The roots of plants release about 5-20% percent of all photosynthetically-fixed carbon, and as a result create a carbon-rich environment for numerous rhizosphere organisms, including several plant pathogens and symbiotic microbes. An important result of the Arabidopsis genome project is that it is now feasible to begin identifying the genes that are expressed in roots and that mediate root-rhizosphere interactions. Although some chemical characterization of root exudates has been achieved specially for secondary metabolites, much less is known about volatile organic compounds (VOCs) released by roots. In this project, a novel approach to explore these rhizosphere interactions will be investigated. A new technology, proton-transfer-reaction mass spectrometry (PTR-MS), that allows rapid and real time analysis of virtually all biogenic VOCs without preconcentration or chromatography will be applied to the analysis of root VOCs. Specific objectives are: (1) application of PTR-MS to analyze total VOC emission from Arabidopsis roots in response to normal conditions versus abiotic and biotic stresses; (2) screening a subset of Arabidopsis T-DNA mutants for key biotic-induced root VOCs. This research will provide the broader benefit of the training of a postdoctoral scholar in a multidisciplinary research atmosphere. If successful, this work will demonstrate to the science community that PTR-MS is a valuable analytical tool which offers great potential for discovery when combined with a genomics approach.
