M. Tsionsky et al., PHOTOSYNTHETIC ELECTRON-TRANSPORT IN SINGLE GUARD-CELLS AS MEASURED BY SCANNING ELECTROCHEMICAL MICROSCOPY, Plant physiology, 113(3), 1997, pp. 895-901
Scanning electrochemical microscopy (SECM) is a powerful new tool for
studying chemical and biological processes. It records changes in fara
daic current as a microelectrode (less than or equal to 7 mu m in diam
eter) 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 Tr
adescantia fluminensis, to our knowledge the first such analysis for a
n intact plant. We measured surface topography at the micrometer level
and concentration profiles of O-2 evolved in photosynthetic electron
transport. Comparison of topography and oxygen profiles above single s
tomatal complexes clearly showed photosynthetic electron transport in
guard cells, as indicated by induction of O-2 evolution by photosynthe
tically active radiation. SECM is unique in its ability to measure top
ography 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.