Where most people might look at a white-capped cotton plant and
see the makings of next year's T-shirts, Keerti Rathore sees food
for a hungry world.
Dr. Rathore and his colleagues have figured out how to make
poisonous cottonseeds fit for human consumption. The new, nontoxic
seeds could give 500 million people an additional source of high-
quality protein, the team estimates, if the genetically engineered
plant is approved for cultivation.
In principle, this approach could expand the array of plants or
plant parts humans could eat without heavy processing or precooking
preparation. Rathore's team virtually shuts off the gene responsible
for the toxin. The researchers don't replace the gene or add one to
get the desired trait. Thus, some researchers suggest, the technique
might be more politically palatable to people who oppose genetically
"This is a nice piece of work," says Steve Scofield, a molecular
biologist at Purdue University in West Lafayette, Ind. Still, he
cautions, "the biggest issue they've got is that this will be viewed
as a [genetically modified] plant. So there may be a public-
Crop scientists have been exploring the approach, known as RNA
interference, to reduce or eliminate compounds they have tied to
allergic reactions to foods.
Coming up with a toxin-free cottonseed "is not that
straightforward," says Rathore, who heads the Laboratory for Crop
Transformation at Texas A&M University. His team's results are
reported in the current issue of the Proceedings of the National
Academy of Sciences.
Scientists have pursued the goal for 50 years. Cotton is grown
worldwide, and for every two pounds of fiber, a cotton field also
yields slightly more than three and a half pounds of seed - totaling
some 44 million tons a year.
Cottonseed is the third-largest oil-seed crop in the world,
according to the US Department of Agriculture. But its oil requires
heavy processing for use in cooking. And the raw seeds are fit to
feed only livestock such as cows.
In the 1950s scientists stumbled onto a variety of cotton that
didn't have the toxin and bred it with commercial varieties.
"The seeds were good enough to eat," Rathore says. But without
the toxin, known as gossypol, the plant cannot defend itself against
pests and pathogens.
Thus, for Rathore and colleagues at the USDA's Southern Plains
Agricultural Research Center, gossypol became a prime target for RNA
silencing - a technique for switching genes off that earned two US
scientists a Nobel Prize this year. …