Planta

, Volume 187, Issue 2, pp 275–281

Role of carbonic anhydrase in photosynthesis and inorganic-carbon assimilation in the red alga Gracilaria tenuistipitata

  • Kurt Haglund
  • Mats Björk
  • Ziyadin Ramazanov
  • Guillermo García-Reina
  • Marianne Pedersén
Article

DOI: 10.1007/BF00201951

Cite this article as:
Haglund, K., Björk, M., Ramazanov, Z. et al. Planta (1992) 187: 275. doi:10.1007/BF00201951

Abstract

The mechanism of inorganic-carbon (Ci) accumulation in the red seaweed Gracilaria tenuistipitata Zhang et Xia has been investigated. Extracellular and intracellular carbonic-anhydrase (CA) activities have been detected. Photosynthetic O2 evolution in thalli and protoplasts of G. tenuistipitata were higher at pH 6.5 than at pH 8.6, where HCO3is the predominant form of Ci. Dextran-bound sulfonamide (DBS), a specific inhibitor of extracellular CA, reduced photosynthetic O2 evolution at pH 8.6 and did not have any effect at pH 6.5. After inhibition with DBS, O2 evolution was similar to the rate that could be supported by CO2 from spontaneous dehydration of HCO3. The rate of photosynthetic alkalization of the surrounding medium by the algal thallus was dependent on the concentration of Ci and inhibited by DBS. We suggest that the general form of Ci that enters through the plasma membrane of G. tenuistipitata is CO2. Bicarbonate is utilized mainly by an indirect mechanism after dehydration to CO2, and this mechanism involves extracellular CA.

Key words

Carbon assimilationCarbonic anhydraseCarbon dioxide uptakeGracilariaPhotosynthesis

Abbreviations

Ci

inorganic carbon (CO2 + HCO3)

CA

carbonic anhydrase

DIC

dissolved inorganic carbon (total)

DBS

dextran-bound sulfonamide

EZ

ethoxyzolamide

NSW

natural seawater

PPFD

photosynthetic photon flux density

REA

relative enzyme activity

Rubisco

ribulose-1,5-bisphosphate carboxylase/oxygenase

Copyright information

© Springer-Verlag 1992

Authors and Affiliations

  • Kurt Haglund
    • 1
  • Mats Björk
    • 1
  • Ziyadin Ramazanov
    • 2
  • Guillermo García-Reina
    • 3
  • Marianne Pedersén
    • 1
  1. 1.Department of Physiological BotanyUppsala UniversityUppsalaSweden
  2. 2.Institute of Plant Physiology, Russian Academy of SciencesMoscowRussian Federation
  3. 3.Marine Plant Biotechnology Laboratory, University of Las PalmasLas PalmasSpain
  4. 4.Department of BotanyLouisiana State UniversityBaton RougeUSA