Root Disease and
Biological Control Research
Pat Okubara
Rhizosphere Plant-Microbe
Interactions—Out of Sight,
Not Out of Mind
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Inhabitants of root ecosystems, or the rhizosphere, generally are hidden from sight. Nevertheless, pathogenic and beneficial microbes form complex interactions with host roots that can impact the health and yield of crop plants. Growers in the Pacific Northwest and throughout the world face unique challenges as they adopt water- and fuel-conserving practices such as direct seeding (no-till). One such challenge is posed by soilborne root pathogens that thrive on plant debris left by direct seeding and that are not adequately controlled by current practices.
Dr. Okubara’s research focuses on understanding how to better manage root diseases and how to enhance host resistance to soilborne pathogens. Molecular diagnostic methods are being used to quantify root pathogens in agricultural soils with a high degree of sensitivity and specificity, essential information for improving disease management practices.
Wheat plants with resistance to root pathogens will be an important disease management resource. In collaboration with two other scientists, Dr. Okubara is characterizing an unique commercial wheat that displays resistance to soilborne pathogens. Understanding the basis of the resistance in this wheat variety will provide clues to the susceptibility displayed by all other varieties. Dr. Okubara has identified candidate defense genes in wheat roots and is developing a gene silencing system to evaluate the impact of the genes on root pathogen resistance. Wheat genes that have roles in establishing and maintaining associations with disease-suppressive (biocontrol) bacteria provide a complementary alternative to host resistance. Recent research indicates that wheat plants mediate rhizosphere populations of biocontrol bacteria, and rhizosphere levels of antifungal metabolites produced by the bacteria. The genes controlling these phenomena are being sought.
The Okubara laboratory seeks to advance knowledge of plant genes and molecular pathways that are important for root pathogen defense, bringing together multiple approaches to improve sustainable management of root diseases.
Contact Information
Patricia A. Okubara, Ph.D.
Research Geneticist
USDA ARS, Root Disease and
Biological Control Research Unit
Washington State University
PO Box 646430
Pullman, WA 99164-6430
Telephone: 509-335-7824
E-mail: pokubara@wsu.edu
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