Featured Research

from universities, journals, and other organizations

Costly Plant Tumors Are Found By Cornell Microbiologist To Be Result Of Soil Bacterium 'Smelling' And Entering Wound

Date:
October 26, 2005
Source:
Cornell University
Summary:
A common soil bacteria can 'smell' a wound on plants like roses and wine grapevines, which triggers the microbes to copy their DNA many times over and insert them into plant cells, causing tumors associated with crown gall disease, according to new research by a Cornell microbiologist Steve Winans.

Crown gall disease on the lower trunk of a grapevine in the Finger Lakes region.
Credit: Tom Burr / courtesy of Cornell University

ITHACA, N.Y. -- 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.


Story Source:

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


Cite This Page:

Cornell University. "Costly Plant Tumors Are Found By Cornell Microbiologist To Be Result Of Soil Bacterium 'Smelling' And Entering Wound." ScienceDaily. ScienceDaily, 26 October 2005. <www.sciencedaily.com/releases/2005/10/051023121456.htm>.
Cornell University. (2005, October 26). Costly Plant Tumors Are Found By Cornell Microbiologist To Be Result Of Soil Bacterium 'Smelling' And Entering Wound. ScienceDaily. Retrieved September 19, 2014 from www.sciencedaily.com/releases/2005/10/051023121456.htm
Cornell University. "Costly Plant Tumors Are Found By Cornell Microbiologist To Be Result Of Soil Bacterium 'Smelling' And Entering Wound." ScienceDaily. www.sciencedaily.com/releases/2005/10/051023121456.htm (accessed September 19, 2014).

Share This



More Plants & Animals News

Friday, September 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Elephant Undergoes Surgery in Tbilisi Zoo

Raw: Elephant Undergoes Surgery in Tbilisi Zoo

AP (Sep. 18, 2014) Grand the elephant has successfully undergone surgery to remove a portion of infected tusk at Tbilisi Zoo in Georgia. British veterinary surgeons used an electric drill to extract the infected piece. (Sept. 18) Video provided by AP
Powered by NewsLook.com
Chimp Violence Study Renews Debate On Why They Kill

Chimp Violence Study Renews Debate On Why They Kill

Newsy (Sep. 17, 2014) The study weighs in on a debate over whether chimps are naturally violent or become that way due to human interference in the environment. Video provided by Newsy
Powered by NewsLook.com
Some Tobacco Farmers Thrive Amid Challenges

Some Tobacco Farmers Thrive Amid Challenges

AP (Sep. 16, 2014) The South's tobacco country is surviving, and even thriving in some cases, as demand overseas keeps growers in the fields of one of America's oldest cash crops. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Scientists Given Rare Glimpse of 350-Kilo Colossal Squid

Scientists Given Rare Glimpse of 350-Kilo Colossal Squid

AFP (Sep. 16, 2014) Scientists say a female colossal squid weighing an estimated 350 kilograms (770 lbs) and thought to be only the second intact specimen ever found was carrying eggs when discovered in the Antarctic. Duration: 00:47 Video provided by AFP
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