Crassulacean acid metabolism: a continuous or discrete trait?. Issue 1 (14th May 2015)

• Record Type: Journal Article
• Authors: Winter, Klaus; Holtum, Joseph A. M.; Smith, J. Andrew C.
• Is Part Of: New phytologist. Volume 208:Issue 1(2015:Oct. 01)
• Page Start: 73
• Page End: 78
• Publication Date: 2015-05-14
• Subjects: Botany -- Periodicals; 580
• DOI: 10.1111/nph.13446
• Languages: English
• ISSNs: 0028-646X

Abstract

<abstract abstract-type="main" id="nph13446-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="nph13446-sec-0001" sec-type="opening"> <p> <table-wrap position="anchor" orientation="portrait"> <table width="100%" border="1"> <colgroup span="1"> <col span="1" /> <col span="1" /> <col span="1" /> </colgroup> <tbody> <tr> <td align="left" rowspan="1" colspan="1"> </td> <td align="left" rowspan="1" colspan="1"> <xref ref-type="link" rid="nph13446-sec-0101" /> </td> <td align="left" rowspan="1" colspan="1">73</td> </tr> <tr> <td align="left" rowspan="1" colspan="1">I.</td> <td align="left" rowspan="1" colspan="1"> <xref ref-type="link" rid="nph13446-sec-0002">I.</xref> </td> <td align="left" rowspan="1" colspan="1">73</td> </tr> <tr> <td align="left" rowspan="1" colspan="1">II.</td> <td align="left" rowspan="1" colspan="1"> <xref ref-type="link" rid="nph13446-sec-0003">II.</xref> </td> <td align="left" rowspan="1" colspan="1">74</td> </tr> <tr> <td align="left" rowspan="1" colspan="1">III.</td> <td align="left" rowspan="1" colspan="1"> <xref ref-type="link" rid="nph13446-sec-0004">III.</xref> </td> <td align="left" rowspan="1" colspan="1">74</td> </tr> <tr> <td align="left" rowspan="1" colspan="1">IV.</td> <td align="left" rowspan="1" colspan="1"> <xref ref-type="link" rid="nph13446-sec-0005">IV.</xref> </td> <td align="left" rowspan="1" colspan="1">75</td> </tr> <tr> <td align="left" rowspan="1" colspan="1">V.</td> <td align="left" rowspan="1" colspan="1"> <xref ref-type="link" rid="nph13446-sec-0006">V.</xref> </td> <td align="left" rowspan="1" colspan="1">76</td> </tr> <tr> <td align="left" rowspan="1" colspan="1">VI.</td> <td align="left" rowspan="1" colspan="1"> <xref ref-type="link" rid="nph13446-sec-0007">VI.</xref> </td> <td align="left" rowspan="1" colspan="1">76</td> </tr> <tr> <td align="left" rowspan="1" colspan="1">VII.</td> <td align="left" rowspan="1" colspan="1"> <xref ref-type="link" rid="nph13446-sec-0008">VII.</xref> </td> <td align="left" rowspan="1" colspan="1">77</td> </tr> <tr> <td align="left" rowspan="1" colspan="1"> </td> <td align="left" rowspan="1" colspan="1"> <xref ref-type="link" rid="nph13446-sec-0009" /> </td> <td align="left" rowspan="1" colspan="1">77</td> </tr> <tr> <td align="left" rowspan="1" colspan="1"> </td> <td align="left" rowspan="1" colspan="1"> <xref ref-type="link" rid="nph13446-bibl-0001">References</xref> </td> <td align="left" rowspan="1" colspan="1">77</td> </tr> </tbody> </table> </table-wrap> </p> </sec> <sec id="nph13446-sec-0101" sec-type="section"> <title>Summary</title> <p>The key components of crassulacean acid metabolism (CAM) – nocturnal fixation of atmospheric CO<sub>2</sub> 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 C<sub>3</sub> photosynthesis is highly variable. Depending upon species, ontogeny and environment, the contribution of nocturnal CO<sub>2</sub> fixation to 24‐h carbon gain can range continuously from close to 0% to 100%. Nevertheless, not all possible combinations of light and dark CO<sub>2</sub> 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 C<sub>3</sub>‐type isotope signatures. While questions remain concerning the adaptive significance of dark CO<sub>2</sub> 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 C<sub>3</sub> to CAM.</p> </sec> </abstract>