Abstract
The effect of photon flux density on inorganic carbon accumulation and photosynthetic CO2 assimilation was determined by CO2 exchange studies at three, limiting CO2 concentrations with a ca-1 mutant of Chlamydomonas reinhardiii. This mutant accumulates a large internal inorganic carbon pool in the light which apparently is unavailable for photosynthetic assimilation. Although steady-state photosynthetic CO2 assimilation did not respond to the varying photon flux densities because of CO2 limitation, components of inorganic-carbon accumulation were not clearly light saturated even at 1100 μmol photons m-2 s-1, indicating a substantial energy requirement for inorganic carbon transport and accumulation. Steady-state photosynthetic CO2 assimilation responded to external CO2 concentrations but not to changing internal inorganic carbon concentrations, confirming that diffusion of CO2 into the cells supplies most of the CO2 for photosynthetic assimilation and that the internal inorganic carbon pool is essentially unavailable for photosynthetic assimilation. The estimated concentration of the internal inorganic carbon pool was found to be relatively insensitive to the external CO2 concentration over the small range tested, as would be expected if the concentration of this pool is limited by the internal to external inorganic carbon gradient. An attempt to use this CO2 exchange method to determine whether inorganic carbon accumulation and photosynthetic CO2 assimilation compete for energy at low photon flux densities proved inconclusive.
Similar content being viewed by others
References
Badger MR (1987) The CO2-concentrating mechanism in aquatic phototrophs. In: Hatch MD and Boardman NK (eds) The Biochemistry of Plants, a Comprehensive Treatise, Vol 10, pp 219–274. Photosynthesis, Academic Press, San Diego
Badger MR, Kaplan A and Berry JA (1980) Internal inorganic carbon pool of Chlamydomonas reinhardtii. Evidence for a carbon dioxide concentrating mechanism. Plant Physiol 66: 407–413
Moroney JV, Husic HD and Tolbert NE (1985) Effect of carbonic anhydrase inhibitors on inorganic carbon accumulation by Chlamydomonas reinhardtii. Plant Physiol 79: 177–183
Moroney JV, Togasaki RK, Husic HD and Tolbert NE (1987) Evidence that an internal carbonic anhydrase is present in 5% CO2 grown and air-grown Chlamydomonas. Plant Physiol 84: 757–761
Ogawa T, Miyano A and Inoue Y (1985) Photosystem-I-driven inorganic carbon transport in the cyanobacterium Anacystis nidulans. Biochim Biophys Acta 808: 77–84
Spalding MH (1989) Photosynthesis and photorespiration in freshwater green algae. Aquatic Botany 34: 181–209
Spalding MH and Ogren WL (1983) Evidence for a saturable transport component in the inorganic carbon uptake of Chlamydomonas reinhardtii. FEBS Lett. 154: 335–338
Splading MH and Ogren WL (1985) CO2 exchange characteristics during dark-light transitions in wild-type and mutant Chlamydomonas reinhardtii cells. Photosynth Res 6: 363–369
Spalding MH and Portis AR (1985) A model of carbon dioxide assimilation in Chlamydomonas reinhardtii. Planta 164: 308–320
Splading MH, Spreitzer RJ and Ogren WL (1983a) Carbonic anhydrase deficient mutant of Chlamydomonas requires elevated carbon dioxide concentration for photoautotrophic growth. Plant Physiol 73: 268–272
Spalding MH, Spreitzer RJ and Ogren WL (1983b) Reduced inorganic carbon transport in a CO2-requiring mutant of Chlamydomonas reinhardtii. Plant Physiol 73: 273–276
Spalding MH, Spreitzer RH and Ogren WL (1985) Use of mutants in analysis of the CO2-concentrating pathway of Chlamydomonas reinhardtii. In: Lucas WJ and Berry JA (eds) Inorganic Carbon Uptake by Aquatic Photosythetic Organisms, American Society of Plant Physiologists, pp 361–375. Rockville, MD
Sültemeyer DF, Klug K and Fock HP (1986) Effect of photon fluence rate on oxygen evolution and uptake by Chlamydomonas reinhardtii suspensions grown in ambient and CO2-enriched air. Plant Physiol 81: 372–375
Suzuki K and Spalding MH (1989a) Adaptation of Chlamydomonas reinhardtii high-CO2-requiring mutants to limiting CO2. Plant Physiol 90: 1195–1200
Suzuki K and Spalding MH (1989b) Effect of O2 and CO2 on net CO2 exchange in a high-CO2-requiring mutant of Chlamydomonas reinhardtii during dark-light-dark transitions. Photosynth Res 21: 181–186
Wintermans JFGM and De Mots A (1965) Spectrophotometric characteristics of chlorophyll and their pheophytins in ethanol. Biochim Biophys Acta 109: 448–453
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Spalding, M.H. Effect of photon flux density on inorganic carbon accumulation and net CO2 exchange in a high-CO2-requiring mutant of Chlamydomonas reinhardtii . Photosynth Res 24, 245–252 (1990). https://doi.org/10.1007/BF00032312
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00032312