainly goes to industrial agriculture, not to small-scale farmers."

Because UCT's maize is homegrown and was supported with very little
corporate money--Pannar was the project's only corporate
contributor--Thomson and Rybicki hope it can dodge some of these criticisms.
Private foundations that typically give money with no strings attached and
the South African government funded the project's bulk. To recoup its share
of investment, Pannar expects the seed to cost no more than 15% higher than
non-GM seed, says Kloppers. Small-scale or subsistence farmers would likely
be charged much less, he adds.

If UCT's plant succeeds, it would be the first GM crop developed by a
developing country. But Africans might not be the only beneficiaries. It
might also become the poster child of what many argue is a useful and
important technology--and for better or worse, one that desperately needs a
public relations makeover.

[www.sciencemag.org]