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van Hooren M, van Wijk R, Vaseva II, Van Der Straeten D, Haring M, Munnik T. Ectopic Expression of Distinct PLC Genes Identifies 'Compactness' as a Possible Architectural Shoot Strategy to Cope with Drought Stress. PLANT & CELL PHYSIOLOGY 2024; 65:885-903. [PMID: 37846160 PMCID: PMC11209554 DOI: 10.1093/pcp/pcad123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 09/13/2023] [Accepted: 11/13/2023] [Indexed: 10/18/2023]
Abstract
Phospholipase C (PLC) has been implicated in several stress responses, including drought. Overexpression (OE) of PLC has been shown to improve drought tolerance in various plant species. Arabidopsis contains nine PLC genes, which are subdivided into four clades. Earlier, OE of PLC3, PLC5 or PLC7 was found to increase Arabidopsis' drought tolerance. Here, we confirm this for three other PLCs: PLC2, the only constitutively expressed AtPLC; PLC4, reported to have reduced salt tolerance and PLC9, of which the encoded enzyme was presumed to be catalytically inactive. To compare each PLC and to discover any other potential phenotype, two independent OE lines of six AtPLC genes, representing all four clades, were simultaneously monitored with the GROWSCREEN-FLUORO phenotyping platform, under both control- and mild-drought conditions. To investigate which tissues were most relevant to achieving drought survival, we additionally expressed AtPLC5 using 13 different cell- or tissue-specific promoters. While no significant differences in plant size, biomass or photosynthesis were found between PLC lines and wild-type (WT) plants, all PLC-OE lines, as well as those tissue-specific lines that promoted drought survival, exhibited a stronger decrease in 'convex hull perimeter' (= increase in 'compactness') under water deprivation compared to WT. Increased compactness has not been associated with drought or decreased water loss before although a hyponastic decrease in compactness in response to increased temperatures has been associated with water loss. We propose that the increased compactness could lead to decreased water loss and potentially provide a new breeding trait to select for drought tolerance.
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Affiliation(s)
- Max van Hooren
- Plant Cell Biology, Swammerdam Institute for Life Sciences, University of Amsterdam, PO Box 1210, Amsterdam 1000BE, The Netherlands
| | - Ringo van Wijk
- Plant Cell Biology, Swammerdam Institute for Life Sciences, University of Amsterdam, PO Box 1210, Amsterdam 1000BE, The Netherlands
| | - Irina I Vaseva
- Laboratory of Functional Plant Biology, Department of Biology, Ghent University, K.L. Ledeganckstraat 35, Ghent B-9000, Belgium
| | - Dominique Van Der Straeten
- Laboratory of Functional Plant Biology, Department of Biology, Ghent University, K.L. Ledeganckstraat 35, Ghent B-9000, Belgium
| | - Michel Haring
- Plant Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, PO Box 1210, Amsterdam 1000BE, The Netherlands
| | - Teun Munnik
- Plant Cell Biology, Swammerdam Institute for Life Sciences, University of Amsterdam, PO Box 1210, Amsterdam 1000BE, The Netherlands
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2
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Pérez-Sancho J, Van den Broeck L, García-Caparros P, Sozzani R. Insights into multilevel spatial regulation within the root stem cell niche. Curr Opin Genet Dev 2024; 86:102200. [PMID: 38704928 DOI: 10.1016/j.gde.2024.102200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 04/08/2024] [Accepted: 04/09/2024] [Indexed: 05/07/2024]
Abstract
All differentiated root cells derive from stem cells spatially organized within the stem cell niche (SCN), a microenvironment located within the root tip. Here, we compiled recent advances in the understanding of how the SCN drives the establishment and maintenance of cell types. The quiescent center (QC) is widely recognized as the primary driver of cell fate determination, but it is recently considered a convergence center of multiple signals. Cell identity of the cortex endodermis initials is mainly driven by the regulatory feedback loops between transcription factors (TFs), acting as mobile signals between neighboring cells, including the QC. As exemplified in the vascular initials, the precise spatial expression of these regulatory TFs is connected with a dynamic hormonal interplay. Thus, stem cell maintenance and cell differentiation are regulated by a plethora of signals forming a complex, multilevel regulatory network. Integrating the transcriptional and post-translational regulations, protein-protein interactions, and mobile signals into models will be fundamental for the comprehensive understanding of SCN maintenance and differentiation.
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Affiliation(s)
| | - Lisa Van den Broeck
- Plant and Microbial Biology Department and NC Plant Sciences Initiative, North Carolina State University, Raleigh, NC 27695, USA. https://twitter.com/@LisaVandenBroec
| | | | - Rosangela Sozzani
- Plant and Microbial Biology Department and NC Plant Sciences Initiative, North Carolina State University, Raleigh, NC 27695, USA.
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3
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Aliaga Fandino AC, Jelínková A, Marhava P, Petrášek J, Hardtke CS. Ectopic assembly of an auxin efflux control machinery shifts developmental trajectories. THE PLANT CELL 2024; 36:1791-1805. [PMID: 38267818 PMCID: PMC11062438 DOI: 10.1093/plcell/koae023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 12/05/2023] [Accepted: 01/18/2024] [Indexed: 01/26/2024]
Abstract
Polar auxin transport in the Arabidopsis (Arabidopsis thaliana) root tip maintains high auxin levels around the stem cell niche that gradually decrease in dividing cells but increase again once they transition toward differentiation. Protophloem differentiates earlier than other proximal tissues and employs a unique auxin "canalization" machinery that is thought to balance auxin efflux with retention. It consists of a proposed activator of PIN-FORMED (PIN) auxin efflux carriers, the cAMP-, cGMP- and Calcium-dependent (AGC) kinase PROTEIN KINASE ASSOCIATED WITH BRX (PAX); its inhibitor, BREVIS RADIX (BRX); and PHOSPHATIDYLINOSITOL-4-PHOSPHATE-5-KINASE (PIP5K) enzymes, which promote polar PAX and BRX localization. Because of a dynamic PAX-BRX-PIP5K interplay, the net cellular output of this machinery remains unclear. In this study, we deciphered the dosage-sensitive regulatory interactions among PAX, BRX, and PIP5K by their ectopic expression in developing xylem vessels. The data suggest that the dominant collective output of the PAX-BRX-PIP5K module is a localized reduction in PIN abundance. This requires PAX-stimulated clathrin-mediated PIN endocytosis upon site-specific phosphorylation, which distinguishes PAX from other AGC kinases. An ectopic assembly of the PAX-BRX-PIP5K module is sufficient to cause cellular auxin retention and affects root growth vigor by accelerating the trajectory of xylem vessel development. Our data thus provide direct evidence that local manipulation of auxin efflux alters the timing of cellular differentiation in the root.
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Affiliation(s)
| | - Adriana Jelínková
- Institute of Experimental Botany, Czech Academy of Sciences, Prague 165 02, Czech Republic
| | - Petra Marhava
- Department of Plant Molecular Biology, University of Lausanne, Lausanne CH-1015, Switzerland
| | - Jan Petrášek
- Institute of Experimental Botany, Czech Academy of Sciences, Prague 165 02, Czech Republic
| | - Christian S Hardtke
- Department of Plant Molecular Biology, University of Lausanne, Lausanne CH-1015, Switzerland
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4
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von der Mark C, Minne M, De Rybel B. Studying plant vascular development using single-cell approaches. CURRENT OPINION IN PLANT BIOLOGY 2024; 78:102526. [PMID: 38479078 DOI: 10.1016/j.pbi.2024.102526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 02/20/2024] [Accepted: 02/28/2024] [Indexed: 04/07/2024]
Abstract
Vascular cells form a highly complex and heterogeneous tissue. Its composition, function, shape, and arrangement vary with the developmental stage and between organs and species. Understanding the transcriptional regulation underpinning this complexity thus requires a high-resolution technique that is capable of capturing rapid events during vascular cell formation. Single-cell and single-nucleus RNA sequencing (sc/snRNA-seq) approaches provide powerful tools to extract transcriptional information from these lowly abundant and dynamically changing cell types, which allows the reconstruction of developmental trajectories. Here, we summarize and reflect on recent studies using single-cell transcriptomics to study vascular cell types and discuss current and future implementations of sc/snRNA-seq approaches in the field of vascular development.
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Affiliation(s)
- Claudia von der Mark
- Ghent University, Department of Plant Biotechnology and Bioinformatics, Ghent, Belgium; VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Max Minne
- Ghent University, Department of Plant Biotechnology and Bioinformatics, Ghent, Belgium; VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Bert De Rybel
- Ghent University, Department of Plant Biotechnology and Bioinformatics, Ghent, Belgium; VIB Center for Plant Systems Biology, Ghent, Belgium.
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5
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Tessi TM, Maurino VG, Shahriari M, Meissner E, Novak O, Pasternak T, Schumacher BS, Ditengou F, Li Z, Duerr J, Flubacher NS, Nautscher M, Williams A, Kazimierczak Z, Strnad M, Thumfart JO, Palme K, Desimone M, Teale WD. AZG1 is a cytokinin transporter that interacts with auxin transporter PIN1 and regulates the root stress response. THE NEW PHYTOLOGIST 2023; 238:1924-1941. [PMID: 36918499 DOI: 10.1111/nph.18879] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 01/29/2023] [Indexed: 05/04/2023]
Abstract
An environmentally responsive root system is crucial for plant growth and crop yield, especially in suboptimal soil conditions. This responsiveness enables the plant to exploit regions of high nutrient density while simultaneously minimizing abiotic stress. Despite the vital importance of root systems in regulating plant growth, significant gaps of knowledge exist in the mechanisms that regulate their architecture. Auxin defines both the frequency of lateral root (LR) initiation and the rate of LR outgrowth. Here, we describe a search for proteins that regulate root system architecture (RSA) by interacting directly with a key auxin transporter, PIN1. The native separation of Arabidopsis plasma membrane protein complexes identified several PIN1 co-purifying proteins. Among them, AZG1 was subsequently confirmed as a PIN1 interactor. Here, we show that, in Arabidopsis, AZG1 is a cytokinin (CK) import protein that co-localizes with and stabilizes PIN1, linking auxin and CK transport streams. AZG1 expression in LR primordia is sensitive to NaCl, and the frequency of LRs is AZG1-dependent under salt stress. This report therefore identifies a potential point for auxin:cytokinin crosstalk, which shapes RSA in response to NaCl.
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Affiliation(s)
- Tomás M Tessi
- Instituto Multidisciplinario de Biología Vegetal, Velez Sarsfield 249, 5000, Córdoba, Argentina
| | - Veronica G Maurino
- Molecular Plant Physiology, Institute of Cellular and Molecular Botany, University of Bonn, Kirschallee 1, 53115, Bonn, Germany
| | - Mojgan Shahriari
- Institute of Biology II, University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
| | - Esther Meissner
- Conservation Ecology, Department Biology, Philipps-Universität Marburg, Karl-von-Frisch-Straße 8, 35032, Marburg, Germany
| | - Ondrej Novak
- Laboratory of Growth Regulators, Institute of Experimental Botany ASCR and Palacky, Šlechtitelů 27, 783 71, Olomouc, Czech Republic
| | - Taras Pasternak
- Institute of Biology II, University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
| | - Benjamin S Schumacher
- Zentrum für Molekularbiologie der Pflanzen, Universität Tübingen, Auf der Morgenstelle 1, 72076, Tübingen, Germany
| | - Franck Ditengou
- Institute of Biology II, University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
| | - Zenglin Li
- Institute of Biology II, University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
| | - Jasmin Duerr
- Institute of Biology II, University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
| | - Noemi S Flubacher
- Institute of Biology II, University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
| | - Moritz Nautscher
- Institute of Biology II, University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
| | - Alyssa Williams
- Institute of Biology II, University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
| | - Zuzanna Kazimierczak
- Institute of Biology II, University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
| | - Miroslav Strnad
- Laboratory of Growth Regulators, Institute of Experimental Botany ASCR and Palacky, Šlechtitelů 27, 783 71, Olomouc, Czech Republic
| | - Jörg-Oliver Thumfart
- Faculty of Medicine, Institute of Physiology II, University of Freiburg, Hermann-Herder-Strasse 7, 79104, Freiburg, Germany
- Labormedizinisches Zentrum Ostschweiz, Lagerstrasse 30, 9470, Buchs, SG, Switzerland
| | - Klaus Palme
- Molecular Plant Physiology, Institute of Cellular and Molecular Botany, University of Bonn, Kirschallee 1, 53115, Bonn, Germany
- Centre of Biological Systems Analysis, University of Freiburg, 79104, Freiburg, Germany
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104, Freiburg, Germany
| | - Marcelo Desimone
- Instituto Multidisciplinario de Biología Vegetal, Velez Sarsfield 249, 5000, Córdoba, Argentina
| | - William D Teale
- Institute of Biology II, University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
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6
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von der Mark C, Cruz TMD, Blanco‐Touriñan N, Rodriguez‐Villalon A. Bipartite phosphoinositide-dependent modulation of auxin signaling during xylem differentiation in Arabidopsis thaliana roots. THE NEW PHYTOLOGIST 2022; 236:1734-1747. [PMID: 36039703 PMCID: PMC9826227 DOI: 10.1111/nph.18448] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 08/14/2022] [Indexed: 06/15/2023]
Abstract
Efficient root-to-shoot delivery of water and nutrients in plants relies on the correct differentiation of xylem cells into hollow elements. While auxin is integral to the formation of xylem cells, it remains poorly characterized how each subcellular pool of this hormone regulates this process. Combining genetic and cell biological approaches, we investigated the bipartite activity of nucleoplasmic vs plasma membrane-associated phosphatidylinositol 4-phosphate kinases PIP5K1 and its homolog PIP5K2 in Arabidopsis thaliana roots and uncovered a novel mechanism by which phosphoinositides integrate distinct aspects of the auxin signaling cascade and, in turn, regulate the onset of xylem differentiation. The appearance of undifferentiated cells in protoxylem strands of pip5k1 pip5k2 is phenomimicked in auxin transport and perception mutants and can be partially restored by the nuclear residence of PIP5K1. By contrast, exclusion of PIP5K1 from the nucleus hinders the auxin-mediated induction of the xylem master regulator VASCULAR RELATED NAC DOMAIN (VND) 7. A xylem-specific increase of auxin levels abolishes pip5k1 pip5k2 vascular defects, indicating that the establishment of auxin maxima is required to activate VND7-mediated xylem differentiation. Our results describe a new mechanism by which distinct subcellular pools of phosphoinositides integrate auxin transport and perception to initiate xylem differentiation in a spatiotemporal manner.
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Affiliation(s)
- Claudia von der Mark
- Department of BiologySwiss Federal Institute of Technology (ETH) ZurichCH‐8092ZurichSwitzerland
| | - Tiago M. D. Cruz
- Department of BiologySwiss Federal Institute of Technology (ETH) ZurichCH‐8092ZurichSwitzerland
| | - Noel Blanco‐Touriñan
- Department of BiologySwiss Federal Institute of Technology (ETH) ZurichCH‐8092ZurichSwitzerland
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7
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Zluhan-Martínez E, López-Ruíz BA, García-Gómez ML, García-Ponce B, de la Paz Sánchez M, Álvarez-Buylla ER, Garay-Arroyo A. Integrative Roles of Phytohormones on Cell Proliferation, Elongation and Differentiation in the Arabidopsis thaliana Primary Root. FRONTIERS IN PLANT SCIENCE 2021; 12:659155. [PMID: 33981325 PMCID: PMC8107238 DOI: 10.3389/fpls.2021.659155] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 03/24/2021] [Indexed: 05/17/2023]
Abstract
The growth of multicellular organisms relies on cell proliferation, elongation and differentiation that are tightly regulated throughout development by internal and external stimuli. The plasticity of a growth response largely depends on the capacity of the organism to adjust the ratio between cell proliferation and cell differentiation. The primary root of Arabidopsis thaliana offers many advantages toward understanding growth homeostasis as root cells are continuously produced and move from cell proliferation to elongation and differentiation that are processes spatially separated and could be studied along the longitudinal axis. Hormones fine tune plant growth responses and a huge amount of information has been recently generated on the role of these compounds in Arabidopsis primary root development. In this review, we summarized the participation of nine hormones in the regulation of the different zones and domains of the Arabidopsis primary root. In some cases, we found synergism between hormones that function either positively or negatively in proliferation, elongation or differentiation. Intriguingly, there are other cases where the interaction between hormones exhibits unexpected results. Future analysis on the molecular mechanisms underlying crosstalk hormone action in specific zones and domains will unravel their coordination over PR development.
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Affiliation(s)
- Estephania Zluhan-Martínez
- Laboratorio de Genética Molecular, Desarrollo y Evolución de Plantas, Departamento de Ecología Funcional, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - Brenda Anabel López-Ruíz
- Laboratorio de Genética Molecular, Desarrollo y Evolución de Plantas, Departamento de Ecología Funcional, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - Mónica L. García-Gómez
- Laboratorio de Genética Molecular, Desarrollo y Evolución de Plantas, Departamento de Ecología Funcional, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
- Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - Berenice García-Ponce
- Laboratorio de Genética Molecular, Desarrollo y Evolución de Plantas, Departamento de Ecología Funcional, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - María de la Paz Sánchez
- Laboratorio de Genética Molecular, Desarrollo y Evolución de Plantas, Departamento de Ecología Funcional, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - Elena R. Álvarez-Buylla
- Laboratorio de Genética Molecular, Desarrollo y Evolución de Plantas, Departamento de Ecología Funcional, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
- Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - Adriana Garay-Arroyo
- Laboratorio de Genética Molecular, Desarrollo y Evolución de Plantas, Departamento de Ecología Funcional, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
- Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
- *Correspondence: Adriana Garay-Arroyo,
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8
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Seo M, Lee JY. Dissection of Functional Modules of AT-HOOK MOTIF NUCLEAR LOCALIZED PROTEIN 4 in the Development of the Root Xylem. FRONTIERS IN PLANT SCIENCE 2021; 12:632078. [PMID: 33889164 PMCID: PMC8056045 DOI: 10.3389/fpls.2021.632078] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 02/25/2021] [Indexed: 05/13/2023]
Abstract
Xylem development in the Arabidopsis root apical meristem requires a complex cross talk between plant hormone signaling and transcriptional factors (TFs). The key processes involve fine-tuning between neighboring cells, mediated via the intercellular movement of signaling molecules. As an example, we previously reported that AT-HOOK MOTIF NUCLEAR LOCALIZED PROTEIN (AHL) 4 (AHL4), a member of the 29 AT-hook family TFs in Arabidopsis, moves into xylem precursors from their neighbors to determine xylem differentiation. As part of the effort to understand the molecular functions of AHL4, we performed domain swapping analyses using AHL1 as a counterpart, finding that AHL4 has three functionally distinctive protein modules. The plant and prokaryotes conserved (PPC) domain of AHL4 acts as a mediator of protein-protein interactions with AHL members. The N-terminus of AHL4 is required for the regulation of xylem development likely via its unique DNA-binding activity. The C-terminus of AHL4 confers intercellular mobility. Our characterization of modules in the AHL4 protein will augment our understanding of the complexity of regulation and the evolution of intercellular mobility in AHL4 and its relatives.
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Affiliation(s)
- Minji Seo
- School of Biological Sciences, College of Natural Science, Seoul National University, Seoul, South Korea
| | - Ji-Young Lee
- School of Biological Sciences, College of Natural Science, Seoul National University, Seoul, South Korea
- Plant Genomics and Breeding Institute, Seoul National University, Seoul, South Korea
- *Correspondence: Ji-Young Lee,
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9
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Eeda SK, Werr W. Transcription of the WUSCHEL-RELATED HOMEOBOX 4 gene in Arabidopsis thaliana. Gene Expr Patterns 2020; 38:119150. [PMID: 33065216 DOI: 10.1016/j.gep.2020.119150] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 09/13/2020] [Accepted: 10/08/2020] [Indexed: 11/29/2022]
Abstract
Phylogenetic shadowing and chromatin accessibility data suggested that essential regulatory elements are absent in the 2.9 kb immediate upstream region of the published WOX4pro::YFP cambium marker. Inclusion of an additional 6.3 kb of upstream promoter sequence and confocal imaging with different fluorophores in transgenic Arabidopsis lines revealed a much wider cell-type-specific expression pattern in parenchymous cells of the aerial plant body. The previously demonstrated activity of the WOX4pro::YFP marker in the cambium of vascular strands in the young Arabidopsis inflorescence stem depicts only sectors of a circular subcortical layer of parenchymous AtWOX4-positive cells. Transcription starts in subepidermal cells within the inflorescence apex in a phyllotactic pattern and extends into successively branching lateral organs, which are connected via small tube-like domains of AtWOX4-expressing cells with the circular subcortical parenchymal layer that extends basipetally down the stem. AtWOX4 expression is most dynamic in leaves, where promoter activity is observed transiently at the adaxial side of the lamina and remains detectable later in the palisade parenchyma, although at a weaker level than in the vasculature. In the root the extended AtWOX4 promoter is active through the proximal root meristem, i.e. in the quiescent centre (QC) and its surrounding initials, a pattern that is broader than transcription of its stem cell promoting relative AtWOX5 in the QC. Outside the proximal meristem AtWOX4 transcription is observed in upper cell layers of the columella root cap beneath or above within the stele in proto- and metaxylem cells, in a ribbon-type pattern which divides the central cylinder in two equal halves. This xylem-specific expression it the root stele relates to established AtWOX4 activity in xylem parenchyma specificity within vascular bundles of the stem.
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Affiliation(s)
- Satish Kumar Eeda
- Developmental Biology, Department of Biology, Biocenter, University of Cologne, Zülpicher Str. 47b, D-50674, Cologne, Germany
| | - Wolfgang Werr
- Developmental Biology, Department of Biology, Biocenter, University of Cologne, Zülpicher Str. 47b, D-50674, Cologne, Germany.
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10
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11
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Hofhuis HF, Heidstra R. Transcription factor dosage: more or less sufficient for growth. CURRENT OPINION IN PLANT BIOLOGY 2018; 45:50-58. [PMID: 29852330 DOI: 10.1016/j.pbi.2018.05.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 04/26/2018] [Accepted: 05/12/2018] [Indexed: 06/08/2023]
Abstract
Recent findings highlight three instances in which major aspects of plant development are controlled by dosage-dependent protein levels. In the shoot apical meristem the mobile transcription factor WUS displays an intricate function with respect to target regulation that involves WUS dosage, binding site affinity and protein dimerization. The size of the root meristem is controlled by dosage-dependent PLT protein activity. Recent identification of targets and feedbacks provide new insights and entry into possible mechanisms of dosage read-out. Finally, HD-ZIPIII dosage, enforced by a gradient of mobile miRNAs, presents a relatively unexplored case in the radial patterning of vasculature and ground tissue. We evaluate our current knowledge of these three examples and address molecular mechanisms of dosage translation where possible.
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Affiliation(s)
- Hugo F Hofhuis
- Department of Plant Sciences, Wageningen University Research, Netherlands
| | - Renze Heidstra
- Department of Plant Sciences, Wageningen University Research, Netherlands.
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