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Zhao J, Bui MT, Ma J, Künzl F, Picchianti L, De La Concepcion JC, Chen Y, Petsangouraki S, Mohseni A, García-Leon M, Gomez MS, Giannini C, Gwennogan D, Kobylinska R, Clavel M, Schellmann S, Jaillais Y, Friml J, Kang BH, Dagdas Y. Plant autophagosomes mature into amphisomes prior to their delivery to the central vacuole. J Cell Biol 2022; 221:213556. [PMID: 36260289 PMCID: PMC9584626 DOI: 10.1083/jcb.202203139] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 08/12/2022] [Accepted: 09/14/2022] [Indexed: 12/13/2022] Open
Abstract
Autophagosomes are double-membraned vesicles that traffic harmful or unwanted cellular macromolecules to the vacuole for recycling. Although autophagosome biogenesis has been extensively studied, autophagosome maturation, i.e., delivery and fusion with the vacuole, remains largely unknown in plants. Here, we have identified an autophagy adaptor, CFS1, that directly interacts with the autophagosome marker ATG8 and localizes on both membranes of the autophagosome. Autophagosomes form normally in Arabidopsis thaliana cfs1 mutants, but their delivery to the vacuole is disrupted. CFS1's function is evolutionarily conserved in plants, as it also localizes to the autophagosomes and plays a role in autophagic flux in the liverwort Marchantia polymorpha. CFS1 regulates autophagic flux by bridging autophagosomes with the multivesicular body-localized ESCRT-I component VPS23A, leading to the formation of amphisomes. Similar to CFS1-ATG8 interaction, disrupting the CFS1-VPS23A interaction blocks autophagic flux and renders plants sensitive to nitrogen starvation. Altogether, our results reveal a conserved vacuolar sorting hub that regulates autophagic flux in plants.
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Affiliation(s)
- Jierui Zhao
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenter, Vienna, Austria,Vienna BioCenter PhD Program, Doctoral School of the University at Vienna and Medical University of Vienna, Vienna, Austria
| | - Mai Thu Bui
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenter, Vienna, Austria
| | - Juncai Ma
- School of Life Sciences, Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Fabian Künzl
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenter, Vienna, Austria
| | - Lorenzo Picchianti
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenter, Vienna, Austria,Vienna BioCenter PhD Program, Doctoral School of the University at Vienna and Medical University of Vienna, Vienna, Austria
| | | | - Yixuan Chen
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenter, Vienna, Austria
| | - Sofia Petsangouraki
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenter, Vienna, Austria
| | - Azadeh Mohseni
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenter, Vienna, Austria
| | - Marta García-Leon
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenter, Vienna, Austria
| | - Marta Salas Gomez
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenter, Vienna, Austria
| | - Caterina Giannini
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Dubois Gwennogan
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, École normale supérieure de Lyon, Centre national de la recherche scientifique (CNRS), Institut National de la Recherche Agronomique (INRAE), Lyon, France
| | - Roksolana Kobylinska
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenter, Vienna, Austria
| | - Marion Clavel
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenter, Vienna, Austria
| | - Swen Schellmann
- Botanik III, Biocenter, University of Cologne, Cologne, Germany
| | - Yvon Jaillais
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, École normale supérieure de Lyon, Centre national de la recherche scientifique (CNRS), Institut National de la Recherche Agronomique (INRAE), Lyon, France
| | - Jiri Friml
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Byung-Ho Kang
- School of Life Sciences, Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China,Correspondence to Byung-Ho Kang:
| | - Yasin Dagdas
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenter, Vienna, Austria,Yasin Dagdas:
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2
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Bellstaedt J, Trenner J, Lippmann R, Poeschl Y, Zhang X, Friml J, Quint M, Delker C. A Mobile Auxin Signal Connects Temperature Sensing in Cotyledons with Growth Responses in Hypocotyls. Plant Physiol 2019; 180:757-766. [PMID: 31000634 PMCID: PMC6548272 DOI: 10.1104/pp.18.01377] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 04/07/2019] [Indexed: 05/19/2023]
Abstract
Plants have a remarkable capacity to adjust their growth and development to elevated ambient temperatures. Increased elongation growth of roots, hypocotyls, and petioles in warm temperatures are hallmarks of seedling thermomorphogenesis. In the last decade, significant progress has been made to identify the molecular signaling components regulating these growth responses. Increased ambient temperature utilizes diverse components of the light sensing and signal transduction network to trigger growth adjustments. However, it remains unknown whether temperature sensing and responses are universal processes that occur uniformly in all plant organs. Alternatively, temperature sensing may be confined to specific tissues or organs, which would require a systemic signal that mediates responses in distal parts of the plant. Here, we show that Arabidopsis (Arabidopsis thaliana) seedlings show organ-specific transcriptome responses to elevated temperatures and that thermomorphogenesis involves both autonomous and organ-interdependent temperature sensing and signaling. Seedling roots can sense and respond to temperature in a shoot-independent manner, whereas shoot temperature responses require both local and systemic processes. The induction of cell elongation in hypocotyls requires temperature sensing in cotyledons, followed by the generation of a mobile auxin signal. Subsequently, auxin travels to the hypocotyl, where it triggers local brassinosteroid-induced cell elongation in seedling stems, which depends upon a distinct, permissive temperature sensor in the hypocotyl.
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Affiliation(s)
- Julia Bellstaedt
- Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany
- Department of Molecular Signal Processing, Leibniz Institute of Plant Biochemistry, 06120 Halle (Saale), Germany
| | - Jana Trenner
- Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany
- Department of Molecular Signal Processing, Leibniz Institute of Plant Biochemistry, 06120 Halle (Saale), Germany
| | - Rebecca Lippmann
- Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany
| | - Yvonne Poeschl
- German Centre for Integrative Biodiversity Research Halle-Jena-Leipzig, 04103 Leipzig, Germany
- Institute of Computer Science, Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany
| | - Xixi Zhang
- Developmental and Cell Biology of Plants, Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, 1190 Vienna, Austria
| | - Jiri Friml
- Developmental and Cell Biology of Plants, Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
| | - Marcel Quint
- Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany
- Department of Molecular Signal Processing, Leibniz Institute of Plant Biochemistry, 06120 Halle (Saale), Germany
| | - Carolin Delker
- Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany
- Department of Molecular Signal Processing, Leibniz Institute of Plant Biochemistry, 06120 Halle (Saale), Germany
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3
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Yoshida S, van der Schuren A, van Dop M, van Galen L, Saiga S, Adibi M, Möller B, Ten Hove CA, Marhavy P, Smith R, Friml J, Weijers D. A SOSEKI-based coordinate system interprets global polarity cues in Arabidopsis. Nat Plants 2019; 5:160-166. [PMID: 30737509 PMCID: PMC6420093 DOI: 10.1038/s41477-019-0363-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 01/08/2019] [Indexed: 05/05/2023]
Abstract
Multicellular development requires coordinated cell polarization relative to body axes, and translation to oriented cell division1-3. In plants, it is unknown how cell polarities are connected to organismal axes and translated to division. Here, we identify Arabidopsis SOSEKI proteins that integrate apical-basal and radial organismal axes to localize to polar cell edges. Localization does not depend on tissue context, requires cell wall integrity and is defined by a transferrable, protein-specific motif. A Domain of Unknown Function in SOSEKI proteins resembles the DIX oligomerization domain in the animal Dishevelled polarity regulator. The DIX-like domain self-interacts and is required for edge localization and for influencing division orientation, together with a second domain that defines the polar membrane domain. Our work shows that SOSEKI proteins locally interpret global polarity cues and can influence cell division orientation. Furthermore, this work reveals that, despite fundamental differences, cell polarity mechanisms in plants and animals converge on a similar protein domain.
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Affiliation(s)
- Saiko Yoshida
- Laboratory of Biochemistry, Wageningen University, Wageningen, The Netherlands.
- Institute of Science and Technology, Klosterneuburg, Austria.
- Department of Comparative Development and Genetics, Max Planck Institute for Plant Breeding Research, Cologne, Germany.
| | - Alja van der Schuren
- Laboratory of Biochemistry, Wageningen University, Wageningen, The Netherlands
- Department of Plant Molecular Biology, University of Lausanne, Lausanne, Switzerland
| | - Maritza van Dop
- Laboratory of Biochemistry, Wageningen University, Wageningen, The Netherlands
| | - Luc van Galen
- Laboratory of Biochemistry, Wageningen University, Wageningen, The Netherlands
| | - Shunsuke Saiga
- Laboratory of Biochemistry, Wageningen University, Wageningen, The Netherlands
- Department of Plant and Microbial Biology, University of Zürich, Zürich, Switzerland
| | - Milad Adibi
- Department of Comparative Development and Genetics, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Barbara Möller
- Laboratory of Biochemistry, Wageningen University, Wageningen, The Netherlands
- VIB-UGent Center for Plant Systems Biology, Ghent, Belgium
| | - Colette A Ten Hove
- Laboratory of Biochemistry, Wageningen University, Wageningen, The Netherlands
| | - Peter Marhavy
- Institute of Science and Technology, Klosterneuburg, Austria
- Department of Plant Molecular Biology, University of Lausanne, Lausanne, Switzerland
| | - Richard Smith
- Department of Comparative Development and Genetics, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Jiri Friml
- Institute of Science and Technology, Klosterneuburg, Austria
| | - Dolf Weijers
- Laboratory of Biochemistry, Wageningen University, Wageningen, The Netherlands.
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4
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Nishiyama T, Sakayama H, de Vries J, Buschmann H, Saint-Marcoux D, Ullrich KK, Haas FB, Vanderstraeten L, Becker D, Lang D, Vosolsobě S, Rombauts S, Wilhelmsson PK, Janitza P, Kern R, Heyl A, Rümpler F, Villalobos LIAC, Clay JM, Skokan R, Toyoda A, Suzuki Y, Kagoshima H, Schijlen E, Tajeshwar N, Catarino B, Hetherington AJ, Saltykova A, Bonnot C, Breuninger H, Symeonidi A, Radhakrishnan GV, Van Nieuwerburgh F, Deforce D, Chang C, Karol KG, Hedrich R, Ulvskov P, Glöckner G, Delwiche CF, Petrášek J, Van de Peer Y, Friml J, Beilby M, Dolan L, Kohara Y, Sugano S, Fujiyama A, Delaux PM, Quint M, Theißen G, Hagemann M, Harholt J, Dunand C, Zachgo S, Langdale J, Maumus F, Van Der Straeten D, Gould SB, Rensing SA. The Chara Genome: Secondary Complexity and Implications for Plant Terrestrialization. Cell 2018; 174:448-464.e24. [DOI: 10.1016/j.cell.2018.06.033] [Citation(s) in RCA: 271] [Impact Index Per Article: 45.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 03/27/2018] [Accepted: 06/14/2018] [Indexed: 01/11/2023]
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5
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Pernisova M, Prat T, Grones P, Harustiakova D, Matonohova M, Spichal L, Nodzynski T, Friml J, Hejatko J. Cytokinins influence root gravitropism via differential regulation of auxin transporter expression and localization in Arabidopsis. New Phytol 2016; 212:497-509. [PMID: 27322763 DOI: 10.1111/nph.14049] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 05/05/2016] [Indexed: 05/06/2023]
Abstract
Redirection of intercellular auxin fluxes via relocalization of the PIN-FORMED 3 (PIN3) and PIN7 auxin efflux carriers has been suggested to be necessary for the root gravitropic response. Cytokinins have also been proposed to play a role in controlling root gravitropism, but conclusive evidence is lacking. We present a detailed study of the dynamics of root bending early after gravistimulation, which revealed a delayed gravitropic response in transgenic lines with depleted endogenous cytokinins (Pro35S:AtCKX) and cytokinin signaling mutants. Pro35S:AtCKX lines, as well as a cytokinin receptor mutant ahk3, showed aberrations in the auxin response distribution in columella cells consistent with defects in the auxin transport machinery. Using in vivo real-time imaging of PIN3-GFP and PIN7-GFP in AtCKX3 overexpression and ahk3 backgrounds, we observed wild-type-like relocalization of PIN proteins in the columella early after gravistimulation, with gravity-induced relocalization of PIN7 faster than that of PIN3. Nonetheless, the cellular distribution of PIN3 and PIN7 and expression of PIN7 and the auxin influx carrier AUX1 was affected in AtCKX overexpression lines. Based on the retained cytokinin sensitivity in pin3 pin4 pin7 mutant, we propose the AUX1-mediated auxin transport rather than columella-located PIN proteins as a target of endogenous cytokinins in the control of root gravitropism.
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Affiliation(s)
- Marketa Pernisova
- CEITEC - Central European Institute of Technology, Masaryk University, Brno, CZ-62500, Czech Republic
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, CZ-62500, Czech Republic
| | - Tomas Prat
- CEITEC - Central European Institute of Technology, Masaryk University, Brno, CZ-62500, Czech Republic
| | - Peter Grones
- Institute of Science and Technology (IST), Klosterneuburg, AT-3400, Austria
| | - Danka Harustiakova
- Institute of Biostatistics and Analyses, Faculty of Medicine and Faculty of Science, Masaryk University, Brno, CZ-62500, Czech Republic
| | - Martina Matonohova
- CEITEC - Central European Institute of Technology, Masaryk University, Brno, CZ-62500, Czech Republic
| | - Lukas Spichal
- Department of Chemical Biology and Genetics, Centre of the Region Hana for Biotechnological and Agricultural Research, Faculty of Science, Palacky University, Olomouc, CZ-78371, Czech Republic
| | - Tomasz Nodzynski
- CEITEC - Central European Institute of Technology, Masaryk University, Brno, CZ-62500, Czech Republic
| | - Jiri Friml
- Institute of Science and Technology (IST), Klosterneuburg, AT-3400, Austria
| | - Jan Hejatko
- CEITEC - Central European Institute of Technology, Masaryk University, Brno, CZ-62500, Czech Republic.
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, CZ-62500, Czech Republic.
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6
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Jia Y, Tian H, Li H, Yu Q, Wang L, Friml J, Ding Z. The Arabidopsis thaliana elongator complex subunit 2 epigenetically affects root development. J Exp Bot 2015; 66:4631-42. [PMID: 25998905 PMCID: PMC4507768 DOI: 10.1093/jxb/erv230] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The elongator complex subunit 2 (ELP2) protein, one subunit of an evolutionarily conserved histone acetyltransferase complex, has been shown to participate in leaf patterning, plant immune and abiotic stress responses in Arabidopsis thaliana. Here, its role in root development was explored. Compared to the wild type, the elp2 mutant exhibited an accelerated differentiation of its root stem cells and cell division was more active in its quiescent centre (QC). The key transcription factors responsible for maintaining root stem cell and QC identity, such as AP2 transcription factors PLT1 (PLETHORA1) and PLT2 (PLETHORA2), GRAS transcription factors such as SCR (SCARECROW) and SHR (SHORT ROOT) and WUSCHEL-RELATED HOMEOBOX5 transcription factor WOX5, were all strongly down-regulated in the mutant. On the other hand, expression of the G2/M transition activator CYCB1 was substantially induced in elp2. The auxin efflux transporters PIN1 and PIN2 showed decreased protein levels and PIN1 also displayed mild polarity alterations in elp2, which resulted in a reduced auxin content in the root tip. Either the acetylation or methylation level of each of these genes differed between the mutant and the wild type, suggesting that the ELP2 regulation of root development involves the epigenetic modification of a range of transcription factors and other developmental regulators.
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Affiliation(s)
- Yuebin Jia
- The Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, College of Life Science, Shandong University, Jinan 250100, China
| | - Huiyu Tian
- The Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, College of Life Science, Shandong University, Jinan 250100, China
| | - Hongjiang Li
- Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
| | - Qianqian Yu
- The Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, College of Life Science, Shandong University, Jinan 250100, China
| | - Lei Wang
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Jiri Friml
- Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
| | - Zhaojun Ding
- The Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, College of Life Science, Shandong University, Jinan 250100, China
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7
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Bailly A, Wang B, Zwiewka M, Pollmann S, Schenck D, Lüthen H, Schulz A, Friml J, Geisler M. Expression of TWISTED DWARF1 lacking its in-plane membrane anchor leads to increased cell elongation and hypermorphic growth. Plant J 2014; 77:108-118. [PMID: 24313847 DOI: 10.1111/tpj.12369] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 10/11/2013] [Accepted: 10/22/2013] [Indexed: 06/02/2023]
Abstract
Plant growth is achieved predominantly by cellular elongation, which is thought to be controlled on several levels by apoplastic auxin. Auxin export into the apoplast is achieved by plasma membrane efflux catalysts of the PIN-FORMED (PIN) and ATP-binding cassette protein subfamily B/phosphor-glycoprotein (ABCB/PGP) classes; the latter were shown to depend on interaction with the FKBP42, TWISTED DWARF1 (TWD1). Here by using a transgenic approach in combination with phenotypical, biochemical and cell biological analyses we demonstrate the importance of a putative C-terminal in-plane membrane anchor of TWD1 in the regulation of ABCB-mediated auxin transport. In contrast with dwarfed twd1 loss-of-function alleles, TWD1 gain-of-function lines that lack a putative in-plane membrane anchor (HA-TWD1-Ct ) show hypermorphic plant architecture, characterized by enhanced stem length and leaf surface but reduced shoot branching. Greater hypocotyl length is the result of enhanced cell elongation that correlates with reduced polar auxin transport capacity for HA-TWD1-Ct . As a consequence, HA-TWD1-Ct displays higher hypocotyl auxin accumulation, which is shown to result in elevated auxin-induced cell elongation rates. Our data highlight the importance of C-terminal membrane anchoring for TWD1 action, which is required for specific regulation of ABCB-mediated auxin transport. These data support a model in which TWD1 controls lateral ABCB1-mediated export into the apoplast, which is required for auxin-mediated cell elongation.
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Affiliation(s)
- Aurélien Bailly
- Department of Biology - Plant Biology, University of Fribourg, Fribourg, Switzerland; Institute of Plant Biology, University of Zurich, Zurich, Switzerland
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8
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Remy E, Cabrito TR, Baster P, Batista RA, Teixeira MC, Friml J, Sá-Correia I, Duque P. A major facilitator superfamily transporter plays a dual role in polar auxin transport and drought stress tolerance in Arabidopsis. Plant Cell 2013; 25:901-26. [PMID: 23524662 PMCID: PMC3634696 DOI: 10.1105/tpc.113.110353] [Citation(s) in RCA: 135] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 02/01/2013] [Accepted: 03/05/2013] [Indexed: 05/18/2023]
Abstract
Many key aspects of plant development are regulated by the polarized transport of the phytohormone auxin. Cellular auxin efflux, the rate-limiting step in this process, has been shown to rely on the coordinated action of PIN-formed (PIN) and B-type ATP binding cassette (ABCB) carriers. Here, we report that polar auxin transport in the Arabidopsis thaliana root also requires the action of a Major Facilitator Superfamily (MFS) transporter, Zinc-Induced Facilitator-Like 1 (ZIFL1). Sequencing, promoter-reporter, and fluorescent protein fusion experiments indicate that the full-length ZIFL1.1 protein and a truncated splice isoform, ZIFL1.3, localize to the tonoplast of root cells and the plasma membrane of leaf stomatal guard cells, respectively. Using reverse genetics, we show that the ZIFL1.1 transporter regulates various root auxin-related processes, while the ZIFL1.3 isoform mediates drought tolerance by regulating stomatal closure. Auxin transport and immunolocalization assays demonstrate that ZIFL1.1 indirectly modulates cellular auxin efflux during shootward auxin transport at the root tip, likely by regulating plasma membrane PIN2 abundance. Finally, heterologous expression in yeast revealed that ZIFL1.1 and ZIFL1.3 share H(+)-coupled K(+) transport activity. Thus, by determining the subcellular and tissue distribution of two isoforms, alternative splicing dictates a dual function for the ZIFL1 transporter. We propose that this MFS carrier regulates stomatal movements and polar auxin transport by modulating potassium and proton fluxes in Arabidopsis cells.
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Affiliation(s)
- Estelle Remy
- Instituto Gulbenkian de Ciência, 2780-156 Oeiras, Portugal
| | - Tânia R. Cabrito
- Institute for Biotechnology and BioEngineering, Center for Biological and Chemical Engineering, Department of Bioengineering, Instituto Superior Técnico, Technical University of Lisbon, 1049-001 Lisbon, Portugal
| | - Pawel Baster
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB), and Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
| | | | - Miguel C. Teixeira
- Institute for Biotechnology and BioEngineering, Center for Biological and Chemical Engineering, Department of Bioengineering, Instituto Superior Técnico, Technical University of Lisbon, 1049-001 Lisbon, Portugal
| | - Jiri Friml
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB), and Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
- Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
| | - Isabel Sá-Correia
- Institute for Biotechnology and BioEngineering, Center for Biological and Chemical Engineering, Department of Bioengineering, Instituto Superior Técnico, Technical University of Lisbon, 1049-001 Lisbon, Portugal
| | - Paula Duque
- Instituto Gulbenkian de Ciência, 2780-156 Oeiras, Portugal
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9
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Abstract
The third EMBO Conference on Plant Molecular Biology, which focused on ‘Plant development and environmental interactions’, was held in May 2012 in Matera, Italy. Here, we review some of the topics and themes that emerged from the various contributions; namely, steering technologies, transcriptional networks and hormonal regulation, small RNAs, cell and tissue polarity, environmental control and natural variation. We intend to provide the reader who might have missed this remarkable event with a glimpse of the recent progress made in this blossoming research field.
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Affiliation(s)
- Tom Beeckman
- Department of Plant Systems Biology, VIB, Technologiepark 927, B-9052 Gent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, B-9052 Gent, Belgium
| | - Jiri Friml
- Department of Plant Systems Biology, VIB, Technologiepark 927, B-9052 Gent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, B-9052 Gent, Belgium
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10
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Nagawa S, Xu T, Lin D, Dhonukshe P, Zhang X, Friml J, Scheres B, Fu Y, Yang Z. ROP GTPase-dependent actin microfilaments promote PIN1 polarization by localized inhibition of clathrin-dependent endocytosis. PLoS Biol 2012; 10:e1001299. [PMID: 22509133 PMCID: PMC3317906 DOI: 10.1371/journal.pbio.1001299] [Citation(s) in RCA: 154] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Accepted: 02/21/2012] [Indexed: 01/11/2023] Open
Abstract
Cell polarization via asymmetrical distribution of structures or molecules is essential for diverse cellular functions and development of organisms, but how polarity is developmentally controlled has been poorly understood. In plants, the asymmetrical distribution of the PIN-FORMED (PIN) proteins involved in the cellular efflux of the quintessential phytohormone auxin plays a central role in developmental patterning, morphogenesis, and differential growth. Recently we showed that auxin promotes cell interdigitation by activating the Rho family ROP GTPases in leaf epidermal pavement cells. Here we found that auxin activation of the ROP2 signaling pathway regulates the asymmetric distribution of PIN1 by inhibiting its endocytosis. ROP2 inhibits PIN1 endocytosis via the accumulation of cortical actin microfilaments induced by the ROP2 effector protein RIC4. Our findings suggest a link between the developmental auxin signal and polar PIN1 distribution via Rho-dependent cytoskeletal reorganization and reveal the conservation of a design principle for cell polarization that is based on Rho GTPase-mediated inhibition of endocytosis.
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Affiliation(s)
- Shingo Nagawa
- Center for Plant Cell Biology, Department of Botany and Plant Sciences, University of California, Riverside, California, United States of America
| | - Tongda Xu
- Center for Plant Cell Biology, Department of Botany and Plant Sciences, University of California, Riverside, California, United States of America
- Temasek Lifesciences Laboratory Ltd, National University of Singapore, Singapore
| | - Deshu Lin
- Center for Plant Cell Biology, Department of Botany and Plant Sciences, University of California, Riverside, California, United States of America
- State Key Laboratory of Plant Physiology and Biochemistry, Department of Plant Sciences, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Pankaj Dhonukshe
- Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Xingxing Zhang
- State Key Laboratory of Plant Physiology and Biochemistry, Department of Plant Sciences, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Jiri Friml
- Department of Plant Systems Biology, VIB and Department of Plant Biotechnology and Genetics, Ghent University, Ghent, Belgium
| | - Ben Scheres
- Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Ying Fu
- State Key Laboratory of Plant Physiology and Biochemistry, Department of Plant Sciences, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Zhenbiao Yang
- Center for Plant Cell Biology, Department of Botany and Plant Sciences, University of California, Riverside, California, United States of America
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Ge L, Peer W, Robert S, Swarup R, Ye S, Prigge M, Cohen J, Friml J, Murphy A, Tang D, Estelle M. Arabidopsis ROOT UVB SENSITIVE2/WEAK AUXIN RESPONSE1 is required for polar auxin transport. Plant Cell 2010; 22:1749-61. [PMID: 20562234 PMCID: PMC2910957 DOI: 10.1105/tpc.110.074195] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Auxin is an essential phytohormone that regulates many aspects of plant development. To identify new genes that function in auxin signaling, we performed a genetic screen for Arabidopsis thaliana mutants with an alteration in the expression of the auxin-responsive reporter DR5rev:GFP (for green fluorescent protein). One of the mutants recovered in this screen, called weak auxin response1 (wxr1), has a defect in auxin response and exhibits a variety of auxin-related growth defects in the root. Polar auxin transport is reduced in wxr1 seedlings, resulting in auxin accumulation in the hypocotyl and cotyledons and a reduction in auxin levels in the root apex. In addition, the levels of the PIN auxin transport proteins are reduced in the wxr1 root. We also show that WXR1 is ROOT UV-B SENSITIVE2 (RUS2), a member of the broadly conserved DUF647 domain protein family found in diverse eukaryotic organisms. Our data indicate that RUS2/WXR1 is required for auxin transport and to maintain the normal levels of PIN proteins in the root.
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Affiliation(s)
- L. Ge
- Cell and Developmental Biology, University of California San Diego, La Jolla, California 92093-0116
| | - W. Peer
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907
| | - S. Robert
- Department of Plant Systems Biology, Flanders Institute for Biotechnology, and Department of Plant Biotechnology and Genetics, Ghent University, 9053 Ghent, Belgium
| | - R. Swarup
- School of Biosciences and Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - S. Ye
- Department of Horticultural Science and Microbial and Plant Genomics Institute, University of Minnesota, St. Paul, Minnesota 55108
| | - M. Prigge
- Cell and Developmental Biology, University of California San Diego, La Jolla, California 92093-0116
| | - J.D. Cohen
- Department of Horticultural Science and Microbial and Plant Genomics Institute, University of Minnesota, St. Paul, Minnesota 55108
| | - J. Friml
- Department of Plant Systems Biology, Flanders Institute for Biotechnology, and Department of Plant Biotechnology and Genetics, Ghent University, 9053 Ghent, Belgium
| | - A. Murphy
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907
| | - D. Tang
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - M. Estelle
- Cell and Developmental Biology, University of California San Diego, La Jolla, California 92093-0116
- Address correspondence to
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12
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Titapiwatanakun B, Blakeslee JJ, Bandyopadhyay A, Yang H, Mravec J, Sauer M, Cheng Y, Adamec J, Nagashima A, Geisler M, Sakai T, Friml J, Peer WA, Murphy AS. ABCB19/PGP19 stabilises PIN1 in membrane microdomains in Arabidopsis. Plant J 2009; 57:27-44. [PMID: 18774968 DOI: 10.1111/j.1365-313x.2008.03668.x] [Citation(s) in RCA: 167] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Auxin transport is mediated at the cellular level by three independent mechanisms that are characterised by the PIN-formed (PIN), P-glycoprotein (ABCB/PGP) and AUX/LAX transport proteins. The PIN and ABCB transport proteins, best represented by PIN1 and ABCB19 (PGP19), have been shown to coordinately regulate auxin efflux. When PIN1 and ABCB19 coincide on the plasma membrane, their interaction enhances the rate and specificity of auxin efflux and the dynamic cycling of PIN1 is reduced. However, ABCB19 function is not regulated by the dynamic cellular trafficking mechanisms that regulate PIN1 in apical tissues, as localisation of ABCB19 on the plasma membrane was not inhibited by short-term treatments with latrunculin B, oryzalin, brefeldin A (BFA) or wortmannin--all of which have been shown to alter PIN1 and/or PIN2 plasma membrane localisation. When taken up by endocytosis, the styryl dye FM4-64 labels diffuse rather than punctuate intracellular bodies in abcb19 (pgp19), and some aggregations of PIN1 induced by short-term BFA treatment did not disperse after BFA washout in abcb19. Although the subcellular localisations of ABCB19 and PIN1 in the reciprocal mutant backgrounds were like those in wild type, PIN1 plasma membrane localisation in abcb19 roots was more easily perturbed by the detergent Triton X-100, but not other non-ionic detergents. ABCB19 is stably associated with sterol/sphingolipid-enriched membrane fractions containing BIG/TIR3 and partitions into Triton X-100 detergent-resistant membrane (DRM) fractions. In the wild type, PIN1 was also present in DRMs, but was less abundant in abcb19 DRMs. These observations suggested a rationale for the observed lack of auxin transport activity when PIN1 is expressed in a non-plant heterologous system. PIN1 was therefore expressed in Schizosaccharomyces pombe, which has plant-like sterol-enriched microdomains, and catalysed auxin transport in these cells. These data suggest that ABCB19 stabilises PIN1 localisation at the plasma membrane in discrete cellular subdomains where PIN1 and ABCB19 expression overlaps.
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13
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Swarup K, Benková E, Swarup R, Casimiro I, Péret B, Yang Y, Parry G, Nielsen E, De Smet I, Vanneste S, Levesque MP, Carrier D, James N, Calvo V, Ljung K, Kramer E, Roberts R, Graham N, Marillonnet S, Patel K, Jones JDG, Taylor CG, Schachtman DP, May S, Sandberg G, Benfey P, Friml J, Kerr I, Beeckman T, Laplaze L, Bennett MJ. The auxin influx carrier LAX3 promotes lateral root emergence. Nat Cell Biol 2008; 10:946-54. [PMID: 18622388 DOI: 10.1038/ncb1754] [Citation(s) in RCA: 489] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2008] [Accepted: 06/23/2008] [Indexed: 12/24/2022]
Abstract
Lateral roots originate deep within the parental root from a small number of founder cells at the periphery of vascular tissues and must emerge through intervening layers of tissues. We describe how the hormone auxin, which originates from the developing lateral root, acts as a local inductive signal which re-programmes adjacent cells. Auxin induces the expression of a previously uncharacterized auxin influx carrier LAX3 in cortical and epidermal cells directly overlaying new primordia. Increased LAX3 activity reinforces the auxin-dependent induction of a selection of cell-wall-remodelling enzymes, which are likely to promote cell separation in advance of developing lateral root primordia.
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Affiliation(s)
- Kamal Swarup
- School of Biosciences & Centre for Plant Integrative Biology, University of Nottingham, LE12 5RD, UK
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14
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Laplaze L, Benkova E, Casimiro I, Maes L, Vanneste S, Swarup R, Weijers D, Calvo V, Parizot B, Herrera-Rodriguez MB, Offringa R, Graham N, Doumas P, Friml J, Bogusz D, Beeckman T, Bennett M. Cytokinins act directly on lateral root founder cells to inhibit root initiation. Plant Cell 2007; 19:3889-900. [PMID: 18065686 PMCID: PMC2217640 DOI: 10.1105/tpc.107.055863] [Citation(s) in RCA: 178] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
In Arabidopsis thaliana, lateral roots are formed from root pericycle cells adjacent to the xylem poles. Lateral root development is regulated antagonistically by the plant hormones auxin and cytokinin. While a great deal is known about how auxin promotes lateral root development, the mechanism of cytokinin repression is still unclear. Elevating cytokinin levels was observed to disrupt lateral root initiation and the regular pattern of divisions that characterizes lateral root development in Arabidopsis. To identify the stage of lateral root development that is sensitive to cytokinins, we targeted the expression of the Agrobacterium tumefaciens cytokinin biosynthesis enzyme isopentenyltransferase to either xylem-pole pericycle cells or young lateral root primordia using GAL4-GFP enhancer trap lines. Transactivation experiments revealed that xylem-pole pericycle cells are sensitive to cytokinins, whereas young lateral root primordia are not. This effect is physiologically significant because transactivation of the Arabidopsis cytokinin degrading enzyme cytokinin oxidase 1 in lateral root founder cells results in increased lateral root formation. We observed that cytokinins perturb the expression of PIN genes in lateral root founder cells and prevent the formation of an auxin gradient that is required to pattern lateral root primordia.
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Affiliation(s)
- Laurent Laplaze
- Institut de Recherche pour le Développement, Unité Mixte de Recherche Diversité et Adaptation des Plantes Cultivées, Agro.M, Université Montpellier 2, Equipe Rhizogenèse, France.
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15
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Bandyopadhyay A, Blakeslee JJ, Lee OR, Mravec J, Sauer M, Titapiwatanakun B, Makam SN, Bouchard R, Geisler M, Martinoia E, Friml J, Peer WA, Murphy AS. Interactions of PIN and PGP auxin transport mechanisms. Biochem Soc Trans 2007; 35:137-41. [PMID: 17233620 DOI: 10.1042/bst0350137] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Polarized transport of the plant hormone auxin influences multiple growth processes in plants and is regulated by plasma-membrane-localized efflux and uptake carriers. The PGP (P-glycoprotein) ABC transporters (ATP-binding-cassette transporters), PIN (pin-formed) subfamily of major facilitator proteins and members of AUX/LAX families have been shown to independently transport auxin both in planta and in heterologous systems. However, PIN- and PGP-mediated transport in heterologous systems exhibits decreased substrate specificity and inhibitor-sensitivity compared with what is seen in plants and plant cells. To determine whether PIN–PGP interactions enhance transport specificity, we analysed interactions of the representative auxin-transporting PGPs with PIN1 and AUX1 in planta and in heterologous systems. Here, we provide evidence that PINs and PGPs interact and function both independently and co-ordinately to control polar auxin transport and impart transport specificity and directionality. These interactions take place in protein complexes stabilized by PGPs in detergent-resistant microdomains.
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Affiliation(s)
- A Bandyopadhyay
- Department of Horticulture, Purdue University, West Lafayette, IN 47907-2010, USA
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16
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Abstract
The plant hormone auxin plays crucial roles in regulating plant growth development, including embryo and root patterning, organ formation, vascular tissue differentiation and growth responses to environmental stimuli. Asymmetric auxin distribution patterns have been observed within tissues, and these so-called auxin gradients change dynamically during different developmental processes. Most auxin is synthesized in the shoot and distributed directionally throughout the plant. This polar auxin transport is mediated by auxin influx and efflux facilitators, whose subcellular polar localizations guide the direction of auxin flow. The polar localization of PIN auxin efflux carriers changes in response to developmental and external cues in order to channel auxin flow in a regulated manner for organized growth. Auxin itself modulates the expression and subcellular localization of PIN proteins, contributing to a complex pattern of feedback regulation. Here we review the available information mainly from studies of a model plant, Arabidopsis thaliana, on the generation of auxin gradients, the regulation of polar auxin transport and further downstream cellular events.
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Affiliation(s)
- H Tanaka
- Zentrum für Molekularbiologie der Pflanzen, Universität Tübingen, 72076, Tübingen, Germany
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17
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18
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Dhonukshe P, Kleine-Vehn J, Friml J. Cell polarity, auxin transport, and cytoskeleton-mediated division planes: who comes first? Protoplasma 2005; 226:67-73. [PMID: 16231102 DOI: 10.1007/s00709-005-0104-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2005] [Accepted: 03/30/2005] [Indexed: 05/04/2023]
Abstract
In plants, cell polarity is an issue more recurring than in other systems, because plants, due to their adaptive and flexible development, often change cell polarity postembryonically according to intrinsic cues and demands of the environment. Recent findings on the directional movement of the plant signalling molecule auxin provide a unique connection between individual cell polarity and the establishment of polarity at the tissue, organ, and whole-plant levels. Decisions about the subcellular polar targeting of PIN auxin transport components determine the direction of auxin flow between cells and consequently mediate multiple developmental events. In addition, mutations or chemical interference with PIN-based auxin transport result in abnormal cell divisions. Thus, the complicated links between cell polarity establishment, auxin transport, cytoskeleton, and oriented cell divisions now begin to emerge. Here we review the available literature on the issues of cell polarity in both plants and animals to extend our understanding on the generation, maintenance, and transmission of cell polarity in plants.
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Affiliation(s)
- Pankaj Dhonukshe
- Zentrum für Molekularbiologie der Pflanzen, Universität Tübingen, Tübingen, Federal Republic of Germany.
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19
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Souter M, Topping J, Pullen M, Friml J, Palme K, Hackett R, Grierson D, Lindsey K. hydra Mutants of Arabidopsis are defective in sterol profiles and auxin and ethylene signaling. Plant Cell 2002; 14:1017-31. [PMID: 12034894 PMCID: PMC150604 DOI: 10.1105/tpc.001248] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The hydra mutants of Arabidopsis are characterized by a pleiotropic phenotype that shows defective embryonic and seedling cell patterning, morphogenesis, and root growth. We demonstrate that the HYDRA1 gene encodes a Delta8-Delta7 sterol isomerase, whereas HYDRA2 encodes a sterol C14 reductase, previously identified as the FACKEL gene product. Seedlings mutant for each gene are similarly defective in the concentrations of the three major Arabidopsis sterols. Promoter::reporter gene analysis showed misexpression of the auxin-regulated DR5 and ACS1 promoters and of the epidermal cell file-specific GL2 promoter in the mutants. The mutants exhibit enhanced responses to auxin. The phenotypes can be rescued partially by inhibition of auxin and ethylene signaling but not by exogenous sterols or brassinosteroids. We propose a model in which correct sterol profiles are required for regulated auxin and ethylene signaling through effects on membrane function.
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Affiliation(s)
- Martin Souter
- Integrative Cell Biology Laboratory, School of Biological and Biomedical Sciences, University of Durham, South Road, Durham DH1 3LE, United Kingdom
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20
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Abstract
The elimination voltammetry with linear scan (EVLS) was used to study adenine and cytosine reduction signals at the mercury electrode. In comparison with the linear scan voltammetry (which provides only one unresolved peak), two elimination functions provide good resolution of individual peaks and significant increase of sensitivity. The first elimination function eliminates the kinetic current (I(k)) and conserves the diffusion current (I(d)). The second elimination function eliminates kinetic and charging currents (I(k) and I(c)) simultaneously and conserves the diffusion current (I(d)). Both functions give two well-resolved peaks of adenine and cytosine in a wide concentration range, while the linear sweep voltammetry gives badly resolved peaks due to hydrogen evolution. The best resolution of peaks is observed in acetate buffer at pH 3.8 and the detection limit for both substances is 500 nM. The concentration dependence of EVLS peak heights for one substance at the constant concentration of the other substance is linear. The peak potentials differ in these elimination functions. The difference in EVLS peak potentials gives the possibility to evaluate alpha n(a). Elimination voltammetry with linear scan contributes to the resolution of cathodic signals of purine and pyrimidine bases at very negative potentials near supporting electrolyte discharge.
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Affiliation(s)
- L Trnková
- Department of Theoretical and Physical Chemistry, Faculty of Science, Masaryk University, Kotlárská 2, 611 37 Brno, Czech Republic.
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21
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Swarup R, Friml J, Marchant A, Ljung K, Sandberg G, Palme K, Bennett M. Localization of the auxin permease AUX1 suggests two functionally distinct hormone transport pathways operate in the Arabidopsis root apex. Genes Dev 2001; 15:2648-53. [PMID: 11641271 PMCID: PMC312818 DOI: 10.1101/gad.210501] [Citation(s) in RCA: 408] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Auxins represent an important class of plant hormone that regulate plant development. Plants use specialized carrier proteins to transport the auxin indole-3-acetic acid (IAA) to target tissues. To date, efflux carrier-mediated polar auxin transport has been assumed to represent the sole mode of long distance IAA movement. Localization of the auxin permease AUX1 in the Arabidopsis root apex has revealed a novel phloem-based IAA transport pathway. AUX1, asymmetrically localized to the plasma membrane of root protophloem cells, is proposed to promote the acropetal, post-phloem movement of auxin to the root apex. MS analysis shows that IAA accumulation in aux1 mutant root apices is impaired, consistent with an AUX1 phloem unloading function. AUX1 localization to columella and lateral root cap tissues of the Arabidopsis root apex reveals that the auxin permease regulates a second IAA transport pathway. Expression studies using an auxin-regulated reporter suggest that AUX1 is necessary for root gravitropism by facilitating basipetal auxin transport to distal elongation zone tissues.
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Affiliation(s)
- R Swarup
- School of Biosciences, University of Nottingham, Nottingham NG7 2RD, UK
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22
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Swarup R, Friml J, Marchant A, Ljung K, Sandberg G, Palme K, Bennett M. Localization of the auxin permease AUX1 suggests two functionally distinct hormone transport pathways operate in the Arabidopsis root apex. Genes Dev 2001. [PMID: 11641271 DOI: 10.1101/gad.210501.2648] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Auxins represent an important class of plant hormone that regulate plant development. Plants use specialized carrier proteins to transport the auxin indole-3-acetic acid (IAA) to target tissues. To date, efflux carrier-mediated polar auxin transport has been assumed to represent the sole mode of long distance IAA movement. Localization of the auxin permease AUX1 in the Arabidopsis root apex has revealed a novel phloem-based IAA transport pathway. AUX1, asymmetrically localized to the plasma membrane of root protophloem cells, is proposed to promote the acropetal, post-phloem movement of auxin to the root apex. MS analysis shows that IAA accumulation in aux1 mutant root apices is impaired, consistent with an AUX1 phloem unloading function. AUX1 localization to columella and lateral root cap tissues of the Arabidopsis root apex reveals that the auxin permease regulates a second IAA transport pathway. Expression studies using an auxin-regulated reporter suggest that AUX1 is necessary for root gravitropism by facilitating basipetal auxin transport to distal elongation zone tissues.
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Affiliation(s)
- R Swarup
- School of Biosciences, University of Nottingham, Nottingham NG7 2RD, UK
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23
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Abstract
Polar transport of the phytohormone auxin mediates various processes in plant growth and development, such as apical dominance, tropisms, vascular patterning and axis formation. This view is based largely on the effects of polar auxin transport inhibitors. These compounds disrupt auxin efflux from the cell but their mode of action is unknown. It is thought that polar auxin flux is caused by the asymmetric distribution of efflux carriers acting at the plasma membrane. The polar localization of efflux carrier candidate PIN1 supports this model. Here we show that the seemingly static localization of PIN1 results from rapid actin-dependent cycling between the plasma membrane and endosomal compartments. Auxin transport inhibitors block PIN1 cycling and inhibit trafficking of membrane proteins that are unrelated to auxin transport. Our data suggest that PIN1 cycling is of central importance for auxin transport and that auxin transport inhibitors affect efflux by generally interfering with membrane-trafficking processes. In support of our conclusion, the vesicle-trafficking inhibitor brefeldin A mimics physiological effects of auxin transport inhibitors.
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Affiliation(s)
- N Geldner
- Zentrum für Molekularbiologie der Pflanzen, Universität Tübingen, Auf der Morgenstelle 3, D-72076 Tübingen, Germany
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24
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Gil P, Dewey E, Friml J, Zhao Y, Snowden KC, Putterill J, Palme K, Estelle M, Chory J. BIG: a calossin-like protein required for polar auxin transport in Arabidopsis. Genes Dev 2001; 15:1985-97. [PMID: 11485992 PMCID: PMC312751 DOI: 10.1101/gad.905201] [Citation(s) in RCA: 205] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Polar auxin transport is crucial for the regulation of auxin action and required for some light-regulated responses during plant development. We have found that two mutants of Arabidopsis-doc1, which displays altered expression of light-regulated genes, and tir3, known for its reduced auxin transport-have similar defects and define mutations in a single gene that we have renamed BIG. BIG is very similar to the Drosophila gene Calossin/Pushover, a member of a gene family also present in Caenorhabditis elegans and human genomes. The protein encoded by BIG is extraordinary in size, 560 kD, and contains several putative Zn-finger domains. Expression-profiling experiments indicate that altered expression of multiple light-regulated genes in doc1 mutants can be suppressed by elevated levels of auxin caused by overexpression of an auxin biosynthetic gene, suggesting that normal auxin distribution is required to maintain low-level expression of these genes in the dark. Double mutants of tir3 with the auxin mutants pin1, pid, and axr1 display severe defects in auxin-dependent growth of the inflorescence. Chemical inhibitors of auxin transport change the intracellular localization of the auxin efflux carrier PIN1 in doc1/tir3 mutants, supporting the idea that BIG is required for normal auxin efflux.
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Affiliation(s)
- P Gil
- Plant Biology Laboratory, Howard Hughes Medical Institute, The Salk Institute for Biological Studies, La Jolla, California 92037 USA
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