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Phytochrome A in plants comprises two structurally and functionally distinct populations — water-soluble phyA′ and amphiphilic phyA″. Biophys Rev 2022; 14:905-921. [DOI: 10.1007/s12551-022-00974-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Accepted: 06/14/2022] [Indexed: 10/17/2022] Open
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Matsusaka D, Filiault D, Sanchez DH, Botto JF. Ultra-High-Density QTL Marker Mapping for Seedling Photomorphogenesis Mediating Arabidopsis Establishment in Southern Patagonia. FRONTIERS IN PLANT SCIENCE 2021; 12:677728. [PMID: 34367202 PMCID: PMC8343176 DOI: 10.3389/fpls.2021.677728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 06/22/2021] [Indexed: 05/15/2023]
Abstract
Arabidopsis thaliana shows a wide range of genetic and trait variation among wild accessions. Because of its unparalleled biological and genomic resources, Arabidopsis has a high potential for the identification of genes underlying ecologically important complex traits, thus providing new insights on genome evolution. Previous research suggested that distinct light responses were crucial for Arabidopsis establishment in a peculiar ecological niche of southern Patagonia. The aim of this study was to explore the genetic basis of contrasting light-associated physiological traits that may have mediated the rapid adaptation to this new environment. From a biparental cross between the photomorphogenic contrasting accessions Patagonia (Pat) and Columbia (Col-0), we generated a novel recombinant inbred line (RIL) population, which was entirely next-generation sequenced to achieve ultra-high-density saturating molecular markers resulting in supreme mapping sensitivity. We validated the quality of the RIL population by quantitative trait loci (QTL) mapping for seedling de-etiolation, finding seven QTLs for hypocotyl length in the dark and continuous blue light (Bc), continuous red light (Rc), and continuous far-red light (FRc). The most relevant QTLs, Rc1 and Bc1, were mapped close together to chromosome V; the former for Rc and Rc/dark, and the latter for Bc, FRc, and dark treatments. The additive effects of both QTLs were confirmed by independent heterogeneous inbred families (HIFs), and we explored TZP and ABA1 as potential candidate genes for Rc1 and Bc1QTLs, respectively. We conclude that the Pat × Col-0 RIL population is a valuable novel genetic resource to explore other adaptive traits in Arabidopsis.
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Affiliation(s)
- Daniel Matsusaka
- IFEVA, UBA, CONICET, Facultad de Agronomía, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Daniele Filiault
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenter, Vienna, Austria
| | - Diego H. Sanchez
- IFEVA, UBA, CONICET, Facultad de Agronomía, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Javier F. Botto
- IFEVA, UBA, CONICET, Facultad de Agronomía, Universidad de Buenos Aires, Buenos Aires, Argentina
- *Correspondence: Javier F. Botto,
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Sheerin DJ, Hiltbrunner A. Molecular mechanisms and ecological function of far-red light signalling. PLANT, CELL & ENVIRONMENT 2017; 40:2509-2529. [PMID: 28102581 DOI: 10.1111/pce.12915] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 01/11/2017] [Accepted: 01/13/2017] [Indexed: 05/18/2023]
Abstract
Land plants possess the ability to sense and respond to far-red light (700-760 nm), which serves as an important environmental cue. Due to the nature of far-red light, it is not absorbed by chlorophyll and thus is enriched in canopy shade and will also penetrate deeper into soil than other visible wavelengths. Far-red light responses include regulation of seed germination, suppression of hypocotyl growth, induction of flowering and accumulation of anthocyanins, which depend on one member of the phytochrome photoreceptor family, phytochrome A (phyA). Here, we review the current understanding of the underlying molecular mechanisms of how plants sense far-red light through phyA and the physiological responses to this light quality. Light-activated phytochromes act on two primary pathways within the nucleus; suppression of the E3 ubiquitin ligase complex CUL4/DDB1COP1/SPA and inactivation of the PHYTOCHROME INTERACTING FACTOR (PIF) family of bHLH transcription factors. These pathways integrate with other signal transduction pathways, including phytohormones, for tissue and developmental stage specific responses. Unlike other phytochromes that mediate red-light responses, phyA is transported from the cytoplasm to the nucleus in far-red light by the shuttle proteins FAR-RED ELONGATED HYPOCOTYL 1 (FHY1) and FHY1-LIKE (FHL). However, additional mechanisms must exist that shift the action of phyA to far-red light; current hypotheses are discussed.
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Affiliation(s)
- David J Sheerin
- Institute of Biology II, Faculty of Biology, University of Freiburg, 79104, Freiburg, Germany
| | - Andreas Hiltbrunner
- Institute of Biology II, Faculty of Biology, University of Freiburg, 79104, Freiburg, Germany
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104, Freiburg, Germany
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Krzymuski M, Cerdán PD, Zhu L, Vinh A, Chory J, Huq E, Casal JJ. Phytochrome A antagonizes PHYTOCHROME INTERACTING FACTOR 1 to prevent over-activation of photomorphogenesis. MOLECULAR PLANT 2014; 7:1415-1428. [PMID: 25009301 DOI: 10.1093/mp/ssu078] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Phytochrome A (phyA) is crucial to initiate the early steps of the transition between skoto- and photomorphogenesis upon light exposure and to complete this process under far-red light (typical of dense vegetation canopies). However, under prolonged red or white light, phyA mutants are hyper-photomorphogenic in many respects. To investigate this issue, we analyzed the late response of the transcriptome of the phyA mutant to red light. Compared to the wild-type (WT), hyper-responsive genes outnumbered the genes showing reduced response to red light in phyA. A network analysis revealed the co-expression of PHYTOCHROME INTERACTING FACTOR 1 (PIF1) with those genes showing hyper-promotion by red light in phyA. The enhanced responses of gene expression, cotyledon unfolding, hypocotyl growth, and greening observed in the phyA mutant compared to the WT were absent in the phyA pif1 double mutant compared to pif1, indicating that the hyper-photomorphogenic phenotype of phyA requires PIF1. PIF1 directly binds to gene promoters that displayed PIF1-mediated enhanced response to red light. Expression of mutant PIF1 deficient in interactions with phyA and phyB enhanced the long-term growth response to red light but reduced the expression of selected genes in response to red light. We propose that phytochrome-mediated degradation of PIF1 prevents over-activation of photomorphogenesis during early seedling development.
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Affiliation(s)
- Martín Krzymuski
- IFEVA, Faculty of Agronomy, University of Buenos Aires, and Consejo Nacional de Investigaciones Científicas y Técnicas, Av. San Martín 4453, 1417-Buenos Aires, Argentina
| | - Pablo D Cerdán
- Fundación Instituto Leloir, IIBBA-CONICET, C1405BWE-Buenos Aires, Argentina
| | - Ling Zhu
- Department of Molecular Biosciences and the Institute for Cellular and Molecular Biology, University of Texas, Austin, TX 78712, USA
| | - Amanda Vinh
- Department of Molecular Biosciences and the Institute for Cellular and Molecular Biology, University of Texas, Austin, TX 78712, USA
| | - Joanne Chory
- Plant Biology Laboratory, Howard Hughes Medical Institute, the Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Enamul Huq
- Department of Molecular Biosciences and the Institute for Cellular and Molecular Biology, University of Texas, Austin, TX 78712, USA
| | - Jorge J Casal
- IFEVA, Faculty of Agronomy, University of Buenos Aires, and Consejo Nacional de Investigaciones Científicas y Técnicas, Av. San Martín 4453, 1417-Buenos Aires, Argentina; Fundación Instituto Leloir, IIBBA-CONICET, C1405BWE-Buenos Aires, Argentina.
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Casal JJ, Candia AN, Sellaro R. Light perception and signalling by phytochrome A. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:2835-45. [PMID: 24220656 DOI: 10.1093/jxb/ert379] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
In etiolated seedlings, phytochrome A (phyA) mediates very-low-fluence responses (VLFRs), which initiate de-etiolation at the interphase between the soil and above-ground environments, and high-irradiance responses (HIR), which complete de-etiolation under dense canopies and require more sustained activation with far-red light. Light-activated phyA is transported to the nucleus by FAR-RED ELONGATED HYPOCOTYL1 (FHY1). The nuclear pool of active phyA increases under prolonged far-red light of relatively high fluence rates. This condition maximizes the rate of FHY1-phyA complex assembly and disassembly, allowing FHY1 to return to the cytoplasm to translocate further phyA to the nucleus, to replace phyA degraded in the proteasome. The core signalling pathways downstream of nuclear phyA involve the negative regulation of CONSTITUTIVE PHOTOMORPHOGENIC 1, which targets for degradation transcription factors required for photomorphogenesis, and PHYTOCHROME-INTERACTING FACTORs, which are transcription factors that repress photomorphogenesis. Under sustained far-red light activation, released FHY1 can also be recruited with active phyA to target gene promoters as a transcriptional activator, and nuclear phyA signalling activates a positive regulatory loop involving BELL-LIKE HOMEODOMAIN 1 that reinforces the HIR.
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Affiliation(s)
- J J Casal
- IFEVA, Facultad de Agronomía, Universidad de Buenos Aires and CONICET, 1417 Buenos Aires, Argentina Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas de Buenos Aires-CONICET, C1405BWE Buenos Aires, Argentina
| | - A N Candia
- IFEVA, Facultad de Agronomía, Universidad de Buenos Aires and CONICET, 1417 Buenos Aires, Argentina
| | - R Sellaro
- IFEVA, Facultad de Agronomía, Universidad de Buenos Aires and CONICET, 1417 Buenos Aires, Argentina
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Possart A, Fleck C, Hiltbrunner A. Shedding (far-red) light on phytochrome mechanisms and responses in land plants. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2014; 217-218:36-46. [PMID: 24467894 DOI: 10.1016/j.plantsci.2013.11.013] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 11/20/2013] [Accepted: 11/21/2013] [Indexed: 05/20/2023]
Abstract
In order to monitor ambient light conditions, plants rely on functionally diversified photoreceptors. Among these, phytochromes perceive red (R) and far-red (FR) light. FR light does not constitute a photosynthetic energy source; it however influences adaptive and developmental processes. In seed plants, phytochrome A (phyA) acts as FR receptor and mediates FR high irradiance responses (FR-HIRs). It exerts a dual role by promoting e.g. germination and seedling de-etiolation in canopy shade and by antagonising shade avoidance growth. Even though cryptogam plants such as mosses and ferns do not have phyA, they show FR-induced responses. In the present review we discuss the mechanistic basis of phyA-dependent FR-HIRs as well as their dual role in seed plants. We compare FR responses in seed plants and cryptogam plants and conclude on different potential concepts for the detection of canopy shade. Scenarios for the evolution of FR perception and responses are discussed.
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Affiliation(s)
- Anja Possart
- Center for Plant Molecular Biology, University of Tübingen, 72076 Tübingen, Germany; Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Christian Fleck
- Laboratory for Systems and Synthetic Biology, Wageningen University, 6703 HB Wageningen, The Netherlands.
| | - Andreas Hiltbrunner
- Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany.
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Kurepin LV, Dahal KP, Savitch LV, Singh J, Bode R, Ivanov AG, Hurry V, Hüner NPA. Role of CBFs as integrators of chloroplast redox, phytochrome and plant hormone signaling during cold acclimation. Int J Mol Sci 2013; 14:12729-63. [PMID: 23778089 PMCID: PMC3709810 DOI: 10.3390/ijms140612729] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 05/24/2013] [Accepted: 06/06/2013] [Indexed: 11/16/2022] Open
Abstract
Cold acclimation of winter cereals and other winter hardy species is a prerequisite to increase subsequent freezing tolerance. Low temperatures upregulate the expression of C-repeat/dehydration-responsive element binding transcription factors (CBF/DREB1) which in turn induce the expression of COLD-REGULATED (COR) genes. We summarize evidence which indicates that the integration of these interactions is responsible for the dwarf phenotype and enhanced photosynthetic performance associated with cold-acclimated and CBF-overexpressing plants. Plants overexpressing CBFs but grown at warm temperatures mimic the cold-tolerant, dwarf, compact phenotype; increased photosynthetic performance; and biomass accumulation typically associated with cold-acclimated plants. In this review, we propose a model whereby the cold acclimation signal is perceived by plants through an integration of low temperature and changes in light intensity, as well as changes in light quality. Such integration leads to the activation of the CBF-regulon and subsequent upregulation of COR gene and GA 2-oxidase (GA2ox) expression which results in a dwarf phenotype coupled with increased freezing tolerance and enhanced photosynthetic performance. We conclude that, due to their photoautotrophic nature, plants do not rely on a single low temperature sensor, but integrate changes in light intensity, light quality, and membrane viscosity in order to establish the cold-acclimated state. CBFs appear to act as master regulators of these interconnecting sensing/signaling pathways.
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Affiliation(s)
- Leonid V. Kurepin
- Department of Biology and the Biotron Center for Experimental Climate Change Research, Western University, London, ON N6A 5B7, Canada; E-Mails: (R.B.); (A.G.I.)
- Department of Plant Physiology, Umeå Plant Science Centre, Umeå University, Umeå 901 87, Sweden; E-Mail:
- Authors to whom correspondence should be addressed; E-Mails: (L.V.K.); (N.P.A.H.); Tel.: +1-519-661-2111 (ext. 86638) (L.V.K.); +1-519-661-2111 (ext. 86488) (N.P.A.H.); Fax: +1-519-850-2343(L.V.K. & N.P.A.H.)
| | - Keshav P. Dahal
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON M1C 1A4, Canada; E-Mail:
| | - Leonid V. Savitch
- Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada; E-Mails: (L.V.S.); (J.S.)
| | - Jas Singh
- Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada; E-Mails: (L.V.S.); (J.S.)
| | - Rainer Bode
- Department of Biology and the Biotron Center for Experimental Climate Change Research, Western University, London, ON N6A 5B7, Canada; E-Mails: (R.B.); (A.G.I.)
| | - Alexander G. Ivanov
- Department of Biology and the Biotron Center for Experimental Climate Change Research, Western University, London, ON N6A 5B7, Canada; E-Mails: (R.B.); (A.G.I.)
| | - Vaughan Hurry
- Department of Plant Physiology, Umeå Plant Science Centre, Umeå University, Umeå 901 87, Sweden; E-Mail:
| | - Norman P. A. Hüner
- Department of Biology and the Biotron Center for Experimental Climate Change Research, Western University, London, ON N6A 5B7, Canada; E-Mails: (R.B.); (A.G.I.)
- Authors to whom correspondence should be addressed; E-Mails: (L.V.K.); (N.P.A.H.); Tel.: +1-519-661-2111 (ext. 86638) (L.V.K.); +1-519-661-2111 (ext. 86488) (N.P.A.H.); Fax: +1-519-850-2343(L.V.K. & N.P.A.H.)
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Toledo-Ortiz G, Kiryu Y, Kobayashi J, Oka Y, Kim Y, Nam HG, Mochizuki N, Nagatani A. Subcellular sites of the signal transduction and degradation of phytochrome A. PLANT & CELL PHYSIOLOGY 2010; 51:1648-1660. [PMID: 20739301 DOI: 10.1093/pcp/pcq121] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Phytochrome regulates various physiological and developmental processes throughout the life cycle of plants. Among the members of the phytochrome family, phytochrome A (phyA) exclusively mediates the far-red light high irradiance response (FR-HIR), which is elicited by continuous far-red light. In FR-HIR, nuclear accumulation of phyA, which precedes physiological responses, is proposed to be required for the response. In contrast to FR, red light induces rapid degradation of phyA to suppress undesirable long-term photomorphogenic responses of phyA. In the present study, we compared biological activities between phyA derivatives to which either a nuclear localization (NLS) or export (NES) signal sequence was attached. Those derivatives were expressed under the control of the PHYA promoter in the Arabidopsis phyA mutant. Detailed microscopic observation revealed that the phyA-green fluorescent protein (GFP) without a signal sequence is localized exclusively in the cytoplasm in darkness. Rapid nuclear entry was observed after exposure to both red and far-red light. Interestingly, both phyA-GFP-NLS and phyA-GFP-NES were rapidly degraded under continuous red light. Furthermore, a proteasome inhibitor delayed degradation equally under these two conditions. Therefore, similar mechanisms for phyA degradation may exist in the cytoplasm and nucleus. As expected from previous reports, phyA-GFP-NLS, but not phyA-GFP-NES, mediated different aspects of FR-HIR, such as inhibition of hypocotyl elongation and rapid induction of gene expression, confirming that phyA nuclear localization is required for FR-HIR. In addition, a detailed time course analysis of phyA-GFP and phyA-GFP-NLS responses revealed that they were almost indistinguishable, raising the question of the physiological relevance of phyA cytoplasmic retention in darkness.
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Affiliation(s)
- Gabriela Toledo-Ortiz
- Department of Botany, Graduate School of Science, Kyoto University, Kyoto, 606-8502 Japan
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Laserna MP, Sánchez RA, Botto JF. Light-related loci controlling seed germination in Ler x Cvi and Bay-0 x Sha recombinant inbred-line populations of Arabidopsis thaliana. ANNALS OF BOTANY 2008; 102:631-42. [PMID: 18684732 PMCID: PMC2701784 DOI: 10.1093/aob/mcn138] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Revised: 06/06/2008] [Accepted: 06/30/2008] [Indexed: 05/22/2023]
Abstract
BACKGROUND AND AIMS Dormancy is a complex trait finely regulated by hormones and environmental factors. The phytochromes that sense red:far-red (R:FR) are the sole photoreceptors involved in the termination of dormancy and the induction of germination by light. The aims of this study were to identify and characterize loci controlling this process in seeds of Arabidopsis thaliana. METHODS Recombinant inbred lines (RILs) derived from Landsberg erecta and Cape Verde Islands (Ler x Cvi), and Bayreuth and Shahdara (Bay-0 x Sha) were used to map loci related to light effects in seeds previously exposed to chilling and after-ripening periods. KEY RESULTS Substantial genetic variation was found between accessions of A. thaliana in the induction of germination by light. Twelve loci were identified under R, FR or darkness, some of which were novel loci: DOG8, DOG9, DOG13, DOG14 and DOG15 detected in the Ler x Cvi RIL population; and DOG10, DOG11 and DOG12 mapped in the Bay-0 x Sha RIL population. Furthermore, independent loci were mapped for the induction of germination by low fluence (DOG-LF1 and DOG-LF2) and very low fluence of light (DOG-VLF1) in the Ler x Cvi RIL population. Several loci were confirmed and characterized after different after-ripening and chilling treatments through near-isogenic lines (NILs) and heterogeneous inbred families (HIFs). CONCLUSIONS The results show that one group of loci act in a wide range of environmental scenarios, whereas a smaller group of loci are relevant only under a narrower set of conditions when the influence of the most-prevalent loci is reduced as a consequence of changes in the physiological status of the seeds. In addition, the identification of specific loci controlling the action modes of the phytochromes improves our understanding of the two independent signalling pathways that promote germination in response to light.
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Kneissl J, Shinomura T, Furuya M, Bolle C. A rice phytochrome A in Arabidopsis: The Role of the N-terminus under red and far-red light. MOLECULAR PLANT 2008; 1:84-102. [PMID: 20031917 DOI: 10.1093/mp/ssm010] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The phytochrome (phy)A and phyB photoreceptors mediate three photobiological response modes in plants; whereas phyA can mediate the very-low-fluence response (VLFR), the high-irradiance response (HIR) and, to some extent, the low fluence response (LFR), phyB and other type II phytochromes only mediate the LFR. To investigate to what level a rice phyA can complement for Arabidopsis phyA or phyB function and to evaluate the role of the serine residues in the first 20 amino acids of the N-terminus of phyA, we examined VLFR, LFR, and HIR responses in phyB and phyAphyB mutant plants transformed with rice PHYA cDNA or a mutant rice PHYA cDNA in which the first 10 serine residues were mutated to alanines (phyA SA). Utilizing mutants without endogenous phyB allowed the evaluation of red-light-derived responses sensed by the rice phyA. In summary, the WT rice phyA could complement VLFR and LFR responses such as inhibition of hypocotyl elongation under pulses of FR or continuous R light, induction of flowering and leaf expansion, whereas the phyA SA was more specific for HIR responses (e.g. inhibition of hypocotyl elongation and anthocyanin accumulation under continuous far-red light). As the N-terminal serines can no longer be phosphorylated in the phyA SA mutant, this suggests a role for phosphorylation discriminating between the different phyA-dependent responses. The efficacy of the rice phyA expressed in Arabidopsis was dependent upon the developmental age of the plants analyzed and on the physiological response, suggesting a stage-dependent downstream modulation of phytochrome signaling.
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Affiliation(s)
- Julia Kneissl
- Ludwig-Maximilians-Universität München, Bereich Botanik, Menzinger Str. 67, 80638 München, Germany
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Passardi F, Dobias J, Valério L, Guimil S, Penel C, Dunand C. Morphological and physiological traits of three major Arabidopsis thaliana accessions. JOURNAL OF PLANT PHYSIOLOGY 2007; 164:980-92. [PMID: 16904792 DOI: 10.1016/j.jplph.2006.06.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2006] [Accepted: 06/07/2006] [Indexed: 05/11/2023]
Abstract
Arabidopsis is currently the most studied organism in plant biology. Its short life cycle and small genome size have rendered it one of the principal model systems. Additionally, numerous large T-DNA insertion mutant collections are available. The advent of molecular biology and the completion of the Arabidopsis genome sequence have contributed to helping researchers discover a large variety of mutants identified for their phenotypes. Yet, it is important to consider that natural phenotypic variations exist and appear in natural ecotypes, differing greatly in several traits. Although there are a vast number of ecotypes available, only a few have been extensively studied, and some have been created in laboratories. In order to identify new phenotypic differences, we chose to study the differences observed between three ecotypes: Columbia (Col-0), Landsberg erecta (Laer-0) and Wassilewskija (Ws-0). Our research focuses on observable morphological traits throughout plant growth and development along the entire plant life cycle. We then attempted to shed some light on phenotypic discrepancies through the study of the class III peroxidase protein family, which is involved in many aspects of plant growth and tissue differentiation. Both morphological and molecular aspects reveal that there are major variations between ecotypes, hence indicating a possibly interesting heterotic effect in the F1 from crosses between different Arabidopsis ecotypes.
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Affiliation(s)
- Filippo Passardi
- Laboratory of Plant Physiology, University of Geneva, Quai Ernest-Ansermet 30, CH-1211 Geneva 4, Switzerland
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Casal JJ, Yanovsky MJ, Luppi JP. Two Photobiological Pathways of Phytochrome A Activity, Only One of Which Shows Dominant Negative Suppression by Phytochrome B. Photochem Photobiol 2007. [DOI: 10.1562/0031-8655(2000)0710481tppopa2.0.co2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Trupkin SA, Debrieux D, Hiltbrunner A, Fankhauser C, Casal JJ. The serine-rich N-terminal region of Arabidopsis phytochrome A is required for protein stability. PLANT MOLECULAR BIOLOGY 2007; 63:669-78. [PMID: 17160561 DOI: 10.1007/s11103-006-9115-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2006] [Accepted: 11/06/2006] [Indexed: 05/12/2023]
Abstract
Deletion or substitution of the serine-rich N-terminal stretch of grass phytochrome A (phyA) has repeatedly been shown to yield a hyperactive photoreceptor when expressed under the control of a constitutive promoter in transgenic tobacco or Arabidopsis seedlings retaining their native phyA. These observations have lead to the proposal that the serine-rich region is involved in negative regulation of phyA signaling. To re-evaluate this conclusion in a more physiological context we produced transgenic Arabidopsis seedlings of the phyA-null background expressing Arabidopsis PHYA deleted in the sequence corresponding to amino acids 6-12, under the control of the native PHYA promoter. Compared to the transgenic seedlings expressing wild-type phyA, the seedlings bearing the mutated phyA showed normal responses to pulses of far-red (FR) light and impaired responses to continuous FR light. In yeast two-hybrid experiments, deleted phyA interacted normally with FHY1 and FHL, which are required for phyA accumulation in the nucleus. Immunoblot analysis showed reduced stability of deleted phyA under continuous red or FR light. The reduced physiological activity can therefore be accounted for by the enhanced destruction of the mutated phyA. These findings do not support the involvement of the serine-rich region in negative regulation but they are consistent with a recent report suggesting that phyA turnover is regulated by phosphorylation.
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Affiliation(s)
- Santiago A Trupkin
- IFEVA, Facultad de Agronomía, Universidad de Buenos Aires and CONICET, Av. San Martín 4453, 1417, Buenos Aires, Argentina
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Oh E, Yamaguchi S, Kamiya Y, Bae G, Chung WI, Choi G. Light activates the degradation of PIL5 protein to promote seed germination through gibberellin in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2006; 47:124-39. [PMID: 16740147 DOI: 10.1111/j.1365-313x.2006.02773.x] [Citation(s) in RCA: 242] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Angiosperm seeds integrate various environmental signals, such as water availability and light conditions, to make a proper decision to germinate. Once the optimal conditions are sensed, gibberellin (GA) is synthesized, triggering germination. Among environmental signals, light conditions are perceived by phytochromes. However, it is not well understood how phytochromes regulate GA biosynthesis. Here we investigated whether phytochromes regulate GA biosynthesis through PIL5, a phytochrome-interacting bHLH protein, in Arabidopsis. We found that pil5 seed germination was inhibited by paclobutrazol, the ga1 mutation was epistatic to the pil5 mutation, and the inhibitory effect of PIL5 overexpression on seed germination could be rescued by exogenous GA, collectively indicating that PIL5 regulates seed germination negatively through GA. Expression analysis revealed that PIL5 repressed the expression of GA biosynthetic genes (GA3ox1 and GA3ox2), and activated the expression of a GA catabolic gene (GA2ox) in both PHYA- and PHYB-dependent germination assays. Consistent with these gene-expression patterns, the amount of bioactive GA was higher in the pil5 mutant and lower in the PIL5 overexpression line. Lastly, we showed that red and far-red light signals trigger PIL5 protein degradation through the 26S proteasome, thus releasing the inhibition of bioactive GA biosynthesis by PIL5. Taken together, our data indicate that phytochromes promote seed germination by degrading PIL5, which leads to increased GA biosynthesis and decreased GA degradation.
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Affiliation(s)
- Eunkyoo Oh
- Department of Biological Sciences, KAIST, Daejeon 305-701, Korea
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16
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Shen Y, Feng S, Ma L, Lin R, Qu LJ, Chen Z, Wang H, Deng XW. Arabidopsis FHY1 protein stability is regulated by light via phytochrome A and 26S proteasome. PLANT PHYSIOLOGY 2005; 139:1234-43. [PMID: 16244150 PMCID: PMC1283761 DOI: 10.1104/pp.105.067645] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2005] [Revised: 08/29/2005] [Accepted: 09/08/2005] [Indexed: 05/05/2023]
Abstract
Phytochrome A (phyA) is the primary photoreceptor mediating responses to far-red light. Among the phyA downstream signaling components, Far-red Elongated Hypocotyl 1 (FHY1) is a genetically defined positive regulator of photomorphogenesis in far-red light. Both physiological and genomic characterization of the fhy1 mutants indicated a close functional relationship of FHY1 with phyA. Here, we showed that FHY1 is most abundant in young seedlings grown in darkness and is quickly down-regulated during further seedling development and by light exposure. By using light-insensitive 35S promoter-driven functional beta-glucuronidase-FHY1 and green fluorescent protein-FHY1 fusion proteins, we showed that this down-regulation of FHY1 protein abundance by light is largely at posttranscriptional level and most evident in the nuclei. The light-triggered FHY1 protein reduction is primarily mediated through the 26S proteasome-dependent protein degradation. Further, phyA is directly involved in mediating the light-triggered down-regulation of FHY1, and the dark accumulation of FHY1 requires functional pleiotropic Constitutive Photomorphogenic/De-Etiolated/Fusca proteins. Our data indicate that phyA, the 26S proteasome, and the Constitutive Photomorphogenic/De-Etiolated/Fusca proteins are all involved in the light regulation of FHY1 protein abundance during Arabidopsis (Arabidopsis thaliana) seedling development.
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Affiliation(s)
- Yunping Shen
- Peking-Yale Joint Center of Plant Molecular Genetics and Agrobiotechnology, College of Life Sciences, Peking University, Beijing 100871, China
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17
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Magliano TMA, Botto JF, Godoy AV, Symonds VV, Lloyd AM, Casal JJ. New Arabidopsis recombinant inbred lines (Landsberg erecta x Nossen) reveal natural variation in phytochrome-mediated responses. PLANT PHYSIOLOGY 2005; 138:1126-35. [PMID: 15908601 PMCID: PMC1150426 DOI: 10.1104/pp.104.059071] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
We used 52 Arabidopsis (Arabidopsis thaliana) accessions and developed a new set of 137 recombinant inbred lines between Landsberg erecta (Ler) and Nossen (No-0) to explore the genetic basis of phytochrome-mediated responses during deetiolation. Unexpectedly, most accessions showed weak or moderate hypocotyl growth and cotyledon unfolding responses to pulses of far-red light (FR). Crosses between Columbia and No-0, two accessions with poor response, segregated seedlings with unfolded cotyledons under pulsed FR, suggesting the occurrence of accession-specific loci in the repression of morphological responses to weak light signals. Confirming the latter expectation, mapping of responses to pulsed FR in the Ler x No-0 lines identified novel loci. Despite its weak response to pulsed FR, No-0 showed a response to continuous FR stronger than that observed in Ler. By mapping the differential effect of pulsed versus continuous FR, we identified two high-irradiance response loci that account for the steeper response to continuous FR in No-0. This underscores the potential of the methodology to identify loci involved in the regulation of the shape of signal input-output relationships. Loci specific for a given phytochrome-mediated response were more frequent than pleiotropic loci. Segregation of these specific loci is predicted to yield different combinations of seedling responsivity to light. Such flexibility in combination of responses is observed among accessions and could aid in the adjustment to different microenvironments.
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Affiliation(s)
- Teresa M Alconada Magliano
- IFEVA, Facultad de Agronomía, Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas, 1417 Buenos Aires, Argentina
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18
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Dieterle M, Thomann A, Renou JP, Parmentier Y, Cognat V, Lemonnier G, Müller R, Shen WH, Kretsch T, Genschik P. Molecular and functional characterization of Arabidopsis Cullin 3A. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2005; 41:386-99. [PMID: 15659098 DOI: 10.1111/j.1365-313x.2004.02302.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Cullin proteins, which belong to multigenic families in all eukaryotes, associate with other proteins to form ubiquitin protein ligases (E3s) that target substrates for proteolysis by the 26S proteasome. Here, we present the molecular and genetic characterization of a plant Cullin3. In contrast to fungi and animals, the genome of the model plant Arabidopsis thaliana contains two related CUL3 genes, called CUL3A and CUL3B. We found that CUL3A is ubiquitously expressed in plants and is able to interact with the ring-finger protein RBX1. A genomic search revealed the existence of at least 76 BTB-domain proteins in Arabidopsis belonging to 11 major families. Yeast two-hybrid experiments indicate that representative members of certain families are able to physically interact with both CUL3A and CUL3B, suggesting that Arabidopsis CUL3 forms E3 protein complexes with certain BTB domain proteins. In order to determine the function of CUL3A, we used a reverse genetic approach. The cul3a null mutant flowers slightly later than the control plants. Furthermore, this mutant exhibits a reduced sensitivity of the inhibition of hypocotyl growth in far-red light and miss-expresses COP1. The viability of the mutant plants suggests functional redundancy between the two CUL3 genes in Arabidopsis.
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Affiliation(s)
- Monika Dieterle
- Institut de Biologie Moléculaire des Plantes du CNRS, 12, rue du Général Zimmer, 67084 Strasbourg cedex, France
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19
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Boccalandro HE, Rossi MC, Saijo Y, Deng XW, Casal JJ. Promotion of photomorphogenesis by COP1. PLANT MOLECULAR BIOLOGY 2004; 56:905-15. [PMID: 15821989 DOI: 10.1007/s11103-004-5919-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2004] [Accepted: 11/06/2004] [Indexed: 05/05/2023]
Abstract
CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1) represses photomorphogenesis in darkness by targeting nuclear-localized transcription factors to proteasome-mediated degradation. Upon light exposure, COP1 migrates to the cytosol allowing photomorphogenesis to proceed but the residual nuclear pool down-regulates light signaling mediated by phytochrome A. Here we show that weak alleles of cop1 exhibit reverse photomorphogenic responses i.e. reduced rather than enhanced cotyledon unfolding under red light compared to darkness. Conversely, COP1 overexpressors which de-etiolate poorly under blue or far-red light, showed enhanced photomorphogenesis under red light. The positive relationship between COP1 and photomorphogenic response required phytochrome B. Thus, genetic manipulation of COP1 levels differentially affects phytochrome A- compared to phytochrome B-mediated responses. We hypothesize that COP1 could be involved in degradation of negative regulators of photomorphogenesis or in transcriptional activation, as observed for some E3 ligases in mammalian development.
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Affiliation(s)
- Hernán E Boccalandro
- I.F.E.V.A., Faculty of Agronomy, University of Buenos Aires, Av. San Martín 4453, 1417, Buenos Aires, Argentina
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20
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Escobar MA, Franklin KA, Svensson AS, Salter MG, Whitelam GC, Rasmusson AG. Light regulation of the Arabidopsis respiratory chain. Multiple discrete photoreceptor responses contribute to induction of type II NAD(P)H dehydrogenase genes. PLANT PHYSIOLOGY 2004; 136:2710-21. [PMID: 15333756 PMCID: PMC523335 DOI: 10.1104/pp.104.046698] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2004] [Revised: 06/23/2004] [Accepted: 07/04/2004] [Indexed: 05/18/2023]
Abstract
Controlled oxidation reactions catalyzed by the large, proton-pumping complexes of the respiratory chain generate an electrochemical gradient across the mitochondrial inner membrane that is harnessed for ATP production. However, several alternative respiratory pathways in plants allow the maintenance of substrate oxidation while minimizing the production of ATP. We have investigated the role of light in the regulation of these energy-dissipating pathways by transcriptional profiling of the alternative oxidase, uncoupling protein, and type II NAD(P)H dehydrogenase gene families in etiolated Arabidopsis seedlings. Expression of the nda1 and ndc1 NAD(P)H dehydrogenase genes was rapidly up-regulated by a broad range of light intensities and qualities. For both genes, light induction appears to be a direct transcriptional effect that is independent of carbon status. Mutant analyses demonstrated the involvement of two separate photoreceptor families in nda1 and ndc1 light regulation: the phytochromes (phyA and phyB) and an undetermined blue light photoreceptor. In the case of the nda1 gene, the different photoreceptor systems generate distinct kinetic induction profiles that are integrated in white light response. Primary transcriptional control of light response was localized to a 99-bp region of the nda1 promoter, which contains an I-box flanked by two GT-1 elements, an arrangement prevalent in the promoters of photosynthesis-associated genes. Light induction was specific to nda1 and ndc1. The only other substantial light effect observed was a decrease in aox2 expression. Overall, these results suggest that light directly influences the respiratory electron transport chain via photoreceptor-mediated transcriptional control, likely for supporting photosynthetic metabolism.
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Affiliation(s)
- Matthew A Escobar
- Lund University Department of Cell and Organism Biology, SE-22362 Lund, Sweden
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21
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Cho DS, Hong SH, Nam HG, Soh MS. FIN5 positively regulates far-red light responses in Arabidopsis thaliana. PLANT & CELL PHYSIOLOGY 2003; 44:565-572. [PMID: 12826621 DOI: 10.1093/pcp/pcg071] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We report the characterization of a semi-dominant mutation fin5-1 (far-red insensitive 5-1) of Arabidopsis, which was isolated from genetic screening of phytochrome A (phyA) signaling components. Plants with the fin5-1 mutation exhibited a long hypocotyl phenotype when grown under far-red (FR) light, but not under red light. Physiological analyses implied that FIN5 might be differentially involved in diverse responses that are regulated by phyA under continuous FR light. Anthocyanin accumulation, gravitropic response of hypocotyl growth, and FR light-preconditioned blocking of greening were also impaired in the fin5-1 mutant, whereas photoperiodic floral induction was not, if at all, significantly affected. Moreover, light-regulated expression of the CHS, PORA and PsbS genes was attenuated in fin5-1 mutant plants, while the light-induced expression of CAB was normal. The mutation exhibited semi-dominance regarding control of hypocotyl growth in FR light. We suggest that FIN5 defines a novel branch in the network of phyA signaling in Arabidopsis.
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Affiliation(s)
- Dae-Shik Cho
- Department of Life Science and School of Environmental Engineering, Pohang University of Science and Technology, San 31, Hyoja-Dong, Nam-Gu, Pohang, Kyungbuk, 790-784 Republic of Korea
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22
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Park DH, Lim PO, Kim JS, Cho DS, Hong SH, Nam HG. The Arabidopsis COG1 gene encodes a Dof domain transcription factor and negatively regulates phytochrome signaling. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2003; 34:161-71. [PMID: 12694592 DOI: 10.1046/j.1365-313x.2003.01710.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Light is a critical environmental factor that influences almost all developmental aspects of plants, including seed germination, seedling morphogenesis, and transition to reproductive growth. Plants have therefore developed an intricate network of mechanisms to perceive and process environmental light information. To further characterize the molecular basis of light-signaling processes in plants, we screened an activation tagging pool of Arabidopsis for altered photoresponses. A dominant mutation, cog1-D, attenuated various red (R) and far-red (FR) light-dependent photoresponses. The mutation was caused by overexpression of a gene encoding a member of the Dof family of transcription factors. The photoresponses in Arabidopsis were inversely correlated with the expression levels of COG1 mRNA. When the COG1 gene was overexpressed in transgenic plants, the plants exhibited hyposensitive responses to R and FR light in a manner inversely dependent on COG1 mRNA levels. On the other hand, transgenic lines expressing antisense COG1 were hypersensitive to R and FR light. Expression of the COG1 gene is light inducible and requires phytochrome A (phyA) for FR light-induced expression and phytochrome B (phyB) for R light-induced expression. Thus, the COG1 gene functions as a negative regulator in both the phyA- and phyB-signaling pathways. We suggest that these phytochromes positively regulate the expression of COG1, a negative regulator, as a mechanism for fine tuning the light-signaling pathway.
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Affiliation(s)
- Don Ha Park
- Division of Molecular Life Sciences, Pohang University of Science and Technology, Pohang, Kyungbuk 790-784, Korea
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23
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Wang H, Deng XW. Dissecting the phytochrome A-dependent signaling network in higher plants. TRENDS IN PLANT SCIENCE 2003; 8:172-8. [PMID: 12711229 DOI: 10.1016/s1360-1385(03)00049-9] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Plants monitor their ambient light environment using a network of photoreceptors. In Arabidopsis, phytochrome A (phyA) is the primary photoreceptor responsible for perceiving and mediating various responses to far-red light. Several breakthroughs in understanding the signaling network mediating phyA-activated responses have been made in recent years. Here, we highlight several key advances: the demonstration that light regulates nuclear translocation of phyA and its associated kinase activity; the revelation of a transcriptional cascade controlling phyA-regulated gene expression; the detection of a direct interaction between phyA and a transcription factor; and the identification and characterization of many phyA-specific signaling intermediates, some of them suggesting the involvement of the ubiquitin-proteasome pathway.
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Affiliation(s)
- Haiyang Wang
- Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, NY 14853, USA
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24
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Kim YM, Woo JC, Song PS, Soh MS. HFR1, a phytochrome A-signalling component, acts in a separate pathway from HY5, downstream of COP1 in Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2002; 30:711-719. [PMID: 12061902 DOI: 10.1046/j.1365-313x.2002.01326.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
HFR1, a basic helix-loop-helix protein, is known to be required for a subset of phytochrome A (phyA)-dependent photoresponses. To investigate the role of HFR1 in light signalling, we have examined the genetic interaction between HFR1 and HY5, a positive regulator of light signalling, and COP1, a repressor of photomorphogenesis. Double mutant analysis suggests that HFR1 mediates phyA-dependent inhibition of hypocotyl elongation independently of HY5. HFR1 was shown to be necessary for a subset of cop1-triggered photomorphogenic phenotypes in the dark, including inhibition of hypocotyl elongation, gravitropic hypocotyl growth, and expression of the light-inducible genes CAB and RBCS. Phenotypic analysis of the triple mutant cop1hy5hfr1 indicated that both HFR1 and HY5 are required for cop1-mediated photomorphogenic seedling development in darkness, consistent with their additive roles in phyA-dependent signalling. Taken together, these results suggest that HFR1 might act downstream of COP1, in a separate pathway from HY5, to mediate photomorphogenesis in Arabidopsis.
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Affiliation(s)
- Young-Mi Kim
- Kumho Life & Environmental Science Laboratory, 1 Oryong-Dong, Buk-Gu, Gwangju 500-712, Republic of Korea
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25
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Wang H, Deng XW. Arabidopsis FHY3 defines a key phytochrome A signaling component directly interacting with its homologous partner FAR1. EMBO J 2002; 21:1339-49. [PMID: 11889039 PMCID: PMC125923 DOI: 10.1093/emboj/21.6.1339] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2001] [Revised: 01/16/2002] [Accepted: 01/22/2002] [Indexed: 11/14/2022] Open
Abstract
In Arabidopsis, phytochrome A (phyA) is the primary photoreceptor mediating various plant responses to far-red (FR) light. Here we show that phyA signaling involves a combinatorial action of downstream intermediates, which controls overlapping yet distinctive sets of FR responses. FHY3 is a prominent phyA signaling intermediate sharing structural similarity to FAR1, a previously identified phyA signaling component. The fhy3 and far1 mutants display similar yet distinctive defects in phyA signaling; however, overexpression of either FHY3 or FAR1 suppresses the mutant phenotype of both genes. Moreover, overexpression of partial fragments of FHY3 can cause a dominant-negative interference phenotype on phyA signaling that is stronger than those of the fhy3 or far1 null mutants. Further, we demonstrate that FHY3 and FAR1 are capable of homo- and hetero-interaction. Our data indicate that FHY3, together with FAR1, defines a key module in a signaling network underlying phyA-mediated FR light responses.
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Affiliation(s)
- Haiyang Wang
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8104, USA
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26
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Yanovsky MJ, Mazzella MA, Whitelam GC, Casal JJ. Resetting of the circadian clock by phytochromes and cryptochromes in Arabidopsis. J Biol Rhythms 2001; 16:523-30. [PMID: 11760010 DOI: 10.1177/074873001129002213] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The authors sought to investigate the role of phytochromes A and B (phyA and phyB) and cryptochromes 1 and 2 (cryl and cry2) in the synchronization of the leaf position rhythm in Arabidopsis thaliana. The seedlings were transferred from white light-dark cycles to free-running conditions with or without exposure to a light treatment during the final hours of the last dark period. The phase advance caused by a far-red light treatment was absent in the phyA mutant, deficient in the fhy1 and fhy3 mutants involved in phyA signaling, and normal in the cryl and cryl cry2 mutants. The phase shift caused by blue light was normal in the cry2 mutant; reduced in the phyA, cryl, phyA cry1, and cry1 cry2 mutants; and abolished in the phyA cryl cry2 triple mutant. The phase shift caused by red light was partially retained by the phyA phyB double mutant. The authors conclude that cryl and cry2 participate as photoreceptors in the blue light input to the clock but are not required for the phyA-mediated effects on the phase of the circadian rhythm of leaf position. The signaling proteins FHY1 and FHY3 are shared by phyA-mediated photomorphogenesis and phyA input to the clock.
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Affiliation(s)
- M J Yanovsky
- IFEVA, Faculty of Agronomy, University of Buenos Aires, Argentina
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27
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McCormac AC, Fischer A, Kumar AM, Söll D, Terry MJ. Regulation of HEMA1 expression by phytochrome and a plastid signal during de-etiolation in Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2001; 25:549-61. [PMID: 11309145 DOI: 10.1046/j.1365-313x.2001.00986.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The synthesis of 5-aminolevulinic acid (ALA) is the rate-limiting step for the formation of all plant tetrapyrroles, including chlorophyll and heme, and regulation of ALA synthesis is therefore critical to plant development. Glutamyl-tRNA reductase (GluTR) is the first committed enzyme of this pathway and is encoded by a small family of nuclear HEMA genes. Here, we have used transgenic Arabidopsis (Arabidopsis thaliana L. Col) lines expressing chimeric HEMA1 promoter:gusA fusion genes, combined with RNA gel blot analyses, to characterise the light-mediated regulation of the Arabidopsis HEMA1 gene during de-etiolation. HEMA1 was expressed strongly, but not exclusively, in photosynthetic tissues and was shown to be light regulated at the transcriptional level by the phytochrome family of photoreceptors acting in both the far-red high irradiance and low fluence response modes. The HEMA2 gene, which is expressed only in roots of seedlings, was not light regulated. Analysis of truncated HEMA1 promoter constructs demonstrated that a -199/+252 promoter fragment was sufficient to confer full light-responsiveness to gusA expression. This fragment contained GT-1/I-box and CCA-1 binding sites that are implicated as the light-responsive cis elements. Both the full-length and truncated HEMA1 promoters required the presence of intact chloroplasts for full expression, consistent with previous indications that light and plastid factor signals converge to co-ordinately regulate expression of photosynthesis-related nuclear genes. These results provide the most comprehensive analysis to date of the light-regulation of a tetrapyrrole biosynthetic gene and support a direct link between regulation of HEMA1 transcription and chlorophyll accumulation during seedling de-etiolation.
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Affiliation(s)
- A C McCormac
- School of Biological Sciences, University of Southampton, Bassett Crescent East, Southampton SO16 7PX, UK
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28
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Abstract
The phytochromes, photoreceptors sensitive to red and far-red light, are critical for sensing foliage shade, canopy breaks, and neighbor proximity. A combination of molecular genetic, evolutionary, and ecological techniques are being used to understand how phytochromes function in the natural environment. We discuss studies on the adaptive value of phytochrome mediated plasticity, as well as the role that variation in phytochrome expression and function might play in allowing plants to adapt to unique light environments. Continued study of phytochrome signaling variation may reveal how natural selection acts at the molecular level.
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Affiliation(s)
- J N Maloof
- Plant Biology Laboratory, The Salk Institute for Biological Sciences, La Jolla, CA 92037, USA.
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29
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Casal JJ, Yanovsky MJ, Luppi JP. Two photobiological pathways of phytochrome A activity, only one of which shows dominant negative suppression by phytochrome B. Photochem Photobiol 2000; 71:481-6. [PMID: 10824602 DOI: 10.1562/0031-8655(2000)071<0481:tppopa>2.0.co;2] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The plant receptor phytochrome A (phyA) mediates responses like hypocotyl growth inhibition and cotyledon unfolding that require continuous far-red (FR) light for maximum expression (high-irradiance responses, HIR), and responses like seed germination that can be induced by a single pulse of FR (very-low-fluence responses, VLFR). It is not known whether this duality results from either phyA interaction with different end-point processes or from the intrinsic properties of phyA activity. Etiolated seedlings of Arabidopsis thaliana were exposed to pulses of FR (3 min) separated by dark intervals of different duration. Hypocotyl-growth inhibition and cotyledon unfolding showed two phases. The first phase (VLFR) between 0.17 and 0.5 pulses.h-1, a plateau between 0.5 and 2 pulses.h-1 and a second phase (HIR) at higher frequencies. Reciprocity between fluence rate and duration of FR was observed within phases, not between phases. The fluence rate for half the maximum effect was 0.1 and 3 mumol.m-2.s-1 for hourly pulses of FR (VLFR) and continuous FR (HIR), respectively. Overexpression of phytochrome B caused dominant negative suppression under continuous but not under hourly FR. We conclude that phyA is intrinsically able to initiate two discrete photoresponses even when a single end-point process is considered.
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Affiliation(s)
- J J Casal
- IFEVA, Facultad de Agronomía, Universidad de Buenos Aires, Argentina.
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30
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Kim L, Kircher S, Toth R, Adam E, Schäfer E, Nagy F. Light-induced nuclear import of phytochrome-A:GFP fusion proteins is differentially regulated in transgenic tobacco and Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2000; 22:125-33. [PMID: 10792828 DOI: 10.1046/j.1365-313x.2000.00729.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Phytochromes (phy) are a family of photoreceptors that control various aspects of light-dependent plant development. Phytochrome A (phyA) is responsible for the very low fluence response (VLFR) under inductive light conditions and for the high irradiance response (HIR) under continuous far-red light. We have recently shown that nuclear import of rice phyA:GFP is regulated by VLFR in transgenic tobacco. The import is preceded by very fast, light-induced formation of sequestered areas of phyA:GFP in the cytosol. Here we report that expression of the Arabidopsis phyA:GFP fusion protein in phyA-deficient Arabidopsis plants complements the mutant phenotype. In these transgenic Arabidopsis lines, both light-dependent cytosolic formation of sequestered areas of the phyA:GFP as well as VLFR or HIR-mediated nuclear import of the fusion protein was observed. By contrast, light-dependent nuclear import of the same fusion protein was induced only by continuous far-red light (HIR) but not by pulses of far-red light (VLFR) in transgenic tobacco. These results demonstrate that photoregulation of intracellular partitioning of the Arabidopsis phyA:GFP differs significantly in different genetic backgrounds.
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Affiliation(s)
- L Kim
- Universitat Freiburg, Institut für Biologie II/Botanik, Schänzlestrasse 1, D-79104 Freiburg, Germany
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31
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Casal JJ. Phytochromes, cryptochromes, phototropin: photoreceptor interactions in plants. Photochem Photobiol 2000. [PMID: 10649883 DOI: 10.1562/0031-8655(2000)071%3c0001:pcppii%3e2.0.co;2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
In higher plants, natural radiation simultaneously activates more than one photoreceptor. Five phytochromes (phyA through phyD), two cryptochromes (cry1, cry2) and phototropin have been identified in the model species Arabidopsis thaliana. There is light-dependent epistasis among certain photoreceptor genes because the action of one pigment can be affected by the activity of others. Under red light, phyA and phyB are antagonistic, but under far-red light, followed by brief red light, phyA and phyB are synergistic in the control of seedling morphology and the expression of some genes during de-etiolation. Under short photoperiods of red and blue light, cry1 and phyB are synergistic, but under continuous exposure to the same light field the actions of phyB and cry1 become independent and additive. Phototropic bending of the shoot toward unilateral blue light is mediated by phototropin, but cry1, cry2, phyA and phyB positively regulate the response. Finally, cry2 and phyB are antagonistic in the induction of flowering. At least some of these interactions are likely to result from cross talk of the photoreceptor signaling pathways and uncover new avenues to approach signal transduction. Experiments under natural radiation are beginning to show that the interactions create a phototransduction network with emergent properties. This provides a more robust system for light perception in plants.
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Affiliation(s)
- J J Casal
- IFEVA, Departamento de Ecología, Facultad de Agronomía, Universidad de Buenos Aires, Argentina.
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Alonso-Blanco C, Koornneef M. Naturally occurring variation in Arabidopsis: an underexploited resource for plant genetics. TRENDS IN PLANT SCIENCE 2000; 5:22-9. [PMID: 10637658 DOI: 10.1016/s1360-1385(99)01510-1] [Citation(s) in RCA: 254] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The definition of gene functions requires the phenotypic characterization of genetic variants. Currently, such functional analysis of Arabidopsis genes is based largely on laboratory-induced mutants that are selected in forward and reverse genetic studies. An alternative complementary source of genetic variation is available: the naturally occurring variation among accessions. The multigenic nature of most of this variation has limited its application until now. However, the use of genetic methods developed to map quantitative trait loci, in combination with the characteristics and resources available for molecular biology in Arabidopsis, allow this variation to be exploited up to the molecular level. Here, we describe the current tools available for the forward genetic analysis of this variation, and review the recent progress in the detection and mapping of loci and the cloning of large-effect genes.
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Affiliation(s)
- C Alonso-Blanco
- Centro Nacional de Biotecnolog a, Departamento de Genética Molecular de Plantas, Campus Universidad Autonoma, Cantoblanco, 28049-Madrid, Spain
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Abstract
In higher plants, natural radiation simultaneously activates more than one photoreceptor. Five phytochromes (phyA through phyD), two cryptochromes (cry1, cry2) and phototropin have been identified in the model species Arabidopsis thaliana. There is light-dependent epistasis among certain photoreceptor genes because the action of one pigment can be affected by the activity of others. Under red light, phyA and phyB are antagonistic, but under far-red light, followed by brief red light, phyA and phyB are synergistic in the control of seedling morphology and the expression of some genes during de-etiolation. Under short photoperiods of red and blue light, cry1 and phyB are synergistic, but under continuous exposure to the same light field the actions of phyB and cry1 become independent and additive. Phototropic bending of the shoot toward unilateral blue light is mediated by phototropin, but cry1, cry2, phyA and phyB positively regulate the response. Finally, cry2 and phyB are antagonistic in the induction of flowering. At least some of these interactions are likely to result from cross talk of the photoreceptor signaling pathways and uncover new avenues to approach signal transduction. Experiments under natural radiation are beginning to show that the interactions create a phototransduction network with emergent properties. This provides a more robust system for light perception in plants.
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Affiliation(s)
- J J Casal
- IFEVA, Departamento de Ecología, Facultad de Agronomía, Universidad de Buenos Aires, Argentina.
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ACKERLY DAVIDD, DUDLEY SUSANA, SULTAN SONIAE, SCHMITT JOHANNA, COLEMAN JAMESS, LINDER CRANDALL, SANDQUIST DARRENR, GEBER MONICAA, EVANS ANNS, DAWSON TODDE, LECHOWICZ MARTINJ. The Evolution of Plant Ecophysiological Traits: Recent Advances and Future Directions. Bioscience 2000. [DOI: 10.1641/0006-3568(2000)050[0979:teopet]2.0.co;2] [Citation(s) in RCA: 321] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Schmitt J, Dudley SA, Pigliucci M. Manipulative Approaches to Testing Adaptive Plasticity: Phytochrome‐Mediated Shade‐Avoidance Responses in Plants. Am Nat 1999; 154:S43-S54. [DOI: 10.1086/303282] [Citation(s) in RCA: 190] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Cerdán PD, Yanovsky MJ, Reymundo FC, Nagatani A, Staneloni RJ, Whitelam GC, Casal JJ. Regulation of phytochrome B signaling by phytochrome A and FHY1 in Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 1999; 18:499-507. [PMID: 10417700 DOI: 10.1046/j.1365-313x.1999.00475.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Phytochrome A (phyA) and phytochrome B (phyB) share the control of many processes but little is known about mutual signaling regulation. Here, we report on the interactions between phyA and phyB in the control of the activity of an Lhcb1*2 gene fused to a reporter, hypocotyl growth and cotyledon unfolding in etiolated Arabidopsis thaliana. The very-low fluence responses (VLFR) induced by pulsed far-red light and the high-irradiance responses (HIR) observed under continuous far-red light were absent in the phyA and phyA phyB mutants, normal in the phyB mutant, and reduced in the fhy1 mutant that is defective in phyA signaling. VLFR were also impaired in Columbia compared to Landsberg erecta. The low-fluence responses (LFR) induced by red-light pulses and reversed by subsequent far-red light pulses were small in the wild type, absent in phyB and phyA phyB mutants but strong in the phyA and fhy1 mutants. This indicates a negative effect of phyA and FHY1 on phyB-mediated responses. However, a pre-treatment with continuous far-red light enhanced the LFR induced by a subsequent red-light pulse. This enhancement was absent in phyA, phyB, or phyA phyB and partial in fhy1. The levels of phyB were not affected by the phyA or fhy1 mutations or by far-red light pre-treatments. We conclude that phyA acting in the VLFR mode (i.e. under light pulses) is antagonistic to phyB signaling whereas phyA acting in the HIR mode (i.e. under continuous far-red light) operates synergistically with phyB signaling, and that both types of interaction require FHY1.
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Affiliation(s)
- P D Cerdán
- Instituto de Investigaciones Bioquímicas Fundación Campomar, Buenos Aires, Argentina
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Soh MS, Hong SH, Hanzawa H, Furuya M, Nam HG. Genetic identification of FIN2, a far red light-specific signaling component of Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 1998; 16:411-419. [PMID: 9881161 DOI: 10.1046/j.1365-313x.1998.00307.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Phytochrome A (PhyA) mediates most, if not all, various plant responses to far-red (FR) light. Here, we report a novel genetic mutation that impairs a variety of responses in the PhyA-signaling pathway of Arabidopsis thaliana. The mutation was isolated by screening seedlings that show reduced sensitivity to continuous far-red (FRc) light irradiation, but not to continuous red (Rc) light irradiation. The mutation named fin2-1 is not allelic to a PHYA mutation. Furthermore, immunoblot analysis indicated that the amount of the phytochrome A apoprotein in the fin2-1 mutant was comparable to that in wild type. Seedling of the fin2-1 mutant showed defects in hypocotyl growth inhibition and apical hook and cotyledon opening in FRc light but not in Rc light. The results showed that the mutation occurred in a downstream signaling component potentially specific to PhyA. Other PhyA-mediated responses such as FR-preconditioned blocking of greening, anthocyanin accumulation, reduction of gravitropic response, and expression of the CAB and CHS genes were impaired by the fin2-1 mutation: the degree of the mutant effect on the responses was variable. However, FR light-mediated seed germination and photoperiodic flowering responses were not affected significantly in the mutant. These results showed that FIN2 defines an upstream branch point in the PhyA signaling pathway.
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Affiliation(s)
- M S Soh
- Department of Life Science and School of Environmental Engineering, Pohang University of Science and Technology, Pohang, Kyungbuk, South Korea
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