Featured Research

from universities, journals, and other organizations

Plant Defenses Prompt Bacterial Countermeasure In The Form Of 'Island' DNA Excision

Date:
January 3, 2006
Source:
Cell Press
Summary:
Seeking to catch an arms-race maneuver in action, researchers have uncovered new evidence to explain how bacteria in the process of infecting a plant can shift molecular gears by excising specific genes from its genome to overcome the host plant's specific defenses.

Seeking to catch an arms-race maneuver in action, researchers have uncovered new evidence to explain how bacteria in the process of infecting a plant can shift molecular gears by excising specific genes from its genome to overcome the host plant's specific defenses.

Throughout evolution -- in the wild and in crops cultivated by humans -- plants have developed systems for resisting the attack of microbial pathogens, while these microbes themselves have depended on their ability to alter molecular attack strategies in order to flourish. In the new work, researchers have essentially caught one step of this arms race in action, and they have shed light on the molecular mechanisms employed by a bacterial pathogen to survive in the face of its host plant's defenses. The research is reported by John Mansfield and colleagues at Imperial College London, the University of the West of England, and the University of Bath.

Studying interactions between strains of the halo-bright pathogen and bean plants, the researchers found that the pathogenic bacteria essentially kicks out a section of its genome when it senses that its presence has been detected by the plant's defense system. Excising this so-called "genomic island" eliminates production of the bacterial protein detected by the plant and allows a more stealthy -- and successful -- invasion.

The reason the strategy can be successful is that the plant has evolved to recognize the presence of only certain bacterial proteins as warnings of an infection. This means that the bacteria can, in principle, evade detection if it can shut down production of the offending protein or proteins. In their study, the authors identify within the halo-bright pathogen genome a special island of DNA that encodes one such offending protein. But this genomic island also encodes enzymes that, when switched on, snip the DNA on either side of the island, resulting in the excision of the entire island from the genome. The researchers found that this excision occurs in response to a so-called hypersensitive resistance reaction by the plant . The specific plant signals that are sensed by the pathogen to trigger the excision event remain to be identified.

If some bacterial proteins give away the presence of the pathogen to the plant, why are they and their surrounding genomic islands maintained by the bacteria at all? There are many genes included in the genomic island that is excised by the halo-bright strains studied here, and these other genes may well encode proteins that allow the pathogen to survive optimally in the light-intensive regions of eastern and southern Africa where these strains are found. Remarkably, bacteria that have excised the genomic island do not appear compromised in their ability to grow and cause disease within the host bean plant.

These findings offer a molecular explanation for how exposure to plant resistance mechanisms can directly drive the evolution of new virulent forms of a bacterial pathogen.

###

The researchers include Andrew R. Pitman and Dawn L. Arnold of the University of the West of England in Bristol, United Kingdom; Robert W. Jackson of the University of the West of England in Bristol, United Kingdom and the University of Bath in Bath, United Kingdom; John W. Mansfield and Victor Kaitell of the Imperial College London in Kent, United Kingdom; Richard Thwaites of the Imperial College London in Kent, United Kingdom and Central Science Laboratory in York, United Kingdom. This work was supported by the Biotechnology and Biological Sciences Research Council.

Pitman et al.: "Exposure to Host Resistance Mechanisms Drives Evolution of Bacterial Virulence in Plants." Publishing in Current Biology, Vol. 15, 2230-2235, December 20, 2005, DOI 10.1016/j.cub.2005.10.074, www.current-biology.com.


Story Source:

The above story is based on materials provided by Cell Press. Note: Materials may be edited for content and length.


Cite This Page:

Cell Press. "Plant Defenses Prompt Bacterial Countermeasure In The Form Of 'Island' DNA Excision." ScienceDaily. ScienceDaily, 3 January 2006. <www.sciencedaily.com/releases/2006/01/060103084321.htm>.
Cell Press. (2006, January 3). Plant Defenses Prompt Bacterial Countermeasure In The Form Of 'Island' DNA Excision. ScienceDaily. Retrieved July 24, 2014 from www.sciencedaily.com/releases/2006/01/060103084321.htm
Cell Press. "Plant Defenses Prompt Bacterial Countermeasure In The Form Of 'Island' DNA Excision." ScienceDaily. www.sciencedaily.com/releases/2006/01/060103084321.htm (accessed July 24, 2014).

Share This




More Plants & Animals News

Thursday, July 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Stone Fruit Listeria Scare Causes Sweeping Recall

Stone Fruit Listeria Scare Causes Sweeping Recall

Newsy (July 22, 2014) The Wawona Packing Company has issued a voluntary recall on the stone fruit it distributes due to a possible Listeria outbreak. Video provided by Newsy
Powered by NewsLook.com
Michigan Plant's Goal: Flower and Die

Michigan Plant's Goal: Flower and Die

AP (July 22, 2014) An 80-year-old agave plant, which is blooming for the first and only time at a University of Michigan conservatory, will die when it's done (July 22) Video provided by AP
Powered by NewsLook.com
Huge Schizophrenia Study Finds Dozens Of New Genetic Causes

Huge Schizophrenia Study Finds Dozens Of New Genetic Causes

Newsy (July 22, 2014) The 83 new genetic markers could open dozens of new avenues for schizophrenia treatment research. Video provided by Newsy
Powered by NewsLook.com
CDC Head Concerned About a Post-Antibiotic Era

CDC Head Concerned About a Post-Antibiotic Era

AP (July 22, 2014) Sounding alarms about the growing threat of antibiotic resistance, CDC Director Tom Frieden warned Tuesday if the global community does not confront the problem soon, the world will be living in a devastating post-antibiotic era. (July 22) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins