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Plant function and evolutionary biology
RESEARCH ARTICLE

Crassulacean acid metabolism (CAM) supersedes the turgor loss point (TLP) as an important adaptation across a precipitation gradient, in the genus Clusia

Alistair Leverett https://orcid.org/0000-0002-7064-1917 A B C E , Natalia Hurtado Castaño A D , Kate Ferguson A , Klaus Winter https://orcid.org/0000-0002-0448-2807 B and Anne M. Borland A
+ Author Affiliations
- Author Affiliations

A School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon Tyne, NE1 7RU, UK.

B Smithsonian Tropical Research Institute, PO Box 0843-03092, Balboa, Ancón, Republic of Panama.

C Carl R. Woese Institute for Genomic Biology, 1206 West Gregory Drive, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.

D Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK.

E Corresponding author. Email: alilev93@illinois.edu

Functional Plant Biology 48(7) 703-716 https://doi.org/10.1071/FP20268
Submitted: 25 August 2020  Accepted: 30 January 2021   Published: 5 March 2021

Abstract

As future climates continue to change, precipitation deficits are expected to become more severe across tropical ecosystems. As a result, it is important that we identify plant physiological traits that act as adaptations to drought, and determine whether these traits act synergistically or independently of each other. In this study, we assessed the role of three leaf-level putative adaptations to drought: crassulacean acid metabolism (CAM), the turgor loss point (TLPΨ) and water storage hydrenchyma tissue. Using the genus Clusia as a model, we were able to explore the extent to which these leaf physiological traits co-vary, and also how they contribute to species’ distributions across a precipitation gradient in Central and South America. We found that CAM is independent of the TLPΨ and hydrenchyma depth in Clusia. In addition, we provide evidence that constitutive CAM is an adaptation to year-long water deficits, whereas facultative CAM appears to be more important for surviving acute dry seasons. Finally, we find that the other leaf traits tested did not correlate with environmental precipitation, suggesting that the reduced transpirational rates associated with CAM obviate the need to adapt the TLPΨ and hydrenchyma depth in this genus.

Keywords: crassulacean acid metabolism, CAM plants, hydrenchyma, turgor, Clusia spp., drought tolerance, tropical ecophysiology, rainforest ecology.


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