Journal Article

Chlorophyll Fluorescence and Organic Acid Oscillations during Transition from CAM to C<sub>3</sub>-photosynthesis in<i>Clusia minor</i> L. (Clusiaceae)

Eduardo A. de Mattos and Ulrich LÜttge

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 88, issue 3, pages 457-463
Published in print September 2001 | ISSN: 0305-7364
Published online September 2001 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1006/anbo.2001.1477
Chlorophyll Fluorescence and Organic Acid Oscillations during Transition from CAM to C3-photosynthesis inClusia minor L. (Clusiaceae)

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In species of Clusia, switching from C3-photosynthesis (C3-PS) to crassulacean acid metabolism (CAM) may be a means of optimizing water use, plant carbon balance and photon utilization during periods of stress. We ask whether, in perennial species of Clusia, the switch from CAM back to C3-PS is also of ecophysiological significance. Our objective was to investigate the performance of C. minor L. during a short-term shift from CAM to C3-PS. During the transition from CAM to C3-PS, nocturnal malate and citrate accumulation decreased whereas CO2uptake increased during the daytime. However, after 7 d, marked nocturnal accumulation of citrate and 24 h CO2uptake occurred. In contrast to C3-like photosynthesis, a pronounced reduction in the effective quantum yield of photosystem II, ▵F/F′m, together with a sharp increase in non-photochemical quenching were observed during CAM at the beginning and end of the day. After 7 d, integrated CO2uptake over 24 h approximately doubled; however, water use efficiency was reduced three-fold due to increased rates of daytime transpiration. Despite very similar maximum ▵F/F′mbetween CAM and C3-PS, the results suggest that daily photon utilization increases when there is unrestricted CO2uptake directly from the atmosphere. Thus, under well-watered conditions and with increased rates of transpiration, C. minor performing C3-like photosynthesis may overcome the limitations of the storage capacity of the vacuole for overnight organic acid accumulation, improving its daily carbon balance. Copyright 2001 Annals of Botany Company

Keywords: Gas exchange, organic acid, vacuoles, photoinhibition, C3-photosynthesis, CAM, Clusia minor

Journal Article.  34 words. 

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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