caa a22 4500 469097485 CHVBK 20180323133035.0 cr unu---uuuuu 170328e19920801xx s 000 0 eng 10.1007/BF00317239 doi (NATIONALLICENCE)springer-10.1007/BF00317239 Light and dark CO2 fixation in Clusia uvitana and the effects of plant water status and CO2 availability [Elektronische Daten] [Klaus Winter, Gerhard Zotz, Bernhard Baur, Karl-Josef Dietz] Summary: In well-watered plants of Clusia uvitana, a species capable of carbon fixation by crassulacean acid metabolism (CAM), recently expanded leaves gained 5 to 13-fold more carbon during 12 h light than during 12 h dark periods. When water was withheld from the plants, daytime net CO2 uptake strongly decreased over a period of several days, whereas there was a marked increase in nocturnal carbon gain. Photosynthetic rates in the chloroplasts were hardly affected by the water stress treatment, as demonstrated by measurements of chlorophyll a fluorescence of intact leaves, indicating efficient decarboxylation of organic acids and refixation of carbon in the light. Within a few days after rewatering, plants reverted to the original gas exchange pattern with net CO2 uptake predominantly occurring during daytime. The reversible increase in dark CO2 fixation was paralleled by a reversible increase in the content of phosphoenolpyruvate (PEP) carboxylase protein. In wellwatered plants, short-term changes in the degree of dark CO2 fixation were induced by alterations in CO2 partial pressure during light periods: a decrease from 350 to 170 μbar CO2 caused nocturnal carbon gain, measured in normal air (350 μbar), to increase, whereas an increase to 700 μbar CO2, during the day, caused net dark CO2 fixation to cease. The increased CAM activity in response to water shortage may, at least to some extent, be directly related to the reduced carbon gain during daytime. Springer-Verlag, 1992 Chlorophyll fluorescence nationallicence Clusia nationallicence Crassulacean acid metabolism nationallicence Phosphoenolpyruvate carboxylase nationallicence Winter Klaus Smithsonian Tropical Research Institute, Apdo 2072, Balboa, Republic of Panama aut Zotz Gerhard Smithsonian Tropical Research Institute, Apdo 2072, Balboa, Republic of Panama aut Baur Bernhard Julius von Sachs-Institut für Biowissenschaften, Mittlerer Dallenbergweg 64, W-8700, Würzburg, Federal Republic of Germany aut Dietz Karl-Josef Julius von Sachs-Institut für Biowissenschaften, Mittlerer Dallenbergweg 64, W-8700, Würzburg, Federal Republic of Germany aut Oecologia Springer-Verlag 91/1(1992-08-01), 47-51 0029-8549 91:1<47 1992 91 442 https://doi.org/10.1007/BF00317239 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00317239 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Winter Klaus Smithsonian Tropical Research Institute, Apdo 2072, Balboa, Republic of Panama aut NATIONALLICENCE 700 1- Zotz Gerhard Smithsonian Tropical Research Institute, Apdo 2072, Balboa, Republic of Panama aut NATIONALLICENCE 700 1- Baur Bernhard Julius von Sachs-Institut für Biowissenschaften, Mittlerer Dallenbergweg 64, W-8700, Würzburg, Federal Republic of Germany aut NATIONALLICENCE 700 1- Dietz Karl-Josef Julius von Sachs-Institut für Biowissenschaften, Mittlerer Dallenbergweg 64, W-8700, Würzburg, Federal Republic of Germany aut NATIONALLICENCE 773 0- Oecologia Springer-Verlag 91/1(1992-08-01), 47-51 0029-8549 91:1<47 1992 91 442 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer