Washington: Plants, very much like humans, have to cope with stress - and scientists are in the process of developing plants that handle stress better, says a new study.

For plants, stress comes in the shape of too much salt or too little iron, both widespread environmental challenges for crops around the world.

"High salinity and low iron are both important problems for food security, particularly in developing countries," said Philip Benfey of the Duke Institute for Genome Sciences and Policy.

New evidence might provide clues for developing crop plants better equipped to deal with high salt levels and capable of incorporating more iron in times of scarcity.

It also speaks to a more general principle: that a cell's identity largely determines how it will cope with circumstances outside.

Salt contamination is a problem for more than half the world's arable land and a particular one in parts of Asia now recovering from the tsunami of 2004, said Benfey.

On the other hand, iron-deprived crops present problems for people in developing countries who depend heavily on vegetables for the essential nutrient.

In the many previous studies of plants' response to salt, iron and other stresses, "the plant is generally taken as a single, homogeneous entity", Benfey said.

"We've asked if that is appropriate, and the answer is a very loud and clear no."

Benfey examined cells taken from the roots of the model mustard plant Arabidopsis after they were exposed to high salt or low iron.

Genomic profiles of root cells taken from the various zones revealed highly specific reactions to each of the stresses. Out of the thousands of plant genes, only 244-those that set cells' identity-held steady with either stress.

The results show that the vast majority of plant genes rise and fall in activity as a reaction to the prevailing environment.
"It shows that there are core genes and there are responsive genes - there is both a hard-wired part and a part that is extremely sensitive to the environment," Benfey said.

And, he added, the precise divide between the two might depend on where exactly you happen to look. IANS