Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Plant wounds trigger bacteria

24.10.2005


Tom Burr - Crown gall disease on the lower trunk of a grapevine in the Finger Lakes region.


How does a wound in certain plants like roses and grapevines develop into a tumor? The answer appears to lie in a common soil bacterium that is able to "smell" the wound and speed up the infection process.

Cornell University microbiologist Steve Winans says that the pathogen Agrobacterium tumefaciens enters the wound where it copies the genes required for infection, which can slip into the plant’s cells and their nuclear DNA, causing a cancer-like disease called crown gall. The cells of the crown gall tumor synthesize compounds called opines, which serve as food for the bacterial invaders.

The discovery may lead to a cure for crown gall disease, which takes a large economic toll on fruit and wine-grape crops each year.



"Mutant forms of Agrobacterium are also widely used in agricultural biotechnology for their ability to create transgenic plants containing new genes of scientific or economic interest," said Winans, a professor in Cornell’s Department of Microbiology. "Perhaps these findings could be exploited to get more effective delivery of DNA for biotechnology uses."

He is the senior author of a paper published in a recent issue of the Proceedings of the National Academies of Science (PNAS, Vol. 102, No. 41).

"Many other disease-causing bacteria are like Agrobacterium, in that they can detect specific chemical signal molecules that are released from plants or animals, and respond by initiating an attack on these host organisms," Winans said. "For example, others have shown that the bacteria that cause cholera express protein toxins only when they detect bile salts in the host’s intestine. It will be interesting to see whether those bacteria also increase the replication of the genes necessary for disease."

The bacterium employs a large tumor-inducing plasmid to do its dirty deed. The plasmid is a ring of DNA that is separate from the chromosome and is not essential for the bacterium’s survival but is required for tumor growth. The plasmid can also transmit itself from one bacterial cell to another when the two cells touch one another, in bacterial congress.

The plasmid recognizes organic compounds called phenols that leak out of damaged cells when a plant is wounded. A bacterial protein called VirA acts like an antenna, detecting phenols in a plant wound; the phenols, in turn, signal VirA to add a phosphate (PO4) group to a related protein, VirG, converting it into an active form.

The new study shows that the activated form of VirG causes the tumor-inducing plasmid to replicate up to five times faster than normal by increasing the expression of a protein called RepC, which is required for replication of the plasmid. The extra copies of this DNA enhance the ability of the bacterium to cause tumors, which grow when a fragment of the plasmid DNA invades the plant’s own DNA.

Crown gall tumors mostly strike the trunks or stems of dicot plants, trees or vines near the ground where freezing occurs during winter and a wound forms in spring. Such fruit trees as cherries and peaches, raspberries and high-quality vine grapes like chardonnay and cabernet sauvignon tend to be susceptible to the disease, which can stunt or kill a plant. Grafting can also lead to infections.

"There are really no chemicals, no sprays that can control this disease," said Tom Burr, a plant pathology professor at Cornell and an expert on crown gall disease. "This is really the cutting-edge research on the biology of the pathogen, so now we can think about how to develop novel controls for gall tumors."

The study was funded by Monsanto and the National Institutes of Health.

Simeon Moss | EurekAlert!
Further information:
http://www.cornell.edu

More articles from Agricultural and Forestry Science:

nachricht Ammonium nitrogen input increases the synthesis of anticarcinogenic compounds in broccoli
26.04.2017 | University of the Basque Country

nachricht New data unearths pesticide peril in beehives
21.04.2017 | Cornell University

All articles from Agricultural and Forestry Science >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>