Unfavorable environmental conditions represent considerable stress for plants. A high level of salt content (sodium chloride, NaCl) in the soil is, for example, just such a stressor that has a negative impact on plants. Salinization is a serious problem in agriculture, especially in dry regions of the world.
Biologists at the University of Münster (Germany) have now discovered, for the first time, that salt stress triggers calcium signals in a special group of cells in plant roots and that these signals form a “sodium-sensing niche.” Also, the researchers identified a calcium-binding protein (CBL8) that contributes to salt tolerance, specifically under severe salt stress conditions. The results of the study have now been published in the journal Developmental Cell.
Prof. Jörg Kudla and his team at the Institute of Biology and the Biotechnology of Plants at Münster University studied the question of how plants measure the intensity of salt stress and how they react to it. The model plant they used for their tests was thale cress (Arabidopsis thaliana), which is a member of the largest group of flowering plants – the crucifers, or Brassicaceae. These include many food and forage plants such as cabbages, mustard, and radishes. “First of all,” says Jörg Kudla, “we examined Arabidopsis roots to see whether they had any type of cells which would react especially to salt stress or whether the entire root would show a uniform reaction. We also undertook investigations to see whether the intensity of the salt stress was reflected quantitively in the intensity of the calcium signal.”
The result surprised the experts: although the plant’s entire root system was exposed to stress, only a specific group of cells reacted – and only this group formed a so-called oligo-cellular calcium signal. This group of cells is located in the differentiation zone of the plant root and is formed by only a few hundred cells. Just for comparison: a root has many thousands of cells. Researchers call this area the “sodium-sensing niche.” “This group of cells,” Kudla explains, “is not visible, and we can only distinguish them functionally from other cells by means of high-resolution biosensor technology. It was a chance discovery which was extremely revealing – and significant.”
Read the complete research at www.eurekalert.org.