Abstract
A procedure for following changes in the steady-state yield of chlorophyll a fluorescence (Fs) from single guard cell pairs in variegated leaves of Tradescantia albiflora is described. As an indicator of photosynthetic electron transport, Fs is a very sensitive indirect measure of the balance of adenosine 5′-triphosphate (ATP) and reduced nicotinamide adenine dinucleotide phosphate (NADPH), producing reactions with the sink reactions that utilize those light-generated products. We found that Fs under constant light is sensitive to manipulation of ambient CO2 concentrations, as would be expected if either phosphoenolpyruvate carboxylase or ribulose-1, 5 bisphosphate carboxylase/oxygenase (Rubisco)-dependent CO2 fixation is the sink for photosynthetic ATP and NADPH in guard cells. However, we also found that changing O2 concentration had a strong effect on fluorescence yield, and that O2 sensitivity was only evident when the concentration of CO2 was low. This finding provides evidence that both O2 and CO2 can serve as sinks for ATP and NADPH produced by photosynthetic electron transport in guard cell chloroplasts. Identical responses were observed with mesophyll cell chloroplasts in intact leaves. This finding is difficult to reconcile with the view that guard cell chloroplasts have fundamentally different pathways of photosynthetic metabolism from other chloroplasts in C3 plants. Indeed, Rubisco has been detected at low levels in guard cell chloroplasts, and our studies indicate that it is active in the pathways for photosynthetic carbon reduction and photorespiration in guard cells.
Full text
PDF






Images in this article
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Gotow K., Taylor S., Zeiger E. Photosynthetic Carbon Fixation in Guard Cell Protoplasts of Vicia faba L. : Evidence from Radiolabel Experiments. Plant Physiol. 1988 Mar;86(3):700–705. doi: 10.1104/pp.86.3.700. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Mawson B. T., Franklin A., Filion W. G., Cummins W. R. Comparative Studies of Fluorescence from Mesophyll and Guard Cell Chloroplasts in Saxifraga cernua: Analysis of Fluorescence Kinetics as a Function of Excitation Intensity. Plant Physiol. 1984 Mar;74(3):481–486. doi: 10.1104/pp.74.3.481. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Mawson B. T., Zeiger E. Blue light-modulation of chlorophyll a fluorescence transients in guard cell chloroplasts. Plant Physiol. 1991 Jul;96(3):753–760. doi: 10.1104/pp.96.3.753. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Melis A., Zeiger E. Chlorophyll a Fluorescence Transients in Mesophyll and Guard Cells : MODULATION OF GUARD CELL PHOTOPHOSPHORYLATION BY CO(2). Plant Physiol. 1982 Mar;69(3):642–647. doi: 10.1104/pp.69.3.642. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ogawa T., Grantz D., Boyer J., Govindjee Effects of Cations and Abscisic Acid on Chlorophyll a Fluorescence in Guard Cells of Vicia faba. Plant Physiol. 1982 May;69(5):1140–1144. doi: 10.1104/pp.69.5.1140. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Outlaw W. H., Mayne B. C., Zenger V. E., Manchester J. Presence of Both Photosystems in Guard Cells of Vicia faba L: IMPLICATIONS FOR ENVIRONMENTAL SIGNAL PROCESSING. Plant Physiol. 1981 Jan;67(1):12–16. doi: 10.1104/pp.67.1.12. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Reckmann U., Scheibe R., Raschke K. Rubisco activity in guard cells compared with the solute requirement for stomatal opening. Plant Physiol. 1990 Jan;92(1):246–253. doi: 10.1104/pp.92.1.246. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Serrano E. E., Zeiger E., Hagiwara S. Red light stimulates an electrogenic proton pump in Vicia guard cell protoplasts. Proc Natl Acad Sci U S A. 1988 Jan;85(2):436–440. doi: 10.1073/pnas.85.2.436. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Shimazaki K. Ribulosebisphosphate carboxylase activity and photosynthetic o(2) evolution rate in vicia guard-cell protoplasts. Plant Physiol. 1989 Oct;91(2):459–463. doi: 10.1104/pp.91.2.459. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Shimazaki K., Terada J., Tanaka K., Kondo N. Calvin-Benson Cycle Enzymes in Guard-Cell Protoplasts from Vicia faba L: Implications for the Greater Utilization of Phosphoglycerate/Dihydroxyacetone Phosphate Shuttle between Chloroplasts and the Cytosol. Plant Physiol. 1989 Jul;90(3):1057–1064. doi: 10.1104/pp.90.3.1057. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Shimazaki K., Zeiger E. Cyclic and Noncyclic Photophosphorylation in Isolated Guard Cell Chloroplasts from Vicia faba L. Plant Physiol. 1985 Jun;78(2):211–214. doi: 10.1104/pp.78.2.211. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Shimazaki K., Zeiger E. Red Light-Dependent CO(2) Uptake and Oxygen Evolution in Guard Cell Protoplasts of Vicia faba L.: Evidence for Photosynthetic CO(2) Fixation. Plant Physiol. 1987 May;84(1):7–9. doi: 10.1104/pp.84.1.7. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Zemel E., Gepstein S. Immunological evidence for the presence of ribulose bisphosphate carboxylase in guard cell chloroplasts. Plant Physiol. 1985 Jul;78(3):586–590. doi: 10.1104/pp.78.3.586. [DOI] [PMC free article] [PubMed] [Google Scholar]