Changes in ion permeability and subsequently intracellular ion
concentrations play a crucial role in intracellular and intercellular
communication and, as such, confer a broad array of developmental and
adaptive responses in plants. These changes are mediated by the activity
of plasma-membrane based transport proteins many of which are
controlled by cyclic nucleotides and/or other signaling molecules. The
MIFE technique for noninvasive microelectrode ion flux measuring allows
concurrent quantification of net fluxes of several ions with high
spatial (μm range) and temporal (ca. 5 s) resolution, making it a
powerful tool to study various aspects of downstream signaling events in
plant cells. This chapter details basic protocols enabling the
application of the MIFE technique to study regulation of root membrane
transport in general and cyclic nucleotide mediated transport in
particular.