| dc.description.abstract | Considering the physiological significance of
Mg homeostasis in plants, surprisingly little is known
about the molecular and ionic mechanisms mediating
Mg transport across the plasma membrane and the
impact of Mg availability on transport processes at the
plasmalemma. In this study, a non-invasive ion-selective
microelectrode technique (MIFE) was used to
characterize the effects of Mg availability on the
activity of plasma membrane H+, K+, Ca2+, and
Mg2+ transporters in the mesophyll cells of broad
bean (Vicia faba L.) plants. Based on the stoichiometry
of ion-flux changes and results of pharmacological
experiments, we suggest that at least two mechanisms
are involved in Mg2+ uptake across the plasma
membrane of bean mesophyll cells. One of them is a
non-selective cation channel, also permeable to K+
and Ca2+. The other mechanism, operating at concentrations
below 30 lM, was speculated to be an H+/
Mg+ exchanger. Experiments performed on leaves
grown at different levels of Mg availability (from
deficient to excessive) showed that Mg availability has
a significant impact on the activity of plasma-membrane
transporters for Ca2+, K+, and H+. We discuss
the physiological significance of Mg-induced changes
in leaf electrophysiological responses to light and the
ionic mechanisms underlying this process. | en_US |
