Canopy CO2 exchange of two neotropical tree species exhibiting constitutive and facultative CAM photosynthesis, Clusia rosea and Clusia cylindrica

Winter, Klaus, Garcia, Milton, and Holtum, Joseph A.M. (2009) Canopy CO2 exchange of two neotropical tree species exhibiting constitutive and facultative CAM photosynthesis, Clusia rosea and Clusia cylindrica. Journal of Experimental Botany, 60 (11). pp. 3167-3177.

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Abstract

Photon flux density (PFD) and water availability, the daily and seasonal factors that vary most in tropical environments, were examined to see how they influenced expression of crassulacean acid metabolism (CAM) in 3- year-old Clusia shrubs native to Panama. Instead of the commonly used single-leaf approach, diel CO2 exchange was measured for whole individual canopies of plants in large soil containers inside a naturally illuminated 8.8 m3 chamber. In well-watered C. rosea, a mainly constitutive CAM species, nocturnally fixed CO2 contributed about 50% to 24 h carbon gain on sunny days but the contribution decreased to zero following overcast days. Nonetheless, CO2 fixation in the light responded in such a way that 24 h carbon gain was largely conserved across the range of daily PFDs. The response of C. rosea to drought was similarly buffered. A facultative component of CAM expression led to reversible increases in nocturnal carbon gain that offset drought-induced reductions of CO2 fixation in the light. Clusia cylindrica was a C3 plant when well-watered but exhibited CAM when subjected to water stress. The induction of CAM was fully reversible upon rewatering. C. cylindrica joins C. pratensis as the most unambiguous facultative CAM species reported in the genus Clusia.

Item ID: 8408
Item Type: Article (Refereed Research - C1)
Keywords: Clusia cylindrica, Clusia rosea, CO2 exchange, constitutive CAM, crassulacean acid metabolism, facultative CAM, photosynthetic pathway, tree canopy, whole-plant physiology
ISSN: 1460-2431
Date Deposited: 18 Feb 2010 06:04
FoR Codes: 06 BIOLOGICAL SCIENCES > 0607 Plant Biology > 060705 Plant Physiology @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 100%
Citation Count from Web of Science Web of Science 5
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