UC Davis plant scientists have identified an enzyme that appears to play a key role in the insect-transmitted bacterial infection of grapevines with Pierce's disease, which annually costs California's grape and wine industries more than $100 million.
e researchers hope that the discovery, which runs counter to existing theories, will lead to new diagnostics and potential treatments for Pierce's disease. Their findings will be reported Tuesday, Jan. 12, in Scientific Reports, an online journal of the Nature Publishing Group, at http://www.
"With a bacterial disease -- much like cancer -- if you understand how the virulent form spreads, you can better control or remove it, " said Abhaya Dandekar, a professor of plant sciences and senior author on the study.
"We anticipate that this discovery could open new ways to think about dealing with Pierce's disease and highlight other areas of immune response, in general, that haven't yet been considered," he said.
About Pierce's disease:
Pierce's disease, first identified in the 1890s, is caused by the bacterium Xylella fastidiosa and is characterized by yellowed and browning leaves that eventually drop from the vine. The disease is transmitted from vine to vine by small, winged insects called sharpshooters.
Pierce's disease is established in Northern California, where it is transmitted by the blue-green sharpshooter, which lives near rivers and streams. The disease became a serious threat to California agriculture in 1996 when the glassywinged sharpshooter -- another Pierce's disease carrier native to the Southwest -- was discovered in the Temecula Valley of Southern California.
How infection progresses:
It's been known for a number of years that when Xyllela fastidiosa invades a grapevine, it produces a biofilm or gel in the xylem -- the vascular tissue that transports water and some nutrients throughout the vine.
Scientists have theorized that this biofilm damages the vine by clogging up the xylem, preventing the flow of water to the leaves. That theory seemed to explain the yellowing of the leaf edges and eventual death of the leaf tissue.
But not all of the evidence stacked up to fit that theory, Dandekar said. For example a heavy accumulation of Xyllela fastidiosa in grapevine leaves was not always accompanied by severe disease symptoms in leaves. And, in some infected grapevines as well as other host plants, the leaves showed severe symptoms but the xylem had very little blockage.
So Dandekar and colleagues set out to investigate an alternative mechanism by which Xyllela fastidiosa might be wreaking havoc with the vine's physiology.
Secrets of the "secretome":
The research team began by analyzing the bacteria's secretome -- the entire collection of enzymes and other proteins secreted by a disease-causing agent like Xyllela fastidiosa during the infection process. Such secreted proteins are known to play key roles in triggering many plant diseases.
The resulting data indicated that an enzyme, which the researchers named LesA, was quite abundant during Xyllela fastidiosa infections and shared characteristics with similar enzymes known to be capable of breaking down plant cell walls.
The researchers went on to confirm their suspicions by demonstrating that a mutant strain of Xyllela fastidiosa bacteria -- with a specific gene knocked out, or inactivated -- lacked the ability to cause infection in grapevines.
"The LesA enzyme has the ability to move through cell membranes, equipping the Xyllela fastidiosa bacteria to invade the grapevine and to live in its xylem tissues, where it feeds on fatlike compounds called lipids," Dandekar says.
In this way, the LesA enzyme triggers the process that causes the typical Pierce's disease leaf damage -- a process completely unrelated to the xylem blockage and water stress that had previously been thought to cause the symptomatic leaf damage.
The research for the newly published study was conducted by Rafael Nascimiento and Hossein Gouran, both graduate students in Dandekar's laboratory. Dandekar said that his research team plans to move forward with Pierce's disease research in hopes of developing ways to counteract the disease.
Funding for the newly published study was provided by the Pierce's Disease Board of the California Department of Food and Agriculture.
Abhaya Dandekar, Plant Sciences, (530) 752-7784, firstname.lastname@example.org
Pat Bailey, UC Davis News Service, (530) 752-9843, email@example.com
Patricia Bailey | EurekAlert!
Nanoparticle Exposure Can Awaken Dormant Viruses in the Lungs
16.01.2017 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Cholera bacteria infect more effectively with a simple twist of shape
13.01.2017 | Princeton University
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.
The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...
UMD, NOAA collaboration demonstrates suitability of in-orbit datasets for weather satellite calibration
"Traffic and weather, together on the hour!" blasts your local radio station, while your smartphone knows the weather halfway across the world. A network of...
Fiber-reinforced plastics (FRP) are frequently used in the aeronautic and automobile industry. However, the repair of workpieces made of these composite materials is often less profitable than exchanging the part. In order to increase the lifetime of FRP parts and to make them more eco-efficient, the Laser Zentrum Hannover e.V. (LZH) and the Apodius GmbH want to combine a new measuring device for fiber layer orientation with an innovative laser-based repair process.
Defects in FRP pieces may be production or operation-related. Whether or not repair is cost-effective depends on the geometry of the defective area, the tools...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
16.01.2017 | Power and Electrical Engineering
16.01.2017 | Information Technology
16.01.2017 | Power and Electrical Engineering