Navigation Links
Bacterium signals plant to open up and let friends in
Date:6/13/2012

DURHAM, N.C. -- Researchers have identified the set of tools an infectious microbe uses to persuade a plant to open the windows and let the bug and all of its friends inside.

The microbe is Pseudomonas syringae, a successful bacterial pathogen that produces characteristic brown spots in more than 50 different species of plant. The signal it uses is a molecule called coronatine, which to the plant looks just like its own jasmonic acid, a signal that is part of the plant's immune system. The pathogen "hijacks" a system that balances the plant's two different defense strategies, said Xinnian Dong, a Duke professor of biology.

Plant pathogens have two basic strategies, Dong said. One approach kills cells and harvests what's left of them for food. The other is more like parasitism, setting up housekeeping in and around living cells and using what they provide. So the plant has two kinds of defenses. Against necrotrophs, the cell-killers, the plant produces jasmonic acid and does what it can to keep cells alive. Faced with biotrophs, the parasitic type, it tries to kill the infected cells. These responses work in opposition to one another and through cross-talk to keep the plant carefully calibrated, depending on the pathogens it encounters.

"Breaking the cross-talk between the systems would be a problem because the plant may respond the wrong way," said Dong, who is also a research fellow of the Howard Hughes Medical Institute (HHMI) and Gordon and Betty Moore Foundation (GBMF). "Pseudomonas is successful by hijacking a critical process in this cross-talk."

"It's all connected," said graduate student Xiao-yu Zheng, who worked on the project for four years. "That's the beauty of it." Zheng is the first author on an article appearing in the June 14 edition of Cell Host & Microbe. The research was supported by the National Science Foundation, the National Institutes of Health and the Department of Energy.

Pseudomonas is a biotroph, the parasitic kind of attacker. But the coronatine it produces touches off a cascade of molecular activity that mimics a necrotrophic pathogen invasion. The plant responds to coronatine with three transcription factors that work together to lower the plant's supply of salicylic acid and keep the infected cell alive. Normally, salicylic acid is involved in closing the stomata and an essential signal for the cell-killing defense that would be most effective against a biotroph. So by jamming that signal, pseudomonas keeps the stomata open for more bacteria to invade, and it has free reign to reproduce in the spaces between cells.

In this arms race, the plant can't just abandon its stomata. The openings are essential for exchanging gases and water vapor and the plant adjusts them constantly in response to CO2 concentrations, humidity, sunlight and other environmental factors.

At least being able to shut the stomata is a good first line of defense for many plants, explains Maeli Melotto, an assistant professor of biology at the University of Texas - Arlington, who originally discovered pseudomonas opening the stomata. "This study elegantly adds extremely important pieces to the big puzzle of how coronatine works inside the plant cell," said Melotto, who was not involved in the current study. "Coronatine contributes to disease progression in virtually all stages of the disease," giving scientists a good way to understand the full process of bacterial pathogenesis.

For now, the Duke finding is specific to the well-studied mustard plant Arabidopsis, but it should be possible to identify and test similar transcription factors in other plant species that are manipulated by pseudomonas, Zheng said.


'/>"/>

Contact: Karl Leif Bates
karl.bates@duke.edu
919-681-8054
Duke University
Source:Eurekalert

Related biology news :

1. Virginia Tech and University of Tuscia lead team to unravel origin of devastating kiwifruit bacterium
2. Deterring signals: Tobacco plants advertise their defensive readiness to attacking leafhoppers
3. Evaluation of microscopy techniques may help scientists to better understand ancient plants
4. Scientists identify mechanism for regulating plant oil production
5. NYBG scientists identify 81 new plant and fungus species
6. How plants make cocaine
7. Parasitic plants steal genes from their hosts
8. Herbivores select on floral architecture in a South African bird-pollinated plant
9. Some factors that impact islet transplantation explored in Cell Transplantation papers
10. Some factors that impact islet transplantation explored in Cell Transplantation papers
11. New release of Web-based resource resolves confusion over plant names
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:5/24/2016)... patient care by providing unparalleled technology to leaders of the medical imaging industry.  As ... added to the range of products distributed by Ampronix. Photo - ... ... ... ...
(Date:5/9/2016)... , UAE, May 9, 2016 ... it comes to expanding freedom for high net worth ... Even in today,s globally connected world, there is still ... system could ever duplicate sealing your deal with a ... second passports by taking advantage of citizenship via investment ...
(Date:4/26/2016)... India and LONDON ... Infosys Finacle, part of EdgeVerve Systems, a product ... and Onegini today announced a partnership to integrate ... solutions.      (Logo: http://photos.prnewswire.com/prnh/20151104/283829LOGO ... to provide their customers enhanced security to access ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... June 23, 2016 Houston Methodist Willowbrook ... Cy-Fair Sports Association to serve as their official ... Houston Methodist Willowbrook will provide sponsorship support, athletic ... with association coaches, volunteers, athletes and families. ... Cy-Fair Sports Association and to bring Houston Methodist ...
(Date:6/23/2016)... -- The Biodesign Challenge (BDC), a university competition that asks ... systems and biotechnology, announced its winning teams at the ... York City . The teams, chosen ... MoMA,s Celeste Bartos Theater during the daylong summit. Keynote ... of architecture and design, and Suzanne Lee , ...
(Date:6/23/2016)... ... June 23, 2016 , ... STACS DNA Inc., the sample ... the Arkansas State Crime Laboratory, has joined STACS DNA as a Field Application Specialist. ... said Jocelyn Tremblay, President and COO of STACS DNA. “In further expanding our capacity ...
(Date:6/23/2016)... 23, 2016  Blueprint Bio, a company dedicated to ... medical community, has closed its Series A funding round, ... "We have received a commitment from Forentis ... need to meet our current goals," stated Matthew ... runway to complete validation on the current projects in ...
Breaking Biology Technology: