Student of the Month (January 2009)
Name: Martha M Vaughan (mavaugh1 at vt.edu)
Research project: Volatile Terpene Formation and Function in Arabidopsis Roots in Interaction
with the Root Herbivore Bradysia spp. (fungus gnat)
Advisor: Dorothea Tholl
Departmental affiliation: Department of Biological Sciences
Anticipated defense date: 2010
Project description:
Plants release a bouquet of volatile organic chemicals into the environment that can mediate ecological interactions. Volatile terpenes represent a major class of plant volatiles that play important roles in direct plant defense against herbivores and they also serve as indirect defense compounds by attracting natural predators of plant herbivores. Though research in the past 10 to 15 years has deepened our understanding of the biology of volatile terpenes in aboveground plant tissues, our knowledge of the metabolism of volatile terpenes emitted from roots and their role in root herbivore interactions is still limited. In fact, the chemistry of plant defense against belowground herbivores has been referred to "one of the most neglected aspects of root biology" (Rasmann and Agrawal, 2008).
The goal of my research is to investigate volatile terpene biosynthesis and function in roots with regard to defense against belowground herbivores. In the Tholl lab we have established Arabidopsis thaliana and the opportunistic root herbivore Bradysia spp. (fungus gnat larvae) as a model system. My investigation of Arabidopsis root underground volatile terpene chemistry includes three main objectives: 1) To establish the volatile terpene profiles emitted from Arabidopsis roots under constitutive conditions and in response to defense hormones and fungus gnat larval feeding. 2) To identify and characterize terpene synthases responsible for the constitutive and herbivore-induced formation of volatile terpenes in Arabidopsis roots. 3) To determine the effect of individual root volatiles on Bradysia feeding by conducting bioassays using transgenic Arabidopsis plants with modified terpene volatile profiles.
The ability to influence the behavior of belowground pests by root metabolites has major bearing on plant fitness. The knowledge of the inherent potential of plants to defend themselves against specific insect pests can be transferred to agricultural applications. Deciphering the language of belowground volatile chemistry opens up the opportunity to develop alternative pest controls by engineering plants with enhanced formation of volatile defense compounds in roots.
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