Electrical potentials in stomatal complexes
Guard cells of several species, but predominantly Commelina communis, were impaled by micropipette electrodes and potential differences measured that occurred between cell compartments and the flowing bathing medium. The wall developed a Donnan potential that was between -60 and -70 millivolt in 30 millimolar KC1 at pH 7. The density of the fixed charges ranged from 0.3 to 0.5 molar; its dependence on pH was almost identical with the titration curve of authentic polygalacturonic acid. The vacuolar potential of guard cells of Commelina communis L., Zea mays L., Nicotiana glauca Graham, Allium cepa L., and Vicia faba L. was between -40 and -50 millivolt in 30 millimolar KCl when stomata were open and about -30 millivolt when stomata were closed. The vacuolar potential of guard cells of C. communis was almost linearly related to stomatal aperture and responded to changes in the ionic strength in the bathing medium in a Nernstian manner. No specificity for any alkali ion (except Li/sup +/), ammonium, or choline appeared. Lithium caused hyperpolarization. Calcium in concentrations between 1 and 100 millimolar in the medium led to stomatal closure, also caused hyperpolarization, and triggered transient oscillations in the intracellular potential. Gradients in the electrical potential existed across stomatal complexes with open pores. When stomata closed, these gradients almost disappeared or slightly reverted; all epidermal cells were then at potentials near -30 millivolt in 30 millimolar KCl.
- Research Organization:
- Michigan State Univ., East Lansing
- DOE Contract Number:
- AC02-76ER01338
- OSTI ID:
- 6460533
- Journal Information:
- Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 67:6; ISSN PLPHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
550300 -- Cytology
551000* -- Physiological Systems
59 BASIC BIOLOGICAL SCIENCES
BIOCHEMISTRY
CHARGED PARTICLES
CHEMISTRY
COMPARATIVE EVALUATIONS
DONNAN THEORY
ELECTRIC POTENTIAL
ELECTRODES
ION EXCHANGE MATERIALS
IONS
MATERIALS
OPENINGS
PH VALUE
PHYSIOLOGY
PLANT CELLS
PLANTS
QUANTITY RATIO
STOMATA
UPTAKE