Crassulacean acid metabolism: a continuous or discrete trait?

Winter, Klaus, Holtum, Joseph A.M., and Smith, J.Andrew C. (2015) Crassulacean acid metabolism: a continuous or discrete trait? New Phytologist, 208 (1). pp. 73-78.

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Abstract

The key components of crassulacean acid metabolism (CAM) – nocturnal fixation of atmospheric CO2 and its processing via Rubisco in the subsequent light period – are now reasonably well understood in terms of the biochemical reactions defining this water-saving mode of carbon assimilation. Phenotypically, however, the degree to which plants engage in the CAM cycle relative to regular C3 photosynthesis is highly variable. Depending upon species, ontogeny and environment, the contribution of nocturnal CO2 fixation to 24-h carbon gain can range continuously from close to 0% to 100%. Nevertheless, not all possible combinations of light and dark CO2 fixation appear equally common. Large-scale surveys of carbon-isotope ratios typically show a strongly bimodal frequency distribution, with relatively few intermediate values. Recent research has revealed that many species capable of low-level CAM activity are nested within the peak of C3-type isotope signatures. While questions remain concerning the adaptive significance of dark CO2 fixation in such species, plants with low-level CAM should prove valuable models for investigating the discrete changes in genetic architecture and gene expression that have enabled the evolutionary transition from C3 to CAM.

Item ID: 37621
Item Type: Article (Research - C1)
ISSN: 1469-8137
Date Deposited: 27 May 2016 14:23
FoR Codes: 06 BIOLOGICAL SCIENCES > 0607 Plant Biology > 060705 Plant Physiology @ 20%
06 BIOLOGICAL SCIENCES > 0607 Plant Biology > 060702 Plant Cell and Molecular Biology @ 80%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 100%
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