Tomato altered to thrive in salty water and soil

By Prithi Yelaja
July 31, 2001 Toronto Star

'Since environmental stress due to salinity is one of the most serious factors limiting the productivity of crops, this innovation will have significant implications for agriculture worldwide.'

In a breakthrough that could boost global food production, scientists at the University of Toronto have genetically engineered the first plant able to grow in salty water and soil.

Researchers grew the tomato plant in the university's greenhouse after injecting it with a single gene from the plant Arabidopsis, a relative of the cabbage.

The gene controls a protein that is able to corral excess salt before it inflicts damage on a plant.

The genetically engineered tomato imprisons the salt in compartments within its cells and also removes salt from the soil.

It can grow and produce fruit even in water that is 50 times saltier than normal, or about one third as salty as sea water.

While the leaves of the tomato plant contain high levels of salt, the fruit is unaffected by the sodium. These tomatoes offer hope that other crops can also be genetically modified for planting in parts of the world that have salty irrigation water and salt-damaged soils, said lead researcher Eduardo Blumwald, of the University of California at Davis.

"Since environmental stress due to salinity is one of the most serious factors limiting the productivity of crops, this innovation will have significant implications for agriculture worldwide," he said.

The creation of a salt-tolerant plant addresses one of agriculture's key problems. While irrigated lands make up about 15 per cent of the world's agricultural land, salinity limits crop production on 40 per cent of that land because salt is toxic to crops. Water used for irrigation picks up salt from the ground and leaves it in the crop soil.

"It is a problem that does seem to be getting worse," said Stanley Wood, a scientist with the International Food Policy Research Institute in Washington, D.C.

"Anything that increases the productivity of those lands would obviously be a major breakthrough," he said.

An estimated 10 million hectares of agriculturally productive land around the world is lost annually because of irrigation-induced salinity.

This constant loss of farmland is on a collision course with the expanding global population, said Blumwald, whose research appears today in the journal Nature Biotechnology.

Blumwald said the salt-tolerant tomato plants could be available commercially within three years.

Blumwald and University of Toronto postdoctoral fellow Hong-Xia Zhang said they worked with the tomato plant because it was easy to manipulate genetically. They said they are now working with canola.