How plant cell compartments 'chat' with each other

November 04, 2015

A team of researchers led by scientists from the University of Bonn has discovered a basis of communication in plant cells: The 'MICU' protein controls the calcium ion concentration in the cellular power stations. Using these chemical signatures, the plants regulate, for instance, the formation of organs and react to water stress. The results may be used in the future to optimize agricultural crops. The reputable journal The Plant Cell reports on the results in its current issue.

Plants react to stimuli from their environment by specific responses: If available water becomes limiting, they curb evaporation from their leaves. If a pathogen attacks, they arm themselves with chemical weapons. If a soil fungus wishes to collaborate with a plant root for mutual benefit, both partners discuss their duties. "All of these fine adjustments require a great deal of communication between the individual compartments of the plant cell," says Dr. Markus Schwarzlaender, principle investigator of an Emmy Noether group at the Institute of Crop Science and Resource Conservation at the University of Bonn.

When the various components of plant cells communicate with another, they do not use words but calcium ions, i.e. positively charged calcium atoms, instead. "The information is encoded in the fluctuations of the calcium concentration of the various cell compartments," explains Dr. Schwarzlaender. How can a single ion contain and transduce so much information? This is the question scientists have been asking themselves since it became known how various cell compartments 'chat' with each other.

The 'MICU' protein is a central relay station

The team of Dr. Schwarzlaender, together with scientists from Italy, France, England, Australia and the Max Planck Institute for Plant Breeding Research in Cologne and the University of Muenster, have now shed light on this question. Investigating the cellular power stations (mitochondria) of thale cress (Arabidopsis thaliana), the scientists discovered that the 'MICU' protein fulfills a central role in the control of the calcium ion concentration in the mitochondria.

"In mammals, there is a very similar protein which also regulates the concentration of calcium ions," says Dr. Stephan Wagner from the team working with Dr. Schwarzlaender. Like a turbocharger, it prompts the mitochondria of mammals to provide more energy. The scientists speculated that this could be an interesting candidate, but they were taken by surprise when they found the closely related plant-based 'MICU' to be a central relay station in the communication system of Arabidopsis. "The two, similar proteins in animals and plants have evidently arisen from a common ancestor but over the course of millennia, they have developed distinct characteristics," says Dr. Schwarzlaender.

Fluorescing cellular power stations provide information

By destroying the gene with the MICU blueprint in the Arabidopsis genome, the researchers were able to experimentally explore what influence the protein has on the calcium communication of the plant cells. They equipped the mitochondria with a fluorescing sensor protein. Using the variable fluorescence intensities of the sensor, it was possible to visualize changes in the calcium concentrations of the cellular power stations in the living plants. "We were able to identify a clear influence on the communication of the mitochondria," reports Dr. Wagner. Knockout of the MICU gene resulted, among other consequences, in modified properties of cell respiration.

"With our findings, we have established a basis for influencing the calcium signals in specific parts of the plant cell," Dr. Schwarzlaender summarizes. Since Arabidopsis is considered to be an experimental model for plants in general, the findings may be usable in the future for optimizing crops. Looking ahead the researchers note that if, for example, specific plants could be taught to ally themselves with nitrogen-fixing soil bacteria via modified calcium signals, a large amount of fertilizer used in agriculture may be saved.
-end-
Publication: The EF-Hand Ca2+ Binding Protein MICU Choreographs Mitochondrial Ca2+ Dynamics in Arabidopsis, journal The Plant Cell, DOI: 10.1105/tpc.15.00509

Contact information:

Dr. Markus Schwarzlaender
Plant Energy Biology Lab
49-228-7354266
markus.schwarzlander@uni-bonn.de
Institute of Crop Science and Resource Conservation
University of Bonn

University of Bonn

Related Mitochondria Articles from Brightsurf:

Researchers improve neuronal reprogramming by manipulating mitochondria
Researchers at Helmholtz Zentrum M√ľnchen and Ludwig Maximilians University Munich (LMU) have identified a hurdle towards an efficient conversion: the cell metabolism.

Inside mitochondria and their fascinating genome
EPFL scientists have observed -- for the first time in living cells -- the way mitochondria distribute their transcriptome throughout the cell, and it involves RNA granules that turn out to be highly fluid.

'Cheater mitochondria' may profit from cellular stress coping mechanisms
Cheating mitochondria may take advantage of cellular mechanisms for coping with food scarcity in a simple worm to persist, even though this can reduce the worm's wellbeing.

A ribosome odyssey in mitochondria
The ciliate mitoribosome structure provides new insights into the diversity of translation and its evolution.

Fireflies shed light on the function of mitochondria
By making mice bioluminescent, EPFL scientists have found a way to monitor the activity of mitochondria in living organisms.

First successful delivery of mitochondria to liver cells in animals
This experiment marks the first time researchers have ever successfully introduced mitochondria into specific cells in living animals.

Lack of mitochondria causes severe disease in children
Researchers at Karolinska Institutet in Sweden have discovered that excessive degradation of the power plants of our cells plays an important role in the onset of mitochondrial disease in children.

Unexpected insights into the dynamic structure of mitochondria
As power plants and energy stores, mitochondria are essential components of almost all cells in plants, fungi and animals.

Mitochondria are the 'canary in the coal mine' for cellular stress
Mitochondria, tiny structures present in most cells, are known for their energy-generating machinery.

Master regulator in mitochondria is critical for muscle function and repair
New study identifies how loss of mitochondrial protein MICU1 disrupts calcium balance and causes muscle atrophy and weakness.

Read More: Mitochondria News and Mitochondria Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.