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P. ramorum, which causes Sudden Oak Death, was isolated from leaf material from a Tennessee nursery in 2005, but the disease is not known to have spread across the state. Photo by K. Lamour. Download this image (1.6 MB)

Alon Savidor, a Ph.D. candidate with the UT-ORNL Genome Science and Technology Program, is listed among the co-authors of a paper in the September 1st issue of Science. The paper compares the complete genome sequences of two major plant pathogens: Sudden Oak Death and soybean root rot disease. Both of these pathogens are among 59 Phytophthora species that are common adversaries of agricultural crops and trees and shrubs. P. infestans was responsible for the mid-19th century Irish potato famine and other Phytophthora species threaten production on large-scale farms and in backyard gardens alike.

The species addressed in current Science paper are P. ramorum, which causes Sudden Oak Death, and P. sojae, which attacks primarily soybeans.

Sudden Oak Death was first reported in 1995. The pathogen usually causes infected oak trees to die and is known to be present in more than a dozen California counties and in southern Oregon. It is among the diseases being closely monitored across the nation as oak forests are among the country's most valuable forest resources from both an environmental and an economic prospective.

Fears of widespread Sudden Oak Death contamination have not come to fruition; however, the pathogen has been detected at scores of nurseries across the nation, including in Tennessee in 2004 and 2005. The disease can be transmitted through nursery plant commerce in such plants as California bay laurel, camellia, and rhododendron. When Sudden Oak Death is detected, all the plant material involved is promptly destroyed. Thus far, survey and quarantine efforts have helped stop movement from naturally infested sites on the west coast to natural sites in the eastern United States.

Since more than half of Tennessee is forested, and nearly three-fourths of Tennessee's forests consist of oak-hickory stands, the state is concerned about the spread of Sudden Oak Death. In addition to the natural beauty and diversity of the forests, which help to drive the tourism industry, the state's thriving hardwood lumber industry would be threatened. Some $370 million in annual timber sales typically keeps Tennessee within the top five hardwood-producing states.

The U.S. produces almost half the world's soybeans, and losses attributed to soybean root rot can exceed $1 billion annually. In Tennessee, soybeans are among the state's largest row-crop commodities, accounting for some 42 million bushels of production in 2005.

Kurt Lamour, assistant professor of plant pathology, and M. Hayes McDonald, with the Oak Ridge National Laboratory's Chemical Sciences Division, serve as Savidor's mentors through the Genome Science and Technology Graduate Program. The program is administered jointly by ORNL and UT. Lamour and McDonald are also among the paper's co-authors.

The research is the result of a four-year, $4 million multi-agency project that involves collaborators from around the globe, including the U.S. Department of Energy Joint Genome Institute (DOE JGI). The DOE JGI unites the expertise of five national laboratories, along with the Stanford Human Genome Center.

"This project best exemplifies how the capabilities that were established at the DOE JGI for sequencing the human genome are now proving to be essential for addressing important environmental challenges," said Eddy Rubin, DOE JGI director. "We are now capable of rapidly responding to the urgent needs of the nation's largest industry, agriculture, where genome sequence information can be brought to bear on characterizing such economically important microorganisms as those that cause Sudden Oak Death and soybean root rot. For these pathogens, the genome sequence is the wiring diagram of the cellular processes that can be targeted for novel detection systems and for safe and effective means of control."

The entire project is supported by the DOE, USDA, and the National Science Foundation. The paper appears in the Sept. 1, 2006, edition of Science (vol. 313, No. 5791).

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Contacts:

Kurt Lamour, (865) 974-7954
Patricia McDaniels, (865) 974-7141

See also:

"Phytophthora Genome Sequences Uncover Evolutionary Origins and Mechanisms of Pathogenesis" http://www.sciencemag.org/cgi/content/short/313/5791/1261

"DOE JGI, VBI Describe Evolutionary Origin, Disease-Causing Mechanisms of Sudden Oak Death, Related Soybean Disease Pathogens"
http://www.jgi.doe.gov/News/news_8_31_06.html