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James Tokuhisa

Assistant Professor of Practice, Biological Sciences
3030 Derring Hall (MC 0405)
926 West Campus Drive
Blacksburg, VA 24061

Major Field of Interest

Biochemical and molecular mechanisms of chemical defense fitness in higher plants

Current Research

My lab focuses on two chemical defense systems that protect plants from attack by generalist herbivores.  Crucifer plants produce glucosinolates, nontoxic glycosides, that are bioactivated when herbivores attack the plant.  We humans recognize these bioactivated compounds as the sharp flavor components of arugula, horseradish , mustard, and wasabi.  The bioactivating agent is an enzyme that is heavily modified after it has been synthesized in the plant.  We are investigating how these unusual post-translational modifications contribute to plant fitness in plant-herbivore interactions. 

Plants of the Solanum genus produce steroidal glycoalkaloids as defense compounds against generalist herbivores.  These compounds are the bitter flavors we associate with unripe tomatoes and the jackets of red potato tubers.  The production of these compounds requires increased metabolic flux through the terpenoid biosynthetic pathway.  The enzyme squalene synthase is a critical enzyme of this pathway and in potato is encoded by an unusually large gene family.  We are looking at the individual members of the gene family to identify biochemical and molecular features that contribute to the biosynthesis of the steroidal defense compounds.

  • 2000–2005 Research Scientist, Max-Planck-Institute for Chemical Ecology, Germany
  • 1999–2000 Visiting Scientist, Max-Planck-Institute for Chemical Ecology
  • 1997–2000 Assistant Scientist, Washington State University
  • 1995–1996 Lab Coordinator, Washington State University
  • 1991–1996 Research Associate, Washington State University
  • 1986–1990 Research Scientist, Division of Plant Industry, CSIRO, Australia
  • 1986 (Nov) Visiting Scientist, National Institute Basic Biology, Okazaki, Japan
  • 1986 Ph.D., Botany, minor in Biochemistry, University of Wisconsin, Madison. Advisor: Peter H. Quail. Dissertation: Characterization of a Distinct Species of Phytochrom in Light-Grown Avena sativa L.
  • 1981–1986 Research Assistant, University of Wisconsin-Madison
  • 1982 Teaching Assistant, Bot 130 General Botany, Ray F. Evert
  • 1980 Teaching Assistant, Biocore 304 Cellular Biology Lab, Duane Kolterman, Wayne Becker
  • 1979 B.S., Botany with Distinction, University of Illinois, Urbana. Advisor: Larry N. Vanderhoef. Research: High affinity auxin-binding activity in homogenates of etiolated soybean hypocotyl
  • 1977-1979 Lab Assistant, Intro Plant Biology, R. Edward Dole
  • McKnight Postdoctoral Fellowship, Washington State University, 1991 – 1992
  • Advanced Opportunity Fellowships, University of Wisconsin, 1979 – 1984
  • Davis Fund Travel Fellowship, University of Wisconsin, 1983
  • Graduation with Distinction, University of Illinois, 1979