28 July 2009

GM crop could thrive on salty soils

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Scientists have genetically modified plants to tolerate high levels of salt – offering one potential solution to growing food in poor conditions.
common wheat

Experts hope that plants such as common wheat (pictured) could be made to thrive in arid and poor conditions with the right genetic modifications. Credit: Wikimedia

LONDON: Scientists have genetically modified plants to tolerate high levels of salt – offering one potential solution to growing food in poor conditions.

The researchers inserted a gene to remove salt – in the form of sodium ions – from water taken up by the plant before it reaches the leaves, where it does most damage. The research is published this month in the journal The Plant Cell.

High salinity reduces crop yields on irrigated land, where one-third of the world’s food is produced, and in semi-arid regions such as the Middle East.

Salt diverter

Mark Tester, a scientist at the Australian Centre for Plant Functional Genomics at the University of Adelaide, and co-workers developed a GM salt-tolerant Arabidopsis thaliana plant (thale cress, a species used for research) by introducing a gene into its root that diverts sodium ions into the roots rather than the shoots.

Plants minimise the accumulation of salt naturally, but the gene decreased salt levels in the shoots by up to two-thirds. “We’ve used genetic modification to amplify the process, helping plants to do what they already do – but to do it much better,” says Tester.

The main challenge is applying the technique to crop plants. He said the Arabidopsis gene has already performed well in rice, and the researchers are currently analysing rice, barley and wheat plants containing their own versions of the gene.

Tester says the freely available technology can also alter the accumulation of other chemicals, with implications for human nutrition, plant growth and phytoremediation – using plants to soak up pollutants from soil – all of which are important for developing countries.

Cautious welcome

Rowan Sage, professor of physiological plant ecology at the University of Toronto, in Canada, cautiously welcomed the news, and said: “This is a promising approach to mildly improving salinity tolerance in crops.”

“However, I am sceptical it will produce true [salt-tolerant] crops. Sodium exclusion is but one salinity tolerance mechanism. If a plant has a very strong sodium exclusion mechanism … there are costs in terms of reduced growth potential,” he added.

“One might be able to grow rice on a salty soil, but the yield may not be worth it. The big advantage will be on mildly salty soils where the yield is repressed in non-tolerant crops.”

Genetically modified crops that can grow on poor soils could be the key to boosting crop yields and preventing famine in some developing nations.

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