Well bred

who would have thought that bacterium genes could one day make rice hardy? Biologists from New York-based Cornell University have made this possible. To make a rice strain resistant to drought, cold and salt water, they have fused two genes from the Escherichia coli bacterium, and then inserted them into the plants of a common rice species.

The biologists emphasise that the technique, which involves adding genes to synthesise a naturally occurring sugar called trehalose, should satisfy critics of genetically modified foods, because the chemical composition of the edible parts of the plants remains unchanged. "We have demonstrated the feasibility of engineering rice for increasing tolerance when faced by stress conditions,' says Ray J Wu, professor of molecular biology and genetics at the Cornell University.

The biologists introduced the genes into indica rice varieties, which represent 80 per cent of rice grown worldwide, and include the widely eaten basmati. But the same strategy, they note, should also work in japonica rice varieties, as well as in a range of other crops, including corn, wheat, millet, soybeans and sugarcane.

Ajay K Garg, the lead author of the study, says trehalose synthesis is the basis of their technique. Trehalose is a simple sugar that is produced naturally in a wide variety of organisms, including mushrooms and many invertebrates. But there is normally not much trehalose in plants, with the exception of the so-called resurrection plants that can survive prolonged droughts in the desert. Drought-stressed resurrection plants look like they are dead and gone forever. They pop back to life when moisture is available. "That's the power of trehalose, and it gave us an idea to help important crop plants survive stress,' Garg says.

Previous attempts in other laboratories had used only one gene. Therefore, these experiments had been less successful with the resulting transgenic plants showing so-called