Andy Coghlan
A SIMPLE sugar could come to the rescue of poor farmers whose soils are too salty, drought-ridden or cold to support crops.
The sugar, called trehalose, already enables a desert stalwart, the so-called 鈥渞esurrection plant鈥�, to spring miraculously back to life when rain arrives. Now, with the help of a pair of genes borrowed from a bacterium, biotechnologists have found a way of altering rice so that it makes its own trehalose.
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Ironically, the breakthrough coincides with a warning from Tewolde Gebre Egziabher, the head of Ethiopia鈥檚 environmental protection agency, that genetically modified crops could harm local food production and African export markets.
Millions of hectares of crops are lost every year through drought or soil salinity. To produce a plant that survives such conditions, molecular biologist Ray Wu at Cornell University in New York state and colleagues in South Korea equipped basmati rice with two genes from Escherichia coli that produce trehalose.
The sugar is thought to protect plants growing in salty, dry and cold conditions by stabilising proteins and helping to maintain the balance of nutrients and minerals vital for photosynthesis. Previous attempts to engineer plants to make their own trehalose failed miserably, with plants ending up shrivelled.
But unlike past attempts, which kept the trehalose genes turned on throughout the plant at all times, Wu鈥檚 team used a genetic switch to activate the sugar-producing genes. So the genes are turned on only when the plant is stressed, say by lack of water.
In trials, Wu鈥檚 rice survived easily in conditions that killed ordinary rice. The growth rates and weights of the altered rice plants were just 20 per cent below normal when they were exposed to salty, cold or dry conditions. Unaltered plants died or at best struggled to grow at 20 or 30 per cent of their normal rates.
Although Wu鈥檚 plants will not produce rice grain for another six months, he is confident that the yields will be high, and that the same approach will succeed with other types of rice and other crops. 鈥淲e think it will work with other cereal crops such as wheat or maize,鈥� he says.
But not everyone approves of the breakthrough. Opponents of genetic engineering claim it is too soon to bring in the altered rice. 鈥淲hat we should be arguing about is the extent to which these crops might affect livelihoods, the environment and human health,鈥� says Patrick Mulvany of the British sustainable development charity Intermediate Technology Development Group. But Wu believes such resistance will not last long. 鈥淭hose opposed to GM foods will object, but I hope that in a few years the issue will be resolved,鈥� he says.
The project is backed by the Rockefeller Foundation in New York City, and is aimed specifically at helping poor farmers. 鈥淲e have an agreement that if anything comes of the project, it will be freely available to any developing country,鈥� says Wu. He thinks that modified rice will be ready for farmers within about three years.
The results appear in the online edition of the Proceedings of the National Academy of Sciences (DOI: 10.1073/pnas.252637799).