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 onBased 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
Prof. Dr. Rainer Hedrich, University of Würzburg, T +49 (931) 31-86100, email@example.com
Prof. Dr. Thomas Boller, University of Basel, T +41 (61) 267 23 20, Thomas.Boller@unibas.ch
Building a brain, cell by cell: Researchers make a mini neuron network (of two)
23.05.2018 | Institute of Industrial Science, The University of Tokyo
Research reveals how order first appears in liquid crystals
23.05.2018 | Brown University
At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.
At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...
There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?
At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.
The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
23.05.2018 | Life Sciences
23.05.2018 | Life Sciences
23.05.2018 | Physics and Astronomy