We all know a plant carries out a crucial process- the photosynthesis. This process requires light. It wasn’t clear how plants show their unique response to light until a recent research published in Nature Communications unveiled the light-induced stomatal opening.
Understanding Stomata: Gateways of Plant Respiration and Photosynthesis
Stomata are tiny pores below and on the surface of a leaf. A pair of guard cells surround these pores, which are important for gas exchange between the leaves and the atmosphere. These cells respond to environmental stimuli in the form of light, humidity, and CO2. The stomatal opening, which increases the CO2 absorption by plants has a profound impact on the growth of the plant. Light induces the stomal cells to open through intercellular signal transduction. The opening of the stomata is crucial to harness solar energy through photosynthesis. The mechanism of stomatal opening was unknown at a molecular level. This is what scientists at the Nagoya University have now discovered.
Novel regulatory mechanism discovered: Light and stomal opening
Blue light falling on the surface of a leaf is perceived by phototropism in guard cells. The signal is communicated to different protein kinases and protein phosphate (PP1). This results in the phosphorylation of a Thr 948 (threonine at position 984) in the C terminus of H+ ATPase (present in the plasma membrane). This entire reaction activates the H+ATPase of the plasma membrane. Upon activation, the plasma membrane hyperpolarises and drives the uptake of K+. This also results in the uptake of water. As the water is uptake, it results in the swelling of the guard cells, arching away from each other. This enlarges the stomatal aperture.
Red light, similar to blue light also induces stomatal opening, but through the phosphorylation of pen-Thr. It is a threonine residue, part of the H+ ATPase in the plasma membrane of guard cells.
Thr 881: up close
Upon using extensive phospho-proteomic analysis on Arabidopsis thaliana, the phosphorylation of Thr 881 in response to red and blue light was observed.
Thr 881 along with Thr 948 is essential for the activation of enzyme H+-ATPase which helps activate stomatal opening. Furthermore, the presence of Thr 881 in leaves and shoots indicates it plays a broader role in plant physiology. It helps in the uptake of nutrients in the roots, transport of products of photosynthesis, and also helps in pollen tube elongation.
This crucial discovery opens up possibilities for manipulating plant physiology in specific ways. This can benefit the agricultural field and our environment. How?
Upon discovery of this crucial amino acid, we can control the opening of stomata by modifying this amino acid. We can also contribute to the promotion of plant growth, enhance CO2 absorption, and reduce the use of fertilizers.
For more details about this work, read the full article on Nature Communications.
Insightful, thanks for sharing!