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Gilman IS, Heyduk K, Maya-Lastra C, Hancock LP, Edwards EJ. Predicting photosynthetic pathway from anatomy using machine learning. THE NEW PHYTOLOGIST 2024; 242:1029-1042. [PMID: 38173400 DOI: 10.1111/nph.19488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 11/29/2023] [Indexed: 01/05/2024]
Abstract
Plants with Crassulacean acid metabolism (CAM) have long been associated with a specialized anatomy, including succulence and thick photosynthetic tissues. Firm, quantitative boundaries between non-CAM and CAM plants have yet to be established - if they indeed exist. Using novel computer vision software to measure anatomy, we combined new measurements with published data across flowering plants. We then used machine learning and phylogenetic comparative methods to investigate relationships between CAM and anatomy. We found significant differences in photosynthetic tissue anatomy between plants with differing CAM phenotypes. Machine learning-based classification was over 95% accurate in differentiating CAM from non-CAM anatomy, and had over 70% recall of distinct CAM phenotypes. Phylogenetic least squares regression and threshold analyses revealed that CAM evolution was significantly correlated with increased mesophyll cell size, thicker leaves, and decreased intercellular airspace. Our findings suggest that machine learning may be used to aid the discovery of new CAM species and that the evolutionary trajectory from non-CAM to strong, obligate CAM requires continual anatomical specialization.
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Affiliation(s)
- Ian S Gilman
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, 06520, USA
- Department of Horticulture, Michigan State University, East Lansing, MI, 48824, USA
- Plant Resilience Institute, Michigan State University, East Lansing, MI, 48824, USA
| | - Karolina Heyduk
- Department of Ecology and Evolutionary Biology, The University of Connecticut, Storrs, CT, 06269, USA
| | - Carlos Maya-Lastra
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, 06520, USA
- Department of Biology, Angelo State University, San Angelo, TX, 76909, USA
| | - Lillian P Hancock
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, 06520, USA
| | - Erika J Edwards
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, 06520, USA
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Luján M, Leverett A, Winter K. Forty years of research into crassulacean acid metabolism in the genus Clusia: anatomy, ecophysiology and evolution. ANNALS OF BOTANY 2023; 132:739-752. [PMID: 36891814 PMCID: PMC10799992 DOI: 10.1093/aob/mcad039] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 02/21/2023] [Accepted: 03/08/2023] [Indexed: 06/18/2023]
Abstract
Clusia is the only genus containing dicotyledonous trees with a capacity to perform crassulacean acid metabolism (CAM). Since the discovery of CAM in Clusia 40 years ago, several studies have highlighted the extraordinary plasticity and diversity of life forms, morphology and photosynthetic physiology of this genus. In this review, we revisit aspects of CAM photosynthesis in Clusia and hypothesize about the timing, the environmental conditions and potential anatomical characteristics that led to the evolution of CAM in the group. We discuss the role of physiological plasticity in influencing species distribution and ecological amplitude in the group. We also explore patterns of allometry of leaf anatomical traits and their correlations with CAM activity. Finally, we identify opportunities for further research on CAM in Clusia, such as the role of elevated nocturnal accumulation of citric acid, and gene expression in C3-CAM intermediate phenotypes.
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Affiliation(s)
- Manuel Luján
- Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AE, UK
| | - Alistair Leverett
- School of Life Sciences, University of Essex, Colchester, Essex CO4 3SQ, UK
| | - Klaus Winter
- Smithsonian Tropical Research Institute, PO Box 0843-03092, Balboa, Ancón, Republic of Panama
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Leverett A, Hartzell S, Winter K, Garcia M, Aranda J, Virgo A, Smith A, Focht P, Rasmussen-Arda A, Willats WGT, Cowan-Turner D, Borland AM. Dissecting succulence: Crassulacean acid metabolism and hydraulic capacitance are independent adaptations in Clusia leaves. PLANT, CELL & ENVIRONMENT 2023; 46:1472-1488. [PMID: 36624682 DOI: 10.1111/pce.14539] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Revised: 01/05/2023] [Accepted: 01/08/2023] [Indexed: 06/17/2023]
Abstract
Succulence is found across the world as an adaptation to water-limited niches. The fleshy organs of succulent plants develop via enlarged photosynthetic chlorenchyma and/or achlorophyllous water storage hydrenchyma cells. The precise mechanism by which anatomical traits contribute to drought tolerance is unclear, as the effect of succulence is multifaceted. Large cells are believed to provide space for nocturnal storage of malic acid fixed by crassulacean acid metabolism (CAM), whilst also buffering water potentials by elevating hydraulic capacitance (CFT ). The effect of CAM and elevated CFT on growth and water conservation have not been compared, despite the assumption that these adaptations often occur together. We assessed the relationship between succulent anatomical adaptations, CAM, and CFT , across the genus Clusia. We also simulated the effects of CAM and CFT on growth and water conservation during drought using the Photo3 model. Within Clusia leaves, CAM and CFT are independent traits: CAM requires large palisade chlorenchyma cells, whereas hydrenchyma tissue governs interspecific differences in CFT . In addition, our model suggests that CAM supersedes CFT as a means to maximise CO2 assimilation and minimise transpiration during drought. Our study challenges the assumption that CAM and CFT are mutually dependent traits within succulent leaves.
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Affiliation(s)
- Alistair Leverett
- School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon Tyne, UK
- Smithsonian Tropical Research Institute, Balboa, Ancón, Republic of Panama
| | - Samantha Hartzell
- Department of Civil and Environmental Engineering, Portland State University, Portland, Oregon, USA
| | - Klaus Winter
- Smithsonian Tropical Research Institute, Balboa, Ancón, Republic of Panama
| | - Milton Garcia
- Smithsonian Tropical Research Institute, Balboa, Ancón, Republic of Panama
| | - Jorge Aranda
- Smithsonian Tropical Research Institute, Balboa, Ancón, Republic of Panama
| | - Aurelio Virgo
- Smithsonian Tropical Research Institute, Balboa, Ancón, Republic of Panama
| | - Abigail Smith
- School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - Paulina Focht
- School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - Adam Rasmussen-Arda
- School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - William G T Willats
- School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - Daniel Cowan-Turner
- School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - Anne M Borland
- School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon Tyne, UK
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