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Schiller, Katharina, and Andrea Bräutigam. "Engineering of Crassulacean Acid Metabolism." Annual Review of Plant Biology 72, no. 1 (June 17, 2021): 77–103. http://dx.doi.org/10.1146/annurev-arplant-071720-104814.
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Crassulacean acid metabolism (CAM) has evolved from a C3 ground state to increase water use efficiency of photosynthesis. During CAM evolution, selective pressures altered the abundance and expression patterns of C3 genes and their regulators to enable the trait. The circadian pattern of CO2 fixation and the stomatal opening pattern observed in CAM can be explained largely with a regulatory architecture already present in C3 plants. The metabolic CAM cycle relies on enzymes and transporters that exist in C3 plants and requires tight regulatory control to avoid futile cycles between carboxylation and decarboxylation. Ecological observations and modeling point to mesophyll conductance as a major factor during CAM evolution. The present state of knowledge enables suggestions for genes for a minimal CAM cycle for proof-of-concept engineering, assuming altered regulation of starch synthesis and degradation are not critical elements of CAM photosynthesis and sufficient malic acid export from the vacuole is possible.
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LUTTGE, U. "Ecophysiology of Crassulacean Acid Metabolism (CAM)." Annals of Botany 93, no. 6 (June 1, 2004): 629–52. http://dx.doi.org/10.1093/aob/mch087.
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Silvera, Katia, Kurt M. Neubig, W. Mark Whitten, Norris H. Williams, Klaus Winter, and John C. Cushman. "Evolution along the crassulacean acid metabolism continuum." Functional Plant Biology 37, no. 11 (2010): 995. http://dx.doi.org/10.1071/fp10084.
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Crassulacean acid metabolism (CAM) is a specialised mode of photosynthesis that improves atmospheric CO2 assimilation in water-limited terrestrial and epiphytic habitats and in CO2-limited aquatic environments. In contrast with C3 and C4 plants, CAM plants take up CO2 from the atmosphere partially or predominantly at night. CAM is taxonomically widespread among vascular plants and is present in many succulent species that occupy semiarid regions, as well as in tropical epiphytes and in some aquatic macrophytes. This water-conserving photosynthetic pathway has evolved multiple times and is found in close to 6% of vascular plant species from at least 35 families. Although many aspects of CAM molecular biology, biochemistry and ecophysiology are well understood, relatively little is known about the evolutionary origins of CAM. This review focuses on five main topics: (1) the permutations and plasticity of CAM, (2) the requirements for CAM evolution, (3) the drivers of CAM evolution, (4) the prevalence and taxonomic distribution of CAM among vascular plants with emphasis on the Orchidaceae and (5) the molecular underpinnings of CAM evolution including circadian clock regulation of gene expression.
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Sage, Rowan F. "Are crassulacean acid metabolism and C4 photosynthesis incompatible?" Functional Plant Biology 29, no. 6 (2002): 775. http://dx.doi.org/10.1071/pp01217.
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This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001. Despite sharing a similar metabolism, crassulacean acid metabolism (CAM) and C4 photosynthesis are not known to occur in identical species, with the exception of Portulaca spp. In Portulaca, C4 and weak CAM photosynthesis occur in distinct regions of the leaf, rather than in the same cells. This is in marked contrast to the situation in most CAM species where C3 and CAM photosynthesis are active in the same cell over the course of a day and growing season. The lack of CAM and C4 photosynthesis in identical cells of a plant indicates these photosynthetic pathways are incompatible. Incompatibilities between CAM and C4 photosynthesis could have a number of biochemical, anatomical and evolutionary explanations. Biochemical incompatibilities could result from the requirement for spatial separation of C3 and C4 phases in C4 plants versus temporal separation in CAM plants. In C4 plants, regulatory systems coordinate mesophyll and bundle sheath metabolism, with light intensity being the major environmental signal. In CAM plants, a circadian oscillator coordinates day and night phases of CAM. The requirement for rapid intercellular transport in C4 plants may be incompatible with the intracellular transport and storage needs of CAM. For example, the large vacuole required for malate storage in CAM could impede metabolite diffusion between mesophyll and bundle sheath cells in C4 plants. Anatomical barriers could also exist because both CAM and the C4 pathway require distinct leaf anatomies for efficient function. Efficient function of the C4 pathway generally requires an outer layer of cells specialized for phosphoenolpyruvate (PEP) carboxylation and regeneration and an inner layer for CO2 accumulation and refixation, while CAM species require enlarged vacuoles and tight cell packing. In evolutionary terms, barriers preventing CAM and C4 photosynthesis in the same species may be the initial steps in the respective evolutionary pathways from C3 ancestors. The first steps in C4 photosynthesis are related to scavenging photorespiratory CO2 via localization of glycine decarboxylase in the bundle sheath cells. The initial steps in CAM evolution are associated with the scavenging of respiratory CO2 at night by PEP carboxylation. In each, simplified versions of the specialized anatomy may need to be present for the evolutionary sequence to begin. For C4 evolution, enhanced bundle sheath size may be required in C3 ancestors; for CAM evolution, succulence may be required. Thus, before CAM or C4 photosynthesis began to evolve, the outcome of the evolutionary experiment may have been predetermined.
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Winter, Klaus, and Joseph A. M. Holtum. "Cryptic crassulacean acid metabolism (CAM) in Jatropha curcas." Functional Plant Biology 42, no. 8 (2015): 711. http://dx.doi.org/10.1071/fp15021.
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Jatropha curcas L. is a drought-tolerant shrub or small tree that is a candidate bioenergy feedstock. It is a member of the family Euphorbiaceae in which both CAM and C4 photosynthesis have evolved. Here, we report that J. curcas exhibits features diagnostic of low-level CAM. Small increases in nocturnal acid content were consistently observed in photosynthetic stems and occasionally in leaves. Acidification was associated with transient contractions in CO2 loss at night rather than with net CO2 dark fixation. Although the CAM-type nocturnal CO2 uptake signal was masked by background respiration, estimates of dark CO2 fixation based upon the 2 : 1 stoichiometric relationship between H+ accumulated and CO2 fixed indicated substantial carbon retention in the stems via the CAM cycle. It is proposed that under conditions of drought, low-level CAM in J. curcas stems serves primarily to conserve carbon rather than water.
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Taybi, Tahar, John C. Cushman, and Anne M. Borland. "Environmental, hormonal and circadian regulation of crassulacean acid metabolism expression." Functional Plant Biology 29, no. 6 (2002): 669. http://dx.doi.org/10.1071/pp01244.
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This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001. Expression of crassulacean acid metabolism (CAM) is characterized by the extreme plasticity observed within and between species. Switches between C3 photosynthesis and CAM, and subsequent 24-h patterns of day/night CO2 uptake, are tightly controlled by a variety of environmental and metabolic factors that optimize the response of CAM plants to the most challenging environments over seasonal and daily time scales. Regulation of the genes and enzymes involved in CAM and connected metabolic pathways occurs at a number of levels (transcriptional through to post-translational). Such multiple levels of control are considered to be the key to the photosynthetic plasticity of CAM. Here, we review some of the primary environmental and hormonal factors controlling CAM plasticity in different CAM-inducible species, with emphasis on the regulatory signalling circuits responsible for this control. We also examine the inherent circadian regulation of the pathway, mainly in the context of the diel regulation of phosphoenolpyruvate carboxylase and the dedicated kinase that modulates its activity. We then consider the role of secondary signals, with emphasis on changes in cytosolic [Ca2+]i and the downstream signalling pathways, based on studies conducted on Mesembryanthemum crystallinum L. Besides representing an important metabolic adaptation, CAM provides an intriguing paradigm for studying the complex signalling mechanisms that control and coordinate the expression of genes under a variety of short- and long-term environmental perturbations.
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Barkla, Bronwyn J., and Timothy Rhodes. "Use of infrared thermography for monitoring crassulacean acid metabolism." Functional Plant Biology 44, no. 1 (2017): 46. http://dx.doi.org/10.1071/fp16210.
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Crassulacean acid metabolism (CAM) is an alternative carbon fixation pathway that imparts high water-use efficiency in plants adapted to warm, semiarid climates. With concerns that global warming will negatively influence crop production, turning agricultural focus towards CAM plants may provide a solution to increase productivity using either unconventional crops on marginal land or incorporating CAM molecular mechanisms into conventional crops and improving water-use efficiency. For this to be feasible, deeper insights into CAM pathway regulation are essential. To facilitate this research new tools which simplify procedures for detecting and measuring CAM are needed. Here we describe a non-invasive, non-destructive, simplified method using infrared thermography for monitoring CAM in the annual desert succulent Mesembryanthemum crystallinum L. via detection of changes in leaf temperature brought about by the absence of transpiration due to daytime reduction in stomatal conductance. This method is sensitive, measuring temperature differences of ± 1°C, can be used in both the field and green house and is not restricted by leaf architecture. It offers an alternative to the commonly used gas exchange methods to measure CAM that are technically difficult to acquire and require the use of expensive and cumbersome equipment.
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Nelson, Elizabeth A., Tammy L. Sage, and Rowan F. Sage. "Functional leaf anatomy of plants with crassulacean acid metabolism." Functional Plant Biology 32, no. 5 (2005): 409. http://dx.doi.org/10.1071/fp04195.
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Crassulacean acid metabolism (CAM) has evolved independently on dozens of occasions and is now found in over 7% of plant species. In this study, the leaf structure of a phylogenetically diverse assemblage of 18 CAM plants was compared with six C3 plants and four C4 plants to assess whether consistent anatomical patterns that may reflect functional constraints are present. CAM plants exhibited increased cell size and increased leaf and mesophyll thickness relative to C3 and C4 species. CAM species also exhibited reduced intercellular air space (IAS) and reduced length of mesophyll surface exposed to IAS per unit area (Lmes / area). The low volume of IAS and low exposure of mesophyll surface to IAS likely increases internal resistance to CO2 in CAM tissues. While this diffusional barrier may limit uptake of CO2 during Phases II and IV, carbon economy could be enhanced through the reduced loss of internal CO2 during all four phases of CAM.
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Winter, Klaus, Rowan F. Sage, Erika J. Edwards, Aurelio Virgo, and Joseph A. M. Holtum. "Facultative crassulacean acid metabolism in a C3–C4 intermediate." Journal of Experimental Botany 70, no. 22 (March 1, 2019): 6571–79. http://dx.doi.org/10.1093/jxb/erz085.
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Winter, Klaus. "Ecophysiology of constitutive and facultative CAM photosynthesis." Journal of Experimental Botany 70, no. 22 (February 27, 2019): 6495–508. http://dx.doi.org/10.1093/jxb/erz002.
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NOSE, Akihiro. "Viriations in Crassulacean Acid Metabolism(CAM) and Its Regulation." Japanese journal of crop science 61, no. 1 (1992): 161–71. http://dx.doi.org/10.1626/jcs.61.161.
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Niechayev, Nicholas A., Paula N. Pereira, and John C. Cushman. "Understanding trait diversity associated with crassulacean acid metabolism (CAM)." Current Opinion in Plant Biology 49 (June 2019): 74–85. http://dx.doi.org/10.1016/j.pbi.2019.06.004.
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KEELEY, J. E., and S. C. KEELEY. "Crassulacean acid metabolism (CAM) in high elevation tropical cactus." Plant, Cell and Environment 12, no. 3 (April 1989): 331–36. http://dx.doi.org/10.1111/j.1365-3040.1989.tb01948.x.
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Kornas, Andrzej, Zbigniew Miszalski, Ewa Surówka, Elke Fischer-Schliebs, and Ulrich Lüttge. "Light Stress Is Not Effective to Enhanced Crassulacean Acid Metabolism." Zeitschrift für Naturforschung C 65, no. 1-2 (February 1, 2010): 79–86. http://dx.doi.org/10.1515/znc-2010-1-214.
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Clusia minor L., a C3-CAM intermediate, and Clusia multifl ora H. B. K., a C3 obligate, present two physiotypes of a similar morphotype occurring sympatrically in the fi eld. Both species, exposed 2 days to high light, show similar responses to this kind of stress: (i) the level of xanthophyll pigments in tested plants during the daycourse adapts to stress, (ii) the levels of antheraxanthin and zeaxanthin clearly increase during the afternoon showing increased de-epoxidation, (iii) the changes in the xanthophyll cycle are similar. Exposure to high light increases the malate levels in C. minor during the afternoon while decreases the day/night changes of the malate levels, and hence the Crassulacean Acid Metabolism (CAM) expression. It can be concluded that strong light applied as a single stress factor to well-watered plants is not effective in strengthing the CAM metabolism in a C3-CAM intermediate plant but rather suppresses the CAM activity despite exposure to high light energy. It is suggested that, when water supply is not limiting and other stresses do not prevail, C3 allows to use up the citrate pool, especially in the afternoon and enables a superior daily photon utilization.
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Males, Jamie. "Concerted anatomical change associated with crassulacean acid metabolism in the Bromeliaceae." Functional Plant Biology 45, no. 7 (2018): 681. http://dx.doi.org/10.1071/fp17071.
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Crassulacean acid metabolism (CAM) is a celebrated example of convergent evolution in plant ecophysiology. However, many unanswered questions surround the relationships among CAM, anatomy and morphology during evolutionary transitions in photosynthetic pathway. An excellent group in which to explore these issues is the Bromeliaceae, a diverse monocot family from the Neotropics in which CAM has evolved multiple times. Progress in the resolution of phylogenetic relationships among the bromeliads is opening new and exciting opportunities to investigate how evolutionary changes in leaf structure has tracked, or perhaps preceded, photosynthetic innovation. This paper presents an analysis of variation in leaf anatomical parameters across 163 C3 and CAM bromeliad species, demonstrating a clear divergence in the fundamental aspects of leaf structure in association with the photosynthetic pathway. Most strikingly, the mean volume of chlorenchyma cells of CAM species is 22 times higher than that of C3 species. In two bromeliad subfamilies (Pitcairnioideae and Tillandsioideae), independent transitions from C3 to CAM are associated with increased cell succulence, whereas evolutionary trends in tissue thickness and leaf air space content differ between CAM origins. Overall, leaf anatomy is clearly and strongly coupled with the photosynthetic pathway in the Bromeliaceae, where the independent origins of CAM have involved significant anatomical restructuring.
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Winter, Klaus, and Joseph A. M. Holtum. "Facultative crassulacean acid metabolism (CAM) in four small C3 and C4 leaf-succulents." Australian Journal of Botany 65, no. 2 (2017): 103. http://dx.doi.org/10.1071/bt16015.
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Measurements of whole-plant gas exchange and titratable acidity demonstrate that the Australian native species Anacampseros australiana J.M.Black (Anacampserotaceae), Crassula sieberiana (Schult. & Schult.f.) Druce (Crassulaceae) and Portulaca australis Endl. (Portulacaceae) and the widespread naturalised tropical exotic, Portulaca pilosa L., exhibit facultative crassulacean acid metabolism (CAM). In well-watered plants, net CO2 uptake was restricted to the daylight hours and occurred via the C3 pathway (A. australiana and C. sieberiana) or the C4 pathway (P. australis and P. pilosa). Leaves of well-watered plants did not accumulate titratable acidity during the night. Following drought treatment, CO2 uptake in the light by shoots decreased markedly, nocturnal gas-exchange shifted from net CO2 loss to a CAM-type pattern that included net CO2 uptake, and leaves acidified at night. Nocturnal CO2 uptake by shoots and leaf acidification were most pronounced in A. australiana and least so in C. sieberiana. The induction of dark CO2 uptake and tissue acidification was fully reversible in all four species: upon rewatering, nocturnal CO2 uptake and acidification ceased and the rates of CO2 incorporation in the light were restored. We suggest that, hitherto considered relatively exceptional globally, facultative CAM may be more common than previously suspected, particularly among the generally small ephemeral leaf-succulents that characterise Australia’s succulent flora.
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Haslam, Richard, Anne Borland, and Howard Griffiths. "Short-term plasticity of crassulacean acid metabolism expression in the epiphytic bromeliad Tillandsia usneoides." Functional Plant Biology 29, no. 6 (2002): 749. http://dx.doi.org/10.1071/pp01214.
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This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001. The regulation and flexibility of the crassulacean acid metabolism (CAM) pathway has been investigated in the 'extreme epiphyte' Tillandsia usneoides (L.). Submerging strands of T. usneoides under water, thereby inhibiting the supply of atmospheric CO2, allowed non-invasive in vivo manipulation of the supply of CO2 during the nocturnal Phase I of CAM. Once the plants were removed from submersion, T. usneoides maintained open stomata, and net CO2 uptake occurred throughout most of the photoperiod. Variability in the expression of CAM allowed T. usneoides to compensate for restricted CO2 availability through Phase I of CAM by adjusting gas exchange rates through the photoperiod and subsequent dark period to maintain a constant internal supply of CO2 in the light. Furthermore, T. usneoides demonstrated a gradual, rather than rapid, change in phosphoenolpyruvate carboxylase (PEPC) activation across the day-night cycle, such that PEPC and Rubisco appear to work in tandem in order to maintain carbon balance for this extreme atmospheric bromeliad.
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Holtum, Joseph A. M., and Klaus Winter. "Degrees of crassulacean acid metabolism in tropical epiphytic and lithophytic ferns." Functional Plant Biology 26, no. 8 (1999): 749. http://dx.doi.org/10.1071/pp99001.
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Crassulacean acid metabolism (CAM) was observed in three species of tropical ferns, the epiphytes Microsorium punctatum and Polypodium crassifolium and the lithophyte Platycerium veitchii. Polypodium crassifolium and P. veitchii exhibited characteristics of weak CAM. Although no net nocturnal CO2 uptake was observed, the presence of CAM was inferred from nocturnal increases in titratable acidity of 4.7 and 4.1 µequiv (g fr wt)–1 respectively, a reduction in the rates of net CO2 evolution during the first half of the dark period, and the presence of a CAM-like decrease in net CO2 uptake during the early light period. In M. punctatum net CO2 uptake during the first half of the dark period was accompanied by an increase in titratable acidity of 39.2 µequiv (g fr wt)–1 and a pronounced reduction in net CO2 uptake during the early light period. When water was withheld from P. crassifolium and M. punctatum, net CO2 uptake during the light was reduced markedly but there was no change in the extent or patterns of CO2 exhange in the dark. As a consequence, the proportion of carbon gained due to CO2 fixation in the dark increased from 2.8 and 10% to 63.5 and 49.3%, respectively (100% being net CO2 uptake during the light plus the estimated CO2 uptake during the dark). After 9 days without added water, dark CO2 uptake was responsible for the maintenance of a net 24 h carbon gain in P. crassifolium. Platycerium veitchii, P. crassifolium and M. punctatum exhibited carbon isotope ratios of between –25.9 and –22.6‰ indicating that carbon isotope ratios may not, by themselves, be sufficient for the identification of weak CAM. We suggest that CAM may be more prevalent in tropical epiphytic and lithophytic ferns than currently envisaged.
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Blasius, B., F. Beck, and U. Lüttge. "A Model for Photosynthetic Oscillations in Crassulacean Acid Metabolism (CAM)." Journal of Theoretical Biology 184, no. 3 (February 1997): 345–51. http://dx.doi.org/10.1006/jtbi.1996.0287.
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Borland, Anne M., and Antony N. Dodd. "Carbohydrate partitioning in crassulacean acid metabolism plants: reconciling potential conflicts of interest." Functional Plant Biology 29, no. 6 (2002): 707. http://dx.doi.org/10.1071/pp01221.
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This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001. The construction of diel leaf carbon budgets, together with analyses of the δ13C composition of biochemical fractions, was used to examine how crassulacean acid metabolism (CAM) plants adjust carbohydrate partitioning in response to shifting sink demands. For Mesembryanthemum crystallinum L., net carbon budgets indicated clear shifts in assimilate partitioning and in the relative proportions of day : night export as CAM was induced. Different patterns of carbohydrate partitioning in primary and axillary leaves of this species may reflect the different sink priorities of determinate and indeterminate growth. In primary leaves, the high level of diel starch turnover may be a strategy for ensuring production of a critical mass of juvenile tissue that poises the plant for CAM induction. In axillary leaves, the high day-night flux through soluble sugars may ensure ready availability of assimilates for export to reproductive sinks. Carbon isotope ratios were measured for various organic fractions isolated from leaves and fruits of two species of Clusia that differ in CAM expression. Similar and C3-like isotopic signatures were obtained for the structural material isolated from fruits of Clusia minor L. and Clusia rosea Jacq. The data suggest that the partitioning of C4- and C3-derived assimilates into discrete storage and transport pools of soluble sugars will ensure reproductive output, regardless of the level of CAM that is induced in these species.
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Wanek, Wolfgang, Werner Huber, Stefan K. Arndt, and Marianne Popp. "Mode of photosynthesis during different life stages of hemiepiphytic Clusia species." Functional Plant Biology 29, no. 6 (2002): 725. http://dx.doi.org/10.1071/pp01206.
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This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001. Carbon isotope fractionation and nocturnal acid accumulation in Clusia osaensis Hammel-ined., C. �peninsulae Hammel-ined. and C. valerii Standl. were investigated during the seedling, epiphytic and hemiepiphytic phases in a lowland tropical forest in Costa Ricato study photosynthetic adaptations of different plant growth stages to their habitat. Foliar δ 13C values around -24 to -32‰ indicate predominant C3 fixation of CO2 and low crassulacean acid metabolism (CAM) activity in all three Clusia species. Only terrestrially rooted plants of C. osaensis showed increased CAM expression. However, all developmental stages exhibited significant CAM cycling as shown by significant day-night fluctuations of titratable protons and of malic and citric acid. In C. valerii and C. peninsulae, an increase in CAM expression with plant development was not observed, and CAM cycling in hemiepiphytic-stage plants was completely repressed during the high rainfall season. The expression of CAM in the three Clusia species is therefore not developmentally controlled but triggered by environmental factors such as water availability and light intensity. These factors remain relatively stable in this ecosystem and CAM is therefore not fully expressed. However, CAM cycling may be of ecophysiological significance in all life stages as it serves as a mechanism to improve carbon economy by reducing respiratory CO2 losses.
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Schöttler, Mark Aurel, Helmut Kirchhoff, Engelbert Weis, and Katharina Siebke. "Metabolic control of photosynthetic electron transport in crassulacean acid metabolism-induced Mesembryanthemum crystallinum." Functional Plant Biology 29, no. 6 (2002): 697. http://dx.doi.org/10.1071/pp01222.
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This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001. We investigated photosynthetic electron transport in leaves of the facultative crassulacean acid metabolism (CAM) plant Mesembryanthemum crystallinum L. After CAM induction, electron transport exhibited variable redox kinetics during the diurnal CAM cycle. In CAM Phase IV, most of PSI (P700) and chlorophyll a fluorescence relaxed with a halftime of 20 ms after a saturating light pulse. This time-constant may reflect the overall linear electron flux from PSII to PSI in saturating light. Comparable relaxation kinetics were also determined for C3 plants. At the end of CAM Phase I and during Phase II, slow components (> 50% of signal amplitude) appeared in both P700 reduction and fluorescence relaxation. They displayed halftimes > 250 ms and > 1 s, suggesting a strong restriction of the linear electron flux from H2O to NADP. The appearance of the slow redox components was accompanied by a decrease in the Fv/Fm ratio of chlorophyll a fluorescence, suggesting a reversible detachment of light-harvesting complex (LHC) II from PSII. The slow redox fractions and the depression of Fv/Fm disappeared again in parallel to malate decarboxylation during CAM Phase III. We discuss a reversible downregulation of linear electron flux during CAM Phases II and III, due to a reversible deprivation of cytochrome-b6f complexes (cyt-bfs) and PSI from the linear system. In parallel, a redistribution of some LHCIIs could also occur. This could be an adaptive response to a reduced metabolic demand for NADPH due to a limited carbon flux through the Calvin cycle, resulting from low Rubisco activation. Furthermore, the cyt-bfs and PSIs deprived of linear electron transport could support cyclic electron flux to cover an increased ATP demand during gluconeogenesis in CAM Phase III.
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Nimmo, H. G. "How to tell the time: the regulation of phosphoenolpyruvate carboxylase in Crassulacean acid metabolism (CAM) plants." Biochemical Society Transactions 31, no. 3 (June 1, 2003): 728–30. http://dx.doi.org/10.1042/bst0310728.
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Crassulacean acid metabolism (CAM) plants exhibit persistent circadian rhythms of CO2 metabolism. These rhythms are driven by changes in the flux through phosphoenolpyruvate carboxylase, which is regulated by reversible phosphorylation in response to a circadian oscillator. This article reviews progress in our understanding of the circadian expression of phosphoenolpyruvate carboxylase kinase.
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Holtum, Joseph A. M., J. Andrew C. Smith, and H. Ekkehard Neuhaus. "Intracellular transport and pathways of carbon flow in plants with crassulacean acid metabolism." Functional Plant Biology 32, no. 5 (2005): 429. http://dx.doi.org/10.1071/fp04189.
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The massive daily reciprocal transfer of carbon between acids and carbohydrates that is unique to crassulacean acid metabolism (CAM) involves extensive and regulated transport of metabolites between chloroplasts, vacuoles, the cytosol and mitochondria. In this review of the CAM pathways of carbon flow and intracellular transport, we highlight what is known and what has been postulated. For three of the four CAM pathway variants currently known (malic enzyme- or PEP carboxykinase-type decarboxylase, and starch- or soluble sugar-type carbohydrate storage), the mechanisms of intracellular transport are still hypothetical and have yet to be demonstrated experimentally. Even in malic enzyme starch-storing species such as Kalanchoë daigremontiana Hamet et Perr. and Mesembryanthemum crystallinum L., the best-described variants of plants with the second-most common mode of photosynthetic carbon metabolism known, no tonoplast or mitochondrial transporter has been functionally described at a molecular level.
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Winter, Klaus, Jorge Aranda, and Joseph A. M. Holtum. "Carbon isotope composition and water-use efficiency in plants with crassulacean acid metabolism." Functional Plant Biology 32, no. 5 (2005): 381. http://dx.doi.org/10.1071/fp04123.
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The relationship between water-use efficiency, measured as the transpiration ratio (g H2O transpired g–1 above- plus below-ground dry mass accumulated), and 13C / 12C ratio (expressed as δ13C value) of bulk biomass carbon was compared in 15 plant species growing under tropical conditions at two field sites in the Republic of Panama. The species included five constitutive crassulacean acid metabolism (CAM) species [Aloe vera (L.) Webb & Berth., Ananas comosus (L.) Merr., Euphorbia tirucalli L., Kalanchoë daigremontiana Hamet et Perr., Kalanchoë pinnata (Lam.) Pers.], two species of tropical C3 trees (Tectona grandis Linn. f. and Swietenia macrophylla King), one C4 species (Zea mays L.), and seven arborescent species of the neotropical genus Clusia, of which two exhibited pronounced CAM. The transpiration ratios of the C3 and CAM species, which ranged between 496 g H2O g–1 dry mass in the C3–CAM species Clusia pratensis Seeman to 54 g H2O g–1 dry mass in the constitutive CAM species Aloe vera, correlated strongly with δ13C values and nocturnal CO2 gain suggesting that δ13C value can be used to estimate both water-use efficiency and the proportion of CO2 gained by CAM species during the light and the dark integrated over the lifetime of the tissues.
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Guralnick, Lonnie J., Gerald Edwards, Maurice S. B. Ku, Brandon Hockema, and Vince Franceschi. "Photosynthetic and anatomical characteristics in the C4crassulacean acid metabolism-cycling plant Portulaca grandiflora." Functional Plant Biology 29, no. 6 (2002): 763. http://dx.doi.org/10.1071/pp01176.
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This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001. Portulaca grandiflora (Lind.) is a succulent species with C4 photosynthesis and crassulacean acid metabolism (CAM) cycling in leaves, and CAM-idling type photosynthesis in stems. We investigated the level and localization of carbon fixation enzymes and photosynthetic activity of leaves and stems of P. grandiflora under well-watered and drought conditions. As CAM activity increased during water stress, the leaf water-storage tissue collapsed, presumably transferring water to the bundle sheath and mesophyll cells, and so maintaining the C4 photosynthetic pathway. Tissue prints indicated an increase in phosphoenolpyruvate carboxylase (PEPC) in the water-storage tissue of leaves and the cortex of stems. Immunoblot analyses after 10 d of water stress showed that leaves had a slight decrease in the proteins of the C4-CAM pathway, while at the same time a new isoform of NADP-malic enzyme (NADP-ME) appeared. In contrast, the stem showed increases in proteins of the CAM pathway when water stressed. Under water stress, diurnal fluctuation in acidity in leaves was not accompanied by a net gain or loss of CO2 at night, and there was sustained, but decreased, fixation of CO2 during the day, characteristic of CAM cycling. High gross rates of O2 evolution were maintained during the day under water stress, suggesting induction of alternative electron sinks. With induced diurnal fluctuations in acidity in stems, there was no net carbon gain during the day or night. These results demonstrate, for the first time, that the stem of P. grandiflora is an inducible CAM-idling tissue. Our results also indicate that the C4 and CAM pathways operate independently of one another in P. grandiflora.
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Liu, Degao, Mei Chen, Brian Mendoza, Hua Cheng, Rongbin Hu, Linling Li, Cong T. Trinh, Gerald A. Tuskan, and Xiaohan Yang. "CRISPR/Cas9-mediated targeted mutagenesis for functional genomics research of crassulacean acid metabolism plants." Journal of Experimental Botany 70, no. 22 (September 28, 2019): 6621–29. http://dx.doi.org/10.1093/jxb/erz415.
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Abstract Crassulacean acid metabolism (CAM) is an important photosynthetic pathway in diverse lineages of plants featuring high water-use efficiency and drought tolerance. A big challenge facing the CAM research community is to understand the function of the annotated genes in CAM plant genomes. Recently, a new genome editing technology using CRISPR/Cas9 has become a more precise and powerful tool than traditional approaches for functional genomics research in C3 and C4 plants. In this study, we explore the potential of CRISPR/Cas9 to characterize the function of CAM-related genes in the model CAM species Kalanchoë fedtschenkoi. We demonstrate that CRISPR/Cas9 is effective in creating biallelic indel mutagenesis to reveal previously unknown roles of blue light receptor phototropin 2 (KfePHOT2) in the CAM pathway. Knocking out KfePHOT2 reduced stomatal conductance and CO2 fixation in late afternoon and increased stomatal conductance and CO2 fixation during the night, indicating that blue light signaling plays an important role in the CAM pathway. Lastly, we provide a genome-wide guide RNA database targeting 45 183 protein-coding transcripts annotated in the K. fedtschenkoi genome.
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Torres-Morales, Germán, Eloisa Lasso, Katia Silvera, Benjamin L. Turner, and Klaus Winter. "Occurrence of crassulacean acid metabolism in Colombian orchids determined by leaf carbon isotope ratios." Botanical Journal of the Linnean Society 193, no. 4 (July 8, 2020): 431–77. http://dx.doi.org/10.1093/botlinnean/boaa027.
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Abstract Many Orchidaceae, especially those occupying periodically dry, epiphytic microhabitats in the humid tropics, are believed to engage in the water-conserving crassulacean acid metabolism (CAM) photosynthetic pathway. However, the photosynthetic pathway has been studied in only c. 5% of all orchid species. Here we extend the survey to 1079 orchid species, mainly from Colombia, by assessing the presence of CAM based on the carbon isotopic signature (δ 13C values) of herbarium specimens. Ninety-six species, representing 8.9% of those analysed, had δ 13C values less negative than −20‰, indicating CAM. Epiphytism was the predominant life form (75.2% of species sampled), and 9.4% of these epiphytes showed a CAM-type isotopic signature. Isotope values suggested CAM in 19 terrestrial orchid species, 14 species from high elevation (2000–3400 m) and species from six genera that were previously unknown to engage in CAM (Jacquiniella, Meiracyllium, Pabstiella, Psychopsis, Pterostemma and Solenidium). We conclude that CAM is the major pathway of carbon acquisition in a small but broadly distributed fraction of tropical orchids and is more prevalent at lower elevations.
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Yu, Kailiang, and Paolo D’Odorico. "Direct and Indirect Facilitation of Plants with Crassulacean Acid Metabolism (CAM)." Ecosystems 18, no. 6 (April 28, 2015): 985–99. http://dx.doi.org/10.1007/s10021-015-9877-6.
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Silvera, Katia, Louis S. Santiago, and Klaus Winter. "Distribution of crassulacean acid metabolism in orchids of Panama: evidence of selection for weak and strong modes." Functional Plant Biology 32, no. 5 (2005): 397. http://dx.doi.org/10.1071/fp04179.
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Crassulacean acid metabolism (CAM) is one of three metabolic pathways found in vascular plants for the assimilation of carbon dioxide. In this study, we investigate the occurrence of CAM photosynthesis in 200 native orchid species from Panama and 14 non-native species by carbon isotopic composition (δ13C) and compare these values with nocturnal acid accumulation measured by titration in 173 species. Foliar δ13C showed a bimodal distribution with the majority of species exhibiting values of approximately –28‰ (typically associated with the C3 pathway), or –15‰ (strong CAM). Although thick leaves were related to δ13C values in the CAM range, some thin-leaved orchids were capable of CAM photosynthesis, as demonstrated by acid titration. We also found species with C3 isotopic values and significant acid accumulation at night. Of 128 species with δ13C more negative than –22‰, 42 species showed nocturnal acid accumulation per unit fresh mass characteristic of weakly expressed CAM. These data suggest that among CAM orchids, there may be preferential selection for species to exhibit strong CAM or weak CAM, rather than intermediate metabolism.
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Guralnick, Lonnie J., and Kate Gladsky. "Crassulacean acid metabolism as a continuous trait: variability in the contribution of Crassulacean acid metabolism (CAM) in populations of Portulacaria afra." Heliyon 3, no. 4 (April 2017): e00293. http://dx.doi.org/10.1016/j.heliyon.2017.e00293.
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Deshumukh, R. B., and C. V. Murumkar. "Occurrence of crassulacean acid metabolism in leaves of Aristolochia bracteata Ritz." Acta Societatis Botanicorum Poloniae 65, no. 3-4 (2014): 297–99. http://dx.doi.org/10.5586/asbp.1996.045.
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<em>Aristolochia bracteata</em> Ritz. is a common weed of fallowlands of hot, semi-arid region of Baramati area. High succulence index was noticed in leaf tissues along with marked diurnal fluctuations in titratable acidity status, and pH of leaf sap. Stomatal behaviour also followed typical CAM pattern. All these findings conclude that Crassulacean Acid Metabolism is in operation in this species.
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Christopher, John T., and Joseph A. M. Holtum. "Carbohydrate partitioning in the leaves of Bromeliaceae performing C3 photosynthesis or Crassulacean acid metabolism." Functional Plant Biology 25, no. 3 (1998): 371. http://dx.doi.org/10.1071/pp98005.
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Carbohydrate accumulation was measured in the leaves of 11 speciesrepresenting the three subfamilies of Bromeliaceae. In the Tillandsioideae the C3 species Vriesea carinata Wawra accumulated starch and sucrose while the Crassulacean acid metabolism (CAM)species Tillandsia tricolor Schlechtendal & Chamissoaccumulated mainly starch. In the Pitcairnioideae the C3species Pitcairnia paniculata Ruiz & Pavon and two CAM species Dyckia sp. andFosterella schidosperma Barker accumulated sucrose butnot starch. Of six CAM species in the Bromelioideae, threeCryptanthus zonatus (Visiani) Beer,Neoregalia spectabilis Moore andPortea petropolitana Wawra accumulated starch but notsoluble sugars while three (Ananus comosus Linnaeus,Orthophytum vagans M.B. Foster andNidularium bilbergioides Schultes filius) accumulatedstarch as well as soluble sugars. Carbohydrate accumulation patterns weresimilar for species within each subfamily in that the Pitcairnioideae speciesdid not accumulate starch but accumulated sucrose while species from theTillandsioideae and Bromelioideae all accumulated starch (some alsoaccumulated soluble sugars). Carbohydrate accumulation patterns were notsimilar for C3 species versus CAM species from thedifferent subfamilies. These data suggest that variations in carbohydratebiochemistry resulting from different evolutionary histories have a greaterinfluence on carbohydrate accumulation patterns in CAM bromeliads than theconstraints of the CAM pathway itself.
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Matsuo, Takami, Yusuke Totoki, and Haruo Suemitsu. "Adaptive Estimation of Biological Rhythm in Crassulacean Acid Metabolism with Critical Manifold." ISRN Applied Mathematics 2013 (June 18, 2013): 1–9. http://dx.doi.org/10.1155/2013/856404.
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The mechanism of endogenous circadian photosynthesis oscillations of plants performing crassulacean acid metabolism (CAM) is investigated in terms of a nonlinear theoretical model. Blasius et al. used throughout continuous time differential equations which adequately reflect the CAM dynamics. The model shows regular endogenous limit cycle oscillations that are stable for a wide range of temperatures in a manner that complies well with experimental data. In this paper, we pay attention to the approximation of the fast modes of the CAM dynamics. Using the zero-epsilon approximation of the slow manifold, we derive the critical manifold that is defined by two algebraic nonlinear equations. The critical manifold allows us to give the algebraic estimate of the order of the tonoplast membrane. The dynamic equation of the order of the tonoplast membrane includes the nonlinear function that gives the equilibrium value of the lipid order of tonoplast functions as a hysteresis switch. We identify the nonlinear function with the measurement signals. Using the basis function expansion of the nonlinear and the critical manifold, we propose an adaptive observer to estimate the tonoplast order and the nonlinear function.
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Maleckova, Eva, Dominik Brilhaus, Thomas J. Wrobel, and Andreas P. M. Weber. "Transcript and metabolite changes during the early phase of abscisic acid-mediated induction of crassulacean acid metabolism in Talinum triangulare." Journal of Experimental Botany 70, no. 22 (April 24, 2019): 6581–96. http://dx.doi.org/10.1093/jxb/erz189.
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Abstract Crassulacean acid metabolism (CAM) has evolved as a water-saving strategy, and its engineering into crops offers an opportunity to improve their water use efficiency. This requires a comprehensive understanding of the regulation of the CAM pathway. Here, we use the facultative CAM species Talinum triangulare as a model in which CAM can be induced rapidly by exogenous abscisic acid. RNA sequencing and metabolite measurements were employed to analyse the changes underlying CAM induction and identify potential CAM regulators. Non-negative matrix factorization followed by k-means clustering identified an early CAM-specific cluster and a late one, which was specific for the early light phase. Enrichment analysis revealed abscisic acid metabolism, WRKY-regulated transcription, sugar and nutrient transport, and protein degradation in these clusters. Activation of the CAM pathway was supported by up-regulation of phosphoenolpyruvate carboxylase, cytosolic and chloroplastic malic enzymes, and several transport proteins, as well as by increased end-of-night titratable acidity and malate accumulation. The transcription factors HSFA2, NF-YA9, and JMJ27 were identified as candidate regulators of CAM induction. With this study we promote the model species T. triangulare, in which CAM can be induced in a controlled way, enabling further deciphering of CAM regulation.
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Herrera, Ana. "Are thick leaves, large mesophyll cells and small intercellular air spaces requisites for CAM?" Annals of Botany 125, no. 6 (January 23, 2020): 859–68. http://dx.doi.org/10.1093/aob/mcaa008.
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Abstract Background and Aims It is commonly accepted that the leaf of a crassulacean acid metabolism (CAM) plant is thick, with large mesophyll cells and vacuoles that can accommodate the malic acid produced during the night. The link between mesophyll characteristics and CAM mode, whether obligate or C3/CAM, was evaluated. Methods Published values of the carbon isotopic ratio (δ 13C) as an indicator of CAM, leaf thickness, leaf micrographs and other evidence of CAM operation were used to correlate cell density, cell area, the proportion of intercellular space in the mesophyll (IAS) and the length of cell wall facing the intercellular air spaces (Lmes/A) with CAM mode. Key Results Based on 81 species and relatively unrelated families (15) belonging to nine orders, neither leaf thickness nor mesophyll traits helped explain the degree of CAM expression. A strong correlation was found between leaf thickness and δ 13C in some species of Crassulaceae and between leaf thickness and nocturnal acid accumulation in a few obligate CAM species of Bromeliaceae but, when all 81 species were pooled together, no significant changes with δ 13C were observed in cell density, cell area, IAS or Lmes/A. Conclusions An influence of phylogeny on leaf anatomy was evidenced in a few cases but this precluded generalization for widely separate taxa containing CAM species. The possible relationships between leaf anatomy and CAM mode should be interpreted cautiously.
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Maxwell, Kate. "Resistance is useful: diurnal patterns of photosynthesis in C3 and crassulacean acid metabolism epiphytic bromeliads." Functional Plant Biology 29, no. 6 (2002): 679. http://dx.doi.org/10.1071/pp01193.
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This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001 Diurnal patterns of photosynthesis in response to environmental variables were investigated in an obligate C3 and a facultative C3-crassulacean acid metabolism (CAM) bromeliad species. A midday depression of photosynthesis occurred in both C3 groups, mediated as a decrease in stomatal conductance in response to increased vapour pressure difference. The response was associated with a reduction in Rubisco activation state during the period of maximum photon flux density. In contrast, the switch to CAM resulted in a strong shift in the pattern of Rubisco carbamylation, with full enzyme activation delayed until the midday period. For the first time it is demonstrated that the pattern of Rubisco activation differs between C3 and CAM plants of the same species under identical conditions. Despite large differences in Rubisco content between C3 and CAM plants, neither the amount of Rubisco or enzyme activity is thought to be limiting for photosynthesis, and it is suggested that Rubisco may function as a nitrogen store. Extreme CO2 diffusion limitation resulted in low rates of atmospheric CO2 assimilation that were associated with high rates of photosynthetic electron transport, and it is likely that photorespiration constitutes a significant electron sink over the entire diurnal course. Leaf morphological and physiological adaptations to drought stress are necessary for the epiphytic lifestyle but limit CO2 assimilation and confound the likelihood of high productivity.
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Andrade, José Luis, Erick De la Barrera, Casandra Reyes-García, M. Fernanda Ricalde, Gustavo Vargas-Soto, and J. Carlos Crevera. "El metabolismo ácido de las crasuláceas: diversidad, fisiología ambiental y productividad." Botanical Sciences, no. 81 (June 4, 2017): 37. http://dx.doi.org/10.17129/botsci.1764.
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Mexico possesses a great species diversity of Crassulacean Acid Metabolism (CAM) plants. These plants can grow in places where water is infrequent, such as arid and semi-arid zones, and tree canopies, or as aquatic plants in places with low CO2 availability. This review presents methodological, evolutionary, ecological, and physiological aspects on CAM plants. Also, it shows data from recent studies related to the environmental effect on changes in the photosynthesis CAM. Finally, we made a consideration about the lack of studies on the physiology of CAM plants in Mexico despite its enormous diversity.
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Maxwell, Kate, Howard Griffiths, Brent Helliker, Andrew Roberts, Richard P. Haslam, Jan Girnus, Wendy E. Robe, and Anne M. Borland. "Regulation of Rubisco activity in crassulacean acid metabolism plants: better late than never." Functional Plant Biology 29, no. 6 (2002): 689. http://dx.doi.org/10.1071/pp01212.
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This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001. The diurnal regulation of Rubisco was compared for a range of crassulacean acid metabolism (CAM) species in the context of high carboxylation and electron transport capacities, which may be an order of magnitude greater than rates of net CO2 uptake. Early in the light period, Rubisco activity and electron transport were limited when phosphoenolpyruvate carboxylase (PEPC) may have been operating, and maximal extractable activities and activation state for Rubisco were achieved at the end of Phase III, prior to the direct atmospheric uptake of CO2 during Phase IV. The delayed activation was associated with levels of Rubisco activase protein, which reached a maximum at midday, and may account for this pattern of Rubisco activation. This regulation may be modified by environmental conditions - processes that tend to restrict PEPC activity, such as drought stress or incubation of leaves overnight in an oxygen-free atmosphere, release Rubisco from inhibition early in the light period. The quantum yield of light use also tracks Rubisco carboxylation, being particularly low at dawn when PEPC is active. The plasticity in expression of the CAM cycle is therefore matched by the regulation of key carboxylases, with extractable Rubisco activity maximal when drawdown of atmospheric CO2 to cells in succulent CAM tissues is most likely to limit photon utilization shortly after midday, during Phase IV.
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Herrera, A. "Effects of photoperiod and drought on the induction of crassulacean acid metabolism and the reproduction of plants of Talinum triangulare." Canadian Journal of Botany 77, no. 3 (August 20, 1999): 404–9. http://dx.doi.org/10.1139/b99-036.
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To examine the effects of day length on the induction of crassulacean acid metabolism (CAM) by drought in the tropical species, Talinum triangulare (Jacq.) Willd. (Portulacaceae), plants were subjected to drought under different photoperiods. Nocturnal acid accumulation was 52 µmol H+··g-1 fresh mass (FM) in plants grown under a 10 h light : 14 h dark photoperiod and 76 µmol H+·g-1 FM in plants grown under 13 h light : 11 h dark, whereas it was only 10 µmol H+·g-1 FM in plants grown under 18 h light : 6 h dark. Plants were subjected to drought under short days and under short days with a night interruption of 1.5 h white light, aiming to simulate a long day, while minimally affecting daily carbon balance. Only droughted plants under normal short days accumulated acids during the night. Absence of CAM could not be attributed to differences due to photoperiod in either biomass allocation, chlorophyll content, or leaf water content. Photoperiod did not significantly affect fecundity in watered plants, whereas drought markedly reduced fecundity in plants with night interruption relative to plants under normal short days. Reproductive effort, calculated as seeds per gram leaf, was significantly higher in droughted plants under normal short days and watered plants with and without night interruption than in droughted plants with night interruption.Key words: CAM, crassulacean acid metabolism, drought, fecundity, induction, photoperiod, reproductive effort, reproduction, Talinum triangulare
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Kore-eda, Shin, Chiyuki Noake, Masahisa Ohishi, Jun-ichi Ohnishi, and John C. Cushman. "Transcriptional profiles of organellar metabolite transporters during induction of crassulacean acid metabolism in Mesembryanthemum crystallinum." Functional Plant Biology 32, no. 5 (2005): 451. http://dx.doi.org/10.1071/fp04188.
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Metabolite transport across multiple organellar compartments is essential for the operation of crassulacean acid metabolism (CAM). To investigate potential circadian regulation of inter-organellar metabolite transport processes, we have identified eight full-length cDNAs encoding an organellar triose phosphate / Pi translocator (McTPT1), a phosphoenolpyruvate / Pi translocator (McPPT1), two glucose-6-phosphate / Pi translocators (McGPT1, 2), two plastidic Pi translocator-like proteins (McPTL1, 2), two adenylate transporters (McANT1, 2), a dicarboxylate transporter (McDCT2), and a partial cDNA encoding a second dicarboxylate transporter (McDCT1) in the model CAM plant, Mesembryanthemum crystallinum L. We next investigated day / night changes in steady-state transcript abundance of each of these transporters in plants performing either C3 photosynthesis or CAM induced by salinity or water-deficit stress. We observed that the expression of both isogenes of the glucose-6-phosphate / Pi translocator (McGPT1, 2) was enhanced by CAM induction, with McGPT2 transcripts exhibiting much more pronounced diurnal changes in transcript abundance than McGPT1. Transcripts for McTPT1, McPPT1, and McDCT1 also exhibited more pronounced diurnal changes in abundance in the CAM mode relative to the C3 mode. McGPT2 and McDCT1 transcripts exhibited sustained oscillations for at least 3 d under constant light and temperature conditions suggesting their expression is under circadian clock control. McTPT1 and McGPT2 transcripts were preferentially expressed in leaf tissues in either C3 or CAM modes. The leaf-specific and / or circadian controlled gene expression patterns are consistent with McTPT1, McGPT2 and McDCT1 playing CAM-specific metabolite transport roles.
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Guralnick, Lonnie J., Kate E. Gilbert, Diana Denio, and Nicholas Antico. "The Development of Crassulacean Acid Metabolism (CAM) Photosynthesis in Cotyledons of the C4 Species, Portulaca grandiflora (Portulacaceae)." Plants 9, no. 1 (January 2, 2020): 55. http://dx.doi.org/10.3390/plants9010055.
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Portulaca grandiflora simultaneously utilizes both the C4 and Crassulacean acid metabolism (CAM) photosynthetic pathways. Our goal was to determine whether CAM developed and was functional simultaneously with the C4 pathway in cotyledons of P. grandiflora. We studied during development whether CAM would be induced with water stress by monitoring the enzyme activity, leaf structure, JO2 (rate of O2 evolution calculated by fluorescence analysis), and the changes in titratable acidity of 10 and 25 days old cotyledons. In the 10 days old cotyledons, C4 and CAM anatomy were evident within the leaf tissue. The cotyledons showed high titratable acid levels but a small CAM induction. In the 25 days old cotyledons, there was a significant acid fluctuation under 7 days of water stress. The overall enzyme activity was reduced in the 10 days old plants, while in the 25 days old plants CAM activity increased under water-stressed conditions. In addition to CAM, the research showed the presence of glycine decarboxylase in the CAM tissue. Thus, it appears both pathways develop simultaneously in the cotyledons but the CAM pathway, due to anatomical constraints, may be slower to develop than the C4 pathway. Cotyledons showed the ancestral Atriplicoid leaf anatomy, which leads to the question: Could a CAM cell be the precursor to the C4 pathway? Further study of this may lead to understanding into the evolution of C4 photosynthesis in the Portulaca.
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Gehrig, Hans H., Joshua A. Wood, Mary Ann Cushman, Aurelio Virgo, John C. Cushman, and Klaus Winter. "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 32, no. 5 (2005): 467. http://dx.doi.org/10.1071/fp05079.
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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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Taisma, María Angélica, and Ana Herrera. "A relationship between fecundity, survival, and the operation of crassulacean acid metabolism in Talinum triangulare." Canadian Journal of Botany 76, no. 11 (November 1, 1998): 1908–15. http://dx.doi.org/10.1139/b98-136.
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In plants of the perennial, deciduous herb Talinum triangulare, crassulacean acid metabolism (CAM) is induced by drought; therefore, CAM may be an adaptation to water deficit in this species. The present study was undertaken to determine the effects of water deficit on fecundity and CAM in plants of T. triangulare. Plants were grown from seed in the greenhouse and the life table was constructed with dynamic cohorts. CAM was induced by drought in plants as young as 45 days old, and its induction was associated with a significant rise in fecundity; values of survival beta mean fecundity by age-class were 30-50% higher in plants subjected to drought than in control plants due to a rise in fecundity. Plants subjected to drought produced more and lighter seeds, which germinated faster than their watered controls. These characteristics could be advantageous for a colonizing species such as T. triangulare. Plants obtained from the germination of seeds of plants subjected to drought did not show higher values of nocturnal acid accumulation when subjected to drought than the droughted offspring of watered plants but they showed higher survival and an earlier and higher reproductive effort than plants obtained from the germination of seeds of watered plants. The fact that values of survival beta mean fecundity were higher in plants subjected to drought than in watered plants suggests, within the context of the life history, that characters associated with the CAM syndrome may be adaptive.Key words: fitness, inducible CAM, life table.
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Winter, Klaus, and Joseph A. M. Holtum. "Induction and reversal of crassulacean acid metabolism in Calandrinia polyandra: effects of soil moisture and nutrients." Functional Plant Biology 38, no. 7 (2011): 576. http://dx.doi.org/10.1071/fp11028.
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Calandrinia polyandra Benth. (Montiaceae), an annual succulent herb endemic to Australia, is an exemplary facultative crassulacean acid metabolism (CAM) plant as demonstrated by continuous whole-plant lifetime CO2 exchange measurements under controlled conditions in the laboratory. Reduced soil water availability induced a shift from solely daytime CO2 fixation to dark CO2 fixation. The shift from C3 photosynthesis to CAM was reversible either upon rewatering alone, or upon a combination of rewatering and addition of nutrients. These observations highlight the role of edaphic conditions in controlling CAM expression in a plant that has the option of fixing CO2 either during the day or during the night, providing further evidence that this extreme form of photosynthetic plasticity is primarily controlled by the environment rather than plant ontogeny. The stimulating effect of soil nutrients on CO2 fixation in the light and its negative effect on dark CO2 fixation have not been described previously and deserve further attention. In the most widely used CAM model system, the halophytic Mesembryanthemum crystallinum L., CAM is typically induced by high salinity, and some metabolic responses may be CAM-unrelated and related to salt stress per se. C. polyandra could be an excellent complementary system for studying the biochemical and molecular foundations of CAM because drought stress elicits a complete C3 to CAM transition.
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Pereira, Paula Natália, and John C. Cushman. "Exploring the Relationship between Crassulacean Acid Metabolism (CAM) and Mineral Nutrition with a Special Focus on Nitrogen." International Journal of Molecular Sciences 20, no. 18 (September 5, 2019): 4363. http://dx.doi.org/10.3390/ijms20184363.
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Crassulacean acid metabolism (CAM) is characterized by nocturnal CO2 uptake and concentration, reduced photorespiration, and increased water-use efficiency (WUE) when compared to C3 and C4 plants. Plants can perform different types of CAM and the magnitude and duration of CAM expression can change based upon several abiotic conditions, including nutrient availability. Here, we summarize the abiotic factors that are associated with an increase in CAM expression with an emphasis on the relationship between CAM photosynthesis and nutrient availability, with particular focus on nitrogen, phosphorus, potassium, and calcium. Additionally, we examine nitrogen uptake and assimilation as this macronutrient has received the greatest amount of attention in studies using CAM species. We also discuss the preference of CAM species for different organic and inorganic sources of nitrogen, including nitrate, ammonium, glutamine, and urea. Lastly, we make recommendations for future research areas to better understand the relationship between macronutrients and CAM and how their interaction might improve nutrient and water-use efficiency in order to increase the growth and yield of CAM plants, especially CAM crops that may become increasingly important as global climate change continues.
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Heyduk, Karolina, Jeremy N. Ray, Saaravanaraj Ayyampalayam, Nida Moledina, Anne Borland, Scott A. Harding, Chung-Jui Tsai, and Jim Leebens-Mack. "Shared expression of crassulacean acid metabolism (CAM) genes pre-dates the origin of CAM in the genus Yucca." Journal of Experimental Botany 70, no. 22 (April 13, 2019): 6597–609. http://dx.doi.org/10.1093/jxb/erz105.
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Although large differences in metabolism exist between C3 and CAM species, we find that many CAM genes have similar expression patterns regardless of photosynthetic pathway, suggesting ancestral propensity for CAM.
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Winter, K., and J. A. M. Holtum. "Facultative crassulacean acid metabolism (CAM) plants: powerful tools for unravelling the functional elements of CAM photosynthesis." Journal of Experimental Botany 65, no. 13 (March 18, 2014): 3425–41. http://dx.doi.org/10.1093/jxb/eru063.
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Kluge, M., Jeanne Brulfert, J. Lipp, D. Ravelomanana, and H. Ziegler. "A Comparative Study by δ13C-Analysis of Crassulacean Acid Metabolism (CAM) inKalanchoë(Crassulaceae) Species of Africa and Madagascar." Botanica Acta 106, no. 4 (August 1993): 320–24. http://dx.doi.org/10.1111/j.1438-8677.1993.tb00755.x.
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Winter, Klaus. "Diversity of CAM plant photosynthesis (crassulacean acid metabolism): a tribute to Barry Osmond." Functional Plant Biology 48, no. 7 (2021): iii. http://dx.doi.org/10.1071/fpv48n7_fo.
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This special issue is a tribute to the Australian plant biologist Professor Charles Barry Osmond – Fellow of the Australian Academy of Sciences, the Royal Society of London, and Leopoldina, the German National Academy of Sciences – and his many contributions to our understanding of the biochemistry and physiological ecology of CAM (crassulacean acid metabolism) photosynthesis. This water-conserving photosynthetic pathway is characterised by nocturnal uptake of atmospheric CO2 and typically enables succulent plants to perform and survive in warm semiarid terrestrial and epiphytic habitats. The idea for this issue is to mark the occasion of Barry’s 80th birthday in 2019. The foreword highlights some of his outstanding contributions and introduces the research papers of the special issue.