The CAM lineages of planet Earth

Gilman, Ian S., Smith, J. Andrew C., Holtum, Joseph A.M., Sage, Rowan F., Silvera, Katia, Winter, Klaus, and Edwards, Erika J. (2023) The CAM lineages of planet Earth. Annals of Botany, 132 (4). pp. 627-654.

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Background and Scope: The growth of experimental studies of crassulacean acid metabolism (CAM) in diverse plant clades, coupled with recent advances in molecular systematics, presents an opportunity to re-assess the phylogenetic distribution and diversity of species capable of CAM. It has been more than two decades since the last comprehensive lists of CAM taxa were published, and an updated survey of the occurrence and distribution of CAM taxa is needed to facilitate and guide future CAM research. We aimed to survey the phylogenetic distribution of these taxa, their diverse morphology, physiology and ecology, and the likely number of evolutionary origins of CAM based on currently known lineages.

Results and Conclusions: We found direct evidence (in the form of experimental or field observations of gas exchange, day-night fluctuations in organic acids, carbon isotope ratios and enzymatic activity) for CAM in 370 genera of vascular plants, representing 38 families. Further assumptions about the frequency of CAM species in CAM clades and the distribution of CAM in the Cactaceae and Crassulaceae bring the currently estimated number of CAM-capable species to nearly 7 % of all vascular plants. The phylogenetic distribution of these taxa suggests a minimum of 66 independent origins of CAM in vascular plants, possibly with dozens more. To achieve further insight into CAM origins, there is a need for more extensive and systematic surveys of previously unstudied lineages, particularly in living material to identify low-level CAM activity, and for denser sampling to increase phylogenetic resolution in CAM-evolving clades. This should allow further progress in understanding the functional significance of this pathway by integration with studies on the evolution and genomics of CAM in its many forms.

Item ID: 82126
Item Type: Article (Research - C1)
ISSN: 1095-8290
Keywords: C3 + CAM, C3 photosynthesis, C4 + CAM, crassulacean acid metabolism, nocturnal acidification, photosynthetic pathway evolution, strong CAM, vascular plants
Copyright Information: © The Author(s) 2023. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail:
Date Deposited: 18 Mar 2024 23:50
FoR Codes: 31 BIOLOGICAL SCIENCES > 3104 Evolutionary biology > 310411 Plant and fungus systematics and taxonomy @ 50%
31 BIOLOGICAL SCIENCES > 3108 Plant biology > 310899 Plant biology not elsewhere classified @ 50%
SEO Codes: 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280102 Expanding knowledge in the biological sciences @ 100%
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