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Christin PA, Arakaki M, Osborne CP, Bräutigam A, Sage RF, Hibberd JM, Kelly S, Covshoff S, Wong GKS, Hancock L, Edwards EJ. Shared origins of a key enzyme during the evolution of C4 and CAM metabolism. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:3609-21. [PMID: 24638902 PMCID: PMC4085957 DOI: 10.1093/jxb/eru087] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
CAM and C4 photosynthesis are two key plant adaptations that have evolved independently multiple times, and are especially prevalent in particular groups of plants, including the Caryophyllales. We investigate the origin of photosynthetic PEPC, a key enzyme of both the CAM and C4 pathways. We combine phylogenetic analyses of genes encoding PEPC with analyses of RNA sequence data of Portulaca, the only plants known to perform both CAM and C4 photosynthesis. Three distinct gene lineages encoding PEPC exist in eudicots (namely ppc-1E1, ppc-1E2 and ppc-2), one of which (ppc-1E1) was recurrently recruited for use in both CAM and C4 photosynthesis within the Caryophyllales. This gene is present in multiple copies in the cacti and relatives, including Portulaca. The PEPC involved in the CAM and C4 cycles of Portulaca are encoded by closely related yet distinct genes. The CAM-specific gene is similar to genes from related CAM taxa, suggesting that CAM has evolved before C4 in these species. The similar origin of PEPC and other genes involved in the CAM and C4 cycles highlights the shared early steps of evolutionary trajectories towards CAM and C4, which probably diverged irreversibly only during the optimization of CAM and C4 phenotypes.
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Affiliation(s)
- Pascal-Antoine Christin
- Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK Department of Ecology and Evolutionary Biology, Brown University, 80 Waterman St., Providence, RI 02912, USA
| | - Monica Arakaki
- Department of Ecology and Evolutionary Biology, Brown University, 80 Waterman St., Providence, RI 02912, USA Departamento de Botánica, Facultad de Ciencias Biológicas and Museo de Historia Natural - UNMSM, Av. Arenales 1256, Lima 11, Peru
| | - Colin P Osborne
- Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Andrea Bräutigam
- Institute of Plant Biochemistry, Heinrich-Heine University, 40225 Duesseldorf, Germany
| | - Rowan F Sage
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario M5S 3B2, Canada
| | - Julian M Hibberd
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, UK
| | - Steven Kelly
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, UK
| | - Sarah Covshoff
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, UK
| | - Gane Ka-Shu Wong
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada Department of Medicine, University of Alberta, Edmonton, Alberta T6G 2E1, Canada BGI-Shenzhen, Beishan Industrial Zone, Yantian District, Shenzhen 518083, China
| | - Lillian Hancock
- Department of Ecology and Evolutionary Biology, Brown University, 80 Waterman St., Providence, RI 02912, USA
| | - Erika J Edwards
- Department of Ecology and Evolutionary Biology, Brown University, 80 Waterman St., Providence, RI 02912, USA
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Ripley BS, Abraham T, Klak C, Cramer MD. How succulent leaves of Aizoaceae avoid mesophyll conductance limitations of photosynthesis and survive drought. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:5485-96. [PMID: 24127513 PMCID: PMC3871808 DOI: 10.1093/jxb/ert314] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
In several taxa, increasing leaf succulence has been associated with decreasing mesophyll conductance (g M) and an increasing dependence on Crassulacean acid metabolism (CAM). However, in succulent Aizoaceae, the photosynthetic tissues are adjacent to the leaf surfaces with an internal achlorophyllous hydrenchyma. It was hypothesized that this arrangement increases g M, obviating a strong dependence on CAM, while the hydrenchyma stores water and nutrients, both of which would only be sporadically available in highly episodic environments. These predictions were tested with species from the Aizoaceae with a 5-fold variation in leaf succulence. It was shown that g M values, derived from the response of photosynthesis to intercellular CO2 concentration (A:C i), were independent of succulence, and that foliar photosynthate δ(13)C values were typical of C3, but not CAM photosynthesis. Under water stress, the degree of leaf succulence was positively correlated with an increasing ability to buffer photosynthetic capacity over several hours and to maintain light reaction integrity over several days. This was associated with decreased rates of water loss, rather than tolerance of lower leaf water contents. Additionally, the hydrenchyma contained ~26% of the leaf nitrogen content, possibly providing a nutrient reservoir. Thus the intermittent use of C3 photosynthesis interspersed with periods of no positive carbon assimilation is an alternative strategy to CAM for succulent taxa (Crassulaceae and Aizoaceae) which occur sympatrically in the Cape Floristic Region of South Africa.
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Affiliation(s)
- Brad S. Ripley
- Department of Botany, Rhodes University, 6140 Grahamstown, South Africa
| | - Trevor Abraham
- Department of Botany, Rhodes University, 6140 Grahamstown, South Africa
| | - Cornelia Klak
- Bolus Herbarium, Department of Biological Sciences, University of Cape Town, 7701 Rondebosch, South Africa
| | - Michael D. Cramer
- Department of Biological Sciences, University of Cape Town, 7701 Rondebosch, South Africa
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Cernusak LA, Ubierna N, Winter K, Holtum JAM, Marshall JD, Farquhar GD. Environmental and physiological determinants of carbon isotope discrimination in terrestrial plants. THE NEW PHYTOLOGIST 2013; 200:950-65. [PMID: 23902460 DOI: 10.1111/nph.12423] [Citation(s) in RCA: 232] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Accepted: 06/25/2013] [Indexed: 05/05/2023]
Abstract
Stable carbon isotope ratios (δ(13) C) of terrestrial plants are employed across a diverse range of applications in environmental and plant sciences; however, the kind of information that is desired from the δ(13) C signal often differs. At the extremes, it ranges between purely environmental and purely biological. Here, we review environmental drivers of variation in carbon isotope discrimination (Δ) in terrestrial plants, and the biological processes that can either damp or amplify the response. For C3 plants, where Δ is primarily controlled by the ratio of intercellular to ambient CO2 concentrations (ci /ca ), coordination between stomatal conductance and photosynthesis and leaf area adjustment tends to constrain the potential environmentally driven range of Δ. For C4 plants, variation in bundle-sheath leakiness to CO2 can either damp or amplify the effects of ci /ca on Δ. For plants with crassulacean acid metabolism (CAM), Δ varies over a relatively large range as a function of the proportion of daytime to night-time CO2 fixation. This range can be substantially broadened by environmental effects on Δ when carbon uptake takes place primarily during the day. The effective use of Δ across its full range of applications will require a holistic view of the interplay between environmental control and physiological modulation of the environmental signal.
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Affiliation(s)
- Lucas A Cernusak
- Department of Marine and Tropical Biology, James Cook University, Cairns, Qld, Australia
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Rodrigues MA, Matiz A, Cruz AB, Matsumura AT, Takahashi CA, Hamachi L, Félix LM, Pereira PN, Latansio-Aidar SR, Aidar MPM, Demarco D, Freschi L, Mercier H, Kerbauy GB. Spatial patterns of photosynthesis in thin- and thick-leaved epiphytic orchids: unravelling C3-CAM plasticity in an organ-compartmented way. ANNALS OF BOTANY 2013; 112:17-29. [PMID: 23618898 PMCID: PMC3690981 DOI: 10.1093/aob/mct090] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Accepted: 03/06/2013] [Indexed: 05/21/2023]
Abstract
BACKGROUND AND AIMS A positive correlation between tissue thickness and crassulacean acid metabolism (CAM) expression has been frequently suggested. Therefore, this study addressed the question of whether water availability modulates photosynthetic plasticity in different organs of two epiphytic orchids with distinct leaf thickness. METHODS Tissue morphology and photosynthetic mode (C3 and/or CAM) were examined in leaves, pseudobulbs and roots of a thick-leaved (Cattleya walkeriana) and a thin-leaved (Oncidium 'Aloha') epiphytic orchid. Morphological features were studied comparing the drought-induced physiological responses observed in each organ after 30 d of either drought or well-watered treatments. KEY RESULTS Cattleya walkeriana, which is considered a constitutive CAM orchid, displayed a clear drought-induced up-regulation of CAM in its thick leaves but not in its non-leaf organs (pseudobulbs and roots). The set of morphological traits of Cattleya leaves suggested the drought-inducible CAM up-regulation as a possible mechanism of increasing water-use efficiency and carbon economy. Conversely, although belonging to an orchid genus classically considered as performing C3 photosynthesis, Oncidium 'Aloha' under drought seemed to express facultative CAM in its roots and pseudobulbs but not in its leaves, indicating that such photosynthetic responses might compensate for the lack of capacity to perform CAM in its thin leaves. Morphological features of Oncidium leaves also indicated lower efficiency in preventing water and CO2 losses, while aerenchyma ducts connecting pseudobulbs and leaves suggested a compartmentalized mechanism of nighttime carboxylation via phosphoenolpyruvate carboxylase (PEPC) (pseudobulbs) and daytime carboxylation via Rubisco (leaves) in drought-exposed Oncidium plants. CONCLUSIONS Water availability modulated CAM expression in an organ-compartmented manner in both orchids studied. As distinct regions of the same orchid could perform different photosynthetic pathways and variable degrees of CAM expression depending on the water availability, more attention should be addressed to this in future studies concerning the abundance of CAM plants.
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Affiliation(s)
- Maria Aurineide Rodrigues
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, 05508-900, São Paulo, SP, Brazil
| | - Alejandra Matiz
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, 05508-900, São Paulo, SP, Brazil
| | - Aline Bertinatto Cruz
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, 05508-900, São Paulo, SP, Brazil
| | - Aline Tiemi Matsumura
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, 05508-900, São Paulo, SP, Brazil
| | - Cassia Ayumi Takahashi
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, 05508-900, São Paulo, SP, Brazil
| | - Leonardo Hamachi
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, 05508-900, São Paulo, SP, Brazil
| | - Lucas Macedo Félix
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, 05508-900, São Paulo, SP, Brazil
| | - Paula Natália Pereira
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, 05508-900, São Paulo, SP, Brazil
| | | | | | - Diego Demarco
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, 05508-900, São Paulo, SP, Brazil
| | - Luciano Freschi
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, 05508-900, São Paulo, SP, Brazil
| | - Helenice Mercier
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, 05508-900, São Paulo, SP, Brazil
| | - Gilberto Barbante Kerbauy
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, 05508-900, São Paulo, SP, Brazil
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55
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Herrera A. Crassulacean acid metabolism-cycling in Euphorbia milii. AOB PLANTS 2013; 5:plt014. [PMID: 23596548 PMCID: PMC3628315 DOI: 10.1093/aobpla/plt014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 02/14/2013] [Indexed: 05/22/2023]
Abstract
Crassulacean acid metabolism (CAM) occurs in many Euphorbiaceae, particularly Euphorbia, a genus with C3 and C4 species as well. With the aim of contributing to our knowledge of the evolution of CAM in this genus, this study examined the possible occurrence of CAM in Euphorbia milii, a species with leaf succulence and drought tolerance suggestive of this carbon fixation pathway. Leaf anatomy consisted of a palisade parenchyma, a spongy parenchyma and a bundle sheath with chloroplasts, which indicates the possible functioning of C2 photosynthesis. No evidence of nocturnal CO2 fixation was found in plants of E. milii either watered or under drought; watered plants had a low nocturnal respiration rate (R). After 12 days without watering, the photosynthetic rate (P N) decreased 85 % and nocturnal R was nearly zero. Nocturnal H(+) accumulation (ΔH(+)) in watered plants was 18 ± 2 (corresponding to malate) and 18 ± 4 (citrate) μmol H(+) (g fresh mass)(-1). Respiratory CO2 recycling through acid synthesis contributed to a night-time water saving of 2 and 86 % in watered plants and plants under drought, respectively. Carbon isotopic composition (δ(13)C) was -25.2 ± 0.7 ‰ in leaves and -24.7 ± 0.1 ‰ in stems. Evidence was found for the operation of weak CAM in E. milii, with statistically significant ΔH(+), no nocturnal CO2 uptake and values of δ(13)C intermediate between C3 and constitutive CAM plants; ΔH(+) was apparently attributable to both malate and citrate. The results suggest that daily malate accumulation results from recycling of part of the nocturnal respiratory CO2, which helps explain the occurrence of an intermediate value of leaf δ(13)C. Euphorbia milii can be considered as a CAM-cycling species. The significance of the operation of CAM-cycling in E. milii lies in water conservation, rather than carbon acquisition. The possible occurrence of C2 photosynthesis merits research.
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Affiliation(s)
- Ana Herrera
- Instituto de Biología Experimental, Facultad de Ciencias, Universidad Central de Venezuela, Caracas, Miranda 1020, Venezuela
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56
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Tsen EWJ, Holtum JAM. Crassulacean acid metabolism (CAM) in an epiphytic ant-plant, Myrmecodia beccarii Hook.f. (Rubiaceae). PHOTOSYNTHESIS RESEARCH 2012; 113:311-320. [PMID: 22442054 DOI: 10.1007/s11120-012-9732-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2012] [Accepted: 02/27/2012] [Indexed: 05/31/2023]
Abstract
This study demonstrates unequivocally the presence of crassulacean acid metabolism (CAM) in a species of the Rubiaceae, the fourth largest angiosperm plant family. The tropical Australian endemic epiphytic ant-plant, Myrmecodia beccarii Hook.f., exhibits net CO(2) uptake in the dark and a concomitant accumulation of titratable acidity in plants in the field and in cultivation. Plants growing near Cardwell, in a north Queensland coastal seasonally dry forest of Melaleuca viridiflora Sol. ex Gaertn., accumulated ~50 % of their 24 h carbon gain in the dark during the warm wet season. During the transition from the wet season to the dry season, 24 h carbon gain was reduced whilst the proportion of carbon accumulated during the dark increased. By mid dry season many plants exhibited zero net carbon uptake over 24 h, but CO(2) uptake in the dark was observed in some plants following localised rainfall. In a shade-house experiment, droughted plants in which CO(2) uptake in the light was absent and dark CO(2) uptake was reduced, were able to return to relatively high rates of CO(2) uptake in the light and dark within 12 h of rewatering.
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Affiliation(s)
- Edward W J Tsen
- Tropical Biology, James Cook University, Townsville, QLD, 4811, Australia
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57
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Freschi L, Mercier H. Connecting Environmental Stimuli and Crassulacean Acid Metabolism Expression: Phytohormones and Other Signaling Molecules. PROGRESS IN BOTANY 2012. [DOI: 10.1007/978-3-642-22746-2_9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Borland AM, Barrera Zambrano VA, Ceusters J, Shorrock K. The photosynthetic plasticity of crassulacean acid metabolism: an evolutionary innovation for sustainable productivity in a changing world. THE NEW PHYTOLOGIST 2011; 191:619-633. [PMID: 21679188 DOI: 10.1111/j.1469-8137.2011.03781.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The photosynthetic specialization of crassulacean acid metabolism (CAM) has evolved many times in response to selective pressures imposed by water limitation. Integration of circadian and metabolite control over nocturnal C₄ and daytime C₃ carboxylation processes in CAM plants provides plasticity for optimizing carbon gain and water use by extending or curtailing the period of net CO₂ uptake over any 24-h period. Photosynthetic plasticity underpins the ecological diversity of CAM species and contributes to the potential for high biomass production in water-limited habitats. Perceived evolutionary constraints on the dynamic range of CO₂ acquisition strategies in CAM species can be reconciled with functional anatomical requirements and the metabolic costs of maintaining the enzymatic machinery required for C₃ and C₄ carboxylation processes. Succulence is highlighted as a key trait for maximizing biomass productivity in water-limited habitats by serving to buffer water availability, by maximizing the magnitude of nocturnal CO₂ uptake and by extending the duration of C₄ carboxylation beyond the night period. Examples are discussed where an understanding of the diverse metabolic and ecological manifestations of CAM can be exploited for the sustainable productivity of economically and ecologically important species.
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Affiliation(s)
- Anne M Borland
- School of Biology, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK
| | | | - Johan Ceusters
- School of Biology, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK
- Department of Biosystems, Division of Crop Biotechnics, Katholieke Universiteit Leuven, Willem De Croylaan 42, B-3001 Heverlee, Belgium
| | - Katherine Shorrock
- School of Biology, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK
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Winter K, Garcia M, Holtum JAM. Drought-stress-induced up-regulation of CAM in seedlings of a tropical cactus, Opuntia elatior, operating predominantly in the C3 mode. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:4037-42. [PMID: 21504876 PMCID: PMC3134358 DOI: 10.1093/jxb/err106] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2011] [Revised: 03/11/2011] [Accepted: 03/14/2011] [Indexed: 05/08/2023]
Abstract
Immediately after unfolding, cotyledons of the tropical platyopuntoid cactus, Opuntia elatior Mill., exhibited a C(3)-type diel CO(2) exchange pattern characterized by net CO(2) uptake in the light. Significant nocturnal increases in titratable acidity typical of crassulacean acid metabolism (CAM) were not detected at this early developmental stage. As cotyledons matured and the first cladode (flattened stem) developed, features of CAM were observed and the magnitude of CAM increased. Nonetheless, in well-watered seedlings up to 10 cm tall, C(3) photosynthetic CO(2) fixation in the light remained the major pathway of carbon fixation. Reduced soil water availability led to an up-regulation of net dark CO(2) fixation and greater nocturnal increases in tissue acidity, consistent with facultative CAM. These observations demonstrate that C(3) photosynthesis, drought-stress-related facultative CAM, and developmentally controlled constitutive CAM can all contribute to the early growth of O. elatior. The strong C(3) component and facultative CAM features expressed in young O. elatior contrast with mature plants in which obligate CAM is the major pathway of carbon acquisition.
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Affiliation(s)
- Klaus Winter
- Smithsonian Tropical Research Institute, Balboa, Ancon, Republic of Panama.
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60
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Ceusters J, Borland AM, Godts C, Londers E, Croonenborghs S, Van Goethem D, De Proft MP. Crassulacean acid metabolism under severe light limitation: a matter of plasticity in the shadows? JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:283-91. [PMID: 20861137 DOI: 10.1093/jxb/erq264] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Despite the increased energetic costs of CAM compared with C(3) photosynthesis, it is hypothesized that the inherent photosynthetic plasticity of CAM allows successful acclimation to light-limiting conditions. The present work sought to determine if CAM presented any constraints to short and longer term acclimation to light limitation and to establish if and how metabolic and photosynthetic plasticity in the deployment of the four phases of CAM might facilitate acclimation to conditions of deep shade. Measurements of leaf gas exchange, organic acids, starch and soluble sugar (glucose, fructose, and sucrose) contents were made in the leaves of the constitutive CAM bromeliad Aechmea 'Maya' over a three month period under severe light limitation. A. 'Maya' was not particularly tolerant of severe light limitation in the short term. A complete absence of net CO(2) uptake and fluctuations in key metabolites (i.e. malate, starch or soluble sugars) indicated a dampened metabolism whilst cell death in the most photosynthetically active leaves was attributed to an over-acidification of the cytoplasm. However, in the longer term, plasticity in the use of the different phases of gas exchange and different storage carbohydrate pools, i.e. a switch from starch to sucrose as the major carbohydrate source, ensured a positive carbon balance for this CAM species under extremely low levels of irradiance. As such, co-ordinated plasticity in the use of C(3) and C(4) carboxylases and different carbohydrate pools together with an increase in the abundance of light-harvesting complexes, appear to underpin the adaptive radiation of the energetically costly CAM pathway within light-limiting environments such as wet cloud forests and shaded understoreys of tropical forests.
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Affiliation(s)
- Johan Ceusters
- Faculty of Bioscience Engineering, Department of Biosystems, Division of Crop Biotechnics, Katholieke Universiteit Leuven, Willem De Croylaan 42, B-3001 Heverlee, Belgium.
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Ricalde MF, Andrade JL, Durán R, Dupuy JM, Simá JL, Us-Santamaría R, Santiago LS. Environmental regulation of carbon isotope composition and crassulacean acid metabolism in three plant communities along a water availability gradient. Oecologia 2010; 164:871-80. [PMID: 20652592 PMCID: PMC2981738 DOI: 10.1007/s00442-010-1724-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2009] [Accepted: 07/04/2010] [Indexed: 10/27/2022]
Abstract
Expression of crassulacean acid metabolism (CAM) is characterized by extreme variability within and between taxa and its sensitivity to environmental variation. In this study, we determined seasonal fluctuations in CAM photosynthesis with measurements of nocturnal tissue acidification and carbon isotopic composition (δ(13)C) of bulk tissue and extracted sugars in three plant communities along a precipitation gradient (500, 700, and 1,000 mm year(-1)) on the Yucatan Peninsula. We also related the degree of CAM to light habitat and relative abundance of species in the three sites. For all species, the greatest tissue acid accumulation occurred during the rainy season. In the 500 mm site, tissue acidification was greater for the species growing at 30% of daily total photon flux density (PFD) than species growing at 80% PFD. Whereas in the two wetter sites, the species growing at 80% total PFD had greater tissue acidification. All species had values of bulk tissue δ(13)C less negative than -20‰, indicating strong CAM activity. The bulk tissue δ(13)C values in plants from the 500 mm site were 2‰ less negative than in plants from the wetter sites, and the only species growing in the three communities, Acanthocereus tetragonus (Cactaceae), showed a significant negative relationship between both bulk tissue and sugar δ(13)C values and annual rainfall, consistent with greater CO(2) assimilation through the CAM pathway with decreasing water availability. Overall, variation in the use of CAM photosynthesis was related to water and light availability and CAM appeared to be more ecologically important in the tropical dry forests than in the coastal dune.
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Affiliation(s)
- M. Fernanda Ricalde
- Unidad de Recursos Naturales, Centro de Investigación Científica de Yucatán, A. C., Calle 43 # 130, Col. Chuburná de Hidalgo, 97200 Mérida, Yucatán Mexico
| | - José Luis Andrade
- Unidad de Recursos Naturales, Centro de Investigación Científica de Yucatán, A. C., Calle 43 # 130, Col. Chuburná de Hidalgo, 97200 Mérida, Yucatán Mexico
| | - Rafael Durán
- Unidad de Recursos Naturales, Centro de Investigación Científica de Yucatán, A. C., Calle 43 # 130, Col. Chuburná de Hidalgo, 97200 Mérida, Yucatán Mexico
| | - Juan Manuel Dupuy
- Unidad de Recursos Naturales, Centro de Investigación Científica de Yucatán, A. C., Calle 43 # 130, Col. Chuburná de Hidalgo, 97200 Mérida, Yucatán Mexico
| | - J. Luis Simá
- Unidad de Recursos Naturales, Centro de Investigación Científica de Yucatán, A. C., Calle 43 # 130, Col. Chuburná de Hidalgo, 97200 Mérida, Yucatán Mexico
| | - Roberth Us-Santamaría
- Unidad de Recursos Naturales, Centro de Investigación Científica de Yucatán, A. C., Calle 43 # 130, Col. Chuburná de Hidalgo, 97200 Mérida, Yucatán Mexico
| | - Louis S. Santiago
- Department of Botany and Plant Sciences, University of California, 2150 Batchelor Hall, Riverside, CA 92521 USA
- Facility for Isotope Ratio Mass Spectrometry (FIRMS), Center for Conservation Biology, University of California, Riverside, CA 92521 USA
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Goode LK, Erhardt EB, Santiago LS, Allen MF. Carbon stable isotopic composition of soluble sugars in Tillandsia epiphytes varies in response to shifts in habitat. Oecologia 2010; 163:583-90. [PMID: 20155286 PMCID: PMC2886131 DOI: 10.1007/s00442-010-1577-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Accepted: 01/25/2010] [Indexed: 11/30/2022]
Abstract
We studied C stable isotopic composition (δ13C) of bulk leaf tissue and extracted sugars of four epiphytic Tillandsia species to investigate flexibility in the use of crassulacean acid metabolism (CAM) and C3 photosynthetic pathways. Plants growing in two seasonally dry tropical forest reserves in Mexico that differ in annual precipitation were measured during wet and dry seasons, and among secondary, mature, and wetland forest types within each site. Dry season sugars were more enriched in 13C than wet season sugars, but there was no seasonal difference in bulk tissues. Bulk tissue δ13C differed by species and by forest type, with values from open-canopied wetlands more enriched in 13C than mature or secondary forest types. The shifts within forest habitat were related to temporal and spatial changes in vapor pressure deficits (VPD). Modeling results estimate a possible 4% increase in the proportional contribution of the C3 pathway during the wet season, emphasizing that any seasonal or habitat-mediated variation in photosynthetic pathway appears to be quite moderate and within the range of isotopic effects caused by variation in stomatal conductance during assimilation through the C3 pathway and environmental variation in VPD. C isotopic analysis of sugars together with bulk leaf tissue offers a useful approach for incorporating short- and long-term measurements of C isotope discrimination during photosynthesis.
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Affiliation(s)
- Laurel K Goode
- Biology Department, University of California, Riverside, CA 92521, USA.
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Winter K, Garcia M, Holtum JAM. Canopy CO2 exchange of two neotropical tree species exhibiting constitutive and facultative CAM photosynthesis, Clusia rosea and Clusia cylindrica. JOURNAL OF EXPERIMENTAL BOTANY 2009; 60:3167-77. [PMID: 19487388 PMCID: PMC2718218 DOI: 10.1093/jxb/erp149] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Revised: 04/07/2009] [Accepted: 04/16/2009] [Indexed: 05/07/2023]
Abstract
Photon flux density (PFD) and water availability, the daily and seasonal factors that vary most in tropical environments, were examined to see how they influenced expression of crassulacean acid metabolism (CAM) in 3-year-old Clusia shrubs native to Panama. Instead of the commonly used single-leaf approach, diel CO(2) exchange was measured for whole individual canopies of plants in large soil containers inside a naturally illuminated 8.8 m(3) chamber. In well-watered C. rosea, a mainly constitutive CAM species, nocturnally fixed CO(2) contributed about 50% to 24 h carbon gain on sunny days but the contribution decreased to zero following overcast days. Nonetheless, CO(2) fixation in the light responded in such a way that 24 h carbon gain was largely conserved across the range of daily PFDs. The response of C. rosea to drought was similarly buffered. A facultative component of CAM expression led to reversible increases in nocturnal carbon gain that offset drought-induced reductions of CO(2) fixation in the light. Clusia cylindrica was a C(3) plant when well-watered but exhibited CAM when subjected to water stress. The induction of CAM was fully reversible upon rewatering. C. cylindrica joins C. pratensis as the most unambiguous facultative CAM species reported in the genus Clusia.
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Affiliation(s)
- Klaus Winter
- Smithsonian Tropical Research Institute, PO Box 0843-03092, Balboa, Ancon, Republic of Panama.
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Borland AM, Griffiths H, Hartwell J, Smith JAC. Exploiting the potential of plants with crassulacean acid metabolism for bioenergy production on marginal lands. JOURNAL OF EXPERIMENTAL BOTANY 2009; 60:2879-96. [PMID: 19395392 DOI: 10.1093/jxb/erp118] [Citation(s) in RCA: 156] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Crassulacean acid metabolism (CAM) is a photosynthetic adaptation that facilitates the uptake of CO(2) at night and thereby optimizes the water-use efficiency of carbon assimilation in plants growing in arid habitats. A number of CAM species have been exploited agronomically in marginal habitats, displaying annual above-ground productivities comparable with those of the most water-use efficient C(3) or C(4) crops but with only 20% of the water required for cultivation. Such attributes highlight the potential of CAM plants for carbon sequestration and as feed stocks for bioenergy production on marginal and degraded lands. This review highlights the metabolic and morphological features of CAM that contribute towards high biomass production in water-limited environments. The temporal separation of carboxylation processes that underpins CAM provides flexibility for modulating carbon gain over the day and night, and poses fundamental questions in terms of circadian control of metabolism, growth, and productivity. The advantages conferred by a high water-storage capacitance, which translate into an ability to buffer fluctuations in environmental water availability, must be traded against diffusive (stomatal plus internal) constraints imposed by succulent CAM tissues on CO(2) supply to the cellular sites of carbon assimilation. The practicalities for maximizing CAM biomass and carbon sequestration need to be informed by underlying molecular, physiological, and ecological processes. Recent progress in developing genetic models for CAM are outlined and discussed in light of the need to achieve a systems-level understanding that spans the molecular controls over the pathway through to the agronomic performance of CAM and provision of ecosystem services on marginal lands.
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Affiliation(s)
- Anne M Borland
- Institute for Research on the Environment and Sustainability, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK.
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Reyes-García C, Andrade JL. Crassulacean acid metabolism under global climate change. THE NEW PHYTOLOGIST 2009; 181:754-757. [PMID: 19281526 DOI: 10.1111/j.1469-8137.2009.02762.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Affiliation(s)
| | - José Luis Andrade
- Unidad de Recursos Naturales, Centro de Investigación Científica de Yucatán, Mérida, Yucatán, México
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Herrera A. Crassulacean acid metabolism and fitness under water deficit stress: if not for carbon gain, what is facultative CAM good for? ANNALS OF BOTANY 2009; 103:645-53. [PMID: 18708641 PMCID: PMC2707347 DOI: 10.1093/aob/mcn145] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2008] [Revised: 04/18/2008] [Accepted: 06/24/2008] [Indexed: 05/25/2023]
Abstract
BACKGROUND In obligate Crassulacean acid metabolism (CAM), up to 99 % of CO(2) assimilation occurs during the night, therefore supporting the hypothesis that CAM is adaptive because it allows CO(2) fixation during the part of the day with lower evaporative demand, making life in water-limited environments possible. By comparison, in facultative CAM (inducible CAM, C(3)-CAM) and CAM-cycling plants drought-induced dark CO(2) fixation may only be, with few exceptions, a small proportion of C(3) CO(2) assimilation in watered plants and occur during a few days. From the viewpoint of survival the adaptive advantages, i.e. increased fitness, of facultative CAM and CAM-cycling are not obvious. Therefore, it is hypothesized that, if it is to increase fitness, CAM must aid in reproduction. Scope An examination of published reports of 23 facultative CAM and CAM-cycling species finds that, in 19 species, drought-induced dark CO(2) fixation represents on average 11 % of C(3) CO(2) assimilation of watered plants. Evidence is discussed on the impact of the operation of CAM in facultative and CAM-cycling plants on their survival--carbon balance, water conservation, water absorption, photo-protection of the photosynthetic apparatus--and reproductive effort. It is concluded that in some species, but not all, facultative and cycling CAM contribute, rather than to increase carbon balance, to increase water-use efficiency, water absorption, prevention of photoinhibition and reproductive output.
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Affiliation(s)
- Ana Herrera
- Instituto de Biología Experimental, Universidad Central de Venezuela, Calle Supure, Colinas de Bello Monte, Caracas, Venezuela.
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Cernusak LA, Mejia-Chang M, Winter K, Griffiths H. Oxygen isotope composition of CAM and C3 Clusia species: non-steady-state dynamics control leaf water 18O enrichment in succulent leaves. PLANT, CELL & ENVIRONMENT 2008; 31:1644-1662. [PMID: 18684241 DOI: 10.1111/j.1365-3040.2008.01868.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Leaf gas exchange and leaf water (18)O enrichment (Delta(18)O(L)) were measured in three Clusia species under field conditions during dry and wet seasons and in Miconia argentea during the dry season in the Republic of Panama. During the dry season, all three Clusia species used crassulacean acid metabolism (CAM); during the wet season Clusia pratensis operated in the C(3) mode, while Clusia uvitana and Clusia rosea used CAM. Large departures from isotopic steady state were observed in daytime Delta(18)O(L) of the Clusia species, especially during the dry season. In contrast, daytime Delta(18)O(L) was near isotopic steady state in the C(3) tree M. argentea. Across the full data set, non-steady-state predictions explained 49% of variation in observed Delta(18)O(L), whereas steady-state predictions explained only 14%. During the wet season, when Delta(18)O(L) could be compared with Clusia individuals operating in both C(3) and CAM modes, steady-state and non-steady-state models gave contrasting predictions with respect to interspecific variation in daytime Delta(18)O(L). The observed Delta(18)O(L) pattern matched that predicted for the non-steady state. The results provided a clear example of how non-steady-state control of leaf water (18)O dynamics can shift the slope of the relationship between transpiration rate and daytime Delta(18)O(L) from negative to positive.
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Affiliation(s)
- Lucas A Cernusak
- Smithsonian Tropical Research Institute, Balboa, Ancon, Republic of Panama.
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68
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Cushman JC, Agarie S, Albion RL, Elliot SM, Taybi T, Borland AM. Isolation and characterization of mutants of common ice plant deficient in crassulacean acid metabolism. PLANT PHYSIOLOGY 2008; 147:228-38. [PMID: 18326789 PMCID: PMC2330286 DOI: 10.1104/pp.108.116889] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2008] [Accepted: 03/02/2008] [Indexed: 05/21/2023]
Abstract
Crassulacean acid metabolism (CAM) is a specialized mode of photosynthesis that improves water use efficiency by shifting part or all of net atmospheric CO2 uptake to the night. Genetic dissection of regulatory and metabolic attributes of CAM has been limited by the difficulty of identifying a reliable phenotype for mutant screening. We developed a novel and simple colorimetric assay to measure leaf pH to screen fast neutron-mutagenized populations of common ice plant (Mesembryanthemum crystallinum), a facultative CAM species, to detect CAM-deficient mutants with limited nocturnal acidification. The isolated CAM-deficient mutants showed negligible net dark CO2 uptake compared with wild-type plants following the imposition of salinity stress. The mutants and wild-type plants accumulated nearly comparable levels of sodium in leaves, but the mutants grew more slowly than the wild-type plants. The mutants also had substantially reduced seed set and seed weight relative to wild type under salinity stress. Carbon-isotope ratios of seed collected from 4-month-old plants indicated that C3 photosynthesis made a greater contribution to seed production in mutants compared to wild type. The CAM-deficient mutants were deficient in leaf starch and lacked plastidic phosphoglucomutase, an enzyme critical for gluconeogenesis and starch formation, resulting in substrate limitation of nocturnal C4 acid formation. The restoration of nocturnal acidification by feeding detached leaves of salt-stressed mutants with glucose or sucrose supported this defect and served to illustrate the flexibility of CAM. The CAM-deficient mutants described here constitute important models for exploring regulatory features and metabolic consequences of CAM.
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Affiliation(s)
- John C Cushman
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, NV 89557-0200, USA.
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Motomura H, Yukawa T, Ueno O, Kagawa A. The occurrence of crassulacean acid metabolism in Cymbidium (Orchidaceae) and its ecological and evolutionary implications. JOURNAL OF PLANT RESEARCH 2008; 121:163-77. [PMID: 18246297 DOI: 10.1007/s10265-007-0144-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2007] [Accepted: 12/09/2007] [Indexed: 05/15/2023]
Abstract
Crassulacean acid metabolism (CAM) is one of the photosynthetic pathways regarded as adaptations to water stress in land plants. Little is known about correlations among the level of CAM activity, environment of habitat, life form, and phylogenetic relationship of a plant group from an evolutionary perspective. We examined these relationships in 18 species of Cymbidium (Orchidaceae) because the genus shows distinctive diversification of habitats and life forms. The photosynthetic type was classed into three categories, strong CAM, weak CAM, and C(3) on the basis of CAM activity. CAM expression in Cymbidium was confined to the epiphytic and lithophytic species. Especially, all of these species from tropical to subtropical rainforest exhibited CAM activity. On the other hand, the terrestrial species always exhibited C(3) metabolism irrespective of their varied habitats. Regarding the evolution of photosynthetic characters, weak CAM was the ancestral state in Cymbidium and strong CAM and C(3) metabolism occurred subsequently. The evolution of strong CAM likely enabled Cymbidium to extend to exposed sites in tropical lowland where marked water stress exists. Further, different levels of CAM activity characterized each species and such potential plasticity of CAM may realize the radiation of Cymbidium into sites with different environmental conditions.
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Affiliation(s)
- H Motomura
- Tsukuba Botanical Garden, National Museum of Nature and Science, Tsukuba, Ibaraki, 305-0005, Japan
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Cushman JC, Tillett RL, Wood JA, Branco JM, Schlauch KA. Large-scale mRNA expression profiling in the common ice plant, Mesembryanthemum crystallinum, performing C3 photosynthesis and Crassulacean acid metabolism (CAM). JOURNAL OF EXPERIMENTAL BOTANY 2008; 59:1875-94. [PMID: 18319238 DOI: 10.1093/jxb/ern008] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The common ice plant (Mesembryanthemum crystallinum L.) has emerged as a useful model for molecular genetic studies of Crassulacean acid metabolism (CAM) because CAM can be induced in this species by water deficit or salinity stress. Non-redundant sequence information from expressed sequence tag data was used to fabricate a custom oligonucleotide microarray to compare large-scale mRNA expression patterns in M. crystallinum plants conducting C(3) photosynthesis versus CAM. Samples were collected every 4 h over a 24 h time period at the start of the subjective second day from plants grown under constant light and temperature conditions in order to capture variation in mRNA expression due to salinity stress and circadian clock control. Of 8455 genes, a total of 2343 genes (approximately 28%) showed a significant change as judged by analysis of variance (ANOVA) in steady-state mRNA abundance at one or more time points over the 24 h period. Of these, 858 (10%) and 599 (7%) exhibited a greater than two-fold ratio (TFR) increase or decrease in mRNA abundance, respectively. Functional categorization of these TFR genes revealed that many genes encoding products that function in CAM-related C(4) acid carboxylation/decarboxylation, glycolysis/gluconeogenesis, polysaccharide, polyol, and starch biosynthesis/degradation, protein degradation, transcriptional activation, signalling, stress response, and transport facilitation, and novel, unclassified proteins exhibited stress-induced increases in mRNA abundance. In contrast, salt stress resulted in a significant decrease in transcript abundance for genes encoding photosynthetic functions, protein synthesis, and cellular biogenesis functions. Many genes with CAM-related functions exhibited phase shifts in their putative circadian expression patterns following CAM induction. This report establishes an extensive catalogue of gene expression patterns for future investigations aimed at understanding the complex, transcriptional hierarchies that govern CAM-specific expression patterns. A novel graph-theoretic approach called 'Max Clique Builder' is introduced that identifies and organizes sets of coordinately regulated genes, such as those encoding subunits of the vacuolar H(+)-ATPase complex, into tighter functionally related clusters with more similar expression patterns compared with standard hierarchical clustering methods.
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Affiliation(s)
- John C Cushman
- Department of Biochemistry, MS200, University of Nevada, Reno, NV 89557-0014, USA.
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Holtum JAM, Winter K, Weeks MA, Sexton TR. Crassulacean acid metabolism in the ZZ plant, Zamioculcas zamiifolia (Araceae). AMERICAN JOURNAL OF BOTANY 2007; 94:1670-1676. [PMID: 21636363 DOI: 10.3732/ajb.94.10.1670] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Zamioculcas zamiifolia (Araceae), a terrestrial East African aroid, with two defining attributes of crassulacean acid metabolism (CAM) (net CO(2) uptake in the dark and diel fluctuations of titratable acidity) is the only CAM plant described within the Araceae, a mainly tropical taxon that contains the second largest number of epiphytes of any vascular plant family. Within the Alismatales, the order to which the Araceae belong, Z. zamiifolia is the only documented nonaquatic CAM species. Zamioculcas zamiifolia has weak CAM that is upregulated in response to water stress. In well-watered plants, day-night fluctuations in titratable acidity were 2.5 μmol H(+)·(g fresh mass)(-1), and net CO(2) uptake in the dark contributed less than 1% to daily carbon gain. Following 10 d of water stress, net CO(2) uptake in the light fell 94% and net CO(2) uptake in the dark increased 7.5-fold, such that its contribution increased to 19% of daily carbon gain. Following rewatering, dark CO(2) uptake returned to within 5% of prestressed levels. We postulate that CAM assists survival of Z. zamiifolia by reducing water loss and maintaining carbon gain during seasonal droughts characteristic of its natural habitat.
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Affiliation(s)
- Joseph A M Holtum
- School of Marine and Tropical Biology, James Cook University, Townsville, Queensland 4811, Australia
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Winter K, Holtum JAM. Environment or development? Lifetime net CO2 exchange and control of the expression of Crassulacean acid metabolism in Mesembryanthemum crystallinum. PLANT PHYSIOLOGY 2007; 143:98-107. [PMID: 17056756 PMCID: PMC1761986 DOI: 10.1104/pp.106.088922] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2006] [Accepted: 10/09/2006] [Indexed: 05/12/2023]
Abstract
The relative influence of plant age and environmental stress signals in triggering a shift from C(3) photosynthesis to Crassulacean acid metabolism (CAM) in the annual halophytic C(3)-CAM species Mesembryanthemum crystallinum was explored by continuously monitoring net CO(2) exchange of whole shoots from the seedling stage until seed set. Plants exposed to high salinity (400 mm NaCl) in hydroponic culture solution or grown in saline-droughted soil acquired between 11% and 24% of their carbon via net dark CO(2) uptake involving CAM. In contrast, plants grown under nonsaline, well-watered conditions were capable of completing their life cycle by operating in the C(3) mode without ever exhibiting net CO(2) uptake at night. These observations are not consistent with the widely expressed view that the induction of CAM by high salinity in M. crystallinum represents an acceleration of preprogrammed developmental processes. Rather, our study demonstrates that the induction of the CAM pathway for carbon acquisition in M. crystallinum is under environmental control.
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Affiliation(s)
- Klaus Winter
- Smithsonian Tropical Research Institute, Balboa, Ancon, Republic of Panama.
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Cushman JC. Crassulacean acid metabolism: recent advances and future opportunities. FUNCTIONAL PLANT BIOLOGY : FPB 2005; 32:375-380. [PMID: 32689139 DOI: 10.1071/fp05111] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2005] [Accepted: 05/13/2005] [Indexed: 06/11/2023]
Affiliation(s)
- John C Cushman
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, NV, 89557-0014, USA. Email
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Gehrig HH, Wood JA, Cushman MA, Virgo A, Cushman JC, Winter K. Research note: Large gene family of phosphoenolpyruvate carboxylase in the crassulacean acid metabolism plant Kalanchoe pinnata (Crassulaceae) characterised by partial cDNA sequence analysis. FUNCTIONAL PLANT BIOLOGY : FPB 2005; 32:467-472. [PMID: 32689147 DOI: 10.1071/fp05079] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2005] [Accepted: 05/03/2005] [Indexed: 06/11/2023]
Abstract
Clones coding for a 1100-bp cDNA sequence of phosphoenolpyruvate carboxylase (PEPC) of the constitutive crassulacean acid metabolism (CAM) plant Kalanchoe pinnata (Lam.) Pers., were isolated by reverse transcription-polymerase chain reaction (RT-PCR) and characterised by restriction fragment length polymorphism analysis and DNA sequencing. Seven distinct PEPC isogenes were recovered, four in leaves and three in roots (EMBL accession numbers: AJ344052-AJ344058). Sequence similarity comparisons and distance neighbour-joining calculations separate the seven PEPC isoforms into two clades, one of which contains the three PEPCs found in roots. The second clade contains the four isoforms found in leaves and is divided into two branches, one of which contains two PEPCs most similar with described previously CAM isoforms. Of these two isoforms, however, only one exhibited abundant expression in CAM-performing leaves, but not in very young leaves, which do not exhibit CAM, suggesting this isoform encodes a CAM-specific PEPC. Protein sequence calculations suggest that all isogenes are likely derived from a common ancestor gene, presumably by serial gene duplication events. To our knowledge, this is the most comprehensive identification of a PEPC gene family from a CAM plant, and the greatest number of PEPC isogenes reported for any vascular plant to date.
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Affiliation(s)
- Hans H Gehrig
- Smithsonian Tropical Research Institute, P.O. Box 2072, Balboa, Ancón, Republic of Panama
| | - Joshua A Wood
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, NV 89557-0014, USA
| | - Mary Ann Cushman
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, NV 89557-0014, USA
| | - Aurelio Virgo
- Smithsonian Tropical Research Institute, P.O. Box 2072, Balboa, Ancón, Republic of Panama
| | - John C Cushman
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, NV 89557-0014, USA
| | - Klaus Winter
- Smithsonian Tropical Research Institute, P.O. Box 2072, Balboa, Ancón, Republic of Panama
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