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Hudeček M, Nožková V, Plíhalová L, Plíhal O. Plant hormone cytokinin at the crossroads of stress priming and control of photosynthesis. FRONTIERS IN PLANT SCIENCE 2023; 13:1103088. [PMID: 36743569 PMCID: PMC9889983 DOI: 10.3389/fpls.2022.1103088] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Accepted: 12/29/2022] [Indexed: 06/18/2023]
Abstract
To cope with biotic and abiotic stress conditions, land plants have evolved several levels of protection, including delicate defense mechanisms to respond to changes in the environment. The benefits of inducible defense responses can be further augmented by defense priming, which allows plants to respond to a mild stimulus faster and more robustly than plants in the naïve (non-primed) state. Priming provides a low-cost protection of agriculturally important plants in a relatively safe and effective manner. Many different organic and inorganic compounds have been successfully tested to induce resistance in plants. Among the plethora of commonly used physicochemical techniques, priming by plant growth regulators (phytohormones and their derivatives) appears to be a viable approach with a wide range of applications. While several classes of plant hormones have been exploited in agriculture with promising results, much less attention has been paid to cytokinin, a major plant hormone involved in many biological processes including the regulation of photosynthesis. Cytokinins have been long known to be involved in the regulation of chlorophyll metabolism, among other functions, and are responsible for delaying the onset of senescence. A comprehensive overview of the possible mechanisms of the cytokinin-primed defense or stress-related responses, especially those related to photosynthesis, should provide better insight into some of the less understood aspects of this important group of plant growth regulators.
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Affiliation(s)
- Martin Hudeček
- Laboratory of Growth Regulators, Faculty of Science of Palacký University and Institute of Experimental Botany of the Czech Academy of Sciences, Olomouc, Czechia
| | - Vladimíra Nožková
- Department of Chemical Biology, Faculty of Science, Palacký University, Olomouc, Czechia
| | - Lucie Plíhalová
- Department of Chemical Biology, Faculty of Science, Palacký University, Olomouc, Czechia
| | - Ondřej Plíhal
- Laboratory of Growth Regulators, Faculty of Science of Palacký University and Institute of Experimental Botany of the Czech Academy of Sciences, Olomouc, Czechia
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Choudhary A, Senthil-Kumar M. Drought attenuates plant defence against bacterial pathogens by suppressing the expression of CBP60g/SARD1 during combined stress. PLANT, CELL & ENVIRONMENT 2022; 45:1127-1145. [PMID: 35102557 DOI: 10.1111/pce.14275] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 11/26/2021] [Accepted: 12/06/2021] [Indexed: 06/14/2023]
Abstract
In nature, plants are frequently exposed to drought and bacterial pathogens simultaneously. However, information on how the drought and defence pathways interact and orchestrate global transcriptional regulation is limited. Here, we show that moderate drought stress enhances the susceptibility of Arabidopsis thaliana to Pseudomonas syringae pv. tomato DC3000. Using transcriptome meta-analysis, we found that drought and bacterial stress antagonistically modulate a large set of genes predominantly involved in salicylic acid (SA) and abscisic acid (ABA) signalling networks. We identified that the levels of SA and ABA are dynamically regulated during the course of stress. Importantly, under combined stress, drought through the ABA pathway downregulates the induction of Calmodulin-binding Protein 60 g (CBP60g) and Systemic Acquired Resistance Deficient 1 (SARD1), two transcription factors crucial for SA production upon bacterial infection. We also identified an important role of NPR1-LIKE PROTEIN 3 and 4 (NPR3/4) transcriptional repressors in the drought-mediated negative regulation of CBP60g/SARD1 expression. Using a genetic approach, we show that CBP60g/SARD1 expression is the key determinant of plant defence against bacterial pathogens under combined stress. Thus, these transcription factors act as critical nodes for the crosstalk between drought and bacterial stress signalling under combined stress in plants.
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Affiliation(s)
- Aanchal Choudhary
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, India
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Cackett L, Luginbuehl LH, Schreier TB, Lopez-Juez E, Hibberd JM. Chloroplast development in green plant tissues: the interplay between light, hormone, and transcriptional regulation. THE NEW PHYTOLOGIST 2022; 233:2000-2016. [PMID: 34729790 DOI: 10.1111/nph.17839] [Citation(s) in RCA: 45] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 10/09/2021] [Indexed: 05/20/2023]
Abstract
Chloroplasts are best known for their role in photosynthesis, but they also allow nitrogen and sulphur assimilation, amino acid, fatty acid, nucleotide and hormone synthesis. How chloroplasts develop is therefore relevant to these diverse and fundamental biological processes, but also to attempts at their rational redesign. Light is strictly required for chloroplast formation in all angiosperms and directly regulates the expression of hundreds of chloroplast-related genes. Light also modulates the levels of several hormones including brassinosteriods, cytokinins, auxins and gibberellins, which themselves control chloroplast development particularly during early stages of plant development. Transcription factors such as GOLDENLIKE1&2 (GLK1&2), GATA NITRATE-INDUCIBLE CARBON METABOLISM-INVOLVED (GNC) and CYTOKININ-RESPONSIVE GATA FACTOR 1 (CGA1) act downstream of both light and phytohormone signalling to regulate chloroplast development. Thus, in green tissues transcription factors, light signalling and hormone signalling form a complex network regulating the transcription of chloroplast- and photosynthesis-related genes to control the development and number of chloroplasts per cell. We use this conceptual framework to identify points of regulation that could be harnessed to modulate chloroplast abundance and increase photosynthetic efficiency of crops, and to highlight future avenues to overcome gaps in current knowledge.
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Affiliation(s)
- Lee Cackett
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
| | - Leonie H Luginbuehl
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
| | - Tina B Schreier
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
| | - Enrique Lopez-Juez
- Department of Biological Sciences, Royal Holloway University of London, Egham, TW20 0EX, UK
| | - Julian M Hibberd
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
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Hönig M, Plíhalová L, Husičková A, Nisler J, Doležal K. Role of Cytokinins in Senescence, Antioxidant Defence and Photosynthesis. Int J Mol Sci 2018; 19:E4045. [PMID: 30558142 PMCID: PMC6321018 DOI: 10.3390/ijms19124045] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 12/05/2018] [Accepted: 12/12/2018] [Indexed: 01/13/2023] Open
Abstract
Cytokinins modulate a number of important developmental processes, including the last phase of leaf development, known as senescence, which is associated with chlorophyll breakdown, photosynthetic apparatus disintegration and oxidative damage. There is ample evidence that cytokinins can slow down all these senescence-accompanying changes. Here, we review relationships between the various mechanisms of action of these regulatory molecules. We highlight their connection to photosynthesis, the pivotal process that generates assimilates, however may also lead to oxidative damage. Thus, we also focus on cytokinin induction of protective responses against oxidative damage. Activation of antioxidative enzymes in senescing tissues is described as well as changes in the levels of naturally occurring antioxidative compounds, such as phenolic acids and flavonoids, in plant explants. The main goal of this review is to show how the biological activities of cytokinins may be related to their chemical structure. New links between molecular aspects of natural cytokinins and their synthetic derivatives with antisenescent properties are described. Structural motifs in cytokinin molecules that may explain why these molecules play such a significant regulatory role are outlined.
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Affiliation(s)
- Martin Hönig
- Department of Chemical Biology and Genetics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic.
- Laboratory of Growth Regulators, Centre of the Region Haná for Biotechnological and Agricultural Research, Palacký University & Institute of Experimental Botany ASCR, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic.
| | - Lucie Plíhalová
- Department of Chemical Biology and Genetics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic.
- Laboratory of Growth Regulators, Centre of the Region Haná for Biotechnological and Agricultural Research, Palacký University & Institute of Experimental Botany ASCR, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic.
| | - Alexandra Husičková
- Department of Biophysics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic.
| | - Jaroslav Nisler
- Department of Chemical Biology and Genetics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic.
- Laboratory of Growth Regulators, Centre of the Region Haná for Biotechnological and Agricultural Research, Palacký University & Institute of Experimental Botany ASCR, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic.
| | - Karel Doležal
- Department of Chemical Biology and Genetics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic.
- Laboratory of Growth Regulators, Centre of the Region Haná for Biotechnological and Agricultural Research, Palacký University & Institute of Experimental Botany ASCR, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic.
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Yamburenko MV, Zubo YO, Börner T. Abscisic acid affects transcription of chloroplast genes via protein phosphatase 2C-dependent activation of nuclear genes: repression by guanosine-3'-5'-bisdiphosphate and activation by sigma factor 5. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 82:1030-1041. [PMID: 25976841 DOI: 10.1111/tpj.12876] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 04/24/2015] [Accepted: 05/01/2015] [Indexed: 05/07/2023]
Abstract
Abscisic acid (ABA) represses the transcriptional activity of chloroplast genes (determined by run-on assays), with the exception of psbD and a few other genes in wild-type Arabidopsis seedlings and mature rosette leaves. Abscisic acid does not influence chloroplast transcription in the mutant lines abi1-1 and abi2-1 with constitutive protein phosphatase 2C (PP2C) activity, suggesting that ABA affects chloroplast gene activity by binding to the pyrabactin resistance (PYR)/PYR1-like or regulatory component of ABA receptor protein family (PYR/PYL/RCAR) and signaling via PP2Cs and sucrose non-fermenting protein-related kinases 2 (SnRK2s). Further we show by quantitative PCR that ABA enhances the transcript levels of RSH2, RSH3, PTF1 and SIG5. RelA/SpoT homolog 2 (RSH2) and RSH3 are known to synthesize guanosine-3'-5'-bisdiphosphate (ppGpp), an inhibitor of the plastid-gene-encoded chloroplast RNA polymerase. We propose, therefore, that ABA leads to an inhibition of chloroplast gene expression via stimulation of ppGpp synthesis. On the other hand, sigma factor 5 (SIG5) and plastid transcription factor 1 (PTF1) are known to be necessary for the transcription of psbD from a specific light- and stress-induced promoter (the blue light responsive promoter, BLRP). We demonstrate that ABA activates the psbD gene by stimulation of transcription initiation at BLRP. Taken together, our data suggest that ABA affects the transcription of chloroplast genes by a PP2C-dependent activation of nuclear genes encoding proteins involved in chloroplast transcription.
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Affiliation(s)
- Maria V Yamburenko
- Institute of Biology-Genetics, Faculty of Life Sciences, Humboldt University, Chausseestrasse 117, 10115, Berlin, Germany
| | - Yan O Zubo
- Institute of Biology-Genetics, Faculty of Life Sciences, Humboldt University, Chausseestrasse 117, 10115, Berlin, Germany
| | - Thomas Börner
- Institute of Biology-Genetics, Faculty of Life Sciences, Humboldt University, Chausseestrasse 117, 10115, Berlin, Germany
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Transcriptome analysis of cytokinin response in tomato leaves. PLoS One 2013; 8:e55090. [PMID: 23372818 PMCID: PMC3555872 DOI: 10.1371/journal.pone.0055090] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 12/24/2012] [Indexed: 01/05/2023] Open
Abstract
Tomato is one of the most economically and agriculturally important Solanaceous species and vegetable crops, serving as a model for examination of fruit biology and compound leaf development. Cytokinin is a plant hormone linked to the control of leaf development and is known to regulate a wide range of genes including many transcription factors. Currently there is little known of the leaf transcriptome in tomato and how it might be regulated by cytokinin. We employ high throughput mRNA sequencing technology and bioinformatic methodologies to robustly analyze cytokinin regulated tomato leaf transcriptomes. Leaf samples of two ages, 13d and 35d were treated with cytokinin or the solvent vehicle control dimethyl sulfoxide (DMSO) for 2 h or 24 h, after which RNA was extracted for sequencing. To confirm the accuracy of RNA sequencing results, we performed qPCR analysis of select transcripts identified as cytokinin regulated by the RNA sequencing approach. The resulting data provide the first hormone transcriptome analysis of leaves in tomato. Specifically we identified several previously untested tomato orthologs of cytokinin-related genes as well as numerous novel cytokinin-regulated transcripts in tomato leaves. Principal component analysis of the data indicates that length of cytokinin treatment and plant age are the major factors responsible for changes in transcripts observed in this study. Two hour cytokinin treatment showed a more robust transcript response indicated by both greater fold change of induced transcripts and the induction of twice as many cytokinin-related genes involved in signaling, metabolism, and transport in young vs. older leaves. This difference in transcriptome response in younger vs. older leaves was also found to a lesser extent with an extended (24 h) cytokinin treatment. Overall data presented here provides a solid foundation for future study of cytokinin and cytokinin regulated genes involved in compound leaf development or other developmental processes in tomato.
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Hu X, Wu X, Li C, Lu M, Liu T, Wang Y, Wang W. Abscisic acid refines the synthesis of chloroplast proteins in maize (Zea mays) in response to drought and light. PLoS One 2012; 7:e49500. [PMID: 23152915 PMCID: PMC3496715 DOI: 10.1371/journal.pone.0049500] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 10/09/2012] [Indexed: 12/18/2022] Open
Abstract
To better understand abscisic acid (ABA) regulation of the synthesis of chloroplast proteins in maize (Zea mays L.) in response to drought and light, we compared leaf proteome differences between maize ABA-deficient mutant vp5 and corresponding wild-type Vp5 green and etiolated seedlings exposed to drought stress. Proteins extracted from the leaves of Vp5 and vp5 seedlings were used for two-dimensional electrophoresis (2-DE) and subsequent matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). After Coomassie brilliant blue staining, approximately 450 protein spots were reproducibly detected on 2-DE gels. A total of 36 differentially expressed protein spots in response to drought and light were identified using MALDI-TOF MS and their subcellular localization was determined based on the annotation of reviewed accession in UniProt Knowledgebase and the software prediction. As a result, corresponding 13 proteins of the 24 differentially expressed protein spots were definitely localized in chloroplasts and their expression was in an ABA-dependent way, including 6 up-regulated by both drought and light, 5 up-regulated by drought but down-regulated by light, 5 up-regulated by light but down-regulated by drought; 5 proteins down-regulated by drought were mainly those involved in photosynthesis and ATP synthesis. Thus, the results in the present study supported the vital role of ABA in regulating the synthesis of drought- and/or light-induced proteins in maize chloroplasts and would facilitate the functional characterization of ABA-induced chloroplast proteins in C(4) plants.
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Affiliation(s)
- Xiuli Hu
- Key Laboratory of Physiological Ecology and Genetic Improvement of Food Crops in Henan Province, Henan Agricultural University, Zhengzhou, China
- College of Life Science, Henan Agricultural University, Zhengzhou, China
| | - Xiaolin Wu
- College of Life Science, Henan Agricultural University, Zhengzhou, China
| | - Chaohai Li
- Key Laboratory of Physiological Ecology and Genetic Improvement of Food Crops in Henan Province, Henan Agricultural University, Zhengzhou, China
- College of Agronomy, Henan Agricultural University, Zhengzhou, China
| | - Minghui Lu
- College of Life Science, Henan Agricultural University, Zhengzhou, China
| | - Tianxue Liu
- Key Laboratory of Physiological Ecology and Genetic Improvement of Food Crops in Henan Province, Henan Agricultural University, Zhengzhou, China
- College of Agronomy, Henan Agricultural University, Zhengzhou, China
| | - Ying Wang
- College of Life Science, Henan Agricultural University, Zhengzhou, China
| | - Wei Wang
- Key Laboratory of Physiological Ecology and Genetic Improvement of Food Crops in Henan Province, Henan Agricultural University, Zhengzhou, China
- College of Life Science, Henan Agricultural University, Zhengzhou, China
- * E-mail:
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Cortleven A, Valcke R. Evaluation of the photosynthetic activity in transgenic tobacco plants with altered endogenous cytokinin content: lessons from cytokinin. PHYSIOLOGIA PLANTARUM 2012; 144:394-408. [PMID: 22182256 DOI: 10.1111/j.1399-3054.2011.01558.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Cytokinin is known to be involved in many processes related to plastid development and function but the exact role of cytokinin in photosynthesis remains elusive. To investigate more profoundly the effects of cytokinin in this process, the photosynthetic activity of transgenic Pssuipt and 35S:CKX1 tobacco (Nicotiana tabacum) plants with respectively elevated and reduced endogenous cytokinin content was evaluated. Pigment analysis indicated that elevated endogenous cytokinin content resulted in increased pigment content. Functional analysis of the photosynthetic apparatus by chlorophyll a fluorescence and in vitro electron transport measurements clearly showed that changing the endogenous cytokinin content affects the activity of the photosynthetic apparatus. Surprisingly, both an increase as well as a decrease in cytokinin content results in a better photosynthetic performance. Quenching analysis revealed that the initial responses of the photosynthetic apparatus on a dark-light transition are not affected by changed cytokinin content. However, it has an effect on the further kinetic behavior. Taken together, we suggest that cytokinins can induce structural changes in the different parts of the electron transport chain as also demonstrated by the in vitro electron transport measurements.
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Affiliation(s)
- Anne Cortleven
- UHasselt, Laboratory of Molecular and Physical Plant Physiology, Faculty of Sciences, Agoralaan, Bldg.D, B-3590 Diepenbeek, Belgium
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Cortleven A, Noben JP, Valcke R. Analysis of the photosynthetic apparatus in transgenic tobacco plants with altered endogenous cytokinin content: a proteomic study. Proteome Sci 2011; 9:33. [PMID: 21703031 PMCID: PMC3151202 DOI: 10.1186/1477-5956-9-33] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Accepted: 06/26/2011] [Indexed: 01/18/2023] Open
Abstract
Background Cytokinin is a plant hormone that plays a crucial role in several processes of plant growth and development. In recent years, major breakthroughs have been achieved in the elucidation of the metabolism, the signal perception and transduction, as well as the biological functions of cytokinin. An important activity of cytokinin is the involvement in chloroplast development and function. Although this biological function has already been known for 50 years, the exact mechanisms remain elusive. Results To elucidate the effects of altered endogenous cytokinin content on the structure and function of the chloroplasts, chloroplast subfractions (stroma and thylakoids) from transgenic Pssu-ipt and 35S:CKX1 tobacco (Nicotiana tabacum) plants with, respectively, elevated and reduced endogenous cytokinin content were analysed using two different 2-DE approaches. Firstly, thykaloids were analysed by blue-native polyacrylamide gel electrophoresis followed by SDS-PAGE (BN/SDS-PAGE). Image analysis of the gel spot pattern thus obtained from thylakoids showed no substantial differences between wild-type and transgenic tobacco plants. Secondly, a quantitative DIGE analysis of CHAPS soluble proteins derived from chloroplast subfractions indicated significant gel spot abundance differences in the stroma fraction. Upon identification by MALDI-TOF/TOF mass spectrometry, these proteins could be assigned to the Calvin-Benson cycle and photoprotective mechanisms. Conclusion Taken together, presented proteomic data reveal that the constitutively altered cytokinin status of transgenic plants does not result in any qualitative changes in either stroma proteins or protein complexes of thylakoid membranes of fully developed chloroplasts, while few but significant quantitative differences are observed in stroma proteins.
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Affiliation(s)
- Anne Cortleven
- Laboratory of Molecular and Physical Plant Physiology, Faculty of Sciences, Hasselt University, Diepenbeek, Belgium.
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Gollan PJ, Bhave M. A thylakoid-localised FK506-binding protein in wheat may be linked to chloroplast biogenesis. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2010; 48:655-662. [PMID: 20570161 DOI: 10.1016/j.plaphy.2010.05.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2009] [Revised: 04/21/2010] [Accepted: 05/03/2010] [Indexed: 05/29/2023]
Abstract
Plant chloroplasts contain a large proportion of immunophilins, comprising the FK506-binding proteins (FKBPs) and cyclophilins (CYPs), which are members of the peptidyl-prolyl cis/trans isomerase (PPIase) family of proline-folding enzymes. Some of the chloroplastic immunophilins are known to chaperone certain photosynthetic proteins, however the functions of a majority of these proteins are unknown. This work focussed on characterisation of genes encoding the chloroplast-localised FKBP16-1 from wheat and its progenitor species, and identification of its putative promoters, as well as investigations into the effects of light regulation and plant development on its expression. The work identified several alternatively spliced FKBP16-1 transcripts, indicating expression of FKBP16-1 may be post-transcriptionally regulated. FKBP16-1 was expressed in both green and etiolated tissues, and highest levels were detected in developing tissues, indicating a role in chloroplast biogenesis. We also report a novel transcription module, designated 'chloroplast biogenesis module' (CBM) in the FKBP16-1 promoter of cereals that also appears to be involved in the regulation of additional genes involved in chloroplast biogenesis or other aspects of plant development. The results point to considerable potential for a role for FKBP16-1 in early chloroplast development, architecture of photosynthetic apparatus and plant development.
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Affiliation(s)
- Peter J Gollan
- Environment and Biotechnology Centre, Faculty of Life and Social Sciences, Swinburne University of Technology, P O Box 218, Hawthorn, Victoria 3122, Australia
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Zavaleta-Mancera HA, López-Delgado H, Loza-Tavera H, Mora-Herrera M, Trevilla-García C, Vargas-Suárez M, Ougham H. Cytokinin promotes catalase and ascorbate peroxidase activities and preserves the chloroplast integrity during dark-senescence. JOURNAL OF PLANT PHYSIOLOGY 2007; 164:1572-82. [PMID: 17485137 DOI: 10.1016/j.jplph.2007.02.003] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Revised: 02/26/2007] [Accepted: 02/26/2007] [Indexed: 05/15/2023]
Abstract
Increased oxidative stress displayed during dark-senescence of wheat leaves (Triticum aestivum L.) is caused not only by the increased levels of radicals but also by a loss of antioxidant capacity. Mature leaves were incubated in 6-benzylaminopurine (BAP 10(-4)M) or water (control) during 6d in the dark. The senescence-delaying effect of BAP was associated with the retention of the chloroplast structure, 60% of the initial content of chlorophyll (Chl) and 77% of the initial content of protein. BAP reduced the degradation of the light-harvesting chlorophyll a/b binding protein (LHCP-2), and the large (LSU) and small subunits (SSU) of Rubisco. Our results indicated that the presence of the NADPH:protochlorophyllide oxidoreductase (POR, EC.1.6.99.1) was not promoted by the cytokinin, leading to the conclusion that BAP maintains the level of Chl, preventing its degradation, rather than inducing Chl biosynthesis. The internal structure of chloroplasts was maintained in BAP-treated leaves for up to 6d, with well-organized grana thylakoids and small plastoglobuli; in contrast, chloroplasts of control leaves deteriorated rapidly from day 4 with disorganized internal membranes, and more and larger plastoglobuli. BAP increased the activities of catalase (CAT, EC 1.11.1.6) and ascorbate peroxidase (APX, EC 1.11.1.11) and reduced the level of H(2)O(2) in the delayed-senescence tissue. The present research indicates that BAP reduces levels of reactive oxygen species (ROS), and enhances the activity of antioxidant enzymes (CAT, APX). Our results suggest that BAP protects the cell membranes and the photosynthetic machinery from oxidative damage during delay of senescence in the dark.
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Zubo YO, Selivankina SY, Yamburenko MV, Zubkova NK, Kulaeva ON, Kusnetsov VV. Cytokinins activate transcription of chloroplast genes. DOKL BIOCHEM BIOPHYS 2005; 400:48-51. [PMID: 15846983 DOI: 10.1007/s10628-005-0030-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Ya O Zubo
- Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow
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Spiro MD, Torabi B, Cornell CN. Cytokinins Induce Photomorphogenic Development in Dark-grown Gametophytes of Ceratopteris richardii. ACTA ACUST UNITED AC 2004; 45:1252-60. [PMID: 15509848 DOI: 10.1093/pcp/pch146] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The cytokinins benzylaminopurine, kinetin and isopentenyladenine induce photomorphogenesis in dark-grown gametophytes of the fern Ceratopteris richardii. At sub-nanomolar concentrations each altered the rate and pattern of cell division, elongation and differentiation, mimicking aspects of the light-mediated transition from filamentous to prothallial growth. Untreated dark-grown gametophytes grow as narrow, elongate, asexual filaments with an apical meristem. Cytokinin treatments as low as 10(-12) M reduced the length-to-width ratio through decreased cell elongation, increased periclinal cell division and induced the formation of rhizoid initials in the cells immediately below the apical meristem. Higher concentrations (10(-9)-10(-8) M) induced conversion of the meristem from apical to notch morphology. Cytokinins induced both red- and blue-light-mediated photomorphogenic events, suggesting stimulation of both phytochrome and cryptochrome signaling; however, cytokinin treatment only partially substituted for light in that it did not induce hermaphroditic sexual development or spore germination in the dark. Additionally, cytokinins did not increase chlorophyll synthesis in dark-grown gametophytes, which unlike angiosperms are able to produce mature chloroplasts in the dark. Cytokinin treatment had only slight effects on light-grown gametophytes. These results suggest evolutionary conservation between angiosperms and pteridophytes in the role of cytokinins in regulating photomorphogenesis.
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Affiliation(s)
- Mark D Spiro
- Biology Department, Bucknell University, Lewisburg, PA 17837, USA.
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