1
|
Perron N, Kirst M, Chen S. Bringing CAM photosynthesis to the table: Paving the way for resilient and productive agricultural systems in a changing climate. PLANT COMMUNICATIONS 2024; 5:100772. [PMID: 37990498 PMCID: PMC10943566 DOI: 10.1016/j.xplc.2023.100772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 07/27/2023] [Accepted: 11/20/2023] [Indexed: 11/23/2023]
Abstract
Modern agricultural systems are directly threatened by global climate change and the resulting freshwater crisis. A considerable challenge in the coming years will be to develop crops that can cope with the consequences of declining freshwater resources and changing temperatures. One approach to meeting this challenge may lie in our understanding of plant photosynthetic adaptations and water use efficiency. Plants from various taxa have evolved crassulacean acid metabolism (CAM), a water-conserving adaptation of photosynthetic carbon dioxide fixation that enables plants to thrive under semi-arid or seasonally drought-prone conditions. Although past research on CAM has led to a better understanding of the inner workings of plant resilience and adaptation to stress, successful introduction of this pathway into C3 or C4 plants has not been reported. The recent revolution in molecular, systems, and synthetic biology, as well as innovations in high-throughput data generation and mining, creates new opportunities to uncover the minimum genetic tool kit required to introduce CAM traits into drought-sensitive crops. Here, we propose four complementary research avenues to uncover this tool kit. First, genomes and computational methods should be used to improve understanding of the nature of variations that drive CAM evolution. Second, single-cell 'omics technologies offer the possibility for in-depth characterization of the mechanisms that trigger environmentally controlled CAM induction. Third, the rapid increase in new 'omics data enables a comprehensive, multimodal exploration of CAM. Finally, the expansion of functional genomics methods is paving the way for integration of CAM into farming systems.
Collapse
Affiliation(s)
- Noé Perron
- Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, FL 32608, USA
| | - Matias Kirst
- Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, FL 32608, USA; School of Forest, Fisheries and Geomatics Sciences, University of Florida, Gainesville, FL 32603, USA.
| | - Sixue Chen
- Department of Biology, University of Mississippi, Oxford, MS 38677-1848, USA.
| |
Collapse
|
2
|
Chomthong M, Griffiths H. Prospects and perspectives: inferring physiological and regulatory targets for CAM from molecular and modelling approaches. ANNALS OF BOTANY 2023; 132:583-596. [PMID: 37742290 PMCID: PMC10799989 DOI: 10.1093/aob/mcad142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Revised: 08/26/2023] [Accepted: 09/21/2023] [Indexed: 09/26/2023]
Abstract
BACKGROUND AND SCOPE This review summarizes recent advances in our understanding of Crassulacean Acid Metabolism (CAM) by integrating evolutionary, ecological, physiological, metabolic and molecular perspectives. A number of key control loops which moderate the expression of CAM phases, and their metabolic and molecular control, are explored. These include nocturnal stomatal opening, activation of phosphoenolpyruvate carboxylase by a specific protein kinase, interactions with circadian clock control, as well as daytime decarboxylation and activation of Rubisco. The vacuolar storage and release of malic acid and the interplay between the supply and demand for carbohydrate reserves are also key metabolic control points. FUTURE OPPORTUNITIES We identify open questions and opportunities, with experimentation informed by top-down molecular modelling approaches allied with bottom-up mechanistic modelling systems. For example, mining transcriptomic datasets using high-speed systems approaches will help to identify targets for future genetic manipulation experiments to define the regulation of CAM (whether circadian or metabolic control). We emphasize that inferences arising from computational approaches or advanced nuclear sequencing techniques can identify potential genes and transcription factors as regulatory targets. However, these outputs then require systematic evaluation, using genetic manipulation in key model organisms over a developmental progression, combining gene silencing and metabolic flux analysis and modelling to define functionality across the CAM day-night cycle. From an evolutionary perspective, the origins and function of CAM succulents and responses to water deficits are set against the mesophyll and hydraulic limitations imposed by cell and tissue succulence in contrasting morphological lineages. We highlight the interplay between traits across shoots (3D vein density, mesophyll conductance and cell shrinkage) and roots (xylem embolism and segmentation). Thus, molecular, biophysical and biochemical processes help to curtail water losses and exploit rapid rehydration during restorative rain events. In the face of a changing climate, we hope such approaches will stimulate opportunities for future research.
Collapse
Affiliation(s)
- Methawi Chomthong
- Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK
| | - Howard Griffiths
- Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK
| |
Collapse
|
3
|
de Barros Dantas LL, Eldridge BM, Dorling J, Dekeya R, Lynch DA, Dodd AN. Circadian regulation of metabolism across photosynthetic organisms. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023; 116:650-668. [PMID: 37531328 PMCID: PMC10953457 DOI: 10.1111/tpj.16405] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 07/15/2023] [Accepted: 07/18/2023] [Indexed: 08/04/2023]
Abstract
Circadian regulation produces a biological measure of time within cells. The daily cycle in the availability of light for photosynthesis causes dramatic changes in biochemical processes in photosynthetic organisms, with the circadian clock having crucial roles in adaptation to these fluctuating conditions. Correct alignment between the circadian clock and environmental day-night cycles maximizes plant productivity through its regulation of metabolism. Therefore, the processes that integrate circadian regulation with metabolism are key to understanding how the circadian clock contributes to plant productivity. This forms an important part of exploiting knowledge of circadian regulation to enhance sustainable crop production. Here, we examine the roles of circadian regulation in metabolic processes in source and sink organ structures of Arabidopsis. We also evaluate possible roles for circadian regulation in root exudation processes that deposit carbon into the soil, and the nature of the rhythmic interactions between plants and their associated microbial communities. Finally, we examine shared and differing aspects of the circadian regulation of metabolism between Arabidopsis and other model photosynthetic organisms, and between circadian control of metabolism in photosynthetic and non-photosynthetic organisms. This synthesis identifies a variety of future research topics, including a focus on metabolic processes that underlie biotic interactions within ecosystems.
Collapse
Affiliation(s)
| | - Bethany M. Eldridge
- Department of Cell and Developmental BiologyJohn Innes Centre, Norwich Research ParkNorwichUK
| | - Jack Dorling
- Department of Cell and Developmental BiologyJohn Innes Centre, Norwich Research ParkNorwichUK
| | - Richard Dekeya
- Department of Cell and Developmental BiologyJohn Innes Centre, Norwich Research ParkNorwichUK
| | - Deirdre A. Lynch
- Department of Cell and Developmental BiologyJohn Innes Centre, Norwich Research ParkNorwichUK
| | - Antony N. Dodd
- Department of Cell and Developmental BiologyJohn Innes Centre, Norwich Research ParkNorwichUK
| |
Collapse
|
4
|
Heyduk K. Evolution of Crassulacean acid metabolism in response to the environment: past, present, and future. PLANT PHYSIOLOGY 2022; 190:19-30. [PMID: 35748752 PMCID: PMC9434201 DOI: 10.1093/plphys/kiac303] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 06/07/2022] [Indexed: 06/15/2023]
Abstract
Crassulacean acid metabolism (CAM) is a mode of photosynthesis that evolved in response to decreasing CO2 levels in the atmosphere some 20 million years ago. An elevated ratio of O2 relative to CO2 caused many plants to face increasing stress from photorespiration, a process exacerbated for plants living under high temperatures or in water-limited environments. Today, our climate is again rapidly changing and plants' ability to cope with and adapt to these novel environments is critical for their success. This review focuses on CAM plant responses to abiotic stressors likely to dominate in our changing climate: increasing CO2 levels, increasing temperatures, and greater variability in drought. Empirical studies that have assessed CAM responses are reviewed, though notably these are concentrated in relatively few CAM lineages. Other aspects of CAM biology, including the effects of abiotic stress on the light reactions and the role of leaf succulence, are also considered in the context of climate change. Finally, more recent studies using genomic techniques are discussed to link physiological changes in CAM plants with the underlying molecular mechanism. Together, the body of work reviewed suggests that CAM plants will continue to thrive in certain environments under elevated CO2. However, how CO2 interacts with other environmental factors, how those interactions affect CAM plants, and whether all CAM plants will be equally affected remain outstanding questions regarding the evolution of CAM on a changing planet.
Collapse
|
5
|
Mayer JA, Wone BWM, Alexander DC, Guo L, Ryals JA, Cushman JC. Metabolic profiling of epidermal and mesophyll tissues under water-deficit stress in Opuntia ficus-indica reveals stress-adaptive metabolic responses. FUNCTIONAL PLANT BIOLOGY : FPB 2021; 48:717-731. [PMID: 33896444 DOI: 10.1071/fp20332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Accepted: 02/20/2021] [Indexed: 06/12/2023]
Abstract
Cactus pear (Opuntia ficus-indica) is a high productivity species within the Cactaceae grown in many semiarid parts of the world for food, fodder, forage, and biofuels. O. ficus-indica utilises obligate crassulacean acid metabolism (CAM), an adaptation that greatly improves water-use efficiency (WUE) and reduces crop water usage. To better understand CAM-related metabolites and water-deficit stress responses of O. ficus-indica, comparative metabolic profiling was performed on mesophyll and epidermal tissues collected from well-watered and water-deficit stressed cladodes at 50% relative water content (RWC). Tissues were collected over a 24-h period to identify metabolite levels throughout the diel cycle and analysed using a combination of acidic/basic ultra-high-performance liquid chromatography/tandem mass spectrometry (UHPLC/MS/MS) and gas chromatography/mass spectrometry (GC/MS) platforms. A total of 382 metabolites, including 210 (55%) named and 172 (45%) unnamed compounds, were characterised across both tissues. Most tricarboxylic acid (TCA) cycle and glycolysis intermediates were depleted in plants undergoing water-deficit stress indicative of CAM idling or post-idling, while the raffinose family oligosaccharides (RFO) accumulated in both mesophyll and epidermal tissues as osmoprotectants. Levels of reduced glutathione and other metabolites of the ascorbate cycle as well as oxylipins, stress hormones such as traumatic acid, and nucleotide degradation products were increased under water-deficit stress conditions. Notably, tryptophan accumulation, an atypical response, was significantly (24-fold) higher during all time points in water-deficit stressed mesophyll tissue compared with well-watered controls. Many of the metabolite increases were indicative of a highly oxidising environment under water-deficit stress. A total of 34 unnamed metabolites also accumulated in response to water-deficit stress indicating that such compounds might play important roles in water-deficit stress tolerance.
Collapse
Affiliation(s)
- Jesse A Mayer
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, NV 89557, USA; and Present address: Thermo Fisher Scientific, Carlsbad, CA 92008, USA
| | - Bernard W M Wone
- Department of Biology, University of South Dakota, SD 57069, USA
| | | | - Lining Guo
- Metabolon Inc., 800 Capitola Drive, Suite 1, Durham, NC 27713, USA
| | - John A Ryals
- Metabolon Inc., 800 Capitola Drive, Suite 1, Durham, NC 27713, USA
| | - John C Cushman
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, NV 89557, USA; and Corresponding author.
| |
Collapse
|
6
|
Ceusters N, Borland AM, Ceusters J. How to resolve the enigma of diurnal malate remobilisation from the vacuole in plants with crassulacean acid metabolism? THE NEW PHYTOLOGIST 2021; 229:3116-3124. [PMID: 33159327 DOI: 10.1111/nph.17070] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 11/02/2020] [Indexed: 06/11/2023]
Abstract
Opening of stomata in plants with crassulacean acid metabolism (CAM) is mainly shifted to the night period when atmospheric CO2 is fixed by phosphoenolpyruvate carboxylase and stored as malic acid in the vacuole. As such, CAM plants ameliorate transpirational water losses and display substantially higher water-use efficiency compared with C3 and C4 plants. In the past decade significant technical advances have allowed an unprecedented exploration of genomes, transcriptomes, proteomes and metabolomes of CAM plants and efforts are ongoing to engineer the CAM pathway in C3 plants. Whilst research efforts have traditionally focused on nocturnal carboxylation, less information is known regarding the drivers behind diurnal malate remobilisation from the vacuole that liberates CO2 to be fixed by RuBisCo behind closed stomata. To shed more light on this process, we provide a stoichiometric analysis to identify potentially rate-limiting steps underpinning diurnal malate mobilisation and help direct future research efforts. Within this remit we address three key questions: Q1 Does light-dependent assimilation of CO2 via RuBisCo dictate the rate of malate mobilisation? Q2: Do the enzymes responsible for malate decarboxylation limit daytime mobilisation from the vacuole? Q3: Does malate efflux from the vacuole set the pace of decarboxylation?
Collapse
Affiliation(s)
- Nathalie Ceusters
- Faculty of Engineering Technology, Department of Biosystems, Division of Crop Biotechnics, Campus Geel, KU Leuven, Kleinhoefstraat 4, Geel, 2440, Belgium
| | - Anne M Borland
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne,, NE1 7RU, UK
| | - Johan Ceusters
- Faculty of Engineering Technology, Department of Biosystems, Division of Crop Biotechnics, Campus Geel, KU Leuven, Kleinhoefstraat 4, Geel, 2440, Belgium
- Centre for Environmental Sciences, Environmental Biology, UHasselt, Campus Diepenbeek, Agoralaan Building D, Diepenbeek, 3590, Belgium
| |
Collapse
|
7
|
Santos MG, Davey PA, Hofmann TA, Borland A, Hartwell J, Lawson T. Stomatal Responses to Light, CO 2, and Mesophyll Tissue in Vicia faba and Kalanchoë fedtschenkoi. FRONTIERS IN PLANT SCIENCE 2021; 12:740534. [PMID: 34777422 PMCID: PMC8579043 DOI: 10.3389/fpls.2021.740534] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 09/22/2021] [Indexed: 05/14/2023]
Abstract
The responses of stomatal aperture to light intensity and CO2 concentration were studied in both Vicia faba (C3) and Kalanchoë fedtschenkoi (Crassulacean acid metabolism; CAM), in material sampled from both light and dark periods. Direct comparison was made between intact leaf segments, epidermises grafted onto exposed mesophyll, and isolated epidermal peels, including transplantations between species and between diel periods. We reported the stomatal opening in response to darkness in isolated CAM peels from the light period, but not from the dark. Furthermore, we showed that C3 mesophyll has stimulated CAM stomata in transplanted peels to behave as C3 in response to light and CO2. By using peels and mesophyll from plants sampled in the dark and the light period, we provided clear evidence that CAM stomata behaved differently from C3. This might be linked to stored metabolites/ions and signalling pathway components within the guard cells, and/or a mesophyll-derived signal. Overall, our results provided evidence for both the involvement of guard cell metabolism and mesophyll signals in stomatal responses in both C3 and CAM species.
Collapse
Affiliation(s)
- Mauro G. Santos
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, United Kingdom
| | - Phillip A. Davey
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, United Kingdom
| | | | - Anne Borland
- School of Natural and Environmental Sciences, Devonshire Building, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - James Hartwell
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Tracy Lawson
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, United Kingdom
- *Correspondence: Tracy Lawson
| |
Collapse
|
8
|
Lefoulon C, Boxall SF, Hartwell J, Blatt MR. Crassulacean acid metabolism guard cell anion channel activity follows transcript abundance and is suppressed by apoplastic malate. THE NEW PHYTOLOGIST 2020; 227:1847-1857. [PMID: 32367511 DOI: 10.1111/nph.16640] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 04/22/2020] [Indexed: 06/11/2023]
Abstract
Plants utilising crassulacean acid metabolism (CAM) concentrate CO2 around RuBisCO while reducing transpirational water loss associated with photosynthesis. Unlike stomata of C3 and C4 species, CAM stomata open at night for the mesophyll to fix CO2 into malate (Mal) and store it in the vacuole. CAM plants decarboxylate Mal in the light, generating high CO2 concentrations within the leaf behind closed stomata for refixation by RuBisCO. CO2 may contribute to stomatal closure but additional mechanisms, plausibly including Mal activation of anion channels, ensure closure in the light. In the CAM species Kalanchoë fedtschenkoi, we found that guard cell anion channel activity, recorded under voltage clamp, follows KfSLAC1 and KfALMT12 transcript abundance, declining to near zero by the end of the light period. Unexpectedly, however, we found that extracellular Mal inhibited the anion current of Kalanchoë guard cells, both in wild-type and RNAi mutants with impaired Mal metabolism. We conclude that the diurnal cycle of anion channel gene transcription, rather than the physiological signal of Mal release, is a key factor in the inverted CAM stomatal cycle.
Collapse
Affiliation(s)
- Cécile Lefoulon
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Bower Building, Glasgow, G12 8QQ, UK
| | - Susanna F Boxall
- Department of Functional and Comparative Genomics, Institute of Integrative Biology, University of Liverpool, Biosciences Building, Crown Street, Liverpool,, L69 7ZB, UK
| | - James Hartwell
- Department of Functional and Comparative Genomics, Institute of Integrative Biology, University of Liverpool, Biosciences Building, Crown Street, Liverpool,, L69 7ZB, UK
| | - Michael R Blatt
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Bower Building, Glasgow, G12 8QQ, UK
| |
Collapse
|
9
|
Chomthong M, Griffiths H. Model approaches to advance crassulacean acid metabolism system integration. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 101:951-963. [PMID: 31943394 DOI: 10.1111/tpj.14691] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 01/02/2020] [Indexed: 06/10/2023]
Abstract
This review summarises recent progress in understanding crassulacean acid metabolism (CAM) systems and the integration of internal and external stimuli to maximise water-use efficiency. Complex CAM traits have been reduced to their minimum and captured as computational models, which can now be refined using recently available data from transgenic manipulations and large-scale omics studies. We identify three key areas in which an appropriate choice of modelling tool could help capture relevant comparative molecular data to address the evolutionary drivers and plasticity of CAM. One focus is to identify the environmental and internal signals that drive inverse stomatal opening at night. Secondly, it is important to identify the regulatory processes required to orchestrate the diel pattern of carbon fluxes within mesophyll layers. Finally, the limitations imposed by contrasting succulent systems and associated hydraulic conductance components should be compared in the context of water-use and evolutionary strategies. While network analysis of transcriptomic data can provide insights via co-expression modules and hubs, alternative forms of computational modelling should be used iteratively to define the physiological significance of key components and informing targeted functional gene manipulation studies. We conclude that the resultant improvements of bottom-up, mechanistic modelling systems can enhance progress towards capturing the physiological controls for phylogenetically diverse CAM systems in the face of the recent surge of information in this omics era.
Collapse
Affiliation(s)
- Methawi Chomthong
- Department of Plant Sciences, University of Cambridge, Downing street, Cambridge, CB2 3EA, UK
| | - Howard Griffiths
- Department of Plant Sciences, University of Cambridge, Downing street, Cambridge, CB2 3EA, UK
| |
Collapse
|
10
|
Heyduk K, Ray JN, Ayyampalayam S, Moledina N, Borland A, Harding SA, Tsai CJ, Leebens-Mack J. Shared expression of crassulacean acid metabolism (CAM) genes pre-dates the origin of CAM in the genus Yucca. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:6597-6609. [PMID: 30870557 PMCID: PMC6883266 DOI: 10.1093/jxb/erz105] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 02/20/2019] [Indexed: 05/05/2023]
Abstract
Crassulacean acid metabolism (CAM) is a carbon-concentrating mechanism that has evolved numerous times across flowering plants and is thought to be an adaptation to water-limited environments. CAM has been investigated from physiological and biochemical perspectives, but little is known about how plants evolve from C3 to CAM at the genetic or metabolic level. Here we take a comparative approach in analyzing time-course data of C3, CAM, and C3+CAM intermediate Yucca (Asparagaceae) species. RNA samples were collected over a 24 h period from both well-watered and drought-stressed plants, and were clustered based on time-dependent expression patterns. Metabolomic data reveal differences in carbohydrate metabolism and antioxidant response between the CAM and C3 species, suggesting that changes to metabolic pathways are important for CAM evolution and function. However, all three species share expression profiles of canonical CAM pathway genes, regardless of photosynthetic pathway. Despite differences in transcript and metabolite profiles between the C3 and CAM species, shared time-structured expression of CAM genes in both CAM and C3Yucca species suggests that ancestral expression patterns required for CAM may have pre-dated its origin in Yucca.
Collapse
Affiliation(s)
- Karolina Heyduk
- Department of Plant Biology, University of Georgia, Athens, GA, USA
| | - Jeremy N Ray
- Department of Plant Biology, University of Georgia, Athens, GA, USA
| | | | - Nida Moledina
- Department of Plant Biology, University of Georgia, Athens, GA, USA
| | - Anne Borland
- School of Natural and Environmental Sciences, Newcastle University, Newcastle, UK
| | - Scott A Harding
- Department of Genetics, University of Georgia, Athens, GA, USA
- Warnell School of Forestry, University of Georgia, Athens, GA, USA
| | - Chung-Jui Tsai
- Department of Genetics, University of Georgia, Athens, GA, USA
- Warnell School of Forestry, University of Georgia, Athens, GA, USA
| | - Jim Leebens-Mack
- Department of Plant Biology, University of Georgia, Athens, GA, USA
| |
Collapse
|
11
|
Ceusters N, Frans M, Van den Ende W, Ceusters J. Maltose Processing and Not β-Amylase Activity Curtails Hydrolytic Starch Degradation in the CAM Orchid Phalaenopsis. FRONTIERS IN PLANT SCIENCE 2019; 10:1386. [PMID: 31798600 PMCID: PMC6868039 DOI: 10.3389/fpls.2019.01386] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 10/08/2019] [Indexed: 05/19/2023]
Abstract
Crassulacean acid metabolism (CAM) is one of the three photosynthetic pathways in higher plants and is characterized by high water use efficiency. This mainly relies on major nocturnal CO2 fixation sustained by degradation of storage carbohydrate such as starch to provide phosphoenolpyruvate (PEP) and energy. In contrast to C3 plants where starch is mainly degraded by the hydrolytic route, different observations suggested the phosphorolytic route to be a major pathway for starch degradation in CAM plants. To elucidate the interplay and relevant contributions of the phosphorolytic and hydrolytic pathways for starch degradation in CAM, we assessed diel patterns for metabolites and enzymes implicated in both the hydrolytic route (β-amylase, DPE1, DPE2, maltase) and the phosphorolytic route (starch phosphorylase) of starch degradation in the CAM orchid Phalaenopsis "Edessa." By comparing the catalytic enzyme activities and starch degradation rates, we showed that the phosphorolytic pathway is the major route to accommodate nocturnal starch degradation and that measured activities of starch phosphorylase perfectly matched calculated starch degradation rates in order to avoid premature exhaustion of starch reserves before dawn. The hydrolytic pathway seemed hampered in starch processing not by β-amylase but through insufficient catalytic capacity of both DPE2 and maltase. These considerations were further corroborated by measurements of enzyme activities in the CAM model plant Kalanchoë fedtschenkoi and strongly contradict with the situation in the C3 plant Arabidopsis. The data support the view that the phosphorolytic pathway might be the main route of starch degradation in CAM to provide substrate for PEP with additional hydrolytic starch breakdown to accommodate mainly sucrose synthesis.
Collapse
Affiliation(s)
- Nathalie Ceusters
- KU Leuven, Department of Biosystems, Division of Crop Biotechnics, Research Group for Sustainable Crop Production & Protection, Campus Geel, Geel, Belgium
| | - Mario Frans
- KU Leuven, Department of Biosystems, Division of Crop Biotechnics, Research Group for Sustainable Crop Production & Protection, Campus Geel, Geel, Belgium
| | - Wim Van den Ende
- KU Leuven, Department of Biology, Laboratory of Molecular Plant Biology, Leuven, Belgium
| | - Johan Ceusters
- KU Leuven, Department of Biosystems, Division of Crop Biotechnics, Research Group for Sustainable Crop Production & Protection, Campus Geel, Geel, Belgium
- UHasselt, Centre for Environmental Sciences, Environmental Biology, Diepenbeek, Belgium
| |
Collapse
|
12
|
Ceusters N, Valcke R, Frans M, Claes JE, Van den Ende W, Ceusters J. Performance Index and PSII Connectivity Under Drought and Contrasting Light Regimes in the CAM Orchid Phalaenopsis. FRONTIERS IN PLANT SCIENCE 2019; 10:1012. [PMID: 31447875 PMCID: PMC6691161 DOI: 10.3389/fpls.2019.01012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 07/18/2019] [Indexed: 05/27/2023]
Abstract
Crassulacean acid metabolism (CAM) is a specialized mode of photosynthesis characterized by improved water use efficiency mediated by major nocturnal CO2 fixation. Due to its inherent metabolic plasticity CAM represents a successful physiological strategy for plant adaptation to abiotic stress. The present study reports on the impact of drought stress and different light intensities (PPFD 50 and 200 μmol m-2 s-1) on the photosynthetic performance of the obligate CAM orchid Phalaenopsis "Edessa" by integrating diel gas exchange patterns with assessments of the light reactions by analyzing fast chlorophyll a fluorescence induction. Parameters such as PIabs (performance index), different energy fluxes per active reaction centre (RC) reflecting the electron flow from photosystem II to photosystem I and the energetic communication between PSII complexes defined as connectivity were considered for the first time in a CAM plant. A higher PS II connectivity for plants grown under low light (p ∼ 0.51) compared to plants grown under high light (p ∼ 0.31) brought about similar specific energy fluxes of light absorbance, dissipation and processing through the electron transport chain, irrespective of the light treatment. With a 25% higher maximum quantum yield and comparable biomass formation, low light grown plants indeed proved to process light energy more efficiently compared to high light grown plants. The performance index was identified as a very reliable and sensitive parameter to indicate the onset and progress of drought stress. Under restricted CO2 availability (due to closed stomata) leaves showed higher energy dissipation and partial inactivation of PSII reaction centres to reduce the energy input to the electron transport chain and as such aid in avoiding overexcitation and photodamage. Especially during CAM idling there is a discrepancy between continuous input of light energy but severely reduced availability of both water and CO2, which represents the ultimate electron acceptor. Taken together, our results show a unique flexibility of CAM plants to optimize the light reactions under different environmental conditions in a dual way by either attenuating or increasing energy flux.
Collapse
Affiliation(s)
- Nathalie Ceusters
- Department of Biosystems, Division of Crop Biotechnics, Research Group for Sustainable Crop Production & Protection, KU Leuven, Geel, Belgium
| | - Roland Valcke
- Molecular and Physical Plant Physiology, UHasselt, Diepenbeek, Belgium
| | - Mario Frans
- Department of Biosystems, Division of Crop Biotechnics, Research Group for Sustainable Crop Production & Protection, KU Leuven, Geel, Belgium
| | - Johan E. Claes
- Department of Microbial and Molecular Systems, Bioengineering Technology TC, KU Leuven, Geel, Belgium
| | - Wim Van den Ende
- Laboratory of Molecular Plant Biology, Department of Biology, KU Leuven, Leuven, Belgium
| | - Johan Ceusters
- Department of Biosystems, Division of Crop Biotechnics, Research Group for Sustainable Crop Production & Protection, KU Leuven, Geel, Belgium
- Centre for Environmental Sciences, Environmental Biology, UHasselt, Diepenbeek, Belgium
| |
Collapse
|
13
|
Ceusters N, Luca S, Feil R, Claes JE, Lunn JE, Van den Ende W, Ceusters J. Hierarchical clustering reveals unique features in the diel dynamics of metabolites in the CAM orchid Phalaenopsis. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:3269-3281. [PMID: 30972416 PMCID: PMC6598073 DOI: 10.1093/jxb/erz170] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 04/01/2019] [Indexed: 05/03/2023]
Abstract
Crassulacean acid metabolism (CAM) is a major adaptation of photosynthesis that involves temporally separated phases of CO2 fixation and accumulation of organic acids at night, followed by decarboxylation and refixation of CO2 by the classical C3 pathway during the day. Transitory reserves such as soluble sugars or starch are degraded at night to provide the phosphoenolpyruvate (PEP) and energy needed for initial carboxylation by PEP carboxylase. The primary photosynthetic pathways in CAM species are well known, but their integration with other pathways of central C metabolism during different phases of the diel light-dark cycle is poorly understood. Gas exchange was measured in leaves of the CAM orchid Phalaenopsis 'Edessa' and leaves were sampled every 2 h during a complete 12-h light-12-h dark cycle for metabolite analysis. A hierarchical agglomerative clustering approach was employed to explore the diel dynamics and relationships of metabolites in this CAM species, and compare these with those in model C3 species. High levels of 3-phosphoglycerate (3PGA) in the light activated ADP-glucose pyrophosphorylase, thereby enhancing production of ADP-glucose, the substrate for starch synthesis. Trehalose 6-phosphate (T6P), a sugar signalling metabolite, was also correlated with ADP-glucose, 3PGA and PEP, but not sucrose, over the diel cycle. Whether or not this indicates a different function of T6P in CAM plants is discussed. T6P levels were low at night, suggesting that starch degradation is regulated primarily by circadian clock-dependent mechanisms. During the lag in starch degradation at dusk, carbon and energy could be supplied by rapid consumption of a large pool of aconitate that accumulates in the light. Our study showed similarities in the diel dynamics and relationships between many photosynthetic metabolites in CAM and C3 plants, but also revealed some major differences reflecting the specialized metabolic fluxes in CAM plants, especially during light-dark transitions and at night.
Collapse
Affiliation(s)
- Nathalie Ceusters
- KU Leuven, Department of Biosystems, Division of Crop Biotechnics, Research group for Sustainable Crop Production & Protection, Campus Geel, Kleinhoefstraat, Geel, Belgium
| | - Stijn Luca
- Ghent University, Department of Data Analysis and Mathematical Modelling, Coupure links, Gent, Belgium
| | - Regina Feil
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg, Potsdam-Golm, Germany
| | - Johan E Claes
- KU Leuven, Department of Microbial and Molecular systems, Bioengineering Technology TC, Campus Geel, Kleinhoefstraat, Geel, Belgium
| | - John E Lunn
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg, Potsdam-Golm, Germany
| | - Wim Van den Ende
- KU Leuven, Department of Biology, Laboratory of Molecular Plant Biology, Kasteelpark Arenberg, Leuven, Belgium
| | - Johan Ceusters
- KU Leuven, Department of Biosystems, Division of Crop Biotechnics, Research group for Sustainable Crop Production & Protection, Campus Geel, Kleinhoefstraat, Geel, Belgium
- UHasselt, Centre for Environmental Sciences, Environmental Biology, Campus Diepenbeek, Agoralaan Building D, Diepenbeek, Belgium
| |
Collapse
|
14
|
Heyduk K, Hwang M, Albert V, Silvera K, Lan T, Farr K, Chang TH, Chan MT, Winter K, Leebens-Mack J. Altered Gene Regulatory Networks Are Associated With the Transition From C 3 to Crassulacean Acid Metabolism in Erycina (Oncidiinae: Orchidaceae). FRONTIERS IN PLANT SCIENCE 2019; 9:2000. [PMID: 30745906 PMCID: PMC6360190 DOI: 10.3389/fpls.2018.02000] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 12/24/2018] [Indexed: 05/21/2023]
Abstract
Crassulacean acid metabolism (CAM) photosynthesis is a modification of the core C3 photosynthetic pathway that improves the ability of plants to assimilate carbon in water-limited environments. CAM plants fix CO2 mostly at night, when transpiration rates are low. All of the CAM pathway genes exist in ancestral C3 species, but the timing and magnitude of expression are greatly altered between C3 and CAM species. Understanding these regulatory changes is key to elucidating the mechanism by which CAM evolved from C3. Here, we use two closely related species in the Orchidaceae, Erycina pusilla (CAM) and Erycina crista-galli (C3), to conduct comparative transcriptomic analyses across multiple time points. Clustering of genes with expression variation across the diel cycle revealed some canonical CAM pathway genes similarly expressed in both species, regardless of photosynthetic pathway. However, gene network construction indicated that 149 gene families had significant differences in network connectivity and were further explored for these functional enrichments. Genes involved in light sensing and ABA signaling were some of the most differently connected genes between the C3 and CAM Erycina species, in agreement with the contrasting diel patterns of stomatal conductance in C3 and CAM plants. Our results suggest changes to transcriptional cascades are important for the transition from C3 to CAM photosynthesis in Erycina.
Collapse
Affiliation(s)
- Karolina Heyduk
- Department of Plant Biology, University of Georgia, Athens, GA, United States
| | - Michelle Hwang
- Department of Plant Biology, University of Georgia, Athens, GA, United States
| | - Victor Albert
- Department of Biological Sciences, University at Buffalo, Buffalo, NY, United States
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Katia Silvera
- Department of Botany and Plant Sciences, University of California, Riverside, Riverside, CA, United States
- Smithsonian Tropical Research Institute, Panama City, Panama
| | - Tianying Lan
- Department of Biological Sciences, University at Buffalo, Buffalo, NY, United States
| | - Kimberly Farr
- Department of Biological Sciences, University at Buffalo, Buffalo, NY, United States
| | - Tien-Hao Chang
- Department of Biological Sciences, University at Buffalo, Buffalo, NY, United States
| | - Ming-Tsair Chan
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan
| | - Klaus Winter
- Smithsonian Tropical Research Institute, Panama City, Panama
| | - Jim Leebens-Mack
- Department of Plant Biology, University of Georgia, Athens, GA, United States
| |
Collapse
|
15
|
Inoue K, Araki T, Endo M. Circadian clock during plant development. JOURNAL OF PLANT RESEARCH 2018; 131:59-66. [PMID: 29134443 PMCID: PMC5897470 DOI: 10.1007/s10265-017-0991-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 10/06/2017] [Indexed: 05/14/2023]
Abstract
Plants have endogenous biological clocks that allow organisms to anticipate and prepare for daily and seasonal environmental changes and increase their fitness in changing environments. The circadian clock in plants, as in animals and insects, mainly consists of multiple interlocking transcriptional/translational feedback loops. The circadian clock can be entrained by environmental cues such as light, temperature and nutrient status to synchronize internal biological rhythms with surrounding environments. Output pathways link the circadian oscillator to various physiological, developmental, and reproductive processes for adjusting the timing of these biological processes to an appropriate time of day or a suitable season. Recent genomic studies have demonstrated that polymorphism in circadian clock genes may contribute to local adaptations over a wide range of latitudes in many plant species. In the present review, we summarize the circadian regulation of biological processes throughout the life cycle of plants, and describe the contribution of the circadian clock to local adaptation.
Collapse
Affiliation(s)
- Keisuke Inoue
- Graduate School of Biostudies, Kyoto University, Kyoto, 606-8502 Japan
| | - Takashi Araki
- Graduate School of Biostudies, Kyoto University, Kyoto, 606-8502 Japan
| | - Motomu Endo
- Graduate School of Biostudies, Kyoto University, Kyoto, 606-8502 Japan
| |
Collapse
|
16
|
Taybi T, Cushman JC, Borland AM. Leaf carbohydrates influence transcriptional and post-transcriptional regulation of nocturnal carboxylation and starch degradation in the facultative CAM plant, Mesembryanthemum crystallinum. JOURNAL OF PLANT PHYSIOLOGY 2017; 218:144-154. [PMID: 28822907 DOI: 10.1016/j.jplph.2017.07.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 07/19/2017] [Accepted: 07/28/2017] [Indexed: 05/09/2023]
Abstract
Nocturnal degradation of transitory starch is a limiting factor for the optimal function of crassulacean acid metabolism and must be coordinated with phosphoenolypyruvate carboxylase (PEPC)-mediated CO2 uptake to optimise carbon gain over the diel cycle. The aim of this study was to test the hypothesis that nocturnal carboxylation is coordinated with starch degradation in CAM via a mechanism whereby the products of these pathways regulate diel transcript abundance and enzyme activities for both processes. To test this hypothesis, a starch and CAM-deficient mutant of Mesembryanthemum crystallinum was compared with wild type plants under well-watered and saline (CAM-inducing) conditions. Exposure to salinity increased the transcript abundance of genes required for nocturnal carboxylation, starch and sucrose degradation in both wild type and mutant, but the transcript abundance of several of these genes was not sustained over the dark period in the low-carbohydrate, CAM-deficient mutant. The diel pattern of transcript abundance for PEPC mirrored that of PEPC protein, as did the transcripts, protein, and activity of chloroplastic starch phosphorylase in both wild type and mutant, suggesting robust diel coordination of these metabolic processes. Activities of several amylase isoforms were low or lacking in the mutant, whilst the activity of a cytosolic isoform of starch phosphorylase was significantly elevated, indicating contrasting modes of metabolic regulation for the hydrolytic and phosphorylytic routes of starch degradation. Externally supplied sucrose resulted in an increase in nocturnal transcript abundance of genes required for nocturnal carboxylation and starch degradation. These results demonstrate that carbohydrates impact on transcriptional and post-transcriptional regulation of nocturnal carboxylation and starch degradation in CAM.
Collapse
Affiliation(s)
- Tahar Taybi
- School of Natural & Environmental Sciences, Ridley Building, Newcastle University, Newcastle upon Tyne NE1 7RU, UK.
| | - John C Cushman
- Department of Biochemistry and Molecular Biology, MS330, University of Nevada, Reno, NV 89557 USA
| | - Anne M Borland
- School of Natural & Environmental Sciences, Ridley Building, Newcastle University, Newcastle upon Tyne NE1 7RU, UK; Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
| |
Collapse
|
17
|
Sharma A, Wai CM, Ming R, Yu Q. Diurnal Cycling Transcription Factors of Pineapple Revealed by Genome-Wide Annotation and Global Transcriptomic Analysis. Genome Biol Evol 2017; 9:2170-2190. [PMID: 28922793 PMCID: PMC5737478 DOI: 10.1093/gbe/evx161] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/22/2017] [Indexed: 12/22/2022] Open
Abstract
Circadian clock provides fitness advantage by coordinating internal metabolic and physiological processes to external cyclic environments. Core clock components exhibit daily rhythmic changes in gene expression, and the majority of them are transcription factors (TFs) and transcription coregulators (TCs). We annotated 1,398 TFs from 67 TF families and 80 TCs from 20 TC families in pineapple, and analyzed their tissue-specific and diurnal expression patterns. Approximately 42% of TFs and 45% of TCs displayed diel rhythmic expression, including 177 TF/TCs cycling only in the nonphotosynthetic leaf tissue, 247 cycling only in the photosynthetic leaf tissue, and 201 cycling in both. We identified 68 TF/TCs whose cycling expression was tightly coupled between the photosynthetic and nonphotosynthetic leaf tissues. These TF/TCs likely coordinate key biological processes in pineapple as we demonstrated that this group is enriched in homologous genes that form the core circadian clock in Arabidopsis and includes a STOP1 homolog. Two lines of evidence support the important role of the STOP1 homolog in regulating CAM photosynthesis in pineapple. First, STOP1 responds to acidic pH and regulates a malate channel in multiple plant species. Second, the cycling expression pattern of the pineapple STOP1 and the diurnal pattern of malate accumulation in pineapple leaf are correlated. We further examined duplicate-gene retention and loss in major known circadian genes and refined their evolutionary relationships between pineapple and other plants. Significant variations in duplicate-gene retention and loss were observed for most clock genes in both monocots and dicots.
Collapse
Affiliation(s)
- Anupma Sharma
- Texas A&M AgriLife Research Center at Dallas, Texas A&M University System, Dallas
| | - Ching Man Wai
- Department of Plant Biology, University of Illinois at Urbana-Champaign
- Center for Genomics and Biotechnology, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, Fujian Province, China
| | - Ray Ming
- Department of Plant Biology, University of Illinois at Urbana-Champaign
- Center for Genomics and Biotechnology, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, Fujian Province, China
| | - Qingyi Yu
- Texas A&M AgriLife Research Center at Dallas, Texas A&M University System, Dallas
- Center for Genomics and Biotechnology, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, Fujian Province, China
- Department of Plant Pathology and Microbiology, Texas A&M University
| |
Collapse
|
18
|
Males J, Griffiths H. Stomatal Biology of CAM Plants. PLANT PHYSIOLOGY 2017; 174:550-560. [PMID: 28242656 PMCID: PMC5462028 DOI: 10.1104/pp.17.00114] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 02/24/2017] [Indexed: 05/19/2023]
Abstract
Recent advances in the stomatal biology of CAM plants are reviewed, and key opportunities for future progress are identified.
Collapse
Affiliation(s)
- Jamie Males
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom
| | - Howard Griffiths
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom
| |
Collapse
|
19
|
Jones MA. Interplay of Circadian Rhythms and Light in the Regulation of Photosynthesis-Derived Metabolism. PROGRESS IN BOTANY VOL. 79 2017:147-171. [PMID: 0 DOI: 10.1007/124_2017_2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
|
20
|
Surówka E, Dziurka M, Kocurek M, Goraj S, Rapacz M, Miszalski Z. Effects of exogenously applied hydrogen peroxide on antioxidant and osmoprotectant profiles and the C3-CAM shift in the halophyte Mesembryanthemum crystallinum L. JOURNAL OF PLANT PHYSIOLOGY 2016; 200:102-10. [PMID: 0 DOI: 10.1016/j.jplph.2016.05.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 05/12/2016] [Accepted: 05/12/2016] [Indexed: 05/21/2023]
|
21
|
Owen NA, Choncubhair ÓN, Males J, Del Real Laborde JI, Rubio-Cortés R, Griffiths H, Lanigan G. Eddy covariance captures four-phase crassulacean acid metabolism (CAM) gas exchange signature in Agave. PLANT, CELL & ENVIRONMENT 2016; 39:295-309. [PMID: 26177873 DOI: 10.1111/pce.12610] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Accepted: 07/05/2015] [Indexed: 06/04/2023]
Abstract
Mass and energy fluxes were measured over a field of Agave tequilana in Mexico using eddy covariance (EC) methodology. Data were gathered over 252 d, including the transition from wet to dry periods. Net ecosystem exchanges (FN,EC ) displayed a crassulacean acid metabolism (CAM) rhythm that alternated from CO2 sink at night to CO2 source during the day, and partitioned canopy fluxes (FA,EC ) showed a characteristic four-phase CO2 exchange pattern. Results were cross-validated against diel changes in titratable acidity, leaf-unfurling rates, energy exchange fluxes and reported biomass yields. Projected carbon balance (g C m(-2) year(-1) , mean ± 95% confidence interval) indicated the site was a net sink of -333 ± 24, of which contributions from soil respiration were +692 ± 7, and FA,EC was -1025 ± 25. EC estimated biomass yield was 20.1 Mg (dry) ha(-1) year(-1) . Average integrated daily FA,EC was -234 ± 5 mmol CO2 m(-2) d(-1) and persisted almost unchanged after 70 d of drought conditions. Regression analyses were performed on the EC data to identify the best environmental predictors of FA . Results suggest that the carbon acquisition strategy of Agave offers productivity and drought resilience advantages over conventional semi-arid C3 and C4 bioenergy candidates.
Collapse
Affiliation(s)
- Nick A Owen
- Department of Plant Sciences, University of Cambridge, Cambridge, UK, CB2 3EA
| | | | - Jamie Males
- Department of Plant Sciences, University of Cambridge, Cambridge, UK, CB2 3EA
| | | | - Ramón Rubio-Cortés
- Rancho el Indio, Tequila Sauza, S. de R.L. de C.V., Tequila, Jalisco, Mexico
| | - Howard Griffiths
- Department of Plant Sciences, University of Cambridge, Cambridge, UK, CB2 3EA
| | - Gary Lanigan
- Teagasc Environmental Research Centre, Johnstown Castle, County Wexford, Ireland
| |
Collapse
|
22
|
Lüttge U. Physics and the molecular revolution in plant biology: union needed for managing the future. AIMS BIOPHYSICS 2016. [DOI: 10.3934/biophy.2016.4.501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
|
23
|
Brilhaus D, Bräutigam A, Mettler-Altmann T, Winter K, Weber APM. Reversible Burst of Transcriptional Changes during Induction of Crassulacean Acid Metabolism in Talinum triangulare. PLANT PHYSIOLOGY 2016; 170:102-22. [PMID: 26530316 PMCID: PMC4704576 DOI: 10.1104/pp.15.01076] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 11/03/2015] [Indexed: 05/14/2023]
Abstract
Drought tolerance is a key factor for agriculture in the 21st century as it is a major determinant of plant survival in natural ecosystems as well as crop productivity. Plants have evolved a range of mechanisms to cope with drought, including a specialized type of photosynthesis termed Crassulacean acid metabolism (CAM). CAM is associated with stomatal closure during the day as atmospheric CO2 is assimilated primarily during the night, thus reducing transpirational water loss. The tropical herbaceous perennial species Talinum triangulare is capable of transitioning, in a facultative, reversible manner, from C3 photosynthesis to weakly expressed CAM in response to drought stress. The transcriptional regulation of this transition has been studied. Combining mRNA-Seq with targeted metabolite measurements, we found highly elevated levels of CAM-cycle enzyme transcripts and their metabolic products in T. triangulare leaves upon water deprivation. The carbohydrate metabolism is rewired to reduce the use of reserves for growth to support the CAM-cycle and the synthesis of compatible solutes. This large-scale expression dataset of drought-induced CAM demonstrates transcriptional regulation of the C3-CAM transition. We identified candidate transcription factors to mediate this photosynthetic plasticity, which may contribute in the future to the design of more drought-tolerant crops via engineered CAM.
Collapse
Affiliation(s)
- Dominik Brilhaus
- Institute of Plant Biochemistry, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich-Heine-University, D-40225 Düsseldorf, Germany (D.B., A.B., T.M.-A., A.P.M.W.); and Smithsonian Tropical Research Institute, Balboa, Ancón, Republic of Panama (K.W.)
| | - Andrea Bräutigam
- Institute of Plant Biochemistry, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich-Heine-University, D-40225 Düsseldorf, Germany (D.B., A.B., T.M.-A., A.P.M.W.); and Smithsonian Tropical Research Institute, Balboa, Ancón, Republic of Panama (K.W.)
| | - Tabea Mettler-Altmann
- Institute of Plant Biochemistry, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich-Heine-University, D-40225 Düsseldorf, Germany (D.B., A.B., T.M.-A., A.P.M.W.); and Smithsonian Tropical Research Institute, Balboa, Ancón, Republic of Panama (K.W.)
| | - Klaus Winter
- Institute of Plant Biochemistry, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich-Heine-University, D-40225 Düsseldorf, Germany (D.B., A.B., T.M.-A., A.P.M.W.); and Smithsonian Tropical Research Institute, Balboa, Ancón, Republic of Panama (K.W.)
| | - Andreas P M Weber
- Institute of Plant Biochemistry, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich-Heine-University, D-40225 Düsseldorf, Germany (D.B., A.B., T.M.-A., A.P.M.W.); and Smithsonian Tropical Research Institute, Balboa, Ancón, Republic of Panama (K.W.)
| |
Collapse
|
24
|
Dever LV, Boxall SF, Kneřová J, Hartwell J. Transgenic perturbation of the decarboxylation phase of Crassulacean acid metabolism alters physiology and metabolism but has only a small effect on growth. PLANT PHYSIOLOGY 2015; 167:44-59. [PMID: 25378692 PMCID: PMC4281012 DOI: 10.1104/pp.114.251827] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 10/28/2014] [Indexed: 05/19/2023]
Abstract
Mitochondrial NAD-malic enzyme (ME) and/or cytosolic/plastidic NADP-ME combined with the cytosolic/plastidic pyruvate orthophosphate dikinase (PPDK) catalyze two key steps during light-period malate decarboxylation that underpin secondary CO(2) fixation in some Crassulacean acid metabolism (CAM) species. We report the generation and phenotypic characterization of transgenic RNA interference lines of the obligate CAM species Kalanchoë fedtschenkoi with reduced activities of NAD-ME or PPDK. Transgenic line rNAD-ME1 had 8%, and rPPDK1 had 5% of the wild-type level of activity, and showed dramatic changes in the light/dark cycle of CAM CO(2) fixation. In well-watered conditions, these lines fixed all of their CO(2) in the light; they thus performed C(3) photosynthesis. The alternative malate decarboxylase, NADP-ME, did not appear to compensate for the reduction in NAD-ME, suggesting that NAD-ME was the key decarboxylase for CAM. The activity of other CAM enzymes was reduced as a consequence of knocking out either NAD-ME or PPDK activity, particularly phosphoenolpyruvate carboxylase (PPC) and PPDK in rNAD-ME1. Furthermore, the circadian clock-controlled phosphorylation of PPC in the dark was reduced in both lines, especially in rNAD-ME1. This had the consequence that circadian rhythms of PPC phosphorylation, PPC kinase transcript levels and activity, and the classic circadian rhythm of CAM CO(2) fixation were lost, or dampened toward arrhythmia, under constant light and temperature conditions. Surprisingly, oscillations in the transcript abundance of core circadian clock genes also became arrhythmic in the rNAD-ME1 line, suggesting that perturbing CAM in K. fedtschenkoi feeds back to perturb the central circadian clock.
Collapse
Affiliation(s)
- Louisa V Dever
- Department of Plant Sciences, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - Susanna F Boxall
- Department of Plant Sciences, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - Jana Kneřová
- Department of Plant Sciences, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - James Hartwell
- Department of Plant Sciences, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| |
Collapse
|
25
|
Ceusters J, Borland AM, Taybi T, Frans M, Godts C, De Proft MP. Light quality modulates metabolic synchronization over the diel phases of crassulacean acid metabolism. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:3705-14. [PMID: 24803500 PMCID: PMC4085966 DOI: 10.1093/jxb/eru185] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Temporal compartmentation of carboxylation processes is a defining feature of crassulacean acid metabolism and involves circadian control of key metabolic and transport steps that regulate the supply and demand for carbon over a 24h cycle. Recent insights on the molecular workings of the circadian clock and its connection with environmental inputs raise new questions on the importance of light quality and, by analogy, certain photoreceptors for synchronizing the metabolic components of CAM. The present work tested the hypothesis that optimal coupling of stomatal conductance, net CO2 uptake, and the reciprocal turnover of carbohydrates and organic acids over the diel CAM cycle requires both blue and red light input signals. Contrasting monochromatic wavelengths of blue, green, and red light (i.e. 475, 530, 630nm) with low fluence rates (10 μmol m(-2) s(-1)) were administered for 16 hours each diel cycle for a total treatment time of 48 hours to the obligate CAM bromeliad, Aechmea 'Maya'. Of the light treatments imposed, low-fluence blue light was a key determinant in regulating stomatal responses, organic acid mobilization from the vacuole, and daytime decarboxylation. However, the reciprocal relationship between starch and organic acid turnover that is typical for CAM was uncoupled under low-fluence blue light. Under low-fluence red or green light, the diel turnover of storage carbohydrates was orchestrated in line with the requirements of CAM, but a consistent delay in acid consumption at dawn compared with plants under white or low-fluence blue light was noted. Consistent with the acknowledged influences of both red and blue light as input signals for the circadian clock, the data stress the importance of both red and blue-light signalling pathways for synchronizing the metabolic and physiological components of CAM over the day/night cycle.
Collapse
Affiliation(s)
- Johan Ceusters
- Faculty of Engineering Technology, Department of Microbial and Molecular systems, Bioengineering Technology TC, KU Leuven Campus Geel, Kleinhoefstraat 4, B-2440 Geel, Belgium
| | - Anne M Borland
- School of Biology, Newcastle Institute for Research on Sustainability, Devonshire Building, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6407, USA
| | - Tahar Taybi
- School of Biology, Newcastle Institute for Research on Sustainability, Devonshire Building, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - Mario Frans
- Faculty of Engineering Technology, Department of Microbial and Molecular systems, Bioengineering Technology TC, KU Leuven Campus Geel, Kleinhoefstraat 4, B-2440 Geel, Belgium
| | - Christof Godts
- Faculty of Bioscience Engineering, Department of Biosystems, Division of Crop Biotechnics, KU Leuven, Willem De Croylaan 42, B-3001 Heverlee, Belgium
| | - Maurice P De Proft
- Faculty of Bioscience Engineering, Department of Biosystems, Division of Crop Biotechnics, KU Leuven, Willem De Croylaan 42, B-3001 Heverlee, Belgium
| |
Collapse
|
26
|
Aldous SH, Weise SE, Sharkey TD, Waldera-Lupa DM, Stühler K, Mallmann J, Groth G, Gowik U, Westhoff P, Arsova B. Evolution of the Phosphoenolpyruvate Carboxylase Protein Kinase Family in C3 and C4 Flaveria spp. PLANT PHYSIOLOGY 2014; 165:1076-1091. [PMID: 24850859 PMCID: PMC4081323 DOI: 10.1104/pp.114.240283] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 05/20/2014] [Indexed: 05/04/2023]
Abstract
The key enzyme for C4 photosynthesis, Phosphoenolpyruvate Carboxylase (PEPC), evolved from nonphotosynthetic PEPC found in C3 ancestors. In all plants, PEPC is phosphorylated by Phosphoenolpyruvate Carboxylase Protein Kinase (PPCK). However, differences in the phosphorylation pattern exist among plants with these photosynthetic types, and it is still not clear if they are due to interspecies differences or depend on photosynthetic type. The genus Flaveria contains closely related C3, C3-C4 intermediate, and C4 species, which are evolutionarily young and thus well suited for comparative analysis. To characterize the evolutionary differences in PPCK between plants with C3 and C4 photosynthesis, transcriptome libraries from nine Flaveria spp. were used, and a two-member PPCK family (PPCKA and PPCKB) was identified. Sequence analysis identified a number of C3- and C4-specific residues with various occurrences in the intermediates. Quantitative analysis of transcriptome data revealed that PPCKA and PPCKB exhibit inverse diel expression patterns and that C3 and C4 Flaveria spp. differ in the expression levels of these genes. PPCKA has maximal expression levels during the day, whereas PPCKB has maximal expression during the night. Phosphorylation patterns of PEPC varied among C3 and C4 Flaveria spp. too, with PEPC from the C4 species being predominantly phosphorylated throughout the day, while in the C3 species the phosphorylation level was maintained during the entire 24 h. Since C4 Flaveria spp. evolved from C3 ancestors, this work links the evolutionary changes in sequence, PPCK expression, and phosphorylation pattern to an evolutionary phase shift of kinase activity from a C3 to a C4 mode.
Collapse
Affiliation(s)
- Sophia H Aldous
- Institut für Entwicklungs- und Molekularbiologie der Pflanzen (S.H.A., J.M., U.G., P.W., B.A.), Molecular Proteomics Laboratory (D.M.W.-L., K.S.), and Biochemische Pflanzenphysiologie (G.G.), Heinrich-Heine-Universität, 40225 Duesseldorf, Germany;Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824 (S.E.W., T.D.S.); andCluster of Excellence on Plant Sciences, From Complex Traits towards Synthetic Modules, 40225 Duesseldorf, Germany (K.S., G.G., U.G., P.W., B.A.)
| | - Sean E Weise
- Institut für Entwicklungs- und Molekularbiologie der Pflanzen (S.H.A., J.M., U.G., P.W., B.A.), Molecular Proteomics Laboratory (D.M.W.-L., K.S.), and Biochemische Pflanzenphysiologie (G.G.), Heinrich-Heine-Universität, 40225 Duesseldorf, Germany;Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824 (S.E.W., T.D.S.); andCluster of Excellence on Plant Sciences, From Complex Traits towards Synthetic Modules, 40225 Duesseldorf, Germany (K.S., G.G., U.G., P.W., B.A.)
| | - Thomas D Sharkey
- Institut für Entwicklungs- und Molekularbiologie der Pflanzen (S.H.A., J.M., U.G., P.W., B.A.), Molecular Proteomics Laboratory (D.M.W.-L., K.S.), and Biochemische Pflanzenphysiologie (G.G.), Heinrich-Heine-Universität, 40225 Duesseldorf, Germany;Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824 (S.E.W., T.D.S.); andCluster of Excellence on Plant Sciences, From Complex Traits towards Synthetic Modules, 40225 Duesseldorf, Germany (K.S., G.G., U.G., P.W., B.A.)
| | - Daniel M Waldera-Lupa
- Institut für Entwicklungs- und Molekularbiologie der Pflanzen (S.H.A., J.M., U.G., P.W., B.A.), Molecular Proteomics Laboratory (D.M.W.-L., K.S.), and Biochemische Pflanzenphysiologie (G.G.), Heinrich-Heine-Universität, 40225 Duesseldorf, Germany;Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824 (S.E.W., T.D.S.); andCluster of Excellence on Plant Sciences, From Complex Traits towards Synthetic Modules, 40225 Duesseldorf, Germany (K.S., G.G., U.G., P.W., B.A.)
| | - Kai Stühler
- Institut für Entwicklungs- und Molekularbiologie der Pflanzen (S.H.A., J.M., U.G., P.W., B.A.), Molecular Proteomics Laboratory (D.M.W.-L., K.S.), and Biochemische Pflanzenphysiologie (G.G.), Heinrich-Heine-Universität, 40225 Duesseldorf, Germany;Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824 (S.E.W., T.D.S.); andCluster of Excellence on Plant Sciences, From Complex Traits towards Synthetic Modules, 40225 Duesseldorf, Germany (K.S., G.G., U.G., P.W., B.A.)
| | - Julia Mallmann
- Institut für Entwicklungs- und Molekularbiologie der Pflanzen (S.H.A., J.M., U.G., P.W., B.A.), Molecular Proteomics Laboratory (D.M.W.-L., K.S.), and Biochemische Pflanzenphysiologie (G.G.), Heinrich-Heine-Universität, 40225 Duesseldorf, Germany;Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824 (S.E.W., T.D.S.); andCluster of Excellence on Plant Sciences, From Complex Traits towards Synthetic Modules, 40225 Duesseldorf, Germany (K.S., G.G., U.G., P.W., B.A.)
| | - Georg Groth
- Institut für Entwicklungs- und Molekularbiologie der Pflanzen (S.H.A., J.M., U.G., P.W., B.A.), Molecular Proteomics Laboratory (D.M.W.-L., K.S.), and Biochemische Pflanzenphysiologie (G.G.), Heinrich-Heine-Universität, 40225 Duesseldorf, Germany;Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824 (S.E.W., T.D.S.); andCluster of Excellence on Plant Sciences, From Complex Traits towards Synthetic Modules, 40225 Duesseldorf, Germany (K.S., G.G., U.G., P.W., B.A.)
| | - Udo Gowik
- Institut für Entwicklungs- und Molekularbiologie der Pflanzen (S.H.A., J.M., U.G., P.W., B.A.), Molecular Proteomics Laboratory (D.M.W.-L., K.S.), and Biochemische Pflanzenphysiologie (G.G.), Heinrich-Heine-Universität, 40225 Duesseldorf, Germany;Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824 (S.E.W., T.D.S.); andCluster of Excellence on Plant Sciences, From Complex Traits towards Synthetic Modules, 40225 Duesseldorf, Germany (K.S., G.G., U.G., P.W., B.A.)
| | - Peter Westhoff
- Institut für Entwicklungs- und Molekularbiologie der Pflanzen (S.H.A., J.M., U.G., P.W., B.A.), Molecular Proteomics Laboratory (D.M.W.-L., K.S.), and Biochemische Pflanzenphysiologie (G.G.), Heinrich-Heine-Universität, 40225 Duesseldorf, Germany;Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824 (S.E.W., T.D.S.); andCluster of Excellence on Plant Sciences, From Complex Traits towards Synthetic Modules, 40225 Duesseldorf, Germany (K.S., G.G., U.G., P.W., B.A.)
| | - Borjana Arsova
- Institut für Entwicklungs- und Molekularbiologie der Pflanzen (S.H.A., J.M., U.G., P.W., B.A.), Molecular Proteomics Laboratory (D.M.W.-L., K.S.), and Biochemische Pflanzenphysiologie (G.G.), Heinrich-Heine-Universität, 40225 Duesseldorf, Germany;Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824 (S.E.W., T.D.S.); andCluster of Excellence on Plant Sciences, From Complex Traits towards Synthetic Modules, 40225 Duesseldorf, Germany (K.S., G.G., U.G., P.W., B.A.)
| |
Collapse
|
27
|
Borland AM, Hartwell J, Weston DJ, Schlauch KA, Tschaplinski TJ, Tuskan GA, Yang X, Cushman JC. Engineering crassulacean acid metabolism to improve water-use efficiency. TRENDS IN PLANT SCIENCE 2014; 19:327-38. [PMID: 24559590 PMCID: PMC4065858 DOI: 10.1016/j.tplants.2014.01.006] [Citation(s) in RCA: 122] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2013] [Revised: 01/01/2014] [Accepted: 01/13/2014] [Indexed: 05/19/2023]
Abstract
Climatic extremes threaten agricultural sustainability worldwide. One approach to increase plant water-use efficiency (WUE) is to introduce crassulacean acid metabolism (CAM) into C3 crops. Such a task requires comprehensive systems-level understanding of the enzymatic and regulatory pathways underpinning this temporal CO2 pump. Here we review the progress that has been made in achieving this goal. Given that CAM arose through multiple independent evolutionary origins, comparative transcriptomics and genomics of taxonomically diverse CAM species are being used to define the genetic 'parts list' required to operate the core CAM functional modules of nocturnal carboxylation, diurnal decarboxylation, and inverse stomatal regulation. Engineered CAM offers the potential to sustain plant productivity for food, feed, fiber, and biofuel production in hotter and drier climates.
Collapse
Affiliation(s)
- Anne M Borland
- School of Biology, Newcastle University, Newcastle upon Tyne NE1 7RU, UK; Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6407, USA
| | - James Hartwell
- Department of Plant Sciences, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - David J Weston
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6407, USA
| | - Karen A Schlauch
- Department of Biochemistry and Molecular Biology, MS330, University of Nevada, Reno, NV 89557-0330, USA
| | | | - Gerald A Tuskan
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6407, USA
| | - Xiaohan Yang
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6407, USA
| | - John C Cushman
- Department of Biochemistry and Molecular Biology, MS330, University of Nevada, Reno, NV 89557-0330, USA.
| |
Collapse
|
28
|
Owen NA, Griffiths H. A system dynamics model integrating physiology and biochemical regulation predicts extent of crassulacean acid metabolism (CAM) phases. THE NEW PHYTOLOGIST 2013; 200:1116-1131. [PMID: 23992169 DOI: 10.1111/nph.12461] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Accepted: 07/19/2013] [Indexed: 06/02/2023]
Abstract
A system dynamics (SD) approach was taken to model crassulacean acid metabolism (CAM) expression from measured biochemical and physiological constants. SD emphasizes state-dependent feedback interaction to describe the emergent properties of a complex system. These mechanisms maintain biological systems with homeostatic limits on a temporal basis. Previous empirical studies on CAM have correlated biological constants (e.g. enzyme kinetic parameters) with expression over the CAM diel cycle. The SD model integrates these constants within the architecture of the CAM 'system'. This allowed quantitative causal connections to be established between biological inputs and the four distinct phases of CAM delineated by gas exchange and malic acid accumulation traits. Regulation at flow junctions (e.g. stomatal and mesophyll conductance, and malic acid transport across the tonoplast) that are subject to feedback control (e.g. stomatal aperture, malic acid inhibition of phosphoenolpyruvate carboxylase, and enzyme kinetics) was simulated. Simulated expression for the leaf-succulent Kalanchoë daigremontiana and more succulent tissues of Agave tequilana showed strong correlation with measured gas exchange and malic acid accumulation (R(2) = 0.912 and 0.937, respectively, for K. daigremontiana and R(2) = 0.928 and 0.942, respectively, for A. tequilana). Sensitivity analyses were conducted to quantitatively identify determinants of diel CO2 uptake. The transition in CAM expression from low to high volume/area tissues (elimination of phase II-IV carbon-uptake signatures) was achieved largely by the manipulation three input parameters.
Collapse
Affiliation(s)
- Nick A Owen
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
| | | |
Collapse
|
29
|
Bolouri Moghaddam MR, Van den Ende W. Sweet immunity in the plant circadian regulatory network. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:1439-49. [PMID: 23564957 DOI: 10.1093/jxb/ert046] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
All organisms have an internal timing mechanism, termed the circadian clock, to anticipate the light/dark cycle. The clock, with an oscillating rhythm that approximates 24h, is a rather robust system persisting to a great extent in continuous light and dark. It is widely accepted that plant growth and development are regulated by the clock, hormones, and sugar signals. On the one hand, sugar signalling can affect circadian rhythms by altering the expression pattern of clock-regulated genes. More in particular, the clock seems to be particularly sensitive to sucrose-mediated signalling which is also associated with immunity and abiotic stress responses. Also, hormonal interaction with the clock can contribute to appropriate plant immune responses. Recent data show a prominent role for the clock in growth and stress responses. On the other hand, the clock seems to be essential in controlling the gene expression and activity of an array of carbohydrate-metabolizing enzymes, suggesting a complex reciprocal relationship between the clock and metabolic signalling processes. Therefore, the clock fulfils a crucial role at the heart of cellular networks. The players involved in the complex plant circadian network and their possible contribution to the novel 'sweet immunity' concept are discussed.
Collapse
|
30
|
Farré EM, Weise SE. The interactions between the circadian clock and primary metabolism. CURRENT OPINION IN PLANT BIOLOGY 2012; 15:293-300. [PMID: 22305520 DOI: 10.1016/j.pbi.2012.01.013] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Revised: 01/11/2012] [Accepted: 01/11/2012] [Indexed: 05/26/2023]
Abstract
Primary metabolism in plants is tightly regulated by environmental factors such as light and nutrient availability at multiple levels. The circadian clock is a self-sustained endogenous oscillator that enables organisms to predict daily and seasonal changes. The regulation of primary metabolism by the circadian clock has been proposed to explain the importance of circadian rhythms in plant growth and survival. Recent transcriptomic and metabolomic analyses indicate a wide spread circadian regulation of different metabolic processes. We review evidence of circadian regulation of pathways in primary metabolism, discuss the challenges faced for discerning the mechanisms regulating circadian metabolic oscillations and present recent evidence of regulation of the circadian clock by metabolites.
Collapse
Affiliation(s)
- Eva M Farré
- Michigan State University, Department of Plant Biology, East Lansing, MI 48824, USA.
| | | |
Collapse
|
31
|
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]
|
32
|
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.
Collapse
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
| |
Collapse
|
33
|
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.
Collapse
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.
| | | | | | | | | | | | | |
Collapse
|
34
|
|
35
|
Garcês H, Sinha N. The 'mother of thousands' (Kalanchoë daigremontiana): a plant model for asexual reproduction and CAM studies. Cold Spring Harb Protoc 2010; 2009:pdb.emo133. [PMID: 20147034 DOI: 10.1101/pdb.emo133] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The genus Kalanchoë plays an important role in the investigation of biochemical, physiological and phylogenetic aspects of Crassulacean acid metabolism (CAM) in plants, which is an important evolutionary adaptation of the photosynthetic carbon assimilation pathway to arid environments. In addition, natural compounds extracted from tissues of Kalanchoë have potential applicability in treating tumors and inflammatory and allergic diseases, and have been shown to have insecticidal properties. Kalanchoë daigremontiana (Hamet & Perrier) originated in Madagascar and reproduces asexually by spontaneously forming whole plantlets on leaves. Plantlets develop symmetrically along the leaf margins on leaf notches, closely resembling zygotic embryos in development, and once the root system is formed, they detach from the mother-leaf, fall to the ground, and grow into new plants. This phenomenon is also found in other species from this same genus; however, the formation of leaf-plantlets is variable among species. Nevertheless, all species illustrate the remarkable ability of plant somatic cells to regenerate an entire organism, which has fascinated the scientific community for many years. It was only recently that the morphogenic process involved in the origin of K. daigremontiana plantlets was determined using molecular and genetic tools: K. daigremontiana forms plantlets by co-opting both organogenesis and embryogenesis programs into leaves. The ability of K. daigremontiana species to form somatic embryos outside of a seed environment provides an attractive model system to study somatic embryogenesis in nature, particularly the molecular mechanism involved in the acquisition of competence by vegetative cells to make embryos without fertilization.
Collapse
Affiliation(s)
- Helena Garcês
- Department of Plant Biology, University of California, Davis, CA 95616, USA
| | | |
Collapse
|
36
|
Ceusters J, Borland AM, Ceusters N, Verdoodt V, Godts C, De Proft MP. Seasonal influences on carbohydrate metabolism in the CAM bromeliad Aechmea 'Maya': consequences for carbohydrate partitioning and growth. ANNALS OF BOTANY 2010; 105:301-9. [PMID: 19914918 PMCID: PMC2814750 DOI: 10.1093/aob/mcp275] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2009] [Revised: 06/29/2009] [Accepted: 10/09/2009] [Indexed: 05/08/2023]
Abstract
BACKGROUND AND AIMS Photosynthetic plasticity in response to a range of environmental factors that include [CO(2)], water availability, light intensity and temperature, is ubiquitous among plants with crassulacean acid metabolism (CAM). The present study examined how seasonal changes in light availability, as experienced by greenhouse CAM crops in northern latitude regions, influence diel carboxylation patterns and impact on carbon gain and seasonal accumulation of biomass. METHODS In the CAM bromeliad Aechmea 'Maya' integrated measurements of leaf gas exchange, diel metabolite dynamics (e.g. malate, soluble sugars and starch) and biomass accumulation were made four times a year, i.e. in winter, spring, summer and autumn. KEY RESULTS During the brighter seasons (spring and summer) daytime Phases II and IV were dominated by C(4) carboxylation, whilst the higher diurnal uptake in the autumn and winter was characterized by equal contributions of both Rubisco and PEPC. As a consequence, net CO(2) uptake showed a significant depression at the end of the day in the darker months when supplementary illumination was turned off. Remarkable seasonal consistency was found in the amount of storage reserves available for nocturnal carboxylation, a consequence of predominantly daytime export of carbohydrate in spring and summer whilst nocturnal export was the major sink for carbohydrate in autumn and winter. CONCLUSIONS Throughout the different seasons Aechmea 'Maya' showed considerable plasticity in the timing and magnitude of C(3) and C(4) carboxylation processes over the diel cycle. Under low PPFD (i.e. winter and autumn) it appears that there was a constraint on the amount of carbohydrate exported during the day in order to maintain a consistent pool of transient carbohydrate reserves. This gave remarkable seasonal consistency in the amount of storage reserves available at night, thereby optimizing biomass gain throughout the year. The data have important practical consequences for horticultural productivity of CAM plants and suggest a scenario for reconciling carbohydrate partitioning between competing sinks of nocturnal acidification and export for growth.
Collapse
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.
| | | | | | | | | | | |
Collapse
|
37
|
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.
Collapse
Affiliation(s)
- Anne M Borland
- Institute for Research on the Environment and Sustainability, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK.
| | | | | | | |
Collapse
|
38
|
Cloutier M, Chen J, Tatge F, McMurray-Beaulieu V, Perrier M, Jolicoeur M. Kinetic metabolic modelling for the control of plant cells cytoplasmic phosphate. J Theor Biol 2009; 259:118-31. [PMID: 19281825 DOI: 10.1016/j.jtbi.2009.02.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Revised: 01/27/2009] [Accepted: 02/26/2009] [Indexed: 10/21/2022]
Abstract
A previously developed kinetic metabolic model for plant metabolism was used in a context of identification and control of intracellular phosphate (Pi) dynamics. Experimental data from batch flask cultures of Eschscholtiza californica cells was used to calibrate the model parameters for the slow dynamics (growth, nutrition, anabolic pathways, etc.). Perturbation experiments were performed using a perfusion small-scale bioreactor monitored by in vivo(31)P NMR. Parameter identification for Pi metabolism was done by measuring the cells dynamic response to different inputs for extracellular Pi (two pulse-response experiments and a step-response experiment). The calibrated model can describe Pi translocation between the cellular pools (vacuole and cytoplasm). The effect of intracellular Pi management on ATP/ADP and phosphomonoesters concentrations is also described by the model. The calibrated model is then used to develop a control strategy on the cytoplasmic Pi pool. From the identification of the systems dynamics, a proportional-integral controller was designed and tuned. The closed-loop control was implemented in the small-scale NMR bioreactor and experimental results were in accordance with model predictions. Thus, the calibrated model is able to predict cellular behaviour for phosphate metabolism and it was demonstrated that it is possible to control the intracellular level of cytoplasmic Pi in plant cells.
Collapse
Affiliation(s)
- Mathieu Cloutier
- Department of Chemical Engineering, Applied Metabolic Engineering, Bio-P2 Research Unit, Ecole Polytechnique de Montreal, Station Centre-ville, Montreal, Quebec, Canada
| | | | | | | | | | | |
Collapse
|
39
|
Antony E, Borland AM. The Role and Regulation of Sugar Transporters in Plants with Crassulacean Acid Metabolism. PROGRESS IN BOTANY 2008. [DOI: 10.1007/978-3-540-68421-3_6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
|
40
|
Feria AB, Alvarez R, Cochereau L, Vidal J, García-Mauriño S, Echevarría C. Regulation of phosphoenolpyruvate carboxylase phosphorylation by metabolites and abscisic acid during the development and germination of barley seeds. PLANT PHYSIOLOGY 2008; 148:761-74. [PMID: 18753284 PMCID: PMC2556803 DOI: 10.1104/pp.108.124982] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2008] [Accepted: 08/14/2008] [Indexed: 05/20/2023]
Abstract
During barley (Hordeum vulgare) seed development, phosphoenolpyruvate carboxylase (PEPC) activity increased and PEPC-specific antibodies revealed housekeeping (103-kD) and inducible (108-kD) subunits. Bacterial-type PEPC fragments were immunologically detected in denatured protein extracts from dry and imbibed conditions; however, on nondenaturing gels, the activity of the recently reported octameric PEPC (in castor [Ricinus communis] oil seeds) was not detected. The phosphorylation state of the PEPC, as judged by l-malate 50% inhibition of initial activity values, phosphoprotein chromatography, and immunodetection of the phosphorylated N terminus, was found to be high between 8 and 18 d postanthesis (DPA) and during imbibition. In contrast, the enzyme appeared to be in a low phosphorylation state from 20 DPA up to dry seed. The time course of 32/36-kD, Ca(2+)-independent PEPC kinase activity exhibited a substantial increase after 30 DPA that did not coincide with the PEPC phosphorylation profile. This kinase was found to be inhibited by l-malate and not by putative protein inhibitors, and the PEPC phosphorylation status correlated with high glucose-6-phosphate to malate ratios, thereby suggesting an in vivo metabolic control of the kinase. PEPC phosphorylation was also regulated by photosynthate supply at 11 DPA. In addition, when fed exogenously to imbibing seeds, abscisic acid significantly increased PEPC kinase activity. This was further enhanced by the cytosolic protein synthesis inhibitor cycloheximide but blocked by protease inhibitors, thereby suggesting that the phytohormone acts on the stability of the kinase. We propose that a similar abscisic acid-dependent effect may contribute to produce the increase in PEPC kinase activity during desiccation stages.
Collapse
Affiliation(s)
- Ana-Belén Feria
- Departamento de Biología Vegetal, Facultad de Biología, Universidad de Sevilla, Seville, Spain
| | | | | | | | | | | |
Collapse
|
41
|
Ceusters J, Borland AM, Londers E, Verdoodt V, Godts C, De Proft MP. Diel shifts in carboxylation pathway and metabolite dynamics in the CAM bromeliad Aechmea 'Maya' in response to elevated CO2. ANNALS OF BOTANY 2008; 102:389-97. [PMID: 18593689 PMCID: PMC2701804 DOI: 10.1093/aob/mcn105] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Revised: 05/06/2008] [Accepted: 05/28/2008] [Indexed: 05/08/2023]
Abstract
BACKGROUND AND AIMS The deployment of temporally separated carboxylation pathways for net CO(2) uptake in CAM plants provides plasticity and thus uncertainty on how species with this photosynthetic pathway will respond to life in a higher-CO(2) world. The present study examined how long-term exposure to elevated CO(2) influences the relative contributions that C(3) and C(4) carboxylation make to net carbon gain and to establish how this impacts on the availability of carbohydrates for export and growth and on water use efficiency over the day/night cycle. METHODS Integrated measurements of leaf gas exchange and diel metabolite dynamics (e.g. malate, soluble sugars, starch) were made in leaves of the CAM bromeliad Aechmea 'Maya' after exposure to 700 micromol mol(-1) CO(2) for 5 months. KEY RESULTS There was a 60 % increase in 24-h carbon gain under elevated CO(2) due to a stimulation of daytime C(3) and C(4) carboxylation in phases II and IV where water use efficiency was comparable with that measured at night. The extra CO(2) taken up under elevated CO(2) was largely accumulated as hexose sugars during phase IV and net daytime export of carbohydrate was abolished. Under elevated CO(2) there was no stimulation of dark carboxylation and nocturnal export and respiration appeared to be the stronger sinks for carbohydrate. CONCLUSIONS Despite the increased size of the soluble sugar storage pool under elevated CO(2), there was no change in the net allocation of carbohydrates between provision of substrates for CAM and export/respiration in A. 'Maya'. The data imply the existence of discrete pools of carbohydrate that provide substrate for CAM or sugars for export/respiration. The 2-fold increase in water-use efficiency could be a major physiological advantage to growth under elevated CO(2) in this CAM bromeliad.
Collapse
Affiliation(s)
- J Ceusters
- Faculty of Bioscience Engineering, Department of Biosystems, Division of Crop Biotechnics, Katholieke Universiteit Leuven, Willem De Croylaan 42, B-3001 Heverlee, Belgium.
| | | | | | | | | | | |
Collapse
|
42
|
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.
Collapse
Affiliation(s)
- John C Cushman
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, NV 89557-0200, USA.
| | | | | | | | | | | |
Collapse
|
43
|
Abstract
Clusia is the only genus with bona fide dicotyledonous trees performing Crassulacean acid metabolism (CAM). Clusia minor L. is extraordinarily flexible, being C(3)/CAM intermediate and expressing the photosynthetic modes C(3), CAM, CAM-cycling, and CAM-idling. C(3) photosynthesis and CAM can be observed simultaneously in two opposite leaves on a node and possibly even within the same leaf in the interveinal lamina and the major vein tissue, respectively. The relative activity of photosystem II (PhiPSII) indicating photosynthetic energy use, is larger under photorespiratory than under non-photorespiratory conditions due to the particular energy demand of photorespiration. The heterogeneity of PhiPSII over the leaves as visualized by chlorophyll fluorescence imaging in the C(3) mode is larger under non-photorespiratory conditions than under photorespiratory conditions. These observations indicate that photorespiration, presumably by its particular energy demand, synchronizes photosynthetic activity over the leaves. In the CAM mode, the heterogeneity of PhiPSII is more dependent on the transitions between CAM phases. Free-running circadian oscillations of photosynthesis are strongly dampened in both the C(3) and the CAM mode. Photorespiration is under circadian clock control in both the C(3) and the CAM mode. PhiPSII and the heterogeneity of PhiPSII oscillate in phase with CO(2) uptake and photorespiration only under non-photorespiratory conditions. Under photorespiratory conditions, PhiPSII does not oscillate and there is no heterogeneity, again indicating the stabilizing function of photorespiration. Plants acclimatized to perform CAM switch to C(3) photosynthesis during free-running oscillations while subjected to constant illumination.
Collapse
Affiliation(s)
- Ulrich Lüttge
- Institut für Botanik, Technische Universität Darmstadt, Schnittspahnstrasse 3-5, D-64287 Darmstadt, Germany.
| |
Collapse
|
44
|
Niewiadomska E, Borland AM. Crassulacean Acid Metabolism: a Cause or Consequence of Oxidative Stress in Planta? PROGRESS IN BOTANY 2008. [DOI: 10.1007/978-3-540-72954-9_10] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
|
45
|
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.
Collapse
Affiliation(s)
- John C Cushman
- Department of Biochemistry, MS200, University of Nevada, Reno, NV 89557-0014, USA.
| | | | | | | | | |
Collapse
|
46
|
Monreal JA, López-Baena FJ, Vidal J, Echevarría C, García-Mauriño S. Effect of LiCl on phosphoenolpyruvate carboxylase kinase and the phosphorylation of phosphoenolpyruvate carboxylase in leaf disks and leaves of Sorghum vulgare. PLANTA 2007; 225:801-12. [PMID: 16983537 DOI: 10.1007/s00425-006-0391-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Accepted: 08/22/2006] [Indexed: 05/11/2023]
Abstract
In the present work, the effect of LiCl on phosphoenolpyruvate carboxylase kinase (PEPCase-k), C4 phosphoenolpyruvate carboxylase (PEPCase: EC 4.1.1.31) and its phosphorylation process has been investigated in illuminated leaf disks and leaves of the C4 plant Sorghum vulgare. Although this salt induced severe damages to older leaves, it did not significantly alter the physiological parameters (photosynthesis, transpiration rate, intercellular CO2 concentration) of young leaves. An immunological approach was used to demonstrate that the PEPCase-k protein accumulated rapidly in illuminated leaf tissues, consistent with the increase in its catalytic activity. In vivo, LiCl was shown to strongly enhance the light effect on PEPCase-k protein content, this process being dependent on protein synthesis. In marked contrast, the salt was found to inhibit the PEPCase-k activity in reconstituted assays and to decrease the C4 PEPCase content and phosphorylation state in LiCl treated plants. Short-term (15 min) LiCl treatment increased IP3 levels, PPCK gene expression, and PEPCase-k accumulation. Extending the treatment (1 h) markedly decreased IP3 and PPCK gene expression, while PEPCase-k activity was kept high. The cytosolic protein synthesis inhibitor cycloheximide (CHX), which blocked the light-dependent up-regulation of the kinase in control plants, was found not to be active on this process in preilluminated, LiCl-treated leaves. This suggested that the salt causes the kinase turnover to be altered, presumably by decreasing degradation of the corresponding polypeptide. Taken together, these results establish PEPCase-k and PEPCase phosphorylation as lithium targets in higher plants and that this salt can provide a means to investigate further the organization and functioning of the cascade controlling the activity of both enzymes.
Collapse
Affiliation(s)
- José Antonio Monreal
- Departamento de Biologia Vegetal, Facultad de Biologia, Universidad de Sevilla, Avenida Reina Mercedes no. 6, 41012 Seville, Spain.
| | | | | | | | | |
Collapse
|
47
|
|
48
|
Abstract
A circadian clock optimizes many aspects of plant biology relative to the light/dark cycle. One example is the circadian control of primary metabolism and CO2 fixation in plants that carry out a metabolic adaptation of photosynthesis called CAM (crassulacean acid metabolism). These plants perform primary CO2 fixation at night using the enzyme phosphoenolpyruvate carboxylase and exhibit a robust rhythm of CO2 fixation under constant conditions. Transcriptomic analysis has revealed that many genes encoding enzymes in primary metabolic pathways such as glycolysis and starch metabolism are under the control of the circadian clock in CAM plants. These transcript changes are accompanied by changes in metabolite levels associated with flux through these pathways. The molecular basis for the circadian control of CAM remains to be elucidated. Current research is focusing on the identity of the CAM central oscillator and the output pathway that links the central oscillator to the control of plant metabolism.
Collapse
|
49
|
Holtum JAM, Smith JAC, Neuhaus HE. Intracellular transport and pathways of carbon flow in plants with crassulacean acid metabolism. FUNCTIONAL PLANT BIOLOGY : FPB 2005; 32:429-449. [PMID: 32689145 DOI: 10.1071/fp04189] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2004] [Accepted: 02/22/2005] [Indexed: 06/11/2023]
Abstract
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.
Collapse
Affiliation(s)
- Joseph A M Holtum
- School of Tropical Biology, James Cook University, Townsville, Qld 4811, Australia
| | - J Andrew C Smith
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
| | - H Ekkehard Neuhaus
- Universität Kaiserslautern, Pflanzenphysiologie, Erwin Schrödinger-Strasse, D-67653 Kaiserslautern, Germany
| |
Collapse
|
50
|
Boxall SF, Foster JM, Bohnert HJ, Cushman JC, Nimmo HG, Hartwell J. Conservation and divergence of circadian clock operation in a stress-inducible Crassulacean acid metabolism species reveals clock compensation against stress. PLANT PHYSIOLOGY 2005; 137:969-82. [PMID: 15734916 PMCID: PMC1065398 DOI: 10.1104/pp.104.054577] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2004] [Revised: 12/23/2004] [Accepted: 01/06/2005] [Indexed: 05/17/2023]
Abstract
One of the best-characterized physiological rhythms in plants is the circadian rhythm of CO(2) metabolism in Crassulacean acid metabolism (CAM) plants, which is the focus here. The central components of the plant circadian clock have been studied in detail only in Arabidopsis (Arabidopsis thaliana). Full-length cDNAs have been obtained encoding orthologs of CIRCADIAN CLOCK-ASSOCIATED1 (CCA1)/LATE ELONGATED HYPOCOTYL (LHY), TIMING OF CAB EXPRESSION1 (TOC1), EARLY FLOWERING4 (ELF4), ZEITLUPE (ZTL), FLAVIN-BINDING KELCH REPEAT F-BOX1 (FKF1), EARLY FLOWERING3 (ELF3), and a partial cDNA encoding GIGANTEA in the model stress-inducible CAM plant, Mesembryanthemum crystallinum (Common Ice Plant). TOC1 and LHY/CCA1 are under reciprocal circadian control in a manner similar to their regulation in Arabidopsis. ELF4, FKF1, ZTL, GIGANTEA, and ELF3 are under circadian control in C(3) and CAM leaves. ELF4 transcripts peak in the evening and are unaffected by CAM induction. FKF1 shows an abrupt transcript peak 3 h before subjective dusk. ELF3 transcripts appear in the evening, consistent with their role in gating light input to the circadian clock. Intriguingly, ZTL transcripts do not oscillate in Arabidopsis, but do in M. crystallinum. The transcript abundance of the clock-associated genes in M. crystallinum is largely unaffected by development and salt stress, revealing compensation of the central circadian clock against development and abiotic stress in addition to the well-known temperature compensation. Importantly, the clock in M. crystallinum is very similar to that in Arabidopsis, indicating that such a clock could control CAM without requiring additional components of the central oscillator or a novel CAM oscillator.
Collapse
Affiliation(s)
- Susanna F Boxall
- Department of Biology, University of York, York YO10 5YW, United Kingdom
| | | | | | | | | | | |
Collapse
|