PLANT PHYSIOLOGY , Vol 113, Issue 3 895-901, Copyright © 1997 by American Society of Plant Biologists
|
WHOLE PLANT, ENVIRONMENTAL, AND STRESS PHYSIOLOGY |
Photosynthetic Electron Transport in Single Guard Cells as Measured by Scanning Electrochemical Microscopy
M. Tsionsky, Z. G. Cardon, A. J. Bard and R. B. Jackson
Department of Chemistry and Biochemistry (M.T., A.J.B.) and Department of Botany (R.B.J.), University of Texas, Austin, Texas 78712
Scanning electrochemical microscopy (SECM) is a powerful new tool for
studying chemical and biological processes. It records changes in faradaic
current as a microelectrode ([less than equal]7 [mu]m in diameter) is moved
across the surface of a sample. The current varies as a function of both
distance from the surface and the surface's chemical and electrical
properties. We used SECM to examine in vivo topography and photosynthetic
electron transport of individual guard cells in Tradescantia fluminensis,
to our knowledge the first such analysis for an intact plant. We measured
surface topography at the micrometer level and concentration profiles of O2
evolved in photosynthetic electron transport. Comparison of topography and
oxygen profiles above single stomatal complexes clearly showed
photosynthetic electron transport in guard cells, as indicated by induction
of O2 evolution by photosynthetically active radiation. SECM is unique in
its ability to measure topography and chemical fluxes, combining some of
the attributes of patch clamping with scanning tunneling microscopy. In
this paper we suggest several questions in plant physiology that it might
address.
