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 Energy crop production on conservation lands may not boost greenhouse gases
13.03.2017 | Penn State

nachricht How nature creates forest diversity
07.03.2017 | International Institute for Applied Systems Analysis (IIASA)

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: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Vanishing capillaries

23.03.2017 | Health and Medicine

Nanomagnetism in X-ray Light

23.03.2017 | Physics and Astronomy

Pulverizing electronic waste is green, clean -- and cold

22.03.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>