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Singh RK, Bhalerao RP, Eriksson ME. Growing in time: exploring the molecular mechanisms of tree growth. TREE PHYSIOLOGY 2021; 41:657-678. [PMID: 32470114 PMCID: PMC8033248 DOI: 10.1093/treephys/tpaa065] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 03/31/2020] [Accepted: 05/27/2020] [Indexed: 05/31/2023]
Abstract
Trees cover vast areas of the Earth's landmasses. They mitigate erosion, capture carbon dioxide, produce oxygen and support biodiversity, and also are a source of food, raw materials and energy for human populations. Understanding the growth cycles of trees is fundamental for many areas of research. Trees, like most other organisms, have evolved a circadian clock to synchronize their growth and development with the daily and seasonal cycles of the environment. These regular changes in light, daylength and temperature are perceived via a range of dedicated receptors and cause resetting of the circadian clock to local time. This allows anticipation of daily and seasonal fluctuations and enables trees to co-ordinate their metabolism and physiology to ensure vital processes occur at the optimal times. In this review, we explore the current state of knowledge concerning the regulation of growth and seasonal dormancy in trees, using information drawn from model systems such as Populus spp.
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Affiliation(s)
- Rajesh Kumar Singh
- Department of Plant Physiology, Umeå Plant Science Centre, Umeå University, Umeå SE-901 87, Sweden
| | - Rishikesh P Bhalerao
- Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, Umeå SE-901 82, Sweden
| | - Maria E Eriksson
- Department of Plant Physiology, Umeå Plant Science Centre, Umeå University, Umeå SE-901 87, Sweden
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Casal JJ, Estevez JM. Auxin-Environment Integration in Growth Responses to Forage for Resources. Cold Spring Harb Perspect Biol 2021; 13:a040030. [PMID: 33431585 PMCID: PMC8015692 DOI: 10.1101/cshperspect.a040030] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Plant fitness depends on the adequate morphological adjustment to the prevailing conditions of the environment. Therefore, plants sense environmental cues through their life cycle, including the presence of full darkness, light, or shade, the range of ambient temperatures, the direction of light and gravity vectors, and the presence of water and mineral nutrients (such as nitrate and phosphate) in the soil. The environmental information impinges on different aspects of the auxin system such as auxin synthesis, degradation, transport, perception, and downstream transcriptional regulation to modulate organ growth. Although a single environmental cue can affect several of these points, the relative impacts differ significantly among the various growth processes and cues. While stability in the generation of precise auxin gradients serves to guide the basic developmental pattern, dynamic changes in the auxin system fine-tune body shape to optimize the capture of environmental resources.
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Affiliation(s)
- Jorge J Casal
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA), Facultad de Agronomía, Buenos Aires 1417, Argentina
- Fundación Instituto Leloir and IIBBA-CONICET, Buenos Aires C1405BWE, Argentina
| | - José M Estevez
- Fundación Instituto Leloir and IIBBA-CONICET, Buenos Aires C1405BWE, Argentina
- Centro de Biotecnología Vegetal, Facultad de Ciencias de la Vida, Universidad Andres Bello and Millennium Institute for Integrative Biology (iBio), Santiago 8370146, Chile
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3
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Fortunato AE, Jaubert M, Enomoto G, Bouly JP, Raniello R, Thaler M, Malviya S, Bernardes JS, Rappaport F, Gentili B, Huysman MJJ, Carbone A, Bowler C, d'Alcalà MR, Ikeuchi M, Falciatore A. Diatom Phytochromes Reveal the Existence of Far-Red-Light-Based Sensing in the Ocean. THE PLANT CELL 2016; 28:616-28. [PMID: 26941092 PMCID: PMC4826011 DOI: 10.1105/tpc.15.00928] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Revised: 02/16/2016] [Accepted: 02/29/2016] [Indexed: 05/22/2023]
Abstract
The absorption of visible light in aquatic environments has led to the common assumption that aquatic organisms sense and adapt to penetrative blue/green light wavelengths but show little or no response to the more attenuated red/far-red wavelengths. Here, we show that two marine diatom species, Phaeodactylum tricornutum and Thalassiosira pseudonana, possess a bona fide red/far-red light sensing phytochrome (DPH) that uses biliverdin as a chromophore and displays accentuated red-shifted absorbance peaks compared with other characterized plant and algal phytochromes. Exposure to both red and far-red light causes changes in gene expression in P. tricornutum, and the responses to far-red light disappear in DPH knockout cells, demonstrating that P. tricornutum DPH mediates far-red light signaling. The identification of DPH genes in diverse diatom species widely distributed along the water column further emphasizes the ecological significance of far-red light sensing, raising questions about the sources of far-red light. Our analyses indicate that, although far-red wavelengths from sunlight are only detectable at the ocean surface, chlorophyll fluorescence and Raman scattering can generate red/far-red photons in deeper layers. This study opens up novel perspectives on phytochrome-mediated far-red light signaling in the ocean and on the light sensing and adaptive capabilities of marine phototrophs.
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Affiliation(s)
- Antonio Emidio Fortunato
- Sorbonne Universités, UPMC, Institut de Biologie Paris-Seine, CNRS, Laboratoire de Biologie Computationnelle et Quantitative UMR 7238, 75006 Paris, France
| | - Marianne Jaubert
- Sorbonne Universités, UPMC, Institut de Biologie Paris-Seine, CNRS, Laboratoire de Biologie Computationnelle et Quantitative UMR 7238, 75006 Paris, France
| | - Gen Enomoto
- Department of Life Sciences (Biology), Graduate School of Arts and Sciences, The University of Tokyo, Meguro, Tokyo 153-8902, Japan
| | - Jean-Pierre Bouly
- Sorbonne Universités, UPMC, Institut de Biologie Paris-Seine, CNRS, Laboratoire de Biologie Computationnelle et Quantitative UMR 7238, 75006 Paris, France
| | | | - Michael Thaler
- Sorbonne Universités, UPMC, Institut de Biologie Paris-Seine, CNRS, Laboratoire de Biologie Computationnelle et Quantitative UMR 7238, 75006 Paris, France
| | - Shruti Malviya
- Ecole Normale Supérieure, PSL Research University, Institut de Biologie de l'Ecole Normale Supérieure, CNRS UMR 8197, INSERM U1024, F-75005 Paris, France
| | - Juliana Silva Bernardes
- Sorbonne Universités, UPMC, Institut de Biologie Paris-Seine, CNRS, Laboratoire de Biologie Computationnelle et Quantitative UMR 7238, 75006 Paris, France
| | - Fabrice Rappaport
- Institut de Biologie Physico-Chimique, UMR 7141 CNRS-UPMC, 75005 Paris, France
| | - Bernard Gentili
- Sorbonne Universités, UPMC Univ-Paris 6, CNRS, UMR 7093, Laboratoire d'Océanologie de Villefranche, F-06230 Villefranche/mer, France
| | - Marie J J Huysman
- Protistology and Aquatic Ecology, Department of Biology, Ghent University, B-9000 Gent, Belgium Department of Plant Systems Biology, VIB, B-9052 Gent, Belgium Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Gent, Belgium
| | - Alessandra Carbone
- Sorbonne Universités, UPMC, Institut de Biologie Paris-Seine, CNRS, Laboratoire de Biologie Computationnelle et Quantitative UMR 7238, 75006 Paris, France Institut Universitaire de France, 75005 Paris, France
| | - Chris Bowler
- Ecole Normale Supérieure, PSL Research University, Institut de Biologie de l'Ecole Normale Supérieure, CNRS UMR 8197, INSERM U1024, F-75005 Paris, France
| | | | - Masahiko Ikeuchi
- Department of Life Sciences (Biology), Graduate School of Arts and Sciences, The University of Tokyo, Meguro, Tokyo 153-8902, Japan
| | - Angela Falciatore
- Sorbonne Universités, UPMC, Institut de Biologie Paris-Seine, CNRS, Laboratoire de Biologie Computationnelle et Quantitative UMR 7238, 75006 Paris, France
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Chen S, Lory N, Stauber J, Hoecker U. Photoreceptor Specificity in the Light-Induced and COP1-Mediated Rapid Degradation of the Repressor of Photomorphogenesis SPA2 in Arabidopsis. PLoS Genet 2015; 11:e1005516. [PMID: 26368289 PMCID: PMC4569408 DOI: 10.1371/journal.pgen.1005516] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 08/19/2015] [Indexed: 11/18/2022] Open
Abstract
The Arabidopsis COP1/SPA E3 ubiquitin ligase is a key negative regulator that represses light signaling in darkness by targeting transcription factors involved in the light response for degradation. The COP1/SPA complex consists of COP1 and members of the four-member SPA protein family (SPA1-SPA4). Genetic analysis indicated that COP1/SPA2 function is particularly strongly repressed by light when compared to complexes carrying the other three SPAs, thereby promoting a light response after exposure of plants to extremely low light. Here, we show that the SPA2 protein is degraded within 5–15 min after exposure of dark-grown seedlings to a pulse of light. Phytochrome photoreceptors are required for the rapid degradation of SPA2 in red, far-red and also in blue light, whereas cryptochromes are not involved in the rapid, blue light-induced reduction in SPA2 protein levels. These results uncover a photoreceptor-specific mechanism of light-induced inhibition of COP1/SPA2 function. Phytochrome A (phyA) is required for the severe blue light responsiveness of spa triple mutants expressing only SPA2, thus confirming the important role of phyA in downregulating SPA2 function in blue light. In blue light, SPA2 forms a complex with cryptochrome 1 (cry1), but not with cryptochrome 2 (cry2) in vivo, indicating that the lack of a rapid blue light response of the SPA2 protein is only in part caused by a failure to interact with cryptochromes. Since SPA1 interacts with both cry1 and cry2, these results provide first molecular evidence that the light-regulation of different SPA proteins diverged during evolution. SPA2 degradation in the light requires COP1 and the COP1-interacting coiled-coil domain of SPA2, supporting that SPA2 is ubiquitinated by COP1. We propose that light perceived by phytochromes causes a switch in the ubiquitination activity of COP1/SPA2 from ubiquitinating downstream substrates to ubiquitinating SPA2, which subsequently causes a repression of COP1/SPA2 function. Plants have evolved photoreceptors that initiate a signaling cascade to adjust growth and development to the ambient light environment. The CUL4-dependent COP1/SPA E3 ubiquitin ligase is a key negative regulator of light signaling whose function is repressed by light. Recent research has identified mechanisms that are common to both phytochrome and cryptochrome photoreceptors. Here, we have identified a mechanism of light-induced COP1/SPA repression that is specific to phytochrome photoreceptors. We show that the SPA2 protein is very rapidly degraded in red, far-red and blue light in a phytochrome-dependent fashion. We further show that SPA2 degradation in the light depends on COP1 and on the interaction of SPA2 with COP1. Hence, our results suggest a light-induced degradation of SPA2, but not of COP1, by the COP1/SPA2 ubiquitin ligase. The human ortholog of COP1, which functions without the plant-specific SPA proteins, is known to be regulated by autodegradation following DNA damage. Hence, autodegradation of components of this E3 ligase is a regulatory mechanism used in both humans and plants.
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Affiliation(s)
- Song Chen
- Botanical Institute and Cluster of Excellence on Plant Sciences (CEPLAS), Biocenter, University of Cologne, Cologne, Germany
| | - Niels Lory
- Botanical Institute and Cluster of Excellence on Plant Sciences (CEPLAS), Biocenter, University of Cologne, Cologne, Germany
| | - Johannes Stauber
- Botanical Institute and Cluster of Excellence on Plant Sciences (CEPLAS), Biocenter, University of Cologne, Cologne, Germany
| | - Ute Hoecker
- Botanical Institute and Cluster of Excellence on Plant Sciences (CEPLAS), Biocenter, University of Cologne, Cologne, Germany
- * E-mail:
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Kanegae T, Kimura I. A phytochrome/phototropin chimeric photoreceptor of fern functions as a blue/far-red light-dependent photoreceptor for phototropism in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 83:480-8. [PMID: 26095327 DOI: 10.1111/tpj.12903] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 05/27/2015] [Accepted: 06/01/2015] [Indexed: 05/07/2023]
Abstract
In the fern Adiantum capillus-veneris, the phototropic response of the protonemal cells is induced by blue light and partially inhibited by subsequent irradiation with far-red light. This observation strongly suggests the existence of a phytochrome that mediates this blue/far-red reversible response; however, the phytochrome responsible for this response has not been identified. PHY3/NEO1, one of the three phytochrome genes identified in Adiantum, encodes a chimeric photoreceptor composed of both a phytochrome and a phototropin domain. It was demonstrated that phy3 mediates the red light-dependent phototropic response of Adiantum, and that phy3 potentially functions as a phototropin. These findings suggest that phy3 is the phytochrome that mediates the blue/far-red response in Adiantum protonemata. In the present study, we expressed Adiantum phy3 in a phot1 phot2 phototropin-deficient Arabidopsis line, and investigated the ability of phy3 to induce phototropic responses under various light conditions. Blue light irradiation clearly induced a phototropic response in the phy3-expressing transgenic seedlings, and this effect was fully inhibited by simultaneous irradiation with far-red light. In addition, experiments using amino acid-substituted phy3 indicated that FMN-cysteinyl adduct formation in the light, oxygen, voltage (LOV) domain was not necessary for the induction of blue light-dependent phototropism by phy3. We thus demonstrate that phy3 is the phytochrome that mediates the blue/far-red reversible phototropic response in Adiantum. Furthermore, our results imply that phy3 can function as a phototropin, but that it acts principally as a phytochrome that mediates both the red/far-red and blue/far-red light responses.
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Affiliation(s)
- Takeshi Kanegae
- Department of Biological Sciences, Graduate School of Science and Technology, Tokyo Metropolitan University, Minami Osawa, Hachioji, Tokyo, 192-0397, Japan
| | - Izumi Kimura
- Department of Biological Sciences, Graduate School of Science and Technology, Tokyo Metropolitan University, Minami Osawa, Hachioji, Tokyo, 192-0397, Japan
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Christie JM, Blackwood L, Petersen J, Sullivan S. Plant flavoprotein photoreceptors. PLANT & CELL PHYSIOLOGY 2015; 56:401-13. [PMID: 25516569 PMCID: PMC4357641 DOI: 10.1093/pcp/pcu196] [Citation(s) in RCA: 139] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 12/02/2014] [Indexed: 05/18/2023]
Abstract
Plants depend on the surrounding light environment to direct their growth. Blue light (300-500 nm) in particular acts to promote a wide variety of photomorphogenic responses including seedling establishment, phototropism and circadian clock regulation. Several different classes of flavin-based photoreceptors have been identified that mediate the effects of blue light in the dicotyledonous genetic model Arabidopsis thaliana. These include the cryptochromes, the phototropins and members of the Zeitlupe family. In this review, we discuss recent advances, which contribute to our understanding of how these photosensory systems are activated by blue light and how they initiate signaling to regulate diverse aspects of plant development.
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Affiliation(s)
- John M Christie
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Lisa Blackwood
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Jan Petersen
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Stuart Sullivan
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
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Yang S, Murphy RL, Morishige DT, Klein PE, Rooney WL, Mullet JE. Sorghum phytochrome B inhibits flowering in long days by activating expression of SbPRR37 and SbGHD7, repressors of SbEHD1, SbCN8 and SbCN12. PLoS One 2014; 9:e105352. [PMID: 25122453 PMCID: PMC4133345 DOI: 10.1371/journal.pone.0105352] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Accepted: 07/20/2014] [Indexed: 11/19/2022] Open
Abstract
Light signaling by phytochrome B in long days inhibits flowering in sorghum by increasing expression of the long day floral repressors PSEUDORESPONSE REGULATOR PROTEIN (SbPRR37, Ma1) and GRAIN NUMBER, PLANT HEIGHT AND HEADING DATE 7 (SbGHD7, Ma6). SbPRR37 and SbGHD7 RNA abundance peaks in the morning and in the evening of long days through coordinate regulation by light and output from the circadian clock. 58 M, a phytochrome B deficient (phyB-1, ma3R) genotype, flowered ∼60 days earlier than 100 M (PHYB, Ma3) in long days and ∼11 days earlier in short days. Populations derived from 58 M (Ma1, ma3R, Ma5, ma6) and R.07007 (Ma1, Ma3, ma5, Ma6) varied in flowering time due to QTL aligned to PHYB/phyB-1 (Ma3), Ma5, and GHD7/ghd7-1 (Ma6). PHYC was proposed as a candidate gene for Ma5 based on alignment and allelic variation. PHYB and Ma5 (PHYC) were epistatic to Ma1 and Ma6 and progeny recessive for either gene flowered early in long days. Light signaling mediated by PhyB was required for high expression of the floral repressors SbPRR37 and SbGHD7 during the evening of long days. In 100 M (PHYB) the floral activators SbEHD1, SbCN8 and SbCN12 were repressed in long days and de-repressed in short days. In 58 M (phyB-1) these genes were highly expressed in long and short days. Furthermore, SbCN15, the ortholog of rice Hd3a (FT), is expressed at low levels in 100 M but at high levels in 58 M (phyB-1) regardless of day length, indicating that PhyB regulation of SbCN15 expression may modify flowering time in a photoperiod-insensitive manner.
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Affiliation(s)
- Shanshan Yang
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Rebecca L. Murphy
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Daryl T. Morishige
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Patricia E. Klein
- Department of Horticultural Sciences and Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, Texas, United States of America
| | - William L. Rooney
- Department of Soil and Crop Sciences, Texas A&M University, College Station, Texas, United States of America
| | - John E. Mullet
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
- * E-mail:
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Roy A, Sahoo D, Tripathy BC. Involvement of phytochrome A in suppression of photomorphogenesis in rice seedling grown in red light. PLANT, CELL & ENVIRONMENT 2013; 36:2120-2134. [PMID: 23495675 DOI: 10.1111/pce.12099] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2010] [Revised: 03/05/2013] [Accepted: 03/06/2013] [Indexed: 06/01/2023]
Abstract
Plants have evolved a remarkable capacity to track and respond to fluctuations of light quality and intensity that influence photomorphogenesis facilitated through several photoreceptors, which include a small family of phytochromes. Rice seedlings grown on germination paper in red light for 48 h having their shoot bottom exposed had suppressed photomorphogenesis and were deficient in chlorophyll. Seedlings grown under identical light regime having their shoot bottom covered were green and accumulated chlorophyll. Further, etiolated seedlings with their shoot bottom exposed, when grown in 4 min red/far-red cycles for 48 h, accumulated chlorophyll demonstrating the reversal of suppression of photomorphogenesis by far-red light. It implicates the involvement of phytochrome. Immunoblot analysis showed the persistence of photolabile phytochrome A protein for 48 h in seedlings grown in red light with their shoot bottom exposed, suggesting its involvement in suppression of photomorphogenesis. This was further corroborated in phyA seedlings that turned green when grown in red light having their shoot bottom exposed. Calmodulin (CaM) antagonist N-(6-aminohexyl)-5-chloro-1-napthalene sulphonamide or trifluoperazine substantially restored photomorphogenesis both in the wild type (WT) and phyA demonstrating the involvement of CaM-dependent kinases in the down-regulation of the greening process. Results demonstrate that red light-induced suppression of photomorphogenesis, perceived in the shoot bottom, is a red high irradiance response of PhyA.
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Affiliation(s)
- Ansuman Roy
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, Delhi, India
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Heyl A, Brault M, Frugier F, Kuderova A, Lindner AC, Motyka V, Rashotte AM, Schwartzenberg KV, Vankova R, Schaller GE. Nomenclature for members of the two-component signaling pathway of plants. PLANT PHYSIOLOGY 2013; 161:1063-5. [PMID: 23324541 PMCID: PMC3585578 DOI: 10.1104/pp.112.213207] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 01/15/2013] [Indexed: 05/22/2023]
Affiliation(s)
- Alexander Heyl
- Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences, Freie Universität Berlin, Albrecht-Thaer-Weg 6, D-14195 Berlin, Germany
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Christie JM, Murphy AS. Shoot phototropism in higher plants: new light through old concepts. AMERICAN JOURNAL OF BOTANY 2013; 100:35-46. [PMID: 23048016 DOI: 10.3732/ajb.1200340] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Light is a key environmental factor that drives many aspects of plant growth and development. Phototropism, the reorientation of growth toward or away from light, represents one of these important adaptive processes. Modern studies of phototropism began with experiments conducted by Charles Darwin demonstrating that light perception at the shoot apex of grass coleoptiles induces differential elongation in the lower epidermal cells. This led to the discovery of the plant growth hormone auxin and the Cholodny-Went hypothesis attributing differential tropic bending to lateral auxin relocalization. In the past two decades, molecular-genetic analyses in the model flowering plant Arabidopsis thaliana has identified the principal photoreceptors for phototropism and their mechanism of activation. In addition, several protein families of auxin transporters have been identified. Despite extensive efforts, however, it still remains unclear as to how photoreceptor activation regulates lateral auxin transport to establish phototropic growth. This review aims to summarize major developments from over the last century and how these advances shape our current understanding of higher plant phototropism. Recent progress in phototropism research and the way in which this research is shedding new light on old concepts, including the Cholodny-Went hypothesis, is also highlighted.
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Affiliation(s)
- John M Christie
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, G12 8QQ, UK.
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11
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Possart A, Hiltbrunner A. An evolutionarily conserved signaling mechanism mediates far-red light responses in land plants. THE PLANT CELL 2013; 25:102-14. [PMID: 23303916 PMCID: PMC3584528 DOI: 10.1105/tpc.112.104331] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 11/22/2012] [Accepted: 12/18/2012] [Indexed: 05/18/2023]
Abstract
Phytochromes are plant photoreceptors important for development and adaptation to the environment. Phytochrome A (PHYA) is essential for the far-red (FR) high-irradiance responses (HIRs), which are of particular ecological relevance as they enable plants to establish under shade conditions. PHYA and HIRs have been considered unique to seed plants because the divergence of seed plants and cryptogams (e.g., ferns and mosses) preceded the evolution of PHYA. Seed plant phytochromes translocate into the nucleus and regulate gene expression. By contrast, there has been little evidence of a nuclear localization and function of cryptogam phytochromes. Here, we identified responses to FR light in cryptogams, which are highly reminiscent of PHYA signaling in seed plants. In the moss Physcomitrella patens and the fern Adiantum capillus-veneris, phytochromes accumulate in the nucleus in response to light. Although P. patens phytochromes evolved independently of PHYA, we have found that one clade of P. patens phytochromes exhibits the molecular properties of PHYA. We suggest that HIR-like responses had evolved in the last common ancestor of modern seed plants and cryptogams and that HIR signaling is more ancient than PHYA. Thus, other phytochromes in seed plants may have lost the capacity to mediate HIRs during evolution, rather than that PHYA acquired it.
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Affiliation(s)
- Anja Possart
- Centre for Plant Molecular Biology, University of Tübingen, 72076 Tuebingen, Germany
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12
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Sokolova V, Bindics J, Kircher S, Ádám É, Schäfer E, Nagy F, Viczián A. Missense mutation in the amino terminus of phytochrome A disrupts the nuclear import of the photoreceptor. PLANT PHYSIOLOGY 2012; 158:107-18. [PMID: 21969386 PMCID: PMC3252074 DOI: 10.1104/pp.111.186288] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Phytochromes are the red/far-red photoreceptors in higher plants. Among them, phytochrome A (PHYA) is responsible for the far-red high-irradiance response and for the perception of very low amounts of light, initiating the very-low-fluence response. Here, we report a detailed physiological and molecular characterization of the phyA-5 mutant of Arabidopsis (Arabidopsis thaliana), which displays hyposensitivity to continuous low-intensity far-red light and shows reduced very-low-fluence response and high-irradiance response. Red light-induced degradation of the mutant phyA-5 protein appears to be normal, yet higher residual amounts of phyA-5 are detected in seedlings grown under low-intensity far-red light. We show that (1) the phyA-5 mutant harbors a new missense mutation in the PHYA amino-terminal extension domain and that (2) the complex phenotype of the mutant is caused by reduced nuclear import of phyA-5 under low fluences of far-red light. We also demonstrate that impaired nuclear import of phyA-5 is brought about by weakened binding affinity of the mutant photoreceptor to nuclear import facilitators FHY1 (for FAR-RED ELONGATED HYPOCOTYL1) and FHL (for FHY1-LIKE). Finally, we provide evidence that the signaling and degradation kinetics of constitutively nuclear-localized phyA-5 and phyA are identical. Taken together, our data show that aberrant nucleo/cytoplasmic distribution impairs light-induced degradation of this photoreceptor and that the amino-terminal extension domain mediates the formation of the FHY1/FHL/PHYA far-red-absorbing form complex, whereby it plays a role in regulating the nuclear import of phyA.
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Rausenberger J, Tscheuschler A, Nordmeier W, Wüst F, Timmer J, Schäfer E, Fleck C, Hiltbrunner A. Photoconversion and Nuclear Trafficking Cycles Determine Phytochrome A's Response Profile to Far-Red Light. Cell 2011; 146:813-25. [DOI: 10.1016/j.cell.2011.07.023] [Citation(s) in RCA: 123] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Revised: 06/10/2011] [Accepted: 07/13/2011] [Indexed: 12/23/2022]
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Exner V, Alexandre C, Rosenfeldt G, Alfarano P, Nater M, Caflisch A, Gruissem W, Batschauer A, Hennig L. A gain-of-function mutation of Arabidopsis cryptochrome1 promotes flowering. PLANT PHYSIOLOGY 2010; 154:1633-45. [PMID: 20926618 PMCID: PMC2996009 DOI: 10.1104/pp.110.160895] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Accepted: 10/05/2010] [Indexed: 05/18/2023]
Abstract
Plants use different classes of photoreceptors to collect information about their light environment. Cryptochromes are blue light photoreceptors that control deetiolation, entrain the circadian clock, and are involved in flowering time control. Here, we describe the cry1-L407F allele of Arabidopsis (Arabidopsis thaliana), which encodes a hypersensitive cryptochrome1 (cry1) protein. Plants carrying the cry1-L407F point mutation have elevated expression of CONSTANS and FLOWERING LOCUS T under short-day conditions, leading to very early flowering. These results demonstrate that not only the well-studied cry2, with an unequivocal role in flowering promotion, but also cry1 can function as an activator of the floral transition. The cry1-L407F mutants are also hypersensitive toward blue, red, and far-red light in hypocotyl growth inhibition. In addition, cry1-L407F seeds are hypersensitive to germination-inducing red light pulses, but the far-red reversibility of this response is not compromised. This demonstrates that the cry1-L407F photoreceptor can increase the sensitivity of phytochrome signaling cascades. Molecular dynamics simulation of wild-type and mutant cry1 proteins indicated that the L407F mutation considerably reduces the structural flexibility of two solvent-exposed regions of the protein, suggesting that the hypersensitivity might result from a reduced entropic penalty of binding events during downstream signal transduction. Other nonmutually exclusive potential reasons for the cry1-L407F gain of function are the location of phenylalanine-407 close to three conserved tryptophans, which could change cry1's photochemical properties, and stabilization of ATP binding, which could extend the lifetime of the signaling state of cry1.
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15
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Yu X, Liu H, Klejnot J, Lin C. The Cryptochrome Blue Light Receptors. THE ARABIDOPSIS BOOK 2010; 8:e0135. [PMID: 21841916 PMCID: PMC3155252 DOI: 10.1199/tab.0135] [Citation(s) in RCA: 178] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Cryptochromes are photolyase-like blue light receptors originally discovered in Arabidopsis but later found in other plants, microbes, and animals. Arabidopsis has two cryptochromes, CRY1 and CRY2, which mediate primarily blue light inhibition of hypocotyl elongation and photoperiodic control of floral initiation, respectively. In addition, cryptochromes also regulate over a dozen other light responses, including circadian rhythms, tropic growth, stomata opening, guard cell development, root development, bacterial and viral pathogen responses, abiotic stress responses, cell cycles, programmed cell death, apical dominance, fruit and ovule development, seed dormancy, and magnetoreception. Cryptochromes have two domains, the N-terminal PHR (Photolyase-Homologous Region) domain that bind the chromophore FAD (flavin adenine dinucleotide), and the CCE (CRY C-terminal Extension) domain that appears intrinsically unstructured but critical to the function and regulation of cryptochromes. Most cryptochromes accumulate in the nucleus, and they undergo blue light-dependent phosphorylation or ubiquitination. It is hypothesized that photons excite electrons of the flavin molecule, resulting in redox reaction or circular electron shuttle and conformational changes of the photoreceptors. The photoexcited cryptochrome are phosphorylated to adopt an open conformation, which interacts with signaling partner proteins to alter gene expression at both transcriptional and posttranslational levels and consequently the metabolic and developmental programs of plants.
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Affiliation(s)
- Xuhong Yu
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90095, USA
| | - Hongtao Liu
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90095, USA
| | - John Klejnot
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90095, USA
| | - Chentao Lin
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90095, USA
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16
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Khanna R, Kronmiller B, Maszle DR, Coupland G, Holm M, Mizuno T, Wu SH. The Arabidopsis B-box zinc finger family. THE PLANT CELL 2009; 21:3416-20. [PMID: 19920209 PMCID: PMC2798317 DOI: 10.1105/tpc.109.069088] [Citation(s) in RCA: 250] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
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17
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Müller R, Fernández AP, Hiltbrunner A, Schäfer E, Kretsch T. The histidine kinase-related domain of Arabidopsis phytochrome a controls the spectral sensitivity and the subcellular distribution of the photoreceptor. PLANT PHYSIOLOGY 2009; 150:1297-309. [PMID: 19403732 PMCID: PMC2705050 DOI: 10.1104/pp.109.135988] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2009] [Accepted: 04/26/2009] [Indexed: 05/19/2023]
Abstract
Phytochrome A (phyA) is the primary photoreceptor for sensing extremely low amounts of light and for mediating various far-red light-induced responses in higher plants. Translocation from the cytosol to the nucleus is an essential step in phyA signal transduction. EID1 (for EMPFINDLICHER IM DUNKELROTEN LICHT1) is an F-box protein that functions as a negative regulator in far-red light signaling downstream of the phyA in Arabidopsis (Arabidopsis thaliana). To identify factors involved in EID1-dependent light signal transduction, pools of ethylmethylsulfonate-treated eid1-3 seeds were screened for seedlings that suppress the hypersensitive phenotype of the mutant. The phenotype of the suppressor mutant presented here is caused by a missense mutation in the PHYA gene that leads to an amino acid transition in its histidine kinase-related domain. The novel phyA-402 allele alters the spectral sensitivity and the persistence of far-red light-induced high-irradiance responses. The strong eid1-3 suppressor phenotype of phyA-402 contrasts with the moderate phenotype observed when phyA-402 is introgressed into the wild-type background, which indicates that the mutation mainly alters functions in an EID1-dependent signaling cascade. The mutation specifically inhibits nuclear accumulation of the photoreceptor molecule upon red light irradiation, even though it still interacts with FHY1 (for far-red long hypocotyl 1) and FHL (for FHY1-like protein), two factors that are essential for nuclear accumulation of phyA. Degradation of the mutated phyA is unaltered even under light conditions that inhibit its nuclear accumulation, indicating that phyA degradation may occur mostly in the cytoplasm.
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Affiliation(s)
- Rebecca Müller
- Albert-Ludwigs-Universität Freiburg, Institut für Biologie 2/Botanik, 79104 Freiburg, Germany
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18
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Pratt LH. PHYTOCHROMES: DIFFERENTIAL PROPERTIES, EXPRESSION PATTERNS AND MOLECULAR EVOLUTION*. Photochem Photobiol 2008. [DOI: 10.1111/j.1751-1097.1995.tb09238.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lee H. Pratt
- Botany Department, University of Georgia, Athens, GA 30602, USA
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19
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Tepperman JM, Hudson ME, Khanna R, Zhu T, Chang SH, Wang X, Quail PH. Expression profiling of phyB mutant demonstrates substantial contribution of other phytochromes to red-light-regulated gene expression during seedling de-etiolation. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2004; 38:725-39. [PMID: 15144375 DOI: 10.1111/j.1365-313x.2004.02084.x] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Different Arabidopsis phytochrome (phy) family members (phyA through phyE) display differential photosensory and/or physiological functions in regulating growth and developmental responses to light signals. To identify the genes regulated by phyB in response to continuous monochromatic red light (Rc) during the induction of seedling de-etiolation, we have performed time-course, microarray-based expression profiling of wild type (WT) and phyB null mutants. Comparison of the observed expression patterns with those induced by continuous monochromatic far-red light (FRc; perceived exclusively by phyA) in WT and phyA null-mutant seedlings suggests early convergence of the FRc and Rc photosensory pathways to control a largely common transcriptional network. phyB mutant seedlings retain a surprisingly high level of responsiveness to Rc for the majority of Rc-regulated genes on the microarray, indicating that one or more other phys have a major role in regulating their expression. Combined with the robust visible morphogenic phenotype of the phyB mutant in Rc, these data suggest that different members of the phy family act in organ-specific fashion in regulating seedling de-etiolation. Specifically, phyB appears to be the dominant, if not exclusive, photoreceptor in regulating a minority population of genes involved in suppression of hypocotyl cell elongation in response to Rc signals. By contrast, this sensory function is apparently shared by one or more other phys in regulating the majority Rc-responsive gene set involved in other important facets of the de-etiolation process in the apical region, such as cotyledon cell expansion.
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Affiliation(s)
- James M Tepperman
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA
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20
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Kaczorowski KA, Quail PH. Arabidopsis PSEUDO-RESPONSE REGULATOR7 is a signaling intermediate in phytochrome-regulated seedling deetiolation and phasing of the circadian clock. THE PLANT CELL 2003; 15:2654-65. [PMID: 14563930 PMCID: PMC280569 DOI: 10.1105/tpc.015065] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2003] [Accepted: 09/03/2003] [Indexed: 05/18/2023]
Abstract
To identify new components in the phytochrome (phy) signaling network in Arabidopsis, we used a sensitized genetic screen for deetiolation-defective seedlings. Two allelic mutants were isolated that exhibited reduced sensitivity to both continuous red and far-red light, suggesting involvement in both phyA and phyB signaling. The molecular lesions responsible for the phenotype were shown to be mutations in the Arabidopsis PSEUDO-RESPONSE REGULATOR7 (PRR7) gene. PRR7 is a member of a small gene family in Arabidopsis previously suggested to be involved in circadian rhythms. A PRR7-beta-glucuronidase fusion protein localized to the nucleus, implying a possible function in the regulation of photoresponsive gene expression. Consistent with this suggestion, prr7 seedlings were partially defective in the regulation of the rapidly light-induced genes CIRCADIAN CLOCK ASSOCIATED1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY), observable as a premature increase in expression level during the second peak of the biphasic induction profile that is elicited upon initial exposure of dark-grown seedlings to light. A similar 3- to 6-h coordinated advance in peak free-running expression of CCA1, LHY, and TIMING-OF-CAB1, which are considered to encode the molecular components of the circadian oscillator in Arabidopsis, was observed in entrained fully green prr7 seedlings compared with wild-type seedlings. Collectively, these data suggest that PRR7 functions as a signaling intermediate in the phytochrome-regulated gene expression responsible for both seedling deetiolation and phasing of the circadian clock in response to light.
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Affiliation(s)
- Karen A Kaczorowski
- Department of Plant Biology, University of California, Berkeley, California 94720, USA
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21
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Abstract
Phytochromes are plant photoreceptors that regulate plant growth and development with respect to the light environment. Following the initial light-perception event, the phytochromes initiate a signal-transduction process that eventually results in alterations in cellular behavior, including gene expression. Here we describe the molecular cloning and functional characterization of Arabidopsis FHY1. FHY1 encodes a product (FHY1) that specifically transduces signals downstream of the far-red (FR) light-responsive phytochrome A (PHYA) photoreceptor. We show that FHY1 is a novel light-regulated protein that accumulates in dark (D)-grown but not in FR-grown hypocotyl cells. In addition, FHY1 transcript levels are regulated by light, and by the product of FHY3, another gene implicated in FR signaling. These observations indicate that FHY1 function is both FR-signal transducing and FR-signal regulated, suggesting a negative feedback regulation of FHY1 function. Seedlings homozygous for loss-of-function fhy1 alleles are partially blind to FR, whereas seedlings overexpressing FHY1 exhibit increased responses to FR, but not to white (WL) or red (R) light. The increased FR-responses conferred by overexpression of FHY1 are abolished in a PHYA-deficient mutant background, showing that FHY1 requires a signal from PHYA for function, and cannot modulate growth independently of PHYA.
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Affiliation(s)
- T Desnos
- John Innes Centre, Norwich Research Park, Colney, Norwich NR4 7UH, UK
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22
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Briggs WR, Beck CF, Cashmore AR, Christie JM, Hughes J, Jarillo JA, Kagawa T, Kanegae H, Liscum E, Nagatani A, Okada K, Salomon M, Rüdiger W, Sakai T, Takano M, Wada M, Watson JC. The phototropin family of photoreceptors. THE PLANT CELL 2001; 13:993-7. [PMID: 11424903 PMCID: PMC1464709 DOI: 10.1105/tpc.13.5.993] [Citation(s) in RCA: 174] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
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23
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Abstract
Plants have several blue-light receptors, which regulate different aspects of growth and development. Recent studies have identified three such receptors: cryptochrome 1, cryptochrome 2 and phototropin. Cryptochromes 1 and 2 are photolyase-like receptors that regulate hypocotyl growth and flowering time; phototropin mediates phototropism in response to blue light. In addition, phytochrome A has also been found to mediate various blue-light responses. Although the signal-transduction mechanisms of blue-light receptors remain largely unclear, phototropin is probably a protein kinase that regulates cytoplasmic calcium concentrations, whereas the cryptochromes might regulate anion-channel activity and changes in gene expression.
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Affiliation(s)
- C Lin
- Dept of Molecular, Cell and Developmental Biology, University of California, Los Angeles, 621 C. Young Dr. South, Los Angeles, CA 90095-1606, USA.
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24
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Abstract
In the past few years great progress has been made in identifying and characterizing plant photoreceptors active in the blue/UV-A regions of the spectrum. These photoreceptors include cryptochrome 1 and cryptochrome 2, which are similar in structure and chromophore composition to the prokaryotic DNA photolyases. However, they have a C-terminal extension that is not present in photolyases and lack photolyase activity. They are involved in regulation of cell elongation and in many other processes, including interfacing with circadian rhythms and activating gene transcription. Animal cryptochromes that play a photoreceptor role in circadian rhythms have also been characterized. Phototropin, the protein product of the NPH1 gene in Arabidopsis, likely serves as the photoreceptor for phototropism and appears to have no other role. A plasma membrane protein, it serves as photoreceptor, kinase, and substrate for light-activated phosphorylation. The carotenoid zeaxanthin may serve as the chromophore for a photoreceptor involved in blue-light-activated stomatal opening. The properties of these photoreceptors and some of the downstream events they are known to activate are discussed.
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Affiliation(s)
- W R Briggs
- Department of Plant Biology, Carnegie Institution of Washington, Stanford, California 94305, USA.
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25
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Quail PH. The phytochrome family: dissection of functional roles and signalling pathways among family members. Philos Trans R Soc Lond B Biol Sci 1998; 353:1399-403. [PMID: 9800202 PMCID: PMC1692352 DOI: 10.1098/rstb.1998.0294] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
There is considerable evidence that individual members of the five-membered phytochrome family of photoreceptors in Arabidopsis have differential functional roles in controlling plant photomorphogenesis. Emerging genetic evidence suggests that this differential activity may involve initially separate signalling pathway branches specific to individual family members.
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Affiliation(s)
- P H Quail
- Department of Plant and Microbial Biology, University of California, Berkeley 94720, USA
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26
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Lin C, Yang H, Guo H, Mockler T, Chen J, Cashmore AR. Enhancement of blue-light sensitivity of Arabidopsis seedlings by a blue light receptor cryptochrome 2. Proc Natl Acad Sci U S A 1998; 95:2686-90. [PMID: 9482948 PMCID: PMC19462 DOI: 10.1073/pnas.95.5.2686] [Citation(s) in RCA: 337] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/1997] [Accepted: 12/23/1997] [Indexed: 02/06/2023] Open
Abstract
Cryptochrome is a group of flavin-type blue light receptors that regulate plant growth and development. The function of Arabidopsis cryptochrome 2 in the early photomorphogenesis of seedlings was studied by using transgenic plants overexpressing CRY2 protein, and cry2 mutant plants accumulating no CRY2 protein. It is found that cryptochrome 2 mediates blue light-dependent inhibition of hypocotyl elongation and stimulation of cotyledon opening under low intensities of blue light. In contrast to CRY1, the expression of CRY2 is rapidly down-regulated by blue light in a light-intensity dependent manner, which provides a molecular mechanism to explain at least in part that cryptochrome 2 functions primarily under low light during the early development of seedlings.
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Affiliation(s)
- C Lin
- Department of Molecular, Cell and Developmental Biology, and Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA.
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27
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Lee IJ, Foster KR, Morgan PW. Photoperiod control of gibberellin levels and flowering in sorghum. PLANT PHYSIOLOGY 1998; 116:1003-11. [PMID: 9501132 PMCID: PMC35069 DOI: 10.1104/pp.116.3.1003] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/1997] [Accepted: 11/19/1997] [Indexed: 05/18/2023]
Abstract
Regulation of rhythmic peaks in levels of endogenous gibberellins (GAs) by photoperiod was studied in the short-day monocot sorghum (Sorghum bicolor [L.] Moench). Comparisons were made between three maturity (Ma) genotypes: 58M (Ma1Ma1, Ma2Ma2, phyB-1phyB-1, and Ma4Ma4 [a phytochrome B null mutant]); 90M (Ma1Ma1, Ma2Ma2, phyB-2phyB-2, and Ma4Ma4); and 100M (Ma1Ma1, Ma2Ma2, PHYBPHYB, and Ma4Ma4). Plants were grown for 14 d under 10-, 14-, 16-, 18-, and 20-h photoperiods, and GA levels were assayed by gas chromatography-mass spectrometry every 3 h for 24 h. Under inductive 10-h photoperiods, the peak of GA20 and GA1 levels in 90M and 100M was shifted from midday, observed earlier with 12-h photoperiods, to an early morning peak, and flowering was hastened. In addition, the early morning peaks in levels of GA20 and GA1 in 58M under conditions allowing early flowering (10-, 12-, and 14-h photoperiods) were shifted to midday by noninductive (18- and 20-h) photoperiods, and flowering was delayed. These results are consistent with the possibility that the diurnal rhythm of GA levels plays a role in floral initiation and may be one way by which the absence of phytochrome B causes early flowering in 58M under most photoperiods.
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Affiliation(s)
- IJ Lee
- Department of Soil and Crop Sciences, Texas A&M University, College Station, Texas 77843-2474, USA
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28
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Anderson SL, Kay SA. Phototransduction and circadian clock pathways regulating gene transcription in higher plants. ADVANCES IN GENETICS 1997; 35:1-34. [PMID: 9348644 DOI: 10.1016/s0065-2660(08)60446-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- S L Anderson
- National Science Foundation Center for Biological Timing, Department of Biology, University of Virginia, Charlottesville 22903, USA
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29
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Anderson SL, Somers DE, Millar AJ, Hanson K, Chory J, Kay SA. Attenuation of phytochrome A and B signaling pathways by the Arabidopsis circadian clock. THE PLANT CELL 1997; 9:1727-43. [PMID: 9368413 PMCID: PMC157017 DOI: 10.1105/tpc.9.10.1727] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
In higher plants, environmental cues such as light signals are integrated with circadian clock signals to control precisely the daily rhythms observed for many biological functions. We have used a fusion of the promoter of a chlorophyll a/b binding protein gene, CAB2, with firefly luciferase (cab2::luc) to monitor the detailed kinetics of transcription in response to photoreceptor activation in Arabidopsis. Using this marker in phototransduction and circadian-dysfunctional mutants, we studied how signals from phytochrome and the circadian clock are integrated for the regulation of CAB2 transcription. Results from these mutant studies demonstrate that similar expression features, namely, the acute and circadian responses, are present in both etiolated and green seedlings and that the acute and circadian responses are genetically separable. We also demonstrate that persistent Pfr signaling occurs in red light-pulsed etiolated seedlings, which suggests that the circadian clock antagonizes Pfr-mediated signal transduction. Based on these genetic studies, we propose a model for the regulation of CAB2 transcription in which individual photoreceptors and phototransduction components have been assigned to specific pathways for the regulation of discrete kinetic components of the CAB2 expression pattern.
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Affiliation(s)
- S L Anderson
- National Science Foundation Center for Biological Timing, Department of Cell Biology, Scripps Research Institute, La Jolla, California 92037, USA
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30
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Wagner D, Hoecker U, Quail PH. RED1 is necessary for phytochrome B-mediated red light-specific signal transduction in Arabidopsis. THE PLANT CELL 1997; 9:731-43. [PMID: 9165750 PMCID: PMC156952 DOI: 10.1105/tpc.9.5.731] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Seedlings of a transgenic Arabidopsis line (ABO) that overexpresses phytochrome B (phyB) display enhanced deetiolation specifically in red light. To identify genetic loci necessary for phytochrome signal transduction in red light, we chemically mutagenized ABO seeds and screened M2 seedlings for revertants of the enhanced deetiolation response. One recessive, red light-specific extragenic revertant, designated red1, was isolated. The mutant phenotype was expressed in the original ABO background as well as in the nontransgenic Nossen (No-0) progenitor background. red1 is also deficient in several other aspects of red light-induced responses known to be mediated by phyB, such as inhibition of petiole elongation and the shade avoidance response. red1 was mapped to the bottom of chromosome 4 at a position distinct from all known photoreceptor loci. Together with complementation analysis, the data show that red1 is a novel photomorphogenic mutant. The evidence suggests that red1 represents a putative phytochrome signal transduction mutant potentially specific to the phyB pathway.
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Affiliation(s)
- D Wagner
- Department of Plant Biology, University of California, Berkeley 94720, USA
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31
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Peng J, Harberd NP. Gibberellin deficiency and response mutations suppress the stem elongation phenotype of phytochrome-deficient mutants of Arabidopsis. PLANT PHYSIOLOGY 1997; 113:1051-8. [PMID: 9112768 PMCID: PMC158228 DOI: 10.1104/pp.113.4.1051] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Plant growth and development are regulated by numerous internal and external factors. Among these, gibberellin (GA) (an endogenous plant growth regulator) and phytochrome (a photoreceptor) often influence the same processes. For example, in plants grown in the light Arabidopsis thaliana hypocotyl elongation is reduced by GA deficiency and increased by phytochrome deficiency. Here we describe experiments in which the phenotypes of Arabidopsis plants doubly homozygous for GA-related and phytochrome-related mutations were examined. The double mutants were studied at various stages in the plant life cycle, including the seed germination, young seedling, adult, and reproductive phases of development. The results of these experiments are complex, but indicate that a fully functional GA system is necessary for full expression of the elongated phenotypes conferred by phytochrome deficiency.
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Affiliation(s)
- J Peng
- Department of Molecular Genetics, John Innes Center, Norwich, United Kingdom
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32
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The Phytochrome Family and their Roles in the Regulation of Seed Germination. ACTA ACUST UNITED AC 1997. [DOI: 10.1007/978-94-011-5716-2_19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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33
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Reed JW, Foster KR, Morgan PW, Chory J. Phytochrome B affects responsiveness to gibberellins in Arabidopsis. PLANT PHYSIOLOGY 1996; 112:337-42. [PMID: 8819329 PMCID: PMC157954 DOI: 10.1104/pp.112.1.337] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Plant responses to red and far-red light are mediated by a family of photoreceptors called phytochromes. Arabidopsis thaliana seedlings lacking one of the phytochromes, phyB, have elongated hypocotyls and other tissues, suggesting that they may have an alteration in hormone physiology. We have studied the possibility that phyB mutations affect seedling gibberellin (GA) perception and metabolism by testing the responsiveness of wild-type and phyB seedlings to exogenous GAs. The phyB mutant elongates more than the wild type in response to the same exogenous concentrations of GA3 or GA4, showing that the mutation causes an increase in responsiveness to GAs. Among GAs that we were able to detect, we found no significant difference in endogenous levels between wild-type and phyB mutant seedlings. However, GA4 levels were below our limit of detectability, and the concentration of that active GA could have varied between wild-type and phyB mutant seedlings. These results suggest that, although GAs are required for hypocotyl cell elongation, phyB does not act primarily by changing total seedling GA levels but rather by decreasing seedling responsiveness to GAs.
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Affiliation(s)
- J W Reed
- Plant Biology Laboratory, Salk Institute, San Diego, California 92186-5800, USA
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34
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Abstract
Light control of plant development is most dramatically illustrated by seedling development. Seedling development patterns under light (photomorphogenesis) are distinct from those in darkness (skotomorphogenesis or etiolation) with respect to gene expression, cellular and subcellular differentiation, and organ morphology. A complex network of molecular interactions couples the regulatory photoreceptors to developmental decisions. Rapid progress in defining the roles of individual photoreceptors and the downstream regulators mediating light control of seedling development has been achieved in recent years, predominantly because of molecular genetic studies in Arabidopsis thaliana and other species. This review summarizes those important recent advances and highlights the working models underlying the light control of cellular development. We focus mainly on seedling morphogenesis in Arabidopsis but include complementary findings from other species.
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Affiliation(s)
- Albrecht Von Arnim
- Department of Biology, Yale University, New Haven, Connecticut 06520-8104
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35
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Parks BM, Quail PH, Hangarter RP. Phytochrome A regulates red-light induction of phototropic enhancement in Arabidopsis. PLANT PHYSIOLOGY 1996; 110:155-62. [PMID: 8587979 PMCID: PMC157704 DOI: 10.1104/pp.110.1.155] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Phytochrome A (phyA) and phytochrome B photoreceptors have distinct roles in the regulation of plant growth and development. Studies using specific photomorphogenic mutants and transgenic plants overexpressing phytochrome have supported an evolving picture in which phyA and phytochrome B are responsive to continuous far-red and red light, respectively. Photomorphogenic mutants of Arabidopsis thaliana that had been selected for their inability to respond to continuous irradiance conditions were tested for their ability to carry out red-light-induced enhancement of phototropism, which is an inductive phytochrome response. We conclude that phyA is the primary photoreceptor regulating this response and provide evidence suggesting that a common regulatory domain in the phyA polypeptide functions for both high-irradiance and inductive phytochrome responses.
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Affiliation(s)
- B M Parks
- Department of Plant Biology, Ohio State University, Columbus 43210, USA
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Coté GG, Yueh YG, Crain RC. Phosphoinositide turnover and its role in plant signal transduction. Subcell Biochem 1996; 26:317-43. [PMID: 8744270 DOI: 10.1007/978-1-4613-0343-5_11] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- G G Coté
- Department of Molecular and Cell Biology, University of Connecticut, Storrs 06269-3125, USA
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Robson PR, Smith H. Genetic and transgenic evidence that phytochromes A and B act to modulate the gravitropic orientation of Arabidopsis thaliana hypocotyls. PLANT PHYSIOLOGY 1996; 110:211-6. [PMID: 11536725 PMCID: PMC157711 DOI: 10.1104/pp.110.1.211] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Hypocotyls of Arabidopsis thaliana exhibit negative gravitropism in the dark, growing against the gravity vector. The direction of growth is randomized in red light (R). In single mutants lacking either phytochrome A or B randomization of hypocotyl orientation in R is retained. However, a double mutant lacks this response, indicating that either phytochrome A or B is capable of inducing randomization and phytochrome A and B are the only phytochromes involved in this process. The induction of randomization was confirmed using lines that express to different levels PHYA and PHYB cDNAs. Overexpression of PHYA cDNAs induced randomization of hypocotyl orientation in the dark. Dark randomization was also seen in the phyB-1 mutant but not in two other phyB alleles, suggesting that dark randomization in the phyB-1 line may be due to a second mutation. When germination was induced by gibberellin, rather than exposure to brief white light, randomization in the dark associated with phytochrome A overproduction was not observed but was retained in the phyB-1 mutant. Overexpression of PHYB cDNAs induced a light-dependent randomization of hypocotyl orientation that responded to R:far-red light ratio. We conclude that the default situation in Arabidopsis hypocotyls is, therefore, negative gravitropism, and either phytochrome A or phytochrome B can mediate randomization.
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Affiliation(s)
- P R Robson
- Department of Botany, University of Leicester, United Kingdom
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Xu Y, Parks BM, Short TW, Quail PH. Missense mutations define a restricted segment in the C-terminal domain of phytochrome A critical to its regulatory activity. THE PLANT CELL 1995; 7:1433-43. [PMID: 8589627 PMCID: PMC160967 DOI: 10.1105/tpc.7.9.1433] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The phytochrome family of photoreceptors has dual molecular functions: photosensory, involving light signal perception, and regulatory, involving signal transfer to downstream transduction components. To define residues necessary specifically for the regulatory activity of phytochrome A (phyA), we undertook a genetic screen to identify Arabidopsis mutants producing wild-type levels of biologically defective but photochemically active and dimeric phyA molecules. Of eight such mutants identified, six contain missense mutations (including three in the same residue, glycine 727) clustered within a restricted segment in the C-terminal domain of the polypeptide. Quantitative photobiological analysis revealed retention of varying degrees of partial activity among the different alleles--a result consistent with the extent of conservation at the position mutated. Together with additional data, these results indicate that the photoreceptor subdomain identified here is critical to the regulatory activity of both phyA and phyB.
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Affiliation(s)
- Y Xu
- Department of Plant Biology, University of California at Berkeley 94720, USA
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Bagnall DJ, King RW, Whitelam GC, Boylan MT, Wagner D, Quail PH. Flowering responses to altered expression of phytochrome in mutants and transgenic lines of Arabidopsis thaliana (L.) Heynh. PLANT PHYSIOLOGY 1995; 108:1495-503. [PMID: 7659750 PMCID: PMC157529 DOI: 10.1104/pp.108.4.1495] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The long-day plant Arabidopsis thaliana (L.) Heynh. flowers early in response to brief end-of-day (EOD) exposures to far-red light (FR) following a fluorescent short day of 8 h. FR promotion of flowering was nullified by subsequent brief red light (R) EOD exposure, indicating phytochrome involvement. The EOD response to R or FR is a robust measure of phytochrome action. Along with their wild-type (WT) parents, mutants deficient in either phytochrome A or B responded similarly to the EOD treatments. Thus, neither phytochrome A nor B exclusively regulated flowering, although phytochrome B controlled hypocotyl elongation. Perhaps a third phytochrome species is important for the EOD responses of the mutants and/or their flowering is regulated by the amount of the FR-absorbing form of phytochrome, irrespective of the phytochrome species. Overexpression of phytochrome A or phytochrome B resulted in differing photoperiod and EOD responses among the genotypes. The day-neutral overexpressor of phytochrome A had an EOD response similar to all of the mutants and WTs, whereas R EOD exposure promoted flowering in the overexpressor of phytochrome B and FR EOD exposure inhibited this promotion. The comparisons between relative flowering times and leaf numbers at flowering of the over-expressors and their WTs were not consistent across photoperiods and light treatments, although both phytochromes A and B contributed to regulating flowering of the transgenic plants.
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Affiliation(s)
- D J Bagnall
- Commonwealth Scientific and Industrial Research Organization, Division of Plant Industry, Canberra, Australia
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Conley TR, Shih MC. Effects of light and chloroplast functional state on expression of nuclear genes encoding chloroplast glyceraldehyde-3-phosphate dehydrogenase in long hypocotyl (hy) mutants and wild-type Arabidopsis thaliana. PLANT PHYSIOLOGY 1995; 108:1013-1022. [PMID: 7630933 PMCID: PMC157451 DOI: 10.1104/pp.108.3.1013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
In a previous study of Arabidopsis thaliana (J. Dewdney, T.R. Conley, M.-C. Shih, H.M. Goodman [1993] Plant Physiol 103: 1115-1121), it was postulated that both blue light receptor- and phytochrome-mediated pathways contribute to regulation of the nuclear genes encoding A and B subunits of glyceraldehyde-3-phosphate dehydrogenase (GAPA and GAPB). Here were report on the involvement of a nuclear gene encoding a putative blue-light receptor (HY4) and of a nuclear gene encoding phytochrome A apoprotein (PHYA) in regulation of the GAPA and GAPB genes in response to blue and far-red light. Continuous light irradiation experiments with the hy4 mutant demonstrate that the HY4 gene product is required for full expression of GAPA, GAPB, and one or more of the nuclear genes encoding small subunits of of ribulose-1,5-bisphosphate carboxylase/oxygenase. Continuous light irradiation and fluence-response studies with the phyA-101 mutant show that phytochrome A functions in far-red light regulation of GAPA, GAPB, nuclear genes encoding small subunits of ribulose-1,5-bisphosphate carboxylase/oxygenase, and CAB genes. Phytochromes A and B alone either do not participate in red light-mediated gene regulation or have redundant functions, as shown by analysis of phyA-101 and phyB-1 single mutants. In addition, the hypothesis that chloroplast-nucleus interactions affect GAPA and GAPB gene regulation was tested. Herbicide-mediated photooxidative damage to chloroplasts in A thaliana seedlings strongly decreased the maximum amount of GAPA and GAPB steady-state mRNA detected in continuous-light irradiation experiments. Full expression of the GAPB genes is dependent on the presence of functional chloroplasts.
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Affiliation(s)
- T R Conley
- Department of Biological Sciences, University of Iowa, Iowa City 52242, USA
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Bradley JM, Whitelam GC, Harberd NP. Impaired splicing of phytochrome B pre-mRNA in a novel phyB mutant of Arabidopsis. PLANT MOLECULAR BIOLOGY 1995; 27:1133-1142. [PMID: 7539307 DOI: 10.1007/bf00020886] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Phytochrome is the red/far-red absorbing photoreceptor active in photomorphogenesis, the apoprotein of which is encoded by a small gene family (PHYA, PHYB, PHYC, PHYD and PHYE). A novel phytochrome B-deficient mutant, phyB-103, was isolated from a screen of EMS-mutagenised Arabidopsis M2 seed. phyB-103 carries a G-to-A base substitution at the 5' splice site +1 G nucleotide of intron 1 of PHYB. The phyB-103 PHYB transcript is larger than the wild-type PHYB transcript and DNA sequence analysis showed that the entire intron is retained in the mature PHYB transcript of phyB-103. Thus the phyB-103 G-to-A substitution prevents intron splicing. The retained intron contains within it an in-frame stop codon, and the predicted PHYB-003 apoprotein thus terminates prematurely. phyB-103 is therefore likely to be a null allele of PHYB, consistent with the observation that the phenotype conferred by phyB-103 is as severe as that conferred by previously described phyB null alleles.
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Sineshchekov VA. Photobiophysics and photobiochemistry of the heterogeneous phytochrome system. BIOCHIMICA ET BIOPHYSICA ACTA (BBA) - BIOENERGETICS 1995; 1228:125-164. [DOI: https:/doi.org/10.1016/0005-2728(94)00173-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2023]
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Photobiophysics and photobiochemistry of the heterogeneous phytochrome system. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1995. [DOI: 10.1016/0005-2728(94)00173-3] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Affiliation(s)
- C Bowler
- Stazione Zoologica, Naples, Italy
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Abstract
Genetic and molecular studies are beginning to unravel the complexities of the signaling circuitry that plants use to sense and transduce information concerning the prevailing light environment. The past year has witnessed definition of discrete photosensory roles for phytochromes A and B, the cloning of a gene encoding the first apparent blue-light photoreceptor from any organism, the cloning of genes encoding additional members of the COP/DET/FUS class of light-responsive master regulators, and evidence that G proteins, Ca2+/calmodulin, and cGMP may be signaling intermediates in phototransduction.
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Affiliation(s)
- P H Quail
- Plant Biology, University of California, Berkeley
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