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 Physics of bubbles could explain language patterns
25.07.2017 | University of Portsmouth

nachricht Obstructing the ‘inner eye’
07.07.2017 | Friedrich-Schiller-Universität Jena

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: Physicists Design Ultrafocused Pulses

Physicists working with researcher Oriol Romero-Isart devised a new simple scheme to theoretically generate arbitrarily short and focused electromagnetic fields. This new tool could be used for precise sensing and in microscopy.

Microwaves, heat radiation, light and X-radiation are examples for electromagnetic waves. Many applications require to focus the electromagnetic fields to...

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

 
Latest News

Programming cells with computer-like logic

27.07.2017 | Life Sciences

Identified the component that allows a lethal bacteria to spread resistance to antibiotics

27.07.2017 | Life Sciences

Malaria Already Endemic in the Mediterranean by the Roman Period

27.07.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>