Navigation Links
Bacterium signals plant to open up and let friends in

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
Duke University

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:
(Date:4/26/2016)... , April 27, 2016 ... "Global Multi-modal Biometrics Market 2016-2020"  report to their ... , The analysts forecast the global ... of 15.49% during the period 2016-2020.  ... of sectors such as the healthcare, BFSI, transportation, ...
(Date:4/13/2016)... April 13, 2016  IMPOWER physicians supporting Medicaid patients ... a new clinical standard in telehealth thanks to a ... the higi platform, IMPOWER patients can routinely track key ... body mass index, and, when they opt in, share ... visit to a local retail location at no cost. ...
(Date:3/22/2016)... PUNE, India , March 22, 2016 ... new market research report "Electronic Sensors Market for ... Fingerprint, Proximity, & Others), Application (Communication & ... and Geography - Global Forecast to 2022", ... consumer industry is expected to reach USD ...
Breaking Biology News(10 mins):
(Date:6/24/2016)... Brooklyn, NY (PRWEB) , ... June 24, 2016 , ... ... 15mm, machines such as the Cary 5000 and the 6000i models are higher end ... height is the height of the spectrophotometer’s light beam from the bottom of the ...
(Date:6/23/2016)... ... June 23, 2016 , ... Mosio, ... second eBook, “Clinical Trials Patient Recruitment and Retention Tips.” Partnering with experienced clinical ... eBook by providing practical tips, tools, and strategies for clinical researchers. , “The ...
(Date:6/23/2016)... CAMBRIDGE, Mass. , June 23, 2016 /PRNewswire/ ... the development of novel compounds designed to target ... compound, napabucasin, has been granted Orphan Drug Designation ... in the treatment of gastric cancer, including gastroesophageal ... cancer stemness inhibitor designed to inhibit cancer stemness ...
(Date:6/23/2016)... Md. , June 23, 2016 A person ... from the crime scene to track the criminal down. ... the U.S. Food and Drug Administration (FDA) uses DNA evidence ... Sound far-fetched? It,s not. The FDA ... sequencing to support investigations of foodborne illnesses. Put as simply ...
Breaking Biology Technology: