Photosynthetic electron transport in single guard cells as measured by scanning electrochemical microscopy

Authors: Tsionsky, M, ZG Cardon, AJ Bard, RB Jackson

Scanning Electrochemical Microscopy (SECM) is a powerful new tool for studying chemical and biological processes. SECM records changes in faradaic current as a microelectrode (less than 7 µm 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, 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 (PAR). SECM is unique in its ability to measure topography and chemical fluxes, combining some of the attributes of patch clamping with scanning tunneling microscopy. We suggest several questions in plant physiology that it might address.


plantp97.pdf