Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study: Plants use dual defense system to fight pathogens

03.06.2005


Researchers have uncovered the link between two biochemical pathways that plants use to defend themselves against pathogens – pathways that scientists have long believed worked independently of each other.



Knowing how these pathways of immunity work may one day help researchers breed plants that can better resist a variety of pathogens, said David Mackey, the study’s lead author and an assistant professor of horticulture and crop science at Ohio State University .

He and his colleagues explain their findings in the current issue of the journal Cell.


The researchers infected Arabidopsis plants with a bacterial strain of Pseudomonas syringae, a bacterium that usually infects tomato crops. Both Arabidopsis, a plant of the mustard family, and P. syringae are models that researchers commonly use to conduct basic plant research.

One of the immune pathways that interested the researchers recognizes what they call pathogen-associated molecular patterns, or PAMPs. The PAMP pathway appears to be a plant’s first line of defense against pathogenic attackers.

“The PAMP path induces a fairly weak immune response,” Mackey said. “Even so, there is growing evidence that suggests these kinds of responses are extremely important in restricting the growth of many pathogens.”

The other pathway uses disease-resistant proteins, or R-proteins, which can detect certain molecules, called effectors, that are secreted by pathogens. This pathway produces a stronger immune response than the PAMP pathway, Mackey said.

He and his colleagues found that the R-protein pathway steps in when PAMP is rendered useless by a pathogen.

Certain types of bacteria, including P. syringae, make a hypodermic needle-like structure that pierces the outermost membrane of a healthy plant or animal cell. The pathogen uses this conduit to send infectious effector proteins into the host cell.

While P. syringae injects about 40 different varieties of effector molecules into a plant cell, the researchers focused on the actions of two of these molecules – AvrRpt2 and AvrRpm1. Both target a protein key to Arabidopsis health­.

The scientists found that both of these effector molecules effectively shut down the PAMP pathway. But the plant’s R-proteins detect this, and come to the rescue.

“The R-proteins detect the insidious activity by which the pathogen’s effectors block the PAMP pathway,” Mackey said. “PAMP defense responses are probably often effective, but they may be blocked by the pathogen’s effector proteins. If an R-protein recognizes a pathogen’s presence, it usually induces a very strong immune response, in most cases stopping a would-be infection.

“This work further suggests that plants use an active, complex immune system to combat pathogens,” he said. “They have complicated surveillance systems that detect various infection-causing molecules and trigger defensive responses.”

A next step in this line of work is to look at other pathogen effector proteins and analyze their role in causing infections.

Mackey conducted the study with Ohio State colleagues Min Gab Kim, a graduate student in the department of plant cellular and molecular biology, and graduate student Luis da Cunha and post-doctoral fellow Aidan McFall, both in the department of horticulture and crop science; Youssef Belkhadir and Jeffrey Dangl, both with the department of biology at the University of North Carolina, Chapel Hill; and Sruti DebRoy, formerly of the U.S. Department of Energy Plant Research Laboratory at Michigan State University.

Funding for this work came from the National Science Foundation and the NSF’s Arabidopsis Project; Ohio State’s Ohio Agricultural and Research Development Center; and the U.S. Department of Energy.

| EurekAlert!
Further information:
http://www.osu.edu

More articles from Studies and Analyses:

nachricht The importance of biodiversity in forests could increase due to climate change
17.11.2017 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

nachricht Win-win strategies for climate and food security
02.10.2017 | International Institute for Applied Systems Analysis (IIASA)

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Frictional Heat Powers Hydrothermal Activity on Enceladus

Computer simulation shows how the icy moon heats water in a porous rock core

Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Underwater acoustic localization of marine mammals and vehicles

23.11.2017 | Information Technology

Enhancing the quantum sensing capabilities of diamond

23.11.2017 | Physics and Astronomy

Meadows beat out shrubs when it comes to storing carbon

23.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>