Cotton may help feed half a billion

US researchers have genetically engineered cotton plants that produce toxin-free seeds, potentially unlocking enough nutritional content to feed half a billion people worldwide each year.

Lead author Keerti Rathore from the Institute for Plant Genomics and Biotechnology at Texas A&M University in College Station said that every kilogram of fibre produced from cotton also yields 1.65 kilograms of seed packed with high-quality protein.

So it may be helpful in meeting the protein requirements of millions without any reduction in the output of cotton fibres.

Cottonseed is under utilised due to the presence of gossypol, a toxic molecule belonging to a class of organic chemicals known as terpenoids.

But the scientists have managed to disrupt a key enzyme, and cut the gossypol content in cottonseeds by 98 per cent by using RNA interference technology.

They say that the absence of the toxin is heritable, and that plants lacking gossypol could be suitable for largescale agricultural use.

"What the research does is open up that vast amount of underutilised resource for either direct use as human food or indirect use by making this cottonseed non-toxic to say, chickens, pigs or fish," Nature magazine quoted Rathore as saying.

Deborah Delmer, associate director of the Rockefeller Foundation in New York City, points out that a benefit of using RNAi technology is that it turns off a gene process rather than switching on a novel function.

"So instead of introducing a new foreign protein, you're just shutting down one process. In that sense, I think that the safety concerns should be far less than other GM technologies," Delmer said.

However, the researchers are yet to find out how stable the suppression of toxin will be over many generations.

Rathore thinks that RNAi opens great promise for various other crops that also contain harmful compounds, but may provide a huge source of nutrition if they do not have toxins.

He says that the gossypol-free cotton seeds could be roasted and salted. The meal could also be mixed with flour from wheat, corn, millet or sorghum to provide a protein source in bread.

The authors are hopeful that the crop will catch on, despite current social resistance, to genetically modified crops.

"Not right away, but at least 10 or 20 years down the line, I think people will accept it," Rathore says.

The study has been published in the Proceedings of the National Academies of Science.