A team of German and Chinese researchers has shown, for the first time,
where and how plants detect potassium deficiency in their roots, and
which signaling pathways coordinate the adaptation of root growth and
potassium absorption to uphold potassium supply.

The absorption and transportation of potassium at the level of
individual cells have been well characterized, but it was unknown how
plants detect potassium availability in the soil. The researchers looked
at/Arabidopsis thaliana/plants which were transformed with the newly
developed potassium reporter protein GEPII. This reporter protein
enables the microscopic detection of the concentration and distribution
of potassium ions in cells and tissues. The research team found that the
concentration of potassium in the cytoplasm of the cells increased with
each cell layer within the root, from the outside to the inside.

They also found that in plants subjected to potassium deficiency, the
concentration of potassium is reduced only within certain cells in the
root tip. These cells in the root tip react extremely rapidly to
potassium deficiency and the concentration of potassium inside the cell
(in the cytoplasm) decreases within seconds. It had not previously been
known that a certain group of cells located centrally inside the root
tip reacts to a potassium deficiency in its surroundings. The
researchers named this group of cells "potassium-sensitive niche". They
have also visualized the path of potassium in a living organism.

Researchers show where and how plants detect the nutrient potassium
(uni-muenster.de)
[www.uni-muenster.de]