, Volume 147, Issue 1, pp 31–36 | Cite as

The activity and malate inhibition/stimulation of phosphoenolpyruvate-carboxylase in crassulacean-acid-metabolism plants in their natural environment

  • D. J. von Willert
  • E. Brinckmann
  • B. Scheitler
  • D. A. Thomas
  • S. Treichel


The effect of environmental conditions, temperature, relative humidity, and light, together with the regulation of PEPC (phosphoenolpyruvate-carboxylase) activity by malate and pH on CAM (crassulacean acid metabolism), was studied in members of the Mesembryanthemaceae in their natural environment, the southern Namib desert. It was found that during a 24 h period the characteristics of PEPC change. Before sunrise the activity is higher when measured at pH 7 than 8. With bright sunlight the activity measured at pH 7 drops to 20% of its pre-sunrise value, the activity only recovers gradually after malate disappearance and stays constant throughout the night. When measured at pH 8, PEPC shows an opposite behavior, i.e., activity increases in bright sunlight and declines as the pH 7 activity increases. A day-night oscillation in the capacity of malate to stimulate or inhibit PEPC was found. During the day malate inhibits about 90% of the PEPC activity at both pH 7 and 8. After sunset there is a sudden decrease in this inhibition and, at pH 8, malate stimulates the activity by 50%. At pH 7 the stimulation was less.

Both stomatal conductance and malate formation were found to increase only when the relative humidity at night rose to 80%. Changes in the properties of the PEPC coincided with the exposure to bright sunlight and changes in leaf temperature. The importance of these metabolic and environmental controls on the regulation of CAM in the Mesembryanthemaceae will be discussed.

Key words

CAM regulation Environmental variables Malate inhibition/stimulation Mesembryanthemaceae PEP carboxylase 



crassulacean acid metabolism






Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Bergmeyer, H.U.: Methoden der enzymatischen Analyse. Weinheim: Verlag Chemie 1970Google Scholar
  2. Kluge, M., Osmond, C.B.: Studies on PEP carboxylase and other enzymes of CAM of Bryophyllum tubiflorum and Sedum praealtum. Z. Pflanzenphysiol. 66, 97–105 (1972)Google Scholar
  3. Kluge, M., Ting, J.O.: Crassulacean acid metabolism. Analysis of an ecological adaptation. Ecological Studies 30. Berlin, Heidelberg, New York: Springer 1978Google Scholar
  4. Medina, E., Delgado, M.: Photosynthesis and night CO2 fixation in Echeveria columbiana. Photosynthetica 10, 155–163 (1976)Google Scholar
  5. Stocker, O.: Pflanzenphysiol. Übungen. Jena: Gustav Fischer 1942Google Scholar
  6. Szarek, S.R., Johnson, H.B., Ting, J.P.: Drought adaptation in Opuntia basilaris. Significance of recycling carbon through CAM. Plant Physiol. 52, 539–41 (1973)Google Scholar
  7. Treichel, S., Kirst, G.O., Willert, D.J. v.: Veränderung der Aktivität der PEP-carboxylase durch NACl bei Haleophyten verschiedener Biotope. Z. Pflanzenphysiol. 71, 437–449 (1974)Google Scholar
  8. Willert, D.J. v., Curdts, E., v. Willert, K.: Veränderungen der PEP-Carboxylase während einer durch NaCl geförderten Ausbildung eines CAM bei Mesembryanthemum crystallinum. Biochem. Physiol. Pflanz. 171, 101–107 (1977a)Google Scholar
  9. Willert, D.J. v., Thomas, D.A., Lobin, W., Curdts, E.: Ecophysiologic investigations in the family of Mesembryanthemaceae. Occurrence of a CAM and ion content. Oecologia 29, 67–76 (1977b)Google Scholar
  10. Willert, D.J. v., Brinckmann, E., Schulze, E.-D.: Ecophysiological investigations of plants in the coastal desert of Southern Africa. Ion content and CAM. First Europ. Ecolog. Symp. Blackwell Scientific Publ. (in press)Google Scholar
  11. Willert, D.J. v.: Vorkommen und Regulation des CAM bei Mittagsblumengewächsen (Mesembryanthemaceae). Ber. Dtsch. Bot. Ges. (in press)Google Scholar
  12. Willert, D.J. v., Willert, K. v.: Light modulation of the activity of the PEP-carboxylase in CAM-plants in the Mesembryauthemaceae. Z. Pflanzenphysiol. 95, 43–49 (1979)Google Scholar

Copyright information

© Springer-Verlag 1979

Authors and Affiliations

  • D. J. von Willert
    • 1
  • E. Brinckmann
    • 1
  • B. Scheitler
    • 1
  • D. A. Thomas
    • 1
  • S. Treichel
    • 2
  1. 1.Lehrstuhl für PflanzenökologieUniversität BayreuthBayreuthFederal Republic of Germany
  2. 2.Botanisches Institut TH DarmstadtDarmstadtFederal Republic of Germany

Personalised recommendations