Washington, D.C. Until now it has not been clear how salt, a scourge to agriculture, halts the growth of the plant-root system. A team of researchers, led by the Carnegie Institution's Jos Dinneny and Lina Duan, found that not all types of roots are equally inhibited. They discovered that an inner layer of tissue in the branching roots that anchor the plant is sensitive to salt and activates a stress hormone, which stops root growth. The study, published in the current issue of The Plant Cell, is a boon for understanding the stress response and for developing salt-resistant crops.
Salt accumulates in irrigated soils due to the evaporation of water, which leaves salt behind. The United Nations estimates that salinity affects crops on about 200 million acres (80 million hectares) of arable land and not just in developing countries, but areas such as California as well.
As Dinneny explained: "An important missing piece of the puzzle to understanding how plants cope with stressful environments is knowing when and where stressors act to affect growth."
Roots are intimately associated with their environment and develop highly intricate branched networks that enable them to explore the soil. The branching roots grow horizontally off the main root and are important for water and nutrient uptake.
The scientists grew seedlings of a laboratory plant (Arabidopsis) that is a relative of mustard using a custom imaging system, which enabled them to measure the dynamic process of root growth throughout the salt response. This ability to track root growth in real time led the scientists to observe that branching roots entered a dormant phase of growth as salt was introduced. To determine how dormancy might be regulated, Lina Duan surveyed the role of different plant hormones in this process and found that Abscisic Acid was the key signaling molecule.
"We are familiar with how animals use a fight or flight strategy to fac
|Contact: Jos Dinneny |