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TOR and RPS6 transmit light signals to enhance protein translation in deetiolating Arabidopsis seedlings. Proc Natl Acad Sci U S A 2018; 115:12823-12828. [PMID: 30482859 PMCID: PMC6294885 DOI: 10.1073/pnas.1809526115] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Light enhances the translation efficiency of thousands of mRNAs during photomorphogenic development in Arabidopsis, but the underlying molecular mechanism remains elusive. Here we show that light activates the auxin-target of rapamycin (TOR)-ribosome protein S6 (RPS6) pathway to enhance translation in deetiolating Arabidopsis. We discovered that CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1) represses TOR activity in dark-grown seedlings. The perception of far-red and blue light by photoreceptors inactivates COP1, which leads to the derepression of the auxin-TOR-RPS6 pathway and enhanced de novo protein synthesis. Our study revealed a light-triggered signaling pathway for translational regulation. This sophisticated regulation also functions to ensure that young seedlings have strict skotomorphogenic development in the dark and a timely switch to photomorphogenic development. Deetiolation is an essential developmental process transforming young plant seedlings into the vegetative phase with photosynthetic activities. Light signals initiate this important developmental process by triggering massive reprogramming of the transcriptome and translatome. Compared with the wealth of knowledge of transcriptional regulation, the molecular mechanism underlying this light-triggered translational enhancement remains unclear. Here we show that light-enhanced translation is orchestrated by a light perception and signaling pathway composed of photoreceptors, CONSTITUTIVE PHOTOMORPHOGENESIS 1 (COP1), the phytohormone auxin, target of rapamycin (TOR), and ribosomal protein S6 (RPS6). In deetiolating Arabidopsis seedlings, photoreceptors, including phytochrome A and cryptochromes, perceive far-red and blue light to inactivate the negative regulator COP1, which leads to activation of the auxin pathway for TOR-dependent phosphorylation of RPS6. Arabidopsis mutants defective in TOR, RPS6A, or RPS6B exhibited delayed cotyledon opening, a characteristic of the deetiolating process to ensure timely vegetative development of a young seedling. This study provides a mechanistic view of light-triggered translational enhancement in deetiolating Arabidopsis.
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Yang Y, Yang X, Jang Z, Chen Z, Ruo X, Jin W, Wu Y, Shi X, Xu M. UV RESISTANCE LOCUS 8 From Chrysanthemum morifolium Ramat (CmUVR8) Plays Important Roles in UV-B Signal Transduction and UV-B-Induced Accumulation of Flavonoids. FRONTIERS IN PLANT SCIENCE 2018; 9:955. [PMID: 30022994 PMCID: PMC6040093 DOI: 10.3389/fpls.2018.00955] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 06/13/2018] [Indexed: 05/04/2023]
Abstract
UV Resistance Locus 8 (UVR8), an ultraviolet-B (UV-B; 280-315 nm) photoreceptor, participates in the regulation of various plant growth and developmental processes. UV-B radiation is an important factor enhancing the production of active components in medicinal plants. To-date, however, studies on UV-B photoreceptors have largely focused on Arabidopsis, and the functions of UVR8 in medicinal plants are still largely unknown. In the present study, a homolog of Arabidopsis UVR8, CmUVR8, was isolated from Chrysanthemum morifolium Ramat, and its structure and function were analyzed in detail. Protein sequence analysis showed that CmUVR8 contained nine conserved regulators of chromosome condensation 1 repeats, seven conserved bladed propellers, one C27 region, three "GWRHT" motifs and several crucial amino acid residues (such as 14 Trps and 2 Args), similar to AtUVR8. 3-D structural analysis of CmUVR8 indicated that its structure was similar to AtUVR8. Heterologous expression of CmUVR8 could rescued the deficient phenotype of uvr8-6, a mutant of UVR8 in Arabidopsis, indicating the role of CmUVR8 in the regulation of hypocotyl elongation and HY5 gene expression under UV-B irradiation. Moreover, CmUVR8 regulates UV-B-induced expression of four flavonoids biosynthesis-related genes and the UV-B-induced accumulation of flavonoids. Furthermore, the interaction between CmUVR8 and CmCOP1 were confirmed using a yeast two-hybrid assay. These results indicated that CmUVR8 plays important roles in UV-B signal transduction and the UV-B-induced accumulation of flavonoids, as a counterpart of AtUVR8.
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Affiliation(s)
- Yanjun Yang
- Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, Hangzhou Normal University, Hangzhou, China
- Key Laboratory of Hangzhou City for Quality and Safety of Agricultural Products, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Xiuli Yang
- Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, Hangzhou Normal University, Hangzhou, China
- Key Laboratory of Hangzhou City for Quality and Safety of Agricultural Products, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Zhifang Jang
- Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, Hangzhou Normal University, Hangzhou, China
- Key Laboratory of Hangzhou City for Quality and Safety of Agricultural Products, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Zhehao Chen
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Xiujun Ruo
- Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, Hangzhou Normal University, Hangzhou, China
- Key Laboratory of Hangzhou City for Quality and Safety of Agricultural Products, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Weiyang Jin
- Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, Hangzhou Normal University, Hangzhou, China
- Key Laboratory of Hangzhou City for Quality and Safety of Agricultural Products, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Ying Wu
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Xiaojing Shi
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Maojun Xu
- Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, Hangzhou Normal University, Hangzhou, China
- Key Laboratory of Hangzhou City for Quality and Safety of Agricultural Products, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
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Menon C, Sheerin DJ, Hiltbrunner A. SPA proteins: SPAnning the gap between visible light and gene expression. PLANTA 2016; 244:297-312. [PMID: 27100111 DOI: 10.1007/s00425-016-2509-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2016] [Accepted: 03/26/2016] [Indexed: 05/23/2023]
Abstract
In this review we focus on the role of SPA proteins in light signalling and discuss different aspects, including molecular mechanisms, specificity, and evolution. The ability of plants to perceive and respond to their environment is key to their survival under ever-changing conditions. The abiotic factor light is of particular importance for plants. Light provides plants energy for carbon fixation through photosynthesis, but also is a source of information for the adaptation of growth and development to the environment. Cryptochromes and phytochromes are major photoreceptors involved in control of developmental decisions in response to light cues, including seed germination, seedling de-etiolation, and induction of flowering. The SPA protein family acts in complex with the E3 ubiquitin ligase COP1 to target positive regulators of light responses for degradation by the 26S proteasome to suppress photomorphogenic development in darkness. Light-activated cryptochromes and phytochromes both repress the function of COP1, allowing accumulation of positive photomorphogenic factors in light. In this review, we highlight the role of the SPA proteins in this process and discuss recent advances in understanding how SPAs link light-activation of photoreceptors and downstream signaling.
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Affiliation(s)
- Chiara Menon
- Faculty of Biology, Institute of Biology II, University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
- Center for Plant Molecular Biology, University of Tübingen, Auf der Morgenstelle 32, 72076, Tübingen, Germany
| | - David J Sheerin
- Faculty of Biology, Institute of Biology II, University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
| | - Andreas Hiltbrunner
- Faculty of Biology, Institute of Biology II, University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany.
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Schänzlestrasse 18, 79104, Freiburg, Germany.
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Changing scenario in plant UV-B research:UV-B from a generic stressor to a specific regulator. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2015; 153:334-43. [DOI: 10.1016/j.jphotobiol.2015.10.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 10/08/2015] [Accepted: 10/11/2015] [Indexed: 11/15/2022]
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Zhu L, Bu Q, Xu X, Paik I, Huang X, Hoecker U, Deng XW, Huq E. CUL4 forms an E3 ligase with COP1 and SPA to promote light-induced degradation of PIF1. Nat Commun 2015; 6:7245. [PMID: 26037329 DOI: 10.1038/ncomms8245] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 04/22/2015] [Indexed: 02/01/2023] Open
Abstract
Plants undergo contrasting developmental programs in dark and light. Photomorphogenesis, a light-adapted programme is repressed in the dark by the synergistic actions of CUL4(COP1-SPA) E3 ubiquitin ligase and a subset of basic helix-loop-helix transcription factors called phytochrome interacting factors (PIFs). To promote photomorphogenesis, light activates the phytochrome family of sensory photoreceptors, which inhibits these repressors by poorly understood mechanisms. Here, we show that the CUL4(COP1-SPA) E3 ubiquitin ligase is necessary for the light-induced degradation of PIF1 in Arabidopsis. The light-induced ubiquitylation and subsequent degradation of PIF1 is reduced in the cop1, spaQ and cul4 backgrounds. COP1, SPA1 and CUL4 preferentially form complexes with the phosphorylated forms of PIF1 in response to light. The cop1 and spaQ seeds display strong hyposensitive response to far-red light-mediated seed germination and light-regulated gene expression. These data show a mechanism by which an E3 ligase attenuates its activity by degrading its cofactor in response to light.
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Affiliation(s)
- Ling Zhu
- Department of Molecular Biosciences and The Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Qingyun Bu
- Department of Molecular Biosciences and The Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Xiaosa Xu
- Department of Molecular Biosciences and The Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Inyup Paik
- Department of Molecular Biosciences and The Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Xi Huang
- Peking-Yale Joint Center for Plant Molecular Genetics and Agro-Biotechnology, State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, School of Advanced Agriculture Sciences and School of Life Sciences, Peking University, Beijing 100871, China
| | - Ute Hoecker
- Botanical Institute and Cluster of Excellence on Plant Sciences (CEPLAS), Biocenter, University of Cologne, Zülpicher Strasse 47b, 50674 Cologne, Germany
| | - Xing Wang Deng
- Peking-Yale Joint Center for Plant Molecular Genetics and Agro-Biotechnology, State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, School of Advanced Agriculture Sciences and School of Life Sciences, Peking University, Beijing 100871, China
| | - Enamul Huq
- Department of Molecular Biosciences and The Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA
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Pacín M, Legris M, Casal JJ. COP1 re-accumulates in the nucleus under shade. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 75:631-41. [PMID: 23647163 DOI: 10.1111/tpj.12226] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2013] [Revised: 04/25/2013] [Accepted: 04/29/2013] [Indexed: 05/23/2023]
Abstract
Shade-avoider plants typically respond to shade-light signals by increasing the rate of stem growth. CONSTITTUTIVE PHOTOMORPHOGENESIS 1 (COP1) is an E3 ligase involved in the ubiquitin labelling of proteins targeted for degradation. In dark-grown seedlings, COP1 accumulates in the nucleus and light exposure causes COP1 migration to the cytosol. Here, we show that in Arabidopsis thaliana, COP1 accumulates in the nucleus under natural or simulated shade, despite the presence of far-red light. In plants grown under white light, the transfer to shade-light conditions triggers an unexpectedly rapid re-accumulation of COP1 in the nucleus. The partial simulation of shade by lowering either blue or red light levels (maintaining far-red light) caused COP1 nuclear re-accumulation. Hypocotyl growth of wild-type seedlings is more sensitive to afternoon shade than to morning shade. A residual response to shade was observed in the cop1 mutant background, but these seedlings showed inverted sensitivity as they responded to morning shade and not to afternoon shade. COP1 overexpression exaggerated the wild-type pattern by enhancing afternoon sensitivity and making morning shade inhibitory of growth. COP1 nuclear re-accumulation also responded more strongly to afternoon shade than to morning shade. These results are consistent with a signalling role of COP1 in shade avoidance. We propose a function of COP1 in setting the daily patterns of sensitivity to shade in the fluctuating light environments of plant canopies.
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Affiliation(s)
- Manuel Pacín
- IFEVA, Facultad de Agronomía, Universidad de Buenos Aires and CONICET, 1417, Buenos Aires, Argentina
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Morales LO, Brosché M, Vainonen J, Jenkins GI, Wargent JJ, Sipari N, Strid Å, Lindfors AV, Tegelberg R, Aphalo PJ. Multiple roles for UV RESISTANCE LOCUS8 in regulating gene expression and metabolite accumulation in Arabidopsis under solar ultraviolet radiation. PLANT PHYSIOLOGY 2013; 161:744-59. [PMID: 23250626 PMCID: PMC3561016 DOI: 10.1104/pp.112.211375] [Citation(s) in RCA: 127] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 12/17/2012] [Indexed: 05/18/2023]
Abstract
Photomorphogenic responses triggered by low fluence rates of ultraviolet B radiation (UV-B; 280-315 nm) are mediated by the UV-B photoreceptor UV RESISTANCE LOCUS8 (UVR8). Beyond our understanding of the molecular mechanisms of UV-B perception by UVR8, there is still limited information on how the UVR8 pathway functions under natural sunlight. Here, wild-type Arabidopsis (Arabidopsis thaliana) and the uvr8-2 mutant were used in an experiment outdoors where UV-A (315-400 nm) and UV-B irradiances were attenuated using plastic films. Gene expression, PYRIDOXINE BIOSYNTHESIS1 (PDX1) accumulation, and leaf metabolite signatures were analyzed. The results show that UVR8 is required for transcript accumulation of genes involved in UV protection, oxidative stress, hormone signal transduction, and defense against herbivores under solar UV. Under natural UV-A irradiance, UVR8 is likely to interact with UV-A/blue light signaling pathways to moderate UV-B-driven transcript and PDX1 accumulation. UVR8 both positively and negatively affects UV-A-regulated gene expression and metabolite accumulation but is required for the UV-B induction of phenolics. Moreover, UVR8-dependent UV-B acclimation during the early stages of plant development may enhance normal growth under long-term exposure to solar UV.
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Affiliation(s)
- Luis O Morales
- Division of Plant Biology, Department of Biosciences, University of Helsinki, FI-00014 Helsinki, Finland.
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Moriwaki T, Miyazawa Y, Fujii N, Takahashi H. Light and abscisic acid signalling are integrated by MIZ1 gene expression and regulate hydrotropic response in roots of Arabidopsis thaliana. PLANT, CELL & ENVIRONMENT 2012; 35:1359-68. [PMID: 22321255 DOI: 10.1111/j.1365-3040.2012.02493.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Plant roots undergo tropic growth in response to environmental cues, and each tropic response is affected by several environmental stimuli. Even its importance, molecular regulation of hydrotropism has not been largely uncovered. Tropic responses including hydrotropism were impacted by other environmental signal. We found that hydrotropism was reduced in dark-grown seedling. Moreover, we found that the expression of MIZ1, an essential gene for hydrotropism, was regulated by light signal. From our genetic analysis, phytochrome A (phyA)-, phyB- and HY5-mediated blue-light signalling play curial roles in light-mediated induction of MIZ1 and hydrotropism. In addition, we found that abscisic acid (ABA) also induced MIZ1 expression. ABA treatment could recover weak hydrotropism and MIZ1 expression level of hy5, and ABA synthesis inhibitor, abamineSG, further reduced hydrotropic curvature of hy5. In contrast, ABA treatment did not affect ahydrotropic phenotype of miz1. These results suggest that ABA signalling regulates MIZ1 expression independently from light signalling. Our results demonstrate that environmental signals, such as light and stresses mediated by ABA signalling, are integrated into MIZ1 expression and thus regulate hydrotropism. These machineries will allow plants to acquire sufficient amounts of water.
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Affiliation(s)
- Teppei Moriwaki
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
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9
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Heijde M, Ulm R. UV-B photoreceptor-mediated signalling in plants. TRENDS IN PLANT SCIENCE 2012; 17:230-7. [PMID: 22326562 DOI: 10.1016/j.tplants.2012.01.007] [Citation(s) in RCA: 242] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Revised: 01/12/2012] [Accepted: 01/16/2012] [Indexed: 05/05/2023]
Abstract
Ultraviolet-B radiation (UV-B) is a key environmental signal that is specifically perceived by plants to promote UV acclimation and survival in sunlight. Whereas the plant photoreceptors for visible light are rather well characterised, the UV-B photoreceptor UVR8 was only recently described at the molecular level. Here, we review the current understanding of the UVR8 photoreceptor-mediated pathway in the context of UV-B perception mechanism, early signalling components and physiological responses. We further outline the commonalities in UV-B and visible light signalling as well as highlight differences between these pathways.
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Affiliation(s)
- Marc Heijde
- Department of Botany and Plant Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland
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10
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Smirnova OG, Stepanenko IL, Shumnyi VK. The role of the COP1, SPA, and PIF proteins in plant photomorphogenesis. ACTA ACUST UNITED AC 2011. [DOI: 10.1134/s2079086411040098] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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11
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Yan H, Marquardt K, Indorf M, Jutt D, Kircher S, Neuhaus G, Rodríguez-Franco M. Nuclear localization and interaction with COP1 are required for STO/BBX24 function during photomorphogenesis. PLANT PHYSIOLOGY 2011; 156:1772-82. [PMID: 21685177 PMCID: PMC3149933 DOI: 10.1104/pp.111.180208] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Arabidopsis (Arabidopsis thaliana) SALT TOLERANCE/B-BOX ZINC FINGER PROTEIN24 (STO/BBX24) is a negative regulator of the light signal transduction that localizes to the nucleus of plant cells and interacts with CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1) in the yeast (Saccharomyces cerevisiae) two-hybrid system. The protein contains two B-box zinc-finger motives at the N terminus and a conserved motif at the C-terminal part required for the interaction with COP1. BBX24 accumulates during deetiolation of young seedlings in the first hours of exposure to light. However, this accumulation is transient and decreases after prolonged light irradiation. Here, we identified the amino acidic residues necessary for the nuclear import of the protein. In addition, we created mutated forms of the protein, and analyzed them by overexpression in the bbx24-1 mutant background. Our results indicate that the degradation of BBX24 occurs, or at least is initiated in the nucleus, and this nuclear localization is a prerequisite to fulfill its function in light signaling. Moreover, mutations in the region responsible for the interaction with COP1 revealed that a physical interaction of the proteins is also required for degradation of BBX24 in the light and for normal photomorphogenesis.
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Valverde F. CONSTANS and the evolutionary origin of photoperiodic timing of flowering. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:2453-63. [PMID: 21239381 DOI: 10.1093/jxb/erq449] [Citation(s) in RCA: 109] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
A network of promoting and inhibiting pathways that respond to environmental and internal signals controls the flowering transition. The outcome of this regulatory network establishes, for any particular plant, the correct time of the year to flower. The photoperiod pathway channels inputs from light, day length, and the circadian clock to promote the floral transition. CONSTANS (CO) is a central regulator of this pathway, triggering the production of the mobile florigen hormone FT (FLOWERING LOCUS T) that induces flower differentiation. Because plant reproductive fitness is directly related to its capacity to flower at a precise time, the photoperiod pathway is present in all known plant species. Recent findings have stretched the evolutionary span of this photophase signal to unicellular algae, which show unexpected conserved characteristics with modern plant photoperiodic responses. In this review, a comparative description of the photoperiodic systems in algae and plants will be presented and a general role for the CO family of transcriptional activators proposed.
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Affiliation(s)
- Federico Valverde
- Molecular Plant Development and Metabolism Group, Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas y Universidad de Sevilla, 49 Americo Vespucio Avenue, 41092-Sevilla, Spain.
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13
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Sellaro R, Hoecker U, Yanovsky M, Chory J, Casal JJ. Synergism of red and blue light in the control of Arabidopsis gene expression and development. Curr Biol 2009; 19:1216-20. [PMID: 19559617 DOI: 10.1016/j.cub.2009.05.062] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2009] [Revised: 05/12/2009] [Accepted: 05/18/2009] [Indexed: 12/30/2022]
Abstract
The synergism between red and blue light in the control of plant growth and development requires the coaction of the red light photoreceptor phytochrome B (phyB) and the blue light and UV-A receptor cryptochromes (cry). Here, we describe the mechanism of the coaction of these photoreceptors in controlling both development and physiology. In seedlings grown under red light, a transient supplement with blue light induced persistent changes in the transcriptome and growth patterns. Blue light enhanced the expression of the transcription factors LONG HYPOCOTYL 5 (HY5) and HOMOLOG OF HY5 (HYH) and of SUPPRESSOR OF PHYA 1 (SPA1) and SPA4. HY5 and HYH enhanced phyB signaling output beyond the duration of the blue light signal, and, contrary to their known role as repressors of phyA signaling, SPA1 and SPA4 also enhanced phyB signaling. These observations demonstrate that the mechanism of synergism involves the promotion by cry of positive regulators of phyB signaling. The persistence of the light-derived signal into the night commits the seedling to a morphogenetic and physiological program consistent with a photosynthetic lifestyle.
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Affiliation(s)
- Romina Sellaro
- IFEVA, Facultad de Agronomía, Universidad de Buenos Aires, and CONICET, Av. San Martín 4453, 1417-Buenos Aires, Argentina
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Abstract
UV-B radiation is a key environmental signal that initiates diverse responses in plants that affect metabolism, development, and viability. Many effects of UV-B involve the differential regulation of gene expression. The response to UV-B depends on the nature of the UV-B treatment, the extent of adaptation and acclimation to UV-B, and interaction with other environmental factors. Responses to UV-B are mediated by both nonspecific signaling pathways, involving DNA damage, reactive oxygen species, and wound/defense signaling molecules, and UV-B-specific pathways that mediate photomorphogenic responses to low levels of UV-B. Importantly, photomorphogenic signaling stimulates the expression of genes involved in UV-protection and hence promotes plant survival in UV-B. Photomorphogenic UV-B signaling is mediated by the UV-B-specific component UV RESISTANCE LOCUS8 (UVR8). Both UVR8 and CONSTITUTIVE PHOTOMORPHOGENESIS1 (COP1) are required for UV-B-induced expression of the ELONGATED HYPOCOTYL5 (HY5) transcription factor, which plays a central role in the regulation of genes involved in photomorphogenic UV-B responses.
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Affiliation(s)
- Gareth I. Jenkins
- Plant Science Group, Division of Molecular and Cellular Biology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
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15
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Jiang L, Wang Y, Björn LO, Li S. Arabidopsis radical-induced cell death1 is involved in UV-B signaling. Photochem Photobiol Sci 2009; 8:838-46. [PMID: 19492112 DOI: 10.1039/b901187k] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The Arabidopsis radical-induced cell death1 (rcd1) mutant is sensitive to ozone fumigation and apoplastic superoxide, but tolerant to methyl viologen. In the present article, we report that the rcd1 mutant is also tolerant to supplementary UV-B radiation. The rcd1-1 mutant exhibits less accumulation of TT dimers, increased hypocotyl growth inhibition and higher accumulation of flavonoids under supplemental UV-B radiation. Moreover, the expression of HY5 (elongated hypocotyl5) is increased in the mutant after UV-B treatment. Gene expression downstream of UV-B signaling reveals that COP1 (constitutively photomorphogenic1)-regulated genes have an elevated expression in rcd1-1 mutant under UV-B radiation, while expression of UVR8 (UV resistance locus 8)-regulated and HY5-independent genes are not changed. Interestingly, the expression of RCD1 genes is not significantly changed by UV-B radiation. Previous study has shown that STO protein is interacting with RCD1 in vitro. Here, we found the mRNA level of STO (salt tolerance) is greatly increased in rcd1-1 mutant after UV-B radiation. However, UV-B-induced HY5 and CHS expression is partially inhibited in sto mutant. Based on the above results, it is deduced that the RCD1, working together with STO, is involved in Arabidopsis UV-B signaling.
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Affiliation(s)
- Lei Jiang
- Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, School of Life Science, South China Normal University, Guangzhou 510631, China
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Interaction of COP1 and UVR8 regulates UV-B-induced photomorphogenesis and stress acclimation in Arabidopsis. EMBO J 2009; 28:591-601. [PMID: 19165148 DOI: 10.1038/emboj.2009.4] [Citation(s) in RCA: 434] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2008] [Accepted: 01/05/2009] [Indexed: 12/28/2022] Open
Abstract
The ultraviolet-B (UV-B) portion of the solar radiation functions as an environmental signal for which plants have evolved specific and sensitive UV-B perception systems. The UV-B-specific UV RESPONSE LOCUS 8 (UVR8) and the multifunctional E3 ubiquitin ligase CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) are key regulators of the UV-B response. We show here that uvr8-null mutants are deficient in UV-B-induced photomorphogenesis and hypersensitive to UV-B stress, whereas overexpression of UVR8 results in enhanced UV-B photomorphogenesis, acclimation and tolerance to UV-B stress. By using sun simulators, we provide evidence at the physiological level that UV-B acclimation mediated by the UV-B-specific photoregulatory pathway is indeed required for survival in sunlight. At the molecular level, we demonstrate that the wild type but not the mutant UVR8 and COP1 proteins directly interact in a UV-B-dependent, rapid manner in planta. These data collectively suggest that UV-B-specific interaction of COP1 and UVR8 in the nucleus is a very early step in signalling and responsible for the plant's coordinated response to UV-B ensuring UV-B acclimation and protection in the natural environment.
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Zhu D, Maier A, Lee JH, Laubinger S, Saijo Y, Wang H, Qu LJ, Hoecker U, Deng XW. Biochemical characterization of Arabidopsis complexes containing CONSTITUTIVELY PHOTOMORPHOGENIC1 and SUPPRESSOR OF PHYA proteins in light control of plant development. THE PLANT CELL 2008; 20:2307-23. [PMID: 18812498 PMCID: PMC2570740 DOI: 10.1105/tpc.107.056580] [Citation(s) in RCA: 169] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2007] [Revised: 07/20/2008] [Accepted: 09/10/2008] [Indexed: 05/18/2023]
Abstract
COP1 (for CONSTITUTIVELY PHOTOMORPHOGENIC1) and the four partially redundant SPA (for SUPPRESSOR OF PHYA) proteins work in concert to repress photomorphogenesis in Arabidopsis thaliana by targeting key transcription factors and phytochrome A for degradation via the 26S proteasome. Here, we report a detailed biochemical characterization of the SPA-COP1 complexes. The four endogenous SPA proteins can form stable complexes with COP1 in vivo regardless of light conditions but exhibit distinct expression profiles in different tissues and light conditions. The SPA proteins can self-associate or interact with each other, forming a heterogeneous group of SPA-COP1 complexes in which the exact SPA protein compositions vary depending on the abundance of individual SPA proteins. The four SPA proteins could be divided into two functional groups depending on their interaction affinities, their regulation of ELONGATED HYPOCOTYL5 degradation, and their opposite effects on COP1 protein accumulation. Loss-of-function mutations in a predominant SPA protein may cause a significant reduction in the overall SPA-COP1 E3 ligase activity, resulting in a partial constitutive photomorphogenic phenotype. This study thus provides an in-depth biochemical view of the SPA-COP1 E3 ligase complexes and offers new insights into the molecular basis for their distinct roles in the light control of plant development.
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Affiliation(s)
- Danmeng Zhu
- Peking-Yale Joint Center of Plant Molecular Genetics and Agrobiotechnology, College of Life Sciences, Peking University, Beijing 100871, China
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18
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Hong SH, Kim HJ, Ryu JS, Choi H, Jeong S, Shin J, Choi G, Nam HG. CRY1 inhibits COP1-mediated degradation of BIT1, a MYB transcription factor, to activate blue light-dependent gene expression in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2008; 55:361-71. [PMID: 18397371 DOI: 10.1111/j.1365-313x.2008.03508.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Cryptochromes (CRY) are one of the two major classes of photoreceptors that perceive light stimuli in the UV-A to blue light region and they are involved in multiple aspects of plant growth and development. However, knowledge regarding their signaling transduction components and mechanisms remains limited. Here, we report that a MYB transcription factor Blue Insensitive Trait 1 (BIT1), plays an important role in controlling blue light responses. Hypocotyl growth responses indicate that BIT1 functions as a positive element in blue light signaling, since BIT1 antisense and knock-out lines show a reduced light response in blue light. BIT1 controls blue light-dependent expression of various genes such as PsbS, a member of the light-harvesting complex gene family. A transactivation assay showed that BIT1 regulates promoter activity of PsbS in a blue light-dependent manner and that it requires CRY1 for activation of the PsbS promoter. BIT1 undergoes degradation in darkness and CRY1 functions to stabilize BIT1 in a blue light-dependent manner. In contrast, COP1 binds to BIT1 and mediates its degradation. We propose that the PsbS promoter is activated in blue light via the blue light-dependent stabilization of BIT1 by CRY1, while in darkness BIT1 is degraded by COP1-mediated proteolysis.
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Affiliation(s)
- Sung Hyun Hong
- Division of Molecular and Life Science, POSTECH, Pohang, 790-784, Republic of Korea
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19
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Jang S, Marchal V, Panigrahi KCS, Wenkel S, Soppe W, Deng XW, Valverde F, Coupland G. Arabidopsis COP1 shapes the temporal pattern of CO accumulation conferring a photoperiodic flowering response. EMBO J 2008; 27:1277-88. [PMID: 18388858 PMCID: PMC2291449 DOI: 10.1038/emboj.2008.68] [Citation(s) in RCA: 358] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Accepted: 03/10/2008] [Indexed: 01/17/2023] Open
Abstract
The transcriptional regulator CONSTANS (CO) promotes flowering of Arabidopsis under long summer days (LDs) but not under short winter days (SDs). Post-translational regulation of CO is crucial for this response by stabilizing the protein at the end of a LD, whereas promoting its degradation throughout the night under LD and SD. We show that mutations in CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1), a component of a ubiquitin ligase, cause extreme early flowering under SDs, and that this is largely dependent on CO activity. Furthermore, transcription of the CO target gene FT is increased in cop1 mutants and decreased in plants overexpressing COP1 in phloem companion cells. COP1 and CO interact in vivo and in vitro through the C-terminal region of CO. COP1 promotes CO degradation mainly in the dark, so that in cop1 mutants CO protein but not CO mRNA abundance is dramatically increased during the night. However, in the morning CO degradation occurs independently of COP1 by a phytochrome B-dependent mechanism. Thus, COP1 contributes to day length perception by reducing the abundance of CO during the night and thereby delaying flowering under SDs.
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Affiliation(s)
- Seonghoe Jang
- Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, Cologne, Germany
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20
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Indorf M, Cordero J, Neuhaus G, Rodríguez-Franco M. Salt tolerance (STO), a stress-related protein, has a major role in light signalling. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2007; 51:563-74. [PMID: 17605755 DOI: 10.1111/j.1365-313x.2007.03162.x] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The salt tolerance protein (STO) of Arabidopsis was identified as a protein conferring salt tolerance to yeast cells. In order to uncover its function, we isolated an STO T-DNA insertion line and generated RNAi and overexpressor Arabidopsis plants. Here we present data on the hypocotyl growth of these lines indicating that STO acts as a negative regulator in phytochrome and blue-light signalling. Transcription analysis of STO uncovered a light and circadian dependent regulation of gene expression, and analysis of light-regulated genes revealed that STO is involved in the regulation of CHS expression during de-etiolation. In addition, we could show that CONSTITUTIVE PHOTOMORPHOGENESIS 1 (COP1) represses the transcription of STO and contributes to the destabilization of the protein in etiolated seedlings. Microscopic analysis revealed that the STO:eGFP fusion protein is located in the nucleus, accumulates in a light-dependent manner, and, in transient transformation assays in onion epidermal cells, co-localizes with COP1 in nuclear and cytoplasmic aggregations. However, the analysis of gain- and loss-of-function STO mutants in the cop1-4 background points towards a COP1-independent role during photomorphogenesis.
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Affiliation(s)
- Martin Indorf
- Department of Cell Biology, University of Freiburg, Freiburg D-79104, Germany
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21
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Oravecz A, Baumann A, Máté Z, Brzezinska A, Molinier J, Oakeley EJ, Adám E, Schäfer E, Nagy F, Ulm R. CONSTITUTIVELY PHOTOMORPHOGENIC1 is required for the UV-B response in Arabidopsis. THE PLANT CELL 2006; 18:1975-90. [PMID: 16829591 PMCID: PMC1533968 DOI: 10.1105/tpc.105.040097] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2005] [Revised: 05/11/2006] [Accepted: 06/19/2006] [Indexed: 05/10/2023]
Abstract
CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1) is a negative regulator of photomorphogenesis in Arabidopsis thaliana. COP1 functions as an E3 ubiquitin ligase, targeting select proteins for proteasomal degradation in plants as well as in mammals. Among its substrates is the basic domain/leucine zipper (bZIP) transcription factor ELONGATED HYPOCOTYL5 (HY5), one of the key regulators of photomorphogenesis under all light qualities, including UV-B responses required for tolerance to this environmental threat. Here, we report that, in contrast with the situation in visible light, COP1 is a critical positive regulator of responses to low levels of UV-B. We show that in the cop1-4 mutant, flavonoid accumulation and genome-wide expression changes in response to UV-B are blocked to a large extent. COP1 is required for HY5 gene activation, and both COP1 and HY5 proteins accumulate in the nucleus under supplementary UV-B. SUPPRESSOR OF PHYTOCHROME A-105 family proteins (SPA1 to SPA4) that are required for COP1 function in dark and visible light are not essential in the response to UV-B. We conclude that COP1 performs a specific and novel role in the plants' photomorphogenic response to UV-B, coordinating HY5-dependent and -independent pathways, which eventually results in UV-B tolerance.
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Affiliation(s)
- Attila Oravecz
- Institute of Biology II/Botany, University of Freiburg, D-79104 Freiburg, Germany
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22
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Roig-Villanova I, Bou J, Sorin C, Devlin PF, Martínez-García JF. Identification of primary target genes of phytochrome signaling. Early transcriptional control during shade avoidance responses in Arabidopsis. PLANT PHYSIOLOGY 2006; 141:85-96. [PMID: 16565297 PMCID: PMC1459307 DOI: 10.1104/pp.105.076331] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The phytochrome (phy) photoreceptors modulate plant development after perception of light. Upon illumination of etiolated seedlings, phys initiate a transcriptional cascade by directly transducing light signals to the promoters of genes encoding regulators of morphogenesis. In light-grown plants, however, little is known about the transcriptional cascade modulated by phys in response to changes in light. The phy entry points in this cascade are completely unknown. We are particularly interested in the shade avoidance syndrome (SAS). Here we describe a subset of six genes whose expression is rapidly modulated by phys during both deetiolation and SAS in Arabidopsis (Arabidopsis thaliana). Using cycloheximide, we provide evidence that four of these phy rapidly regulated (PAR) genes are direct targets of phy signaling during SAS, revealing these genes as upstream components of the transcriptional cascade. Promoter-beta-glucuronidase fusions confirmed that PAR genes are photoregulated at the transcriptional level. Analysis of gene expression in light signal transduction mutants showed that COP1 and DET1 (but not DET2 or HY5) play a role in modulating PAR expression in response to shade in light-grown seedlings. Moreover, genetic analyses showed that one of the genes identified as a direct target of phy signaling was phy-interacting factor 3-like-1 (PIL1). PIL1 has previously been implicated in SAS in response to transient shade, but we show here that it also plays a key role in response to long-term shade. The action of PIL1 was particularly apparent in a phyB background, suggesting an important negative role for PIL1 under dense vegetation canopies.
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Affiliation(s)
- Irma Roig-Villanova
- Departament de Genètica Molecular, Institut de Biologia Molecular de Barcelona, Consorci CSIC-IRTA, 08034 Barcelona, Spain
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23
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Molas ML, Kiss JZ, Correll MJ. Gene profiling of the red light signalling pathways in roots. JOURNAL OF EXPERIMENTAL BOTANY 2006; 57:3217-29. [PMID: 16908503 DOI: 10.1093/jxb/erl086] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Red light, acting through the phytochromes, controls numerous aspects of plant development. Many of the signal transduction elements downstream of the phytochromes have been identified in the aerial portions of the plant; however, very few elements in red-light signalling have been identified specifically for roots. Gene profiling studies using microarrays and quantitative Real-Time PCR were performed to characterize gene expression changes in roots of Arabidopsis seedlings exposed to 1 h of red light. Several factors acting downstream of phytochromes in red-light signalling in roots were identified. Some of the genes found to be differentially expressed in this study have already been characterized in the red-light-signalling pathway for whole plants. For example, PHYTOCHROME KINASE 1 (PKS1), LONG HYPOCOTYL 5 (HY5), EARLY FLOWERING 4 (ELF4), and GIGANTEA (GI) were all significantly up-regulated in roots of seedlings exposed to 1 h of red light. The up-regulation of SUPPRESSOR OF PHYTOCHROME A RESPONSES 1 (SPA1) and CONSTITUTIVE PHOTOMORPHOGENIC 1-like (COP1-like) genes suggests that the PHYA-mediated pathway was attenuated by red light. In addition, genes involved in lateral root and root hair formation, root plastid development, phenylpropanoid metabolism, and hormone signalling were also regulated by exposure to red light. Interestingly, members of the RPT2/NPH3 (ROOT PHOTOTROPIC 2/NON PHOTOTROPIC HYPOCOTYL 3) family, which have been shown to mediate blue-light-induced phototropism, were also differentially regulated in roots in red light. Therefore, these results suggest that red and blue light pathways interact in roots of seedlings and that many elements involved in red-light-signalling found in the aerial portions of the plant are differentially expressed in roots within 1 h of red light exposure.
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Affiliation(s)
- Maria Lia Molas
- Department of Botany, Miami University, Oxford, OH 45056, USA
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24
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Shen H, Moon J, Huq E. PIF1 is regulated by light-mediated degradation through the ubiquitin-26S proteasome pathway to optimize photomorphogenesis of seedlings in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2005; 44:1023-35. [PMID: 16359394 DOI: 10.1111/j.1365-313x.2005.02606.x] [Citation(s) in RCA: 183] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Light signals perceived by the phytochrome (phy) family of sensory photoreceptors control multiple aspects of plant development. Recently, PIF1, a phy-interacting basic helix-loop-helix (bHLH) transcription factor, has been shown to negatively regulate facets of the photomorphogenesis of seedlings. Moreover, the transcriptional activation activity of PIF1 is reduced in a phy-dependent manner. In this study we use the luciferase (LUC) activity of the LUC-PIF1 fusion protein as an indicator of the stability of PIF1 in various light conditions. We found that the activity of LUC-PIF1 in both transient and stable transgenic lines is rapidly reduced in light, while the LUC-only control is stable under the same conditions, suggesting that PIF1 is degraded in response to light. Fluence-rate response curves indicate that PIF1 degradation is very sensitive to the quality and quantity of light. The half-life of PIF1 is about 16 min under 10 micromol m-2 sec-1 red light. PIF1 reaccumulates in the subsequent dark period after light-induced degradation, signifying that PIF1 not only functions in the dark and during the transition from etiolated to de-etiolated growth, but may also function during diurnal cycles. Inhibitors of the 26S proteasome increased the stability of PIF1, indicating that degradation of PIF1 is mediated by the ubiquitin-26S proteasome pathway. Further, de novo protein synthesis is not required for degradation of PIF1, as the presence of cycloheximide does not prevent degradation of PIF1 in the light. Taken together, these results suggest that the light signals perceived by phys induce the degradation of PIF1 and other phy-interacting factors to optimize photomorphogenesis.
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Affiliation(s)
- Hui Shen
- Section of Molecular Cell and Developmental Biology and The Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA
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25
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Hoecker U. Regulated proteolysis in light signaling. CURRENT OPINION IN PLANT BIOLOGY 2005; 8:469-76. [PMID: 16039154 DOI: 10.1016/j.pbi.2005.07.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2005] [Accepted: 07/12/2005] [Indexed: 05/03/2023]
Abstract
Photoreceptors regulate many aspects of development throughout the life cycle of a plant. Recent advances have demonstrated the importance of ubiquitin-mediated proteolysis in the control of development by light. Both some of the photoreceptors themselves and, in particular, transcription factors that are involved in transducing the light signal are subject to regulated ubiquitination and subsequent degradation by the 26S proteasome.
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Affiliation(s)
- Ute Hoecker
- Department of Plant Developmental and Molecular Biology, Geb. 26.03.02, University of Düsseldorf, D-40225 Düsseldorf, Germany.
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26
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Yi C, Deng XW. COP1 - from plant photomorphogenesis to mammalian tumorigenesis. Trends Cell Biol 2005; 15:618-25. [PMID: 16198569 DOI: 10.1016/j.tcb.2005.09.007] [Citation(s) in RCA: 235] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2005] [Revised: 08/24/2005] [Accepted: 09/20/2005] [Indexed: 10/25/2022]
Abstract
The COP1 (constitutive photomorphogenic 1) protein, comprising RING finger, coiled-coil and WD40 domains, is conserved in both higher plants and vertebrates. In plants, COP1 acts as an E3 ubiquitin ligase to repress light signaling by targeting photoreceptors and downstream transcription factors for ubiquitylation and degradation. The activity of COP1 in plant cells correlates with its cytoplasmic and nuclear partitioning according to dark or light conditions. In addition, various signaling molecules have been shown to directly interact with COP1 and modulate its activity. Recently, scientists have begun to probe the function and regulation of COP1 in mammalian systems. Initial studies have pointed at possible roles for mammalian COP1 in tumorigenesis and the stress response through regulating the activities of p53 and c-Jun.
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Affiliation(s)
- Chunling Yi
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8104, USA
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