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Hurtado-Castano N, Atkins E, Barnes J, Boxall SF, Dever LV, Kneřová J, Hartwell J, Cushman JC, Borland AM. The starch-deficient plastidic PHOSPHOGLUCOMUTASE mutant of the constitutive crassulacean acid metabolism (CAM) species Kalanchoë fedtschenkoi impacts diel regulation and timing of stomatal CO2 responsiveness. ANNALS OF BOTANY 2023; 132:881-894. [PMID: 36661206 PMCID: PMC10799981 DOI: 10.1093/aob/mcad017] [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: 01/18/2023] [Accepted: 01/19/2023] [Indexed: 06/17/2023]
Abstract
BACKGROUND AND AIMS Crassulacean acid metabolism (CAM) is a specialized type of photosynthesis characterized by a diel pattern of stomatal opening at night and closure during the day, which increases water-use efficiency. Starch degradation is a key regulator of CAM, providing phosphoenolpyruvate as a substrate in the mesophyll for nocturnal assimilation of CO2. Growing recognition of a key role for starch degradation in C3 photosynthesis guard cells for mediating daytime stomatal opening presents the possibility that starch degradation might also impact CAM by regulating the provision of energy and osmolytes to increase guard cell turgor and drive stomatal opening at night. In this study, we tested the hypothesis that the timing of diel starch turnover in CAM guard cells has been reprogrammed during evolution to enable nocturnal stomatal opening and daytime closure. METHODS Biochemical and genetic characterization of wild-type and starch-deficient RNAi lines of Kalanchoë fedtschenkoi with reduced activity of plastidic phosphoglucomutase (PGM) constituted a preliminary approach for the understanding of starch metabolism and its implications for stomatal regulation in CAM plants. KEY RESULTS Starch deficiency reduced nocturnal net CO2 uptake but had negligible impact on nocturnal stomatal opening. In contrast, daytime stomatal closure was reduced in magnitude and duration in the starch-deficient rPGM RNAi lines, and their stomata were unable to remain closed in response to elevated concentrations of atmospheric CO2 administered during the day. Curtailed daytime stomatal closure was linked to higher soluble sugar contents in the epidermis and mesophyll. CONCLUSIONS Nocturnal stomatal opening is not reliant upon starch degradation, but starch biosynthesis is an important sink for carbohydrates, ensuring daytime stomatal closure in this CAM species.
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Affiliation(s)
- Natalia Hurtado-Castano
- School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Elliott Atkins
- School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK
- John Innes Centre, Norwich Research Park, Colney Lane, Norwich NR4 7UH, UK
| | - Jerry Barnes
- School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK
| | - Susanna F Boxall
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool L69 72B, UK
| | - Louisa V Dever
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool L69 72B, UK
| | - Jana Kneřová
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool L69 72B, UK
| | - James Hartwell
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool L69 72B, UK
| | - John C Cushman
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, NV 89557-0330, USA
| | - Anne M Borland
- School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK
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2
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He J, Ng OWJ, Qin L. Salinity and Salt-Priming Impact on Growth, Photosynthetic Performance, and Nutritional Quality of Edible Mesembryanthemum crystallinum L. PLANTS 2022; 11:plants11030332. [PMID: 35161313 PMCID: PMC8838379 DOI: 10.3390/plants11030332] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 01/20/2022] [Accepted: 01/24/2022] [Indexed: 12/18/2022]
Abstract
Mesembryanthemum crystallinum L. is a nutritious edible facultative halophyte. This study aimed to investigate the physiology and quality of M. crystallinum L. grown under different salinities and salt-priming conditions. All plants were first grown in 10% artificial seawater (ASW) for 10 days. After that, some plants remained in 10% ASW while the others were transferred to 20%, 30%, 40%, or 50% ASW for another 10 days. Some plants also underwent a salt priming by transferring them gradually from 10% to 100% ASW over a span of 10 days (defined as salt primed). All plants were green and healthy. However, there were reductions in shoot and root productivity, leaf growth, and water content, but also an increase in leaf succulence after transferring plants to higher salinities. The salt-primed plants showed higher photosynthetic light use efficiency with higher chlorophyll concentration compared to other plants. The concentrations of proline, ascorbic acid (ASC), and total phenolic compounds (TPC) increased as percentages of ASW increased. The salt-primed plants switched from C3 to crassulacean acid metabolism photosynthesis and accumulated the greatest amounts of proline, ASC, and TPC. In conclusion, higher salinities and salt priming enhance the nutritional quality of M. crystallinum L. but compromises productivity.
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Affiliation(s)
- Jie He
- Correspondence: ; Tel.: +65-67903817; Fax: +65-6896-9414
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3
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Ceusters N, Ceusters J, Hurtado-Castano N, Dever LV, Boxall SF, Kneřová J, Waller JL, Rodick R, Van den Ende W, Hartwell J, Borland AM. Phosphorolytic degradation of leaf starch via plastidic α-glucan phosphorylase leads to optimized plant growth and water use efficiency over the diel phases of Crassulacean acid metabolism. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:4419-4434. [PMID: 33754643 PMCID: PMC8266541 DOI: 10.1093/jxb/erab132] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 03/19/2021] [Indexed: 05/27/2023]
Abstract
In plants with Crassulacean acid metabolism (CAM), it has been proposed that the requirement for nocturnal provision of phosphoenolpyruvate as a substrate for CO2 uptake has resulted in a re-routing of chloroplastic starch degradation from the amylolytic route to the phosphorolytic route. To test this hypothesis, we generated and characterized four independent RNAi lines of the obligate CAM species Kalanchoë fedtschenkoi with a >10-fold reduction in transcript abundance of plastidic α-glucan phosphorylase (PHS1). The rPHS1 lines showed diminished nocturnal starch degradation, reduced dark CO2 uptake, a reduction in diel water use efficiency (WUE), and an overall reduction in growth. A re-routing of starch degradation via the hydrolytic/amylolytic pathway was indicated by hyperaccumulation of maltose in all rPHS1 lines. Further examination indicated that whilst operation of the core circadian clock was not compromised, plasticity in modulating net dark CO2 uptake in response to changing photoperiods was curtailed. The data show that phosphorolytic starch degradation is critical for efficient operation of the CAM cycle and for optimizing WUE. This finding has clear relevance for ongoing efforts to engineer CAM into non-CAM species as a means of boosting crop WUE for a warmer, drier future.
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Affiliation(s)
- Nathalie Ceusters
- Faculty of Engineering Technology, Department of Biosystems, Division of Crop Biotechnics, Campus Geel, KU Leuven, Kleinhoefstraat 4, 2440 Geel, Belgium
| | - Johan Ceusters
- Faculty of Engineering Technology, Department of Biosystems, Division of Crop Biotechnics, Campus Geel, KU Leuven, Kleinhoefstraat 4, 2440 Geel, Belgium
- UHasselt, Centre for Environmental Sciences, Environmental Biology, Campus Diepenbeek, Agoralaan Building D, 3590 Diepenbeek, Belgium
| | - Natalia Hurtado-Castano
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UK
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, UK
| | - Louisa V Dever
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - Susanna F Boxall
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - Jana Kneřová
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - Jade L Waller
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - Rebecca Rodick
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - Wim Van den Ende
- Faculty of Science, Department of Biology, Laboratory of Molecular Plant Biology, KU Leuven, Kasteelpark Arenberg 31, B-3001 Heverlee, Belgium
| | - James Hartwell
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - Anne M Borland
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UK
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4
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Abraham PE, Hurtado Castano N, Cowan-Turner D, Barnes J, Poudel S, Hettich R, Flütsch S, Santelia D, Borland AM. Peeling back the layers of crassulacean acid metabolism: functional differentiation between Kalanchoë fedtschenkoi epidermis and mesophyll proteomes. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 103:869-888. [PMID: 32314451 DOI: 10.1111/tpj.14757] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 03/18/2020] [Accepted: 03/23/2020] [Indexed: 06/11/2023]
Abstract
Crassulacean acid metabolism (CAM) is a specialized mode of photosynthesis that offers the potential to engineer improved water-use efficiency (WUE) and drought resilience in C3 plants while sustaining productivity in the hotter and drier climates that are predicted for much of the world. CAM species show an inverted pattern of stomatal opening and closing across the diel cycle, which conserves water and provides a means of maintaining growth in hot, water-limited environments. Recent genome sequencing of the constitutive model CAM species Kalanchoë fedtschenkoi provides a platform for elucidating the ensemble of proteins that link photosynthetic metabolism with stomatal movement, and that protect CAM plants from harsh environmental conditions. We describe a large-scale proteomics analysis to characterize and compare proteins, as well as diel changes in their abundance in guard cell-enriched epidermis and mesophyll cells from leaves of K. fedtschenkoi. Proteins implicated in processes that encompass respiration, the transport of water and CO2 , stomatal regulation, and CAM biochemistry are highlighted and discussed. Diel rescheduling of guard cell starch turnover in K. fedtschenkoi compared with that observed in Arabidopsis is reported and tissue-specific localization in the epidermis and mesophyll of isozymes implicated in starch and malate turnover are discussed in line with the contrasting roles for these metabolites within the CAM mesophyll and stomatal complex. These data reveal the proteins and the biological processes enriched in each layer and provide key information for studies aiming to adapt plants to hot and dry environments by modifying leaf physiology for improved plant sustainability.
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Affiliation(s)
- Paul E Abraham
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Natalia Hurtado Castano
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, UK
| | - Daniel Cowan-Turner
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - Jeremy Barnes
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - Suresh Poudel
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- Department of Genome Science and Technology, University of Tennessee, Knoxville, TN, 37996, USA
| | - Robert Hettich
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | | | - Diana Santelia
- Institute of Integrative Biology, ETH, Zürich, Switzerland
| | - Anne M Borland
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
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5
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Ferrari RC, Bittencourt PP, Rodrigues MA, Moreno-Villena JJ, Alves FRR, Gastaldi VD, Boxall SF, Dever LV, Demarco D, Andrade SCS, Edwards EJ, Hartwell J, Freschi L. C 4 and crassulacean acid metabolism within a single leaf: deciphering key components behind a rare photosynthetic adaptation. THE NEW PHYTOLOGIST 2020; 225:1699-1714. [PMID: 31610019 DOI: 10.1111/nph.16265] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 10/07/2019] [Indexed: 06/10/2023]
Abstract
Although biochemically related, C4 and crassulacean acid metabolism (CAM) systems are expected to be incompatible. However, Portulaca species, including P. oleracea, operate C4 and CAM within a single leaf, and the mechanisms behind this unique photosynthetic arrangement remain largely unknown. Here, we employed RNA-seq to identify candidate genes involved exclusively or shared by C4 or CAM, and provided an in-depth characterization of their transcript abundance patterns during the drought-induced photosynthetic transitions in P. oleracea. Data revealed fewer candidate CAM-specific genes than those recruited to function in C4 . The putative CAM-specific genes were predominantly involved in night-time primary carboxylation reactions and malate movement across the tonoplast. Analysis of gene transcript-abundance regulation and photosynthetic physiology indicated that C4 and CAM coexist within a single P. oleracea leaf under mild drought conditions. Developmental and environmental cues were shown to regulate CAM expression in stems, whereas the shift from C4 to C4 -CAM hybrid photosynthesis in leaves was strictly under environmental control. Moreover, efficient starch turnover was identified as part of the metabolic adjustments required for CAM operation in both organs. These findings provide insights into C4 /CAM connectivity and compatibility, contributing to a deeper understanding of alternative ways to engineer CAM into C4 crop species.
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Affiliation(s)
- Renata C Ferrari
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo, 05508-090, Brasil
| | - Priscila P Bittencourt
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo, 05508-090, Brasil
| | - Maria A Rodrigues
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo, 05508-090, Brasil
| | - Jose J Moreno-Villena
- Department of Ecology and Evolutionary Biology, Yale University, PO Box 208105, New Haven, CT, 06520, USA
| | - Frederico R R Alves
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo, 05508-090, Brasil
| | - Vinícius D Gastaldi
- Departamento e Instituto de Psiquiatria, Hospital das Clínicas (HCFMUSP), Faculdade de Medicina, Universidade de São Paulo, São Paulo, 05403-903, Brasil
| | - Susanna F Boxall
- Department of Functional and Comparative Genomics, Institute of Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, UK
| | - Louisa V Dever
- Department of Functional and Comparative Genomics, Institute of Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, UK
| | - Diego Demarco
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo, 05508-090, Brasil
| | - Sónia C S Andrade
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, 05508-090, Brasil
| | - Erika J Edwards
- Department of Ecology and Evolutionary Biology, Yale University, PO Box 208105, New Haven, CT, 06520, USA
| | - James Hartwell
- Department of Functional and Comparative Genomics, Institute of Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, UK
| | - Luciano Freschi
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo, 05508-090, Brasil
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Wan X, Zou LH, Zheng BQ, Wang Y. Circadian Regulation of Alternative Splicing of Drought-Associated CIPK Genes in Dendrobium catenatum (Orchidaceae). Int J Mol Sci 2019; 20:ijms20030688. [PMID: 30764546 PMCID: PMC6386984 DOI: 10.3390/ijms20030688] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Revised: 01/31/2019] [Accepted: 02/01/2019] [Indexed: 01/23/2023] Open
Abstract
Dendrobium catenatum, an epiphytic and lithophytic species, suffers frequently from perennial shortage of water in the wild. The molecular mechanisms of this orchid’s tolerance to abiotic stress, especially drought, remain largely unknown. It is well-known that CBL-interacting protein kinase (CIPKs) proteins play important roles in plant developmental processes, signal transduction, and responses to abiotic stress. To study the CIPKs’ functions for D. catenatum, we first identified 24 CIPK genes from it. We divided them into three subgroups, with varying intron numbers and protein motifs, based on phylogeny analysis. Expression patterns of CIPK family genes in different tissues and in response to either drought or cold stresses suggested DcaCIPK11 may be associated with signal transduction and energy metabolism. DcaCIPK9, -14, and -16 are predicted to play critical roles during drought treatment specifically. Furthermore, transcript expression abundances of DcaCIPK16 showed polar opposites during day and night. Whether under drought treatment or not, DcaCIPK16 tended to emphatically express transcript1 during the day and transcript3 at night. This implied that expression of the transcripts might be regulated by circadian rhythm. qRT-PCR analysis also indicated that DcaCIPK3, -8, and -20 were strongly influenced by circadian rhythmicity. In contrast with previous studies, for the first time to our knowledge, our study revealed that the major CIPK gene transcript expressed was not always the same and was affected by the biological clock, providing a different perspective on alternative splicing preference.
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Affiliation(s)
- Xiao Wan
- Research Institute of Forestry; State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, Beijing 100091, China.
| | - Long-Hai Zou
- Research Institute of Forestry; State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, Beijing 100091, China.
| | - Bao-Qiang Zheng
- Research Institute of Forestry; State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, Beijing 100091, China.
| | - Yan Wang
- Research Institute of Forestry; State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, Beijing 100091, China.
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7
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Hwang HH, Wang CH, Chen HH, Ho JF, Chi SF, Huang FC, Yen HE. Effective Agrobacterium-mediated transformation protocols for callus and roots of halophyte ice plant (Mesembryanthemum crystallinum). BOTANICAL STUDIES 2019; 60:1. [PMID: 30617933 PMCID: PMC6323063 DOI: 10.1186/s40529-018-0249-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 12/19/2018] [Indexed: 05/21/2023]
Abstract
BACKGROUND Ice plant (Mesembryanthemum crystallinum L.) is a model plant for studying salt-tolerant mechanisms in higher plants. Many salt stress-responsive ice plant genes have been identified with molecular and biochemical approaches. However, no further functional characterization of these genes in host plant due to lack of easy and effective transformation protocols. RESULTS To establish efficient transformation system of ice plants, three types of ice plant materials, hypocotyl-derived callus, aseptically-grown seedlings and pot-grown juvenile plants, were used to develop Agrobacterium-mediated transformation protocols. The highest transient transformation efficiency was with 5-day-old ice plant callus co-incubated with an Agrobacterium tumefaciens at 2.5 × 109 cells mL-1 for 48 h. The 3-day-old ice plant seedlings with root tip removed were successfully infected with A. tumefaciens or A. rhizogenes, and obtained 85% and 33-100% transient transformation rates, respectively. The transient transformation assays in ice plant callus and seedlings demonstrated that the concentrations of Agrobacteria, the durations of co-incubation time, and the plant growth stages were three important factors affecting the transient transformation efficiencies. Additionally, pot-grown juvenile plants were syringe-injected with two A. rhizogenes strains A8196 and NCPPB 1855, to establish transformed roots. After infections, ice plants were grown hydroponically and showed GUS expressions in transformed roots for 8 consecutive weeks. CONCLUSIONS Our Agrobacterium-mediated transformation protocols utilized hypocotyl-derived callus and seedlings as plant materials, which can be easily obtained in large quantity. The average successful transient transformation rates were about 2.4-3.0% with callus and 33.3-100.0% with seedlings. We also developed a rapid and efficient protocol to generate transgenic roots by A. rhizogenes infections without laborious and challenging tissue culture techniques. This protocol to establish composite ice plant system demonstrates excellent improvements in efficiency, efficacy, and ease of use over previous ice plant transformation protocols. These Agrobacterium-mediated transformation protocols can be versatile and efficient tools for exploring gene functions at cellular and organ levels of ice plants.
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Affiliation(s)
- Hau-Hsuan Hwang
- Department of Life Sciences, National Chung Hsing University, No. 145, Xingda Road, Taichung, 402 Taiwan
- Ph.D. Program in Microbial Genomics, National Chung Hsing University, Taichung, Taiwan
- Advanced Plant Biotechnology Center, National Chung Hsing University, Taichung, Taiwan
- Innovation and Development Center of Sustainable Agriculture, National Chung Hsing University, Taichung, Taiwan
| | - Chih-Hao Wang
- Department of Life Sciences, National Chung Hsing University, No. 145, Xingda Road, Taichung, 402 Taiwan
| | - Hsiao-Huei Chen
- Department of Life Sciences, National Chung Hsing University, No. 145, Xingda Road, Taichung, 402 Taiwan
| | - Jia-Fang Ho
- Department of Life Sciences, National Chung Hsing University, No. 145, Xingda Road, Taichung, 402 Taiwan
| | - Shin-Fei Chi
- Department of Life Sciences, National Chung Hsing University, No. 145, Xingda Road, Taichung, 402 Taiwan
| | - Fan-Chen Huang
- Department of Life Sciences, National Chung Hsing University, No. 145, Xingda Road, Taichung, 402 Taiwan
- Ph.D. Program in Microbial Genomics, National Chung Hsing University and Academia Sinica, Taichung, Taiwan
| | - Hungchen Emilie Yen
- Department of Life Sciences, National Chung Hsing University, No. 145, Xingda Road, Taichung, 402 Taiwan
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8
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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.
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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
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9
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Yu K, D'Odorico P, Carr DE, Personius A, Collins SL. The effect of nitrogen availability and water conditions on competition between a facultative CAM plant and an invasive grass. Ecol Evol 2017; 7:7739-7749. [PMID: 29043030 PMCID: PMC5632618 DOI: 10.1002/ece3.3296] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 06/20/2017] [Accepted: 07/03/2017] [Indexed: 11/11/2022] Open
Abstract
Plants with crassulacean acid metabolism (CAM) are increasing their abundance in drylands worldwide. The drivers and mechanisms underlying the increased dominance of CAM plants and CAM expression (i.e., nocturnal carboxylation) in facultative CAM plants, however, remain poorly understood. We investigated how nutrient and water availability affected competition between Mesembryanthemum crystallinum (a model facultative CAM species) and the invasive C3 grass Bromus mollis that co-occur in California's coastal grasslands. Specifically we investigated the extent to which water stress, nutrients, and competition affect nocturnal carboxylation in M. crystallinum. High nutrient and low water conditions favored M. crystallinum over B. mollis, in contrast to high water conditions. While low water conditions induced nocturnal carboxylation in 9-week-old individuals of M. crystallinum, in these low water treatments, a 66% reduction in nutrient applied over the entire experiment did not further enhance nocturnal carboxylation. In high water conditions M. crystallinum both alone and in association with B. mollis did not perform nocturnal carboxylation, regardless of the nutrient levels. Thus, nocturnal carboxylation in M. crystallinum was restricted by strong competition with B. mollis in high water conditions. This study provides empirical evidence of the competitive advantage of facultative CAM plants over grasses in drought conditions and of the restricted ability of M. crystallinum to use their photosynthetic plasticity (i.e., ability to switch to CAM behavior) to compete with grasses in well-watered conditions. We suggest that a high drought tolerance could explain the increased dominance of facultative CAM plants in a future environment with increased drought and nitrogen deposition, while the potential of facultative CAM plants such as M. crystallinum to expand to wet environments is expected to be limited.
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Affiliation(s)
- Kailiang Yu
- Department of Environmental SciencesUniversity of VirginiaCharlottesvilleVAUSA
- Department of BiologyUniversity of UtahSalt Lake CityUTUSA
| | - Paolo D'Odorico
- Department of Environmental SciencesUniversity of VirginiaCharlottesvilleVAUSA
- Department of Environmental Science, Policy and ManagementUniversity of CaliforniaBerkeleyCAUSA
| | - David E. Carr
- Department of BiologyUniversity of UtahSalt Lake CityUTUSA
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10
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Yu K, D'Odorico P, Li W, He Y. Effects of competition on induction of crassulacean acid metabolism in a facultative CAM plant. Oecologia 2017; 184:351-361. [PMID: 28401290 DOI: 10.1007/s00442-017-3868-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 04/06/2017] [Indexed: 10/19/2022]
Abstract
Abiotic drivers of environmental stress have been found to induce CAM expression (nocturnal carboxylation) in facultative CAM species such as Mesembryanthemum crystallinum. The role played by biotic factors such as competition with non-CAM species in affecting CAM expression, however, remains largely understudied. This research investigated the effects of salt and water conditions on the competition between M. crystallinum and the C3 grass Bromus mollis with which it is found to coexist in California's coastal grasslands. We also investigated the extent to which CAM expression in M. crystallinum was affected by the intensity of the competition with B. mollis. We found that M. crystallinum had a competitive advantage over B. mollis in drought and saline conditions, while B. mollis exerted strong competitive effects on M. crystallinum in access to light and soil nutrients in high water conditions. This strong competitive effect even outweighed the favorable effects of salt or water additions in increasing the biomass and productivity of M. crystallinum in mixture. Regardless of salt conditions, M. crystallinum did not switch to CAM photosynthesis in response to this strong competitive effect from B. mollis. Disturbance (i.e., grass cutting) reduced the competitive pressure by B. mollis and allowed for CAM expression in M. crystallinum when it was grown mixed with B. mollis. We suggest that moderate competition with other functional groups can enhance CAM expression in M. crystallinum, thereby affecting its plasticity and ability to cope with biological stress.
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Affiliation(s)
- Kailiang Yu
- Department of Environmental Sciences, University of Virginia, Charlottesville, VA, 22904, USA.
| | - Paolo D'Odorico
- Department of Environmental Sciences, University of Virginia, Charlottesville, VA, 22904, USA
| | - Wei Li
- Department of Environmental Sciences, University of Virginia, Charlottesville, VA, 22904, USA.,State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A and F University, Yangling, 712100, China
| | - Yongli He
- Department of Environmental Sciences, University of Virginia, Charlottesville, VA, 22904, USA.,Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou, 730000, China
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Hartwell J, Dever LV, Boxall SF. Emerging model systems for functional genomics analysis of Crassulacean acid metabolism. CURRENT OPINION IN PLANT BIOLOGY 2016; 31:100-8. [PMID: 27082281 DOI: 10.1016/j.pbi.2016.03.019] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Revised: 03/23/2016] [Accepted: 03/28/2016] [Indexed: 05/25/2023]
Abstract
Crassulacean acid metabolism (CAM) is one of three main pathways of photosynthetic carbon dioxide fixation found in higher plants. It stands out for its ability to underpin dramatic improvements in plant water use efficiency, which in turn has led to a recent renaissance in CAM research. The current ease with which candidate CAM-associated genes and proteins can be identified through high-throughput sequencing has opened up a new horizon for the development of diverse model CAM species that are amenable to genetic manipulations. The adoption of these model CAM species is underpinning rapid advances in our understanding of the complete gene set for CAM. We highlight recent breakthroughs in the functional characterisation of CAM genes that have been achieved through transgenic approaches.
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Affiliation(s)
- James Hartwell
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK.
| | - Louisa V Dever
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Susanna F Boxall
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
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12
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Borland AM, Guo HB, Yang X, Cushman JC. Orchestration of carbohydrate processing for crassulacean acid metabolism. CURRENT OPINION IN PLANT BIOLOGY 2016; 31:118-124. [PMID: 27101569 DOI: 10.1016/j.pbi.2016.04.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 03/31/2016] [Accepted: 04/04/2016] [Indexed: 06/05/2023]
Abstract
The production of phosphoenolpyruvate as a substrate for nocturnal CO2 uptake represents a significant sink for carbohydrate in CAM plants which has to be balanced with the provisioning of carbohydrate for growth and maintenance. In starch-storing CAM species, diversification in chloroplast metabolite transporters, and the deployment of both phosphorolytic and hydrolytic routes of starch degradation accommodate a division of labour in directing C-skeletons towards nocturnal carboxylation or production of sucrose for growth. In soluble-sugar storing CAM plants, the vacuole plays a central role in managing carbon homeostasis. The molecular identities of various types of vacuolar sugar transporters have only been identified for C3 species within the last 10 years. The recent availability of CAM genomes enables the identification of putative orthologues of vacuolar sugar transporters which represent strategic targets for orchestrating the diel provisioning of substrate for nocturnal carboxylation and growth.
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Affiliation(s)
- Anne M Borland
- School of Biology, Newcastle University, Newcastle upon Tyne NE17 RU, UK; Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6407, USA.
| | - Hao-Bo Guo
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Xiaohan Yang
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6407, USA
| | - John C Cushman
- Department of Biochemistry and Molecular Biology, University of Nevada, MS330, Reno, NV 89557-0330, USA
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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.
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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.)
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Holtum JAM, Winter K. Limited photosynthetic plasticity in the leaf-succulent CAM plant Agave angustifolia grown at different temperatures. FUNCTIONAL PLANT BIOLOGY : FPB 2014; 41:843-849. [PMID: 32481038 DOI: 10.1071/fp13284] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 02/19/2014] [Indexed: 06/11/2023]
Abstract
In Agave angustifolia Haw., a leaf-succulent constitutive crassulacean acid metabolism (CAM) plant of tropical Panama, we tested whether nocturnal CO2 uptake and growth were reduced at night temperatures above 20°C. Unlike some CAM model species from habitats with pronounced day-night temperature variations, in A. angustifolia temperature affected little the relative contributions of CAM and C3 photosynthesis to growth. In plants grown under 12h light/dark regimes of 25/17, 30/22 and 35/27°C, biomass increased with temperature. Maintaining day temperature at 35°C and reducing night temperature from 27 to 17°C markedly lowered growth, a reduction partially reversed when roots were heated to 27°C. Across all treatments, whole-shoot δ13C values ranged between -14.6 and -13.2 ‰, indicating a stable proportion of CO2 was fixed at night, between 75 and 83%. Nocturnal acidification reflected growth, varying between 339 and 393μmol H+ g-1 fresh mass and 63-87μmol H+ cm-2. In outdoor open-top chambers, warming the air 3°C above ambient at night did not reduce biomass accumulation. The persistence of a high capacity for nocturnal CO2 fixation at the expense of a limited capacity for switching between C3 and CAM probably makes this Agave, and others like it, potential species for biomass production in seasonally-dry landscapes.
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Affiliation(s)
- Joseph A M Holtum
- Tropical Biology, James Cook University, Townsville, Qld 4811, Australia
| | - Klaus Winter
- Smithsonian Tropical Research Institute, PO Box 0843-03092, Balboa, Ancon, Republic of Panama
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Winter K, Holtum JAM. Facultative crassulacean acid metabolism (CAM) plants: powerful tools for unravelling the functional elements of CAM photosynthesis. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:3425-41. [PMID: 24642847 DOI: 10.1093/jxb/eru063] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Facultative crassulacean acid metabolism (CAM) describes the optional use of CAM photosynthesis, typically under conditions of drought stress, in plants that otherwise employ C3 or C4 photosynthesis. In its cleanest form, the upregulation of CAM is fully reversible upon removal of stress. Reversibility distinguishes facultative CAM from ontogenetically programmed unidirectional C3-to-CAM shifts inherent in constitutive CAM plants. Using mainly measurements of 24h CO2 exchange, defining features of facultative CAM are highlighted in five terrestrial species, Clusia pratensis, Calandrinia polyandra, Mesembryanthemum crystallinum, Portulaca oleracea and Talinum triangulare. For these, we provide detailed chronologies of the shifts between photosynthetic modes and comment on their usefulness as experimental systems. Photosynthetic flexibility is also reviewed in an aquatic CAM plant, Isoetes howellii. Through comparisons of C3 and CAM states in facultative CAM species, many fundamental biochemical principles of the CAM pathway have been uncovered. Facultative CAM species will be of even greater relevance now that new sequencing technologies facilitate the mapping of genomes and tracking of the expression patterns of multiple genes. These technologies and facultative CAM systems, when joined, are expected to contribute in a major way towards our goal of understanding the essence of CAM.
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Affiliation(s)
- Klaus Winter
- Smithsonian Tropical Research Institute, PO Box 0843-03092, Balboa, Ancon, Republic of Panama
| | - Joseph A M Holtum
- Smithsonian Tropical Research Institute, PO Box 0843-03092, Balboa, Ancon, Republic of Panama School of Marine and Tropical Biology, James Cook University, Townsville, Queensland 4811, Australia
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Berry JO, Yerramsetty P, Zielinski AM, Mure CM. Photosynthetic gene expression in higher plants. PHOTOSYNTHESIS RESEARCH 2013; 117:91-120. [PMID: 23839301 DOI: 10.1007/s11120-013-9880-8] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Accepted: 06/26/2013] [Indexed: 05/08/2023]
Abstract
Within the chloroplasts of higher plants and algae, photosynthesis converts light into biological energy, fueling the assimilation of atmospheric carbon dioxide into biologically useful molecules. Two major steps, photosynthetic electron transport and the Calvin-Benson cycle, require many gene products encoded from chloroplast as well as nuclear genomes. The expression of genes in both cellular compartments is highly dynamic and influenced by a diverse range of factors. Light is the primary environmental determinant of photosynthetic gene expression. Working through photoreceptors such as phytochrome, light regulates photosynthetic genes at transcriptional and posttranscriptional levels. Other processes that affect photosynthetic gene expression include photosynthetic activity, development, and biotic and abiotic stress. Anterograde (from nucleus to chloroplast) and retrograde (from chloroplast to nucleus) signaling insures the highly coordinated expression of the many photosynthetic genes between these different compartments. Anterograde signaling incorporates nuclear-encoded transcriptional and posttranscriptional regulators, such as sigma factors and RNA-binding proteins, respectively. Retrograde signaling utilizes photosynthetic processes such as photosynthetic electron transport and redox signaling to influence the expression of photosynthetic genes in the nucleus. The basic C3 photosynthetic pathway serves as the default form used by most of the plant species on earth. High temperature and water stress associated with arid environments have led to the development of specialized C4 and CAM photosynthesis, which evolved as modifications of the basic default expression program. The goal of this article is to explain and summarize the many gene expression and regulatory processes that work together to support photosynthetic function in plants.
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Affiliation(s)
- James O Berry
- Department of Biological Sciences, University at Buffalo, Buffalo, NY, 14260, USA,
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