Bicarbonate utilization by leaf protoplasts from Potamogeton
Leaves from the submerged angiosperm P. lucens are able to assimilate bicarbonate. These leaves behave polarly: during bicarbonate utilization protons (H/sup +/) are excreted by the cells of the lower epidermis, while hydroxyl (OH/sup -/) ions are excreted by the upper epidermal cells. It has been proposed that acidification of the apoplast is a prerequisite for bicarbonate utilization. To test this hypothesis /sup 14/C fixation by protoplasts was determined at different pH values. Also experiments, using the isotopic disequilibrium technique were performed. They showed that at pH values > 8, bicarbonate is a major carbon source for photosynthesis in protoplasts, despite the absence of cell walls and polarity. At pH values around 6, the rate of /sup 14/C-fixation in protoplasts equals that of intact leaves. At pH values > 8, however, intact leaves show a higher rate. From this, and other experiments, the authors conclude that at least 2 processes contribute to bicarbonate utilization in P. lucens leaves: active transport (H/sup +/-HCO/sub 3//sup -/ symport.) and acidification of the apoplast resulting in the conversion of bicarbonate into CO/sub 2/. Polarity may increase the efficiency of both.
- Research Organization:
- Groningen Univ., Haren, Netherlands
- OSTI ID:
- 5603757
- Report Number(s):
- CONF-8707108-
- Journal Information:
- Plant Physiol., Suppl.; (United States), Vol. 83:4; Conference: Annual meeting of the American Society of Plant Physiologists, St. Louis, MO, USA, 19 Jul 1987
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ACID CARBONATES
FOLIAR UPTAKE
MEMBRANE TRANSPORT
PLANT CELLS
ACIDIFICATION
ANIONS
AQUATIC ORGANISMS
BIOLOGICAL EFFECTS
CARBON 14 COMPOUNDS
CARBON DIOXIDE FIXATION
HYDROXIDES
LEAVES
PH VALUE
TRACER TECHNIQUES
CHARGED PARTICLES
HYDROGEN COMPOUNDS
IONS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
OXYGEN COMPOUNDS
UPTAKE
551001* - Physiological Systems- Tracer Techniques