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:4/5/2017)... , April 5, 2017  The Allen Institute ... Allen Cell Explorer: a one-of-a-kind portal and dynamic digital ... 3D imaging data, the first application of deep learning ... human stem cell lines and a growing suite of ... platform for these and future publicly available resources created ...
(Date:4/5/2017)... April 4, 2017 KEY FINDINGS ... expand at a CAGR of 25.76% during the forecast ... the primary factor for the growth of the stem ... https://www.reportbuyer.com/product/4807905/ MARKET INSIGHTS The global stem cell ... application, and geography. The stem cell market of the ...
(Date:4/3/2017)...  Data captured by IsoCode, IsoPlexis Corporation,s ... statistically significant association between the potency of ... objective response of cancer patients post-treatment. The ... cancer patients will respond to CAR-T cell ... to improve both pre-infusion potency testing and cell ...
Breaking Biology News(10 mins):
(Date:9/20/2017)... ... September 20, 2017 , ... RoviSys, a leading ... today the opening of an office in Taipei, Taiwan. This new location allows ... while developing new relationships in the region. Located in the Neihu area of ...
(Date:9/19/2017)... ... September 19, 2017 , ... Participants of this educational webinar ... hood. Along with the advantages and disadvantages of ductless, filtered fume hoods, they ... the laboratory. , Attendees will learn from an industry expert about the different ...
(Date:9/19/2017)... ... September 19, 2017 , ... VetStem Biopharma ’s CEO and founder, Dr. Bob ... in Riordan’s new book "Stem Cell Therapy: A Rising Tide". Dr. Harman and Dr. ... They bonded over an interest in the potential of stem cell therapy and a fast ...
(Date:9/19/2017)... ... September 19, 2017 , ... One of the ... be eliminated, said Lyle Probst, President, CEO and Founder of ExcitePCR ™. ... other pathogen detection solutions, Probst said, “Sample preparation takes place inside our FireflyDX ...
Breaking Biology Technology: