Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How plants detect infections

09.06.2010
The tiniest fragments of bacteria are enough to trigger a defense response from plants to parasites. Researchers from the universities of Würzburg and Basel are now able to describe the molecular details of this response.

In the wild, the life of a plant is constantly in jeopardy: unfavorable environmental conditions, such as prolonged drought or pollutants in the atmosphere, soil, and water are a threat. And lurking nearby, always ready to attack, are fungi, bacteria, and viruses.

If these pathogens were left to their own devices, the flora would no longer be so lush, green and magnificent. Plants must therefore have a way of holding their little enemies at bay. How do they do this, incapable as they are of simply running away or grabbing a first-aid kit?

Published in renowned journals

Teams from the universities of Basel and Würzburg have come up with answers to this question. Professor Thomas Boller from Basel and the Würzburg team led by biophysicist Professor Rainer Hedrich and molecular biologist Dr. Dirk Becker have published their findings in the renowned journals The Plant Journal and Journal of Biological Chemistry.

In these journals, the researchers show how plants put potential pathogens in their place using their innate immune system. They researched this phenomenon using bacteria of the genus Pseudomonas and the model plant Arabidopsis thaliana. Pseudomonas bacteria can cause rot in plants, among other harmful effects.

Receptor detects fragments of bacteria

The choice of the Pseudomonas bacterium was far from random – Thomas Boller’s team had already previously achieved a decisive breakthrough: the Basel scientists had identified a receptor (FLS2) in the membrane of plant cells. This detects fragments of bacterial organs of locomotion, so-called flagella, even in miniscule quantities.

“We were at a conference when we agreed to bundle our expertise in biophysics (Würzburg) and biochemistry (Basel),” reports Rainer Hedrich. The researchers’ goal: to shed light on the early processes that plants use to detect pathogens.

Electrical excitation by bacterial fragments

The Würzburg scientists received from Basel a peptide chain of 22 amino acids in length (Flg22) consisting of the flagella building block flagellin along with receptor mutants of Arabidopsis. With this material, they managed to establish that the bacterial peptide excites plant cells electrically: roughly one minute after administering the bacterial fragment to the plants they noticed a rise in the concentration of calcium together with a ten-minute depolarization of the membrane. “Using calcium, the flagellin receptor activates an anion channel in the membrane,” says Dirk Becker.

Plant distributes antibacterial substances

At the same time, the Basel researchers demonstrated that the excitation of the membrane is communicated to the cell nucleus and stimulates the immune system: the plant activates defense genes, assembles antimicrobial substances and enzymes, and with these overwhelms the bacterial intruders.

To prevent the microbes from spreading, whole groups of cells surround the source of the infection and sacrifice themselves as a kind of last resort. Brown patches and microscopically small “scars” remain as witnesses to the successful defense against the pathogens.

Hundreds of early warning systems to counter intruders

But what if the plant overlooks the flagellin, which is found in many bacteria? That’s no major problem! “The plant identifies intruders using a variety of receptors simultaneously – it takes a typical fingerprint of the respective pathogens,” says Thomas Boller.

The innate immune system of plants consists of hundreds of such early warning systems. These include those of the PEPR1/2 type, which detect endogenous peptides from inside the cell. As soon as microbes damage a plant cell, these peptides reach the surface receptors of surrounding cells and signal the danger.

Anion channel passes the danger signals on

Based on their research, the German/Swiss research alliance has drawn the following conclusion: the different danger signals detected by these receptors are translated into an electrical signal via the same anion channel.

Hedrich: “We are currently working on tracking down the gene for this central ion channel. We have found two gene families that encode anion channels. The task now is to nail the prime suspect.”

"Early signaling through the Arabidopsis pattern recognition receptors FLS2 and EFR involves Ca2+-associated opening of plasma membrane anion channels”, Elena Jeworutzki, M. Rob G. Roelfsema, Uta Anschütz, Elzbieta Krol, J. Theo M. Elzenga, Georg Felix , Thomas Boller , Rainer Hedrich, and Dirk Becker, Plant Journal 2010, Volume 62 Issue 3, Pages 367 – 378 (Published Online), DOI: 10.1111/j.1365-313X.2010.04155.x

"Perception of the Arabidopsis Danger Signal Peptide 1 Involves the Pattern Recognition Receptor AtPEPR1 and Its Close Homologue AtPEPR2”, Elzbieta Krol, Tobias Mentzel, Delphine Chinchilla, Thomas Boller, Georg Felix, Birgit Kemmerling, Sandra Postel, Michael Arents, Elena Jeworutzki, Khaled A. S. Al-Rasheid, Dirk Becker, and Rainer Hedrich, J. Biol. Chem. 2010 285: 13471-13479. First Published on March 3, 2010. DOI:10.1074/jbc.M109.097394

Contact

Prof. Dr. Rainer Hedrich, University of Würzburg, T +49 (931) 31-86100, hedrich@botanik.uni-wuerzburg.de

Prof. Dr. Thomas Boller, University of Basel, T +41 (61) 267 23 20, Thomas.Boller@unibas.ch

Robert Emmerich | idw
Further information:
http://www.unibas.ch
http://www.uni-wuerzburg.de

More articles from Life Sciences:

nachricht Researchers identify potentially druggable mutant p53 proteins that promote cancer growth
09.12.2016 | Cold Spring Harbor Laboratory

nachricht Plant-based substance boosts eyelash growth
09.12.2016 | Fraunhofer-Institut für Angewandte Polymerforschung IAP

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>