Depletion of cytosolic free calcium induced by photosynthesis
Abstract
Cytosolic free calcium is widely believed to behave as a second messenger for a wide variety of metabolic and developmental processes in plant cells1-3. Thus, it is expected that environmental stimuli should provoke a change in the concentration of cytosolic free calcium ([Ca2+]c) which then elicits some further response by the cell. However, although spatial differences in [Ca2+]c have been observed in plant cells4,5, direct measurement of a temporal change of [Ca2+]c in response to an environmental stimulus has so far been restricted to the transient rise, largely complete within 2 s, which occurs during an action potential6. This paucity of data is largely due to the difficulties associated with measurement of [Ca2+]cin plant cells7. We show here that Ca2+-selective microelectrodes can be used to report photosynthetically-related changes of [Ca2+]c in the characean alga Nitellopsis. We propose that the light-induced depletion of [Ca2+]c constitutes a fundamental signal which enables the rate of extrachloroplastic metabolism to be geared to photosynthetic processes in the chloroplast. However, light-induced activation of the electrogenic H+ pump at the plasma membrane is independent of changes in [Ca2+]c.
- Publication:
-
Nature
- Pub Date:
- March 1987
- DOI:
- 10.1038/326397a0
- Bibcode:
- 1987Natur.326..397M