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21 Nov 2006 10:17
Scientists have found a way to use the cotton plant, long a source of fibre for clothing but inedible by humans, to feed potentially half a billion people a year.
Texas A&M University plant biotechnologist Keerti Rathore and colleagues reported on Monday they have genetically altered the plant to reduce the levels of the toxic chemical gossypol in cottonseed, making it fit for human consumption.
“It actually tastes pretty good. It reminds me of chickpea.
It’s a fairly good-tasting seed,” Rathore said in an interview.
“It tasted better than soybean, I can tell you that,” added Rathore, who admitted he had not tasted it until being asked repeatedly about its flavour in the days before the research was published in the journal Proceedings of the National Academy of Sciences.
The new-and-improved cottonseed could be ground into flour and made into bread and other foods, Rathore said.
Rathore and his team turned to a technique also being used in cancer and HIV/Aids research—so-called RNAi or RNA interference technology that can “silence” a gene—to cut the amount of gossypol in the cottonseed, home to significant amounts of protein.
The researchers left gossypol intact in the remainder of the plant because it guards against insects and disease.
“So the trick is not to affect the levels of these compounds in the rest of the plant, but eliminate it from the seed only. And that’s what we have done,” Rathore said.
This cottonseed could serve as a high-protein food for the world’s hungry, and falls well within the criteria set by the World Health Organisation and United States Food and Drug Administration for food consumption, the researchers said.
“Potentially, if all of the cottonseed today which is produced can be utilised for human nutrition directly, it can meet the protein requirements of 500-million people on an annual basis,” Rathore said.
“That is a lot of protein right now really being wasted,” he added, noting that cottonseed often is fed to cattle because bacteria in their stomachs can break down gossypol.
The chemical is present naturally within the glands in the above-ground parts of the cotton plant.
For millennia, people have spun cotton fibres into clothing and other fabrics. But for each half a kilogram of cotton fibre, the plant produces 0,7kg of seed, Rathore said.
About 44-million metric tonnes of cottonseed is produced throughout the world annually, and it has 21% oil and about 23% protein.
Cotton is grown in more than 80 countries worldwide. With the exception of the United States and Australia, Rathore said, it is grown primarily in developing countries.
Researchers estimate that it will take at least another decade to develop cotton varieties with these qualities for broad commercial production.
In the 1950s and 1960s, agricultural scientists bred cotton varieties that had no gossypol glands, but they were a commercial flop because the absence of the toxin made the plants too vulnerable to insects and disease.
US scientists Andrew Fire and Craig Mello won the Nobel Prize for Medicine this year for their discovery of the RNAi technique. In addition to edible cottonseed, the technique might be applied to other crops with toxic components, such as fava beans, to increase their use, the researchers said. â€’ Reuters
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