2. May 2023

Marketa Samalova and her colleagues, led by Jan Hejatko from CEITEC Masaryk University, have elucidated the effect of expansin on the root growth of the model plant Arabidopsis thaliana (thale cress). Their findings (stiffening of the call walls due to expansin overproduction) were surprising for the scientific community, as the original hypothesis assumed the opposite. The results could lead to an improvement in plant production or an increase in plant resistance to stress. The study is a collaboration of an international team of top scientists from several institutions in the Czech Republic, France, Germany, Austria and Russia and was recently published in the prestigious journal Plant Physiology (Oxford University Press).

Cell elongation is a fundamental process that enables plant growth. However, unlike in animals, plant cells are enclosed by a cell wall that limits the enlargement of plant cells. Expansins are proteins that allow plant cells to expand by loosening the structure of the cell wall. These proteins are not only important for plant growth and development but are also involved in responses to various types of stresses. Although the first expansins were identified more than 30 years ago, their mechanism of action is still unclear.

The research team led by Jan Hejatko from CEITEC MUNI wanted to find out more about how expansins work and how they control cell elongation, especially during root growth. They investigated in which parts of the model plant Arabidopsis expansins are produced, how their production is controlled by plant hormones and how they affect plant growth.

They found that different parts of the root are characterised by different types of expansins.  They were the first worldwide to show their localisation in specific regions of the walls of different cell types in living plants. Using a new technique called Brillouin imaging, they found that when the production of one of the expansin types increased, the root cell walls were stiffer and grew less. This was a very surprising finding and contradicted the original hypothesis, which had assumed the opposite.

Using advanced biophysical and genomic techniques, members of the research team described the ability of expansins to induce changes in cell wall composition, pointing to a previously unknown mechanism of action of these proteins in regulating plant cell growth. These findings help scientists understand how plants control their growth and could lead to new ways to improve crop yields.

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