Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Feeding caterpillars make leaves shine

05.06.2015

Scientists visualize calcium signals in plants which are elicited by wounding and ultimately regulate defense responses against herbivores.

When a plant is attacked by herbivores, this triggers a number of physiological responses in the plant. Calcium ions are important messengers for the processing of wound signals in plant cells. They regulate signal transduction and indirectly control plant defense mechanisms.


The image shows the amounts of light accumulated over a period of 30 minutes, highlighting the changing calcium concentrations. These are represented by a color code (blue=low, red=high).

Victoria Kiep / Martin Luther University, Halle-Wittenberg; Jyothilakshmi Vadassery / Max Planck Institute for Chemical Ecology


Spodoptera littoralis larva feeding on a Arabidopsis thaliana (thale cress) plant

Sandra Scholz and Monika Heyer / Max Planck Institute for Chemical Ecology

Scientists of the Max Planck Institute for Chemical Ecology in Jena and the Institute of Agricultural and Nutritional Science of the Martin Luther University in Halle-Wittenberg, Germany, have now succeeded in visualizing the immediate wound or herbivory responses in plants.

They used Arabidopsis thaliana (thale cress) plants that produce a special protein which breaks down after the binding of calcium ions and emits free energy in the form of light. The amount of light corresponds to the calcium concentrations in the cells of the respective leaf areas. By using a highly sensitive camera system the researchers could track the calcium flow in the plants.

Visualization revealed that calcium signals occur systemically and wander from attacked to neighboring leaves within a short period of time, and ultimately put the whole plant into a state of defense readiness. (New Phytologist, May 2015)

Calcium is a universal intracellular messenger. In plants, many physiological processes are mediated by calcium ions, especially responses to abiotic and biotic stresses, such as feeding caterpillars. These trigger the activation of a number of defense mechanisms. If a leaf is attacked by an insect, the wound signal which emanates from the affected leaf is transmitted to other, unattacked leaves.

In order to visualize this signal, the scientists performed experiments with transgenic Arabidopsis plants which were genetically modified to express a protein in the cytosol, the liquid inside the cells, which breaks down and releases light energy after it has bound calcium ions. The emitted light energy correlates with the respective concentrations of calcium ions.

In this way, intracellular changes of calcium levels can be determined directly. Moreover, these processes can be made visible in the plants by applying a highly sensitive camera system which uses charge-coupled devices (CCD). “It is very impressive to see how every bite of a caterpillar makes certain leaf areas shine. The immediate reaction of the plants is clearly visible,” says Victoria Kiep, who carried out most of the experimental work together with Jyothilakshmi Vadassery.

It was very important for the researchers to show that the calcium signal is a systemic process, rather than a local one, as it wanders from the attacked leaf to neighboring leaves within a few minutes to trigger the subsequent defense responses. “We succeeded in visualizing the dynamic signal processing of intracellular calcium as a secondary messenger which is elicited by insect feeding and transmitted systemically to unattacked areas of the plant,” Axel Mithöfer, the leader of the project group “Physiology of Plant Defense” in the Department of Bioorganic Chemistry, summarizes the results of the study.

How calcium signals are elicited in different and separate areas of plants is not yet fully understood. However, the scientists speculate that electric signals which are transmitted via the vascular system of plants, so-called vascular bundles, play an important role. There are no important differences between calcium signals which are elicited by mechanical wounding and those which are triggered by feeding caterpillars. Surprisingly, the application of larval oral secretions inhibited the transduction of calcium signals to neighboring leaves in the experiment. Of general importance for systemic calcium signaling is the wounding of the vascular system of the leaf, which is also responsible for the internal transport of water and nutrients in the plant.

Further experiments are planned in order to find out which kind of wounding triggers the systemic calcium signal, for example, whether a similar wound response is elicited by aphids and spider mites, as these insects puncture the plant tissue to suck the plant sap and damage the tissue only slightly. The scientists would like to investigate how signal transduction is achieved in grasses whose vascular bundles are structured differently in comparison to Arabidopsis which belongs to the Brassicaceae family. They are also interested in determining the operating distance of calcium signals in general and would like to answer the question whether the signals can be transmitted to the plant roots.

This study demonstrates that calcium signals, which are necessary for eliciting plant defense responses, and their spatial and temporal expansion can be visualized. Moreover, the scientists showed that calcium signaling can be studied directly in intact plants in different physiological and ecological contexts, which helps to better understand its role as a secondary messenger in plants. [AO/AM]

Original Publication:
Kiep, V., Vadassery, J., Lattke, J., Maaß, J.-P., Boland, W., Peiter, E., Mithöfer, A. (2015). Systemic cytosolic Ca2+ elevation is activated upon wounding and herbivory in Arabidopsis. New Phytologist. doi: 10.1111/nph.13493
http://dx.doi.org/10.1111/nph.13493

Further Information:
Dr. Axel Mithöfer, Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, 07745 Jena, Tel. +49 3641 57-1263, E-Mail amithoefer@ice.mpg.de

Contact and Picture Requests:
Angela Overmeyer M.A., Max Planck Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07743 Jena, +49 3641 57-2110, E-Mail overmeyer@ice.mpg.de

Download von hochaufgelösten Fotos über http://www.ice.mpg.de/ext/downloads2015.html

Weitere Informationen:

http://www.ice.mpg.de/ext/1214.html
http://www.ice.mpg.de/ext/520.html (Research Group Defense Physiology)

Angela Overmeyer | Max-Planck-Institut für chemische Ökologie

More articles from Life Sciences:

nachricht The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology

nachricht Colorectal cancer risk factors decrypted
13.07.2018 | Max-Planck-Institut für Stoffwechselforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Research finds new molecular structures in boron-based nanoclusters

13.07.2018 | Materials Sciences

Algae Have Land Genes

13.07.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>