Which regulatory protein does calcium bind

Martin-Luther-University Halle-Wittenberg

Number 110/2018 from September 5, 2018
Plant researchers at the Martin Luther University Halle-Wittenberg (MLU) have found evidence that calcium in plants regulates photosynthesis in addition to other processes. So far it was not known how this substance got to its site of action. Prof. Dr. Edgar Peiter and Prof. Dr. Sacha Baginsky have identified transport proteins that perform this task. They are essential for efficient photosynthesis and thus for the growth of plants. The researchers have bundled their results in a publication that appeared in the specialist journal "New Phytologist". A follow-up project aims to clarify the importance of these transport proteins in crops.

During photosynthesis, energy-rich biomolecules and oxygen are generated from carbon dioxide and water with the help of light energy. This makes it a central physiological process in plants and the basis of life on earth. If a parameter is varied in this biological machinery, it can cause far-reaching changes. "It is a widespread misconception that it has already been understood in all its facets. Above all, its regulatory mechanisms have by no means all been deciphered," says Prof. Dr. Sacha Baginsky from the Institute of Biochemistry and Biotechnology.

This is especially true for calcium-dependent signal conduction. Calcium regulates cellular processes in all organisms by binding to special proteins, which changes their function. With their project, which was funded as part of the Collaborative Research Center 648 "Molecular Mechanisms of Information Processing in Plants", the Halle researchers were able to show that calcium also has a decisive influence on photosynthesis in the model plant thale cress. In particular, the question of how the plant manages to transport the calcium involved in the metabolism to its place of action in the chloroplasts has not yet been clarified. The working groups of Peiter and Baginsky, with the participation of specialist colleagues from the university in Louvain-la-Neuve, Belgium, demonstrated in laboratory tests that the transport proteins that have now been found are in the membranes of the chloroplasts and that the calcium can get to where it is needed.

Calcium plays a crucial role in photosynthesis because it is essential for water splitting. It also reacts with enzymes and thus also influences the sugar metabolism of plants. "If you understand the regulation of these complicated physiological processes, you can try to optimize them," says Prof. Dr. Edgar Peiter from the Institute for Agricultural and Nutritional Sciences with a view to a potential practical application of these findings. "Growth, yield and the tolerance to stress from environmental influences such as drought can possibly be influenced by this."

"Application-oriented basic research" is what Peiter calls what has been brought to light within the framework of the interdisciplinary project. "We assume that through our work we have identified a central regulator of the functions of the chloroplast," says Peiter.

In a four-year follow-up project, it is now to be investigated whether the transport proteins found are also as important in crops such as grain and sugar beet as they are in thale cress and whether they can be used to improve the productivity and stress tolerance of these crops. The project is part of the international graduate school entitled "Determinants of Plant Performance", which has been based at MLU for a year and is funded with around two million euros from the European Structural and Investment Fund (ESF), in which eleven projects in the field of plant research are located.

The decoding of functional mechanisms plays a central role in plant research. Because only with this knowledge can agriculture and plant breeding react flexibly to changing environmental influences, which is becoming increasingly important against the background of climate change. Edgar Peiter: "Our state government has recognized this and is placing a strong focus on plant research."

To the publication:
Frank, J., Happeck, R., Meier, B., Hoang, MT, Stribny, J., Häuser, G., Ding, H., Morsomme, P., Baginsky, S. and Peiter, E. (2018 ), Chloroplast? Localized BICAT proteins shape stromal calcium signals and are required for efficient photosynthesis. New Phytol. doi: 10.1111 / nph.15407

 

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