A WAY of breeding trees and crops that can survive in the increasingly salty
soil of much of the world鈥檚 farmland has been discovered by researchers in
Israel. They have managed to make trees more salt-tolerant, and are now seeing
whether the trick will work with crops such as tomatoes, too.
According to some estimates, more than half of the world鈥檚 agricultural land
will become saline in the next half-century. In countries like Israel, where
fresh-water supplies are already overexploited, farmers are being forced to use
salty water for irrigation and will have to use even more in the future. All of
which makes the development of salt-resistant crops and trees essential, says
Arie Altman of the Institute of Plant Sciences and Genetics in Agriculture of
the Hebrew University in Rehovot.
His team has isolated a protein called BspA that helps trees grow in salty
conditions. The protein was discovered in a common European aspen, Populus
tremula, which produces BspA when growing in salty soil. The researchers
think the protein may protect cells from high levels of salt by attracting water
molecules and also by binding to other cell proteins, though they are still
trying to work out the exact mechanism involved.
Advertisement
The researchers managed to increase the aspens鈥� salt tolerance by giving them
more copies of the gene for the protein. While normal aspens shed their leaves
about five days after being exposed to very salty conditions, trees with extra
BspA genes hang onto them for up to 10 days, Altman says. The team is
now transferring the BspA gene to tobacco and tomato plants to see
whether it can make these plants more salt-tolerant too.
However, Altman suspects that many plants already have the BspA
gene. If so, it may not be necessary to genetically engineer the gene into
crops. 鈥淥nce you have a molecular probe for the gene you can use it also in
traditional breeding techniques to speed up selection. By developing molecular
tools you can screen out the trees in which the gene is being expressed the
most,鈥� he says.
Altman鈥檚 work is significant, says Dorothea Bartels of the Max Planck
Institute for Plant Breeding in Cologne and the University of Bonn. Discovering
how a tree protects itself against high salt levels is a major advance, she
says, as most work has focused on other plants.
Altman鈥檚 team is also trying to uncover the secrets of a tree that handles
salt even better than the aspen. The Euphrates poplar, Populus
euphratica, survives in the salty soil near the Avdat spring in Israel.
While part of its tolerance may be due to BspA, Altman suspects the tree uses
other tricks as well.