Researchers from the University of Copenhagen have discovered that
plants can change their root direction and grow away from saline areas.
This discovery changes current understanding of how plants change their
shape and growth direction and may help alleviate the accelerating
global problem of high soil salinity.

Professor Staffan Persson of the University of Copenhagen's Department
of Plant and Environmental Sciences said that the world needs crops that
can better withstand salt. He added that plants can make their roots
grow away from saline areas, but it is unclear how this mechanism works.
With research colleagues, Professor Persson discovered exactly what
happens inside plants at a cellular and molecular level as their roots
grow away from salt. The research group discovered that when a plant
senses local concentrations of salt, the stress hormone abscisic acid
(ABA) is activated, setting into motion a response mechanism.

Professor Persson explains that plants have a stress hormone triggered
by salt. This hormone causes a reorganization of the tiny protein-based
tubes in the cell, called the cytoskeleton. The reorganization then
causes the cellulose fibers surrounding the root cells to make a similar
rearrangement, forcing the root to twist in such a way that it grows
away from the salt. The researchers mutated a single amino acid in a
protein that drives the twisting of the root, reversing the twist so
that the plant could not grow away from the salt.

[news.ku.dk]