1
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Uemura Y, Tsukagoshi H. Quantitative analysis of lateral root development with time-lapse imaging and deep neural network. QUANTITATIVE PLANT BIOLOGY 2024; 5:e1. [PMID: 38385121 PMCID: PMC10877138 DOI: 10.1017/qpb.2024.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 01/15/2024] [Accepted: 01/21/2024] [Indexed: 02/23/2024]
Abstract
During lateral root (LR) development, morphological alteration of the developing single LR primordium occurs continuously. Precise observation of this continuous alteration is important for understanding the mechanism involved in single LR development. Recently, we reported that very long-chain fatty acids are important signalling molecules that regulate LR development. In the study, we developed an efficient method to quantify the transition of single LR developmental stages using time-lapse imaging followed by a deep neural network (DNN) analysis. In this 'insight' paper, we discuss our DNN method and the importance of time-lapse imaging in studies on plant development. Integrating DNN analysis and imaging is a powerful technique for the quantification of the timing of the transition of organ morphology; it can become an important method to elucidate spatiotemporal molecular mechanisms in plant development.
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Affiliation(s)
- Yuta Uemura
- Faculty of Agriculture, Meijo University, Nagoya, Japan
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2
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Bellows S, Janes G, Avitabile D, King JR, Bishopp A, Farcot E. Fluctuations in auxin levels depend upon synchronicity of cell divisions in a one-dimensional model of auxin transport. PLoS Comput Biol 2023; 19:e1011646. [PMID: 38032890 PMCID: PMC10688697 DOI: 10.1371/journal.pcbi.1011646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Accepted: 11/01/2023] [Indexed: 12/02/2023] Open
Abstract
Auxin is a well-studied plant hormone, the spatial distribution of which remains incompletely understood. Here, we investigate the effects of cell growth and divisions on the dynamics of auxin patterning, using a combination of mathematical modelling and experimental observations. In contrast to most prior work, models are not designed or tuned with the aim to produce a specific auxin pattern. Instead, we use well-established techniques from dynamical systems theory to uncover and classify ranges of auxin patterns as exhaustively as possible as parameters are varied. Previous work using these techniques has shown how a multitude of stable auxin patterns may coexist, each attainable from a specific ensemble of initial conditions. When a key parameter spans a range of values, these steady patterns form a geometric curve with successive folds, often nicknamed a snaking diagram. As we introduce growth and cell division into a one-dimensional model of auxin distribution, we observe new behaviour which can be explained in terms of this diagram. Cell growth changes the shape of the snaking diagram, and this corresponds in turn to deformations in the patterns of auxin distribution. As divisions occur this can lead to abrupt creation or annihilation of auxin peaks. We term this phenomenon 'snake-jumping'. Under rhythmic cell divisions, we show how this can lead to stable oscillations of auxin. We also show that this requires a high level of synchronisation between cell divisions. Using 18 hour time-lapse imaging of the auxin reporter DII:Venus in roots of Arabidopsis thaliana, we show auxin fluctuates greatly, both in terms of amplitude and periodicity, consistent with the snake-jumping events observed with non-synchronised cell divisions. Periodic signals downstream of the auxin signalling pathway have previously been recorded in plant roots. The present work shows that auxin alone is unlikely to play the role of a pacemaker in this context.
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Affiliation(s)
- Simon Bellows
- School of Mathematical Sciences, University of Nottingham, Nottingham, United Kingdom
| | - George Janes
- School of Biosciences, University of Nottingham, Nottingham, United Kingdom
| | - Daniele Avitabile
- Department of Mathematics, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - John R. King
- School of Mathematical Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Anthony Bishopp
- School of Biosciences, University of Nottingham, Nottingham, United Kingdom
| | - Etienne Farcot
- School of Mathematical Sciences, University of Nottingham, Nottingham, United Kingdom
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3
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Serre NBC, Wernerová D, Vittal P, Dubey SM, Medvecká E, Jelínková A, Petrášek J, Grossmann G, Fendrych M. The AUX1-AFB1-CNGC14 module establishes a longitudinal root surface pH profile. eLife 2023; 12:e85193. [PMID: 37449525 PMCID: PMC10414970 DOI: 10.7554/elife.85193] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Accepted: 07/10/2023] [Indexed: 07/18/2023] Open
Abstract
Plant roots navigate in the soil environment following the gravity vector. Cell divisions in the meristem and rapid cell growth in the elongation zone propel the root tips through the soil. Actively elongating cells acidify their apoplast to enable cell wall extension by the activity of plasma membrane AHA H+-ATPases. The phytohormone auxin, central regulator of gravitropic response and root development, inhibits root cell growth, likely by rising the pH of the apoplast. However, the role of auxin in the regulation of the apoplastic pH gradient along the root tip is unclear. Here, we show, by using an improved method for visualization and quantification of root surface pH, that the Arabidopsis thaliana root surface pH shows distinct acidic and alkaline zones, which are not primarily determined by the activity of AHA H+-ATPases. Instead, the distinct domain of alkaline pH in the root transition zone is controlled by a rapid auxin response module, consisting of the AUX1 auxin influx carrier, the AFB1 auxin co-receptor, and the CNCG14 calcium channel. We demonstrate that the rapid auxin response pathway is required for an efficient navigation of the root tip.
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Affiliation(s)
- Nelson BC Serre
- Department of Experimental Plant Biology, Faculty of Science, Charles UniversityPragueCzech Republic
| | - Daša Wernerová
- Department of Experimental Plant Biology, Faculty of Science, Charles UniversityPragueCzech Republic
- Institute of Cell and Interaction Biology, Heinrich-Heine-University DüsseldorfDüsseldorfGermany
| | - Pruthvi Vittal
- Department of Experimental Plant Biology, Faculty of Science, Charles UniversityPragueCzech Republic
| | - Shiv Mani Dubey
- Department of Experimental Plant Biology, Faculty of Science, Charles UniversityPragueCzech Republic
| | - Eva Medvecká
- Department of Experimental Plant Biology, Faculty of Science, Charles UniversityPragueCzech Republic
| | - Adriana Jelínková
- Institute of Experimental Botany, Czech Academy of SciencesPragueCzech Republic
| | - Jan Petrášek
- Department of Experimental Plant Biology, Faculty of Science, Charles UniversityPragueCzech Republic
- Institute of Experimental Botany, Czech Academy of SciencesPragueCzech Republic
| | - Guido Grossmann
- Institute of Cell and Interaction Biology, Heinrich-Heine-University DüsseldorfDüsseldorfGermany
- CEPLAS - Cluster of Excellence on Plant Sciences, Heinrich-Heine-University DüsseldorfDüsseldorfGermany
| | - Matyáš Fendrych
- Department of Experimental Plant Biology, Faculty of Science, Charles UniversityPragueCzech Republic
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4
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Hernández-Herrera P, Ugartechea-Chirino Y, Torres-Martínez HH, Arzola AV, Chairez-Veloz JE, García-Ponce B, Sánchez MDLP, Garay-Arroyo A, Álvarez-Buylla ER, Dubrovsky JG, Corkidi G. Live Plant Cell Tracking: Fiji plugin to analyze cell proliferation dynamics and understand morphogenesis. PLANT PHYSIOLOGY 2022; 188:846-860. [PMID: 34791452 PMCID: PMC8825436 DOI: 10.1093/plphys/kiab530] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 10/19/2021] [Indexed: 05/13/2023]
Abstract
Arabidopsis (Arabidopsis thaliana) primary and lateral roots (LRs) are well suited for 3D and 4D microscopy, and their development provides an ideal system for studying morphogenesis and cell proliferation dynamics. With fast-advancing microscopy techniques used for live-imaging, whole tissue data are increasingly available, yet present the great challenge of analyzing complex interactions within cell populations. We developed a plugin "Live Plant Cell Tracking" (LiPlaCeT) coupled to the publicly available ImageJ image analysis program and generated a pipeline that allows, with the aid of LiPlaCeT, 4D cell tracking and lineage analysis of populations of dividing and growing cells. The LiPlaCeT plugin contains ad hoc ergonomic curating tools, making it very simple to use for manual cell tracking, especially when the signal-to-noise ratio of images is low or variable in time or 3D space and when automated methods may fail. Performing time-lapse experiments and using cell-tracking data extracted with the assistance of LiPlaCeT, we accomplished deep analyses of cell proliferation and clonal relations in the whole developing LR primordia and constructed genealogical trees. We also used cell-tracking data for endodermis cells of the root apical meristem (RAM) and performed automated analyses of cell population dynamics using ParaView software (also publicly available). Using the RAM as an example, we also showed how LiPlaCeT can be used to generate information at the whole-tissue level regarding cell length, cell position, cell growth rate, cell displacement rate, and proliferation activity. The pipeline will be useful in live-imaging studies of roots and other plant organs to understand complex interactions within proliferating and growing cell populations. The plugin includes a step-by-step user manual and a dataset example that are available at https://www.ibt.unam.mx/documentos/diversos/LiPlaCeT.zip.
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Affiliation(s)
- Paul Hernández-Herrera
- Laboratorio de Imágenes y Visión por Computadora, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cd. de México, C.P. 04510, Mexico
| | - Yamel Ugartechea-Chirino
- Departamento de Ecología Funcional, Instituto de Ecología, Laboratorio de Genética Molecular, Epigenética, Desarrollo y Evolución de Plantas, Universidad Nacional Autónoma de México, Cd. de México, C.P. 04510, Mexico
| | - Héctor H Torres-Martínez
- Departamento de Biología Molecular de Plantas, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cd. de México, C.P. 04510, Mexico
| | - Alejandro V Arzola
- Instituto de Física, Universidad Nacional Autónoma de México, Cd. de México, C.P. 04510, Mexico
| | - José Eduardo Chairez-Veloz
- Departamento de Control Automático, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Cd. de México, C.P. 07350, Mexico
| | - Berenice García-Ponce
- Departamento de Ecología Funcional, Instituto de Ecología, Laboratorio de Genética Molecular, Epigenética, Desarrollo y Evolución de Plantas, Universidad Nacional Autónoma de México, Cd. de México, C.P. 04510, Mexico
| | - María de la Paz Sánchez
- Departamento de Ecología Funcional, Instituto de Ecología, Laboratorio de Genética Molecular, Epigenética, Desarrollo y Evolución de Plantas, Universidad Nacional Autónoma de México, Cd. de México, C.P. 04510, Mexico
| | - Adriana Garay-Arroyo
- Departamento de Ecología Funcional, Instituto de Ecología, Laboratorio de Genética Molecular, Epigenética, Desarrollo y Evolución de Plantas, Universidad Nacional Autónoma de México, Cd. de México, C.P. 04510, Mexico
| | - Elena R Álvarez-Buylla
- Departamento de Ecología Funcional, Instituto de Ecología, Laboratorio de Genética Molecular, Epigenética, Desarrollo y Evolución de Plantas, Universidad Nacional Autónoma de México, Cd. de México, C.P. 04510, Mexico
- Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, Cd. de México, C.P. 04510, Mexico
| | - Joseph G Dubrovsky
- Departamento de Biología Molecular de Plantas, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cd. de México, C.P. 04510, Mexico
| | - Gabriel Corkidi
- Laboratorio de Imágenes y Visión por Computadora, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cd. de México, C.P. 04510, Mexico
- Author for communication:
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5
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Siqueira JA, Otoni WC, Araújo WL. The hidden half comes into the spotlight: Peeking inside the black box of root developmental phases. PLANT COMMUNICATIONS 2022; 3:100246. [PMID: 35059627 PMCID: PMC8760039 DOI: 10.1016/j.xplc.2021.100246] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 08/13/2021] [Accepted: 09/18/2021] [Indexed: 05/30/2023]
Abstract
Efficient use of natural resources (e.g., light, water, and nutrients) can be improved with a tailored developmental program that maximizes the lifetime and fitness of plants. In plant shoots, a developmental phase represents a time window in which the meristem triggers the development of unique morphological and physiological traits, leading to the emergence of leaves, flowers, and fruits. Whereas developmental phases in plant shoots have been shown to enhance food production in crops, this phenomenon has remained poorly investigated in roots. In light of recent advances, we suggest that root development occurs in three main phases: root apical meristem appearance, foraging, and senescence. We provide compelling evidence suggesting that these phases are regulated by at least four developmental pathways: autonomous, non-autonomous, hormonal, and periodic. Root developmental pathways differentially coordinate organ plasticity, promoting morphological alterations, tissue regeneration, and cell death regulation. Furthermore, we suggest how nutritional checkpoints may allow progression through the developmental phases, thus completing the root life cycle. These insights highlight novel and exciting advances in root biology that may help maximize the productivity of crops through more sustainable agriculture and the reduced use of chemical fertilizers.
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6
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Echevarría C, Gutierrez C, Desvoyes B. Tools for Assessing Cell-Cycle Progression in Plants. PLANT & CELL PHYSIOLOGY 2021; 62:1231-1238. [PMID: 34021583 PMCID: PMC8579159 DOI: 10.1093/pcp/pcab066] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 04/27/2021] [Accepted: 05/25/2021] [Indexed: 06/12/2023]
Abstract
Estimation of cell-cycle parameters is crucial for understanding the developmental programs established during the formation of an organism. A number of complementary approaches have been developed and adapted to plants to assess the cell-cycle status in different proliferative tissues. The most classical methods relying on metabolic labeling are still very much employed and give valuable information on cell-cycle progression in fixed tissues. However, the growing knowledge of plant cell-cycle regulators with defined expression pattern together with the development of fluorescent proteins technology enabled the generation of fusion proteins that function individually or in conjunction as cell-cycle reporters. Together with the improvement of imaging techniques, in vivo live imaging to monitor plant cell-cycle progression in normal growth conditions or in response to different stimuli has been possible. Here, we review these tools and their specific outputs for plant cell-cycle analysis.
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Affiliation(s)
- Clara Echevarría
- Department of Genome Dynamics and Function, Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Nicolás Cabrera 1, Madrid 28049, Spain
| | - Crisanto Gutierrez
- Department of Genome Dynamics and Function, Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Nicolás Cabrera 1, Madrid 28049, Spain
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7
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Desvoyes B, Echevarría C, Gutierrez C. A perspective on cell proliferation kinetics in the root apical meristem. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:6708-6715. [PMID: 34159378 PMCID: PMC8513163 DOI: 10.1093/jxb/erab303] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 06/22/2021] [Indexed: 06/13/2023]
Abstract
Organogenesis in plants is primarily postembryonic and relies on a strict balance between cell division and cell expansion. The root is a particularly well-suited model to study cell proliferation in detail since the two processes are spatially and temporally separated for all the different tissues. In addition, the root is amenable to detailed microscopic analysis to identify cells progressing through the cell cycle. While it is clear that cell proliferation activity is restricted to the root apical meristem (RAM), understanding cell proliferation kinetics and identifying its parameters have required much effort over many years. Here, we review the main concepts, experimental settings, and findings aimed at obtaining a detailed knowledge of how cells proliferate within the RAM. The combination of novel tools, experimental strategies, and mathematical models has contributed to our current view of cell proliferation in the RAM. We also discuss several lines of research that need to be explored in the future.
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Affiliation(s)
- Bénédicte Desvoyes
- Centro de Biologia Molecular Severo Ochoa, CSIC-UAM, Nicolas Cabrera 1, Cantoblanco, 28049 Madrid, Spain
| | - Clara Echevarría
- Centro de Biologia Molecular Severo Ochoa, CSIC-UAM, Nicolas Cabrera 1, Cantoblanco, 28049 Madrid, Spain
| | - Crisanto Gutierrez
- Centro de Biologia Molecular Severo Ochoa, CSIC-UAM, Nicolas Cabrera 1, Cantoblanco, 28049 Madrid, Spain
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8
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Dubrovsky JG, Ivanov VB. The quiescent centre of the root apical meristem: conceptual developments from Clowes to modern times. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:6687-6707. [PMID: 34161558 DOI: 10.1093/jxb/erab305] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 06/23/2021] [Indexed: 06/13/2023]
Abstract
In this review we discuss the concepts of the quiescent centre (QC) of the root apical meristem (RAM) and their change over time, from their formulation by F.A.L. Clowes to the present. This review is dedicated to the 100th anniversary of the birth of Clowes, and we present his short biography and a full bibliography of Clowes' work. Over time, the concept of the QC proved to be useful for the understanding of RAM organization and behaviour. We focus specifically on conceptual developments, from the organization of the QC to understanding its functions in RAM maintenance and activity, ranging from a model species, Arabidopsis thaliana, to crops. Concepts of initial cells, stem cells, and heterogeneity of the QC cells in the context of functional and structural stem cells are considered. We review the role of the QC in the context of cell flux in the RAM and the nature of quiescence of the QC cells. We discuss the origin of the QC and fluctuation of its size in ontogenesis and why the QC cells are more resistant to stress. Contemporary concepts of the organizer and stem cell niche are also considered. We also propose how the stem cell niche in the RAM can be defined in roots of a non-model species.
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Affiliation(s)
- Joseph G Dubrovsky
- Departamento de Biología Molecular de Plantas, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Mexico
| | - Victor B Ivanov
- Department of Root Physiology, Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia
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9
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van den Berg T, Yalamanchili K, de Gernier H, Santos Teixeira J, Beeckman T, Scheres B, Willemsen V, Ten Tusscher K. A reflux-and-growth mechanism explains oscillatory patterning of lateral root branching sites. Dev Cell 2021; 56:2176-2191.e10. [PMID: 34343477 DOI: 10.1016/j.devcel.2021.07.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 03/19/2021] [Accepted: 07/09/2021] [Indexed: 10/20/2022]
Abstract
Modular, repetitive structures are a key component of complex multicellular body plans across the tree of life. Typically, these structures are prepatterned by temporal oscillations in gene expression or signaling. Although a clock-and-wavefront mechanism was identified and plant leaf phyllotaxis arises from a Turing-type patterning for vertebrate somitogenesis and arthropod segmentation, the mechanism underlying lateral root patterning has remained elusive. To resolve this enigma, we combined computational modeling with in planta experiments. Intriguingly, auxin oscillations automatically emerge in our model from the interplay between a reflux-loop-generated auxin loading zone and stem-cell-driven growth dynamics generating periodic cell-size variations. In contrast to the clock-and-wavefront mechanism and Turing patterning, the uncovered mechanism predicts both frequency and spacing of lateral-root-forming sites to positively correlate with root meristem growth. We validate this prediction experimentally. Combined, our model and experimental results support that a reflux-and-growth patterning mechanism underlies lateral root priming.
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Affiliation(s)
- Thea van den Berg
- Computational Developmental Biology, Department of Biology, Utrecht University, Utrecht, the Netherlands
| | - Kavya Yalamanchili
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, Wageningen, the Netherlands
| | - Hugues de Gernier
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium; VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Joana Santos Teixeira
- Computational Developmental Biology, Department of Biology, Utrecht University, Utrecht, the Netherlands
| | - Tom Beeckman
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium; VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Ben Scheres
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, Wageningen, the Netherlands; Rijk Zwaan Breeding B.V., Department of Biotechnology, Eerste Kruisweg 9, 4793 RS Fijnaart, the Netherlands
| | - Viola Willemsen
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, Wageningen, the Netherlands
| | - Kirsten Ten Tusscher
- Computational Developmental Biology, Department of Biology, Utrecht University, Utrecht, the Netherlands.
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10
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Hu P, Chapman SC, Zheng B. Coupling of machine learning methods to improve estimation of ground coverage from unmanned aerial vehicle (UAV) imagery for high-throughput phenotyping of crops. FUNCTIONAL PLANT BIOLOGY : FPB 2021; 48:766-779. [PMID: 33663681 DOI: 10.1071/fp20309] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 02/14/2021] [Indexed: 06/12/2023]
Abstract
Ground coverage (GC) allows monitoring of crop growth and development and is normally estimated as the ratio of vegetation to the total pixels from nadir images captured by visible-spectrum (RGB) cameras. The accuracy of estimated GC can be significantly impacted by the effect of 'mixed pixels', which is related to the spatial resolution of the imagery as determined by flight altitude, camera resolution and crop characteristics (fine vs coarse textures). In this study, a two-step machine learning method was developed to improve the accuracy of GC of wheat (Triticum aestivum L.) estimated from coarse-resolution RGB images captured by an unmanned aerial vehicle (UAV) at higher altitudes. The classification tree-based per-pixel segmentation (PPS) method was first used to segment fine-resolution reference images into vegetation and background pixels. The reference and their segmented images were degraded to the target coarse spatial resolution. These degraded images were then used to generate a training dataset for a regression tree-based model to establish the sub-pixel classification (SPC) method. The newly proposed method (i.e. PPS-SPC) was evaluated with six synthetic and four real UAV image sets (SISs and RISs, respectively) with different spatial resolutions. Overall, the results demonstrated that the PPS-SPC method obtained higher accuracy of GC in both SISs and RISs comparing to PPS method, with root mean squared errors (RMSE) of less than 6% and relative RMSE (RRMSE) of less than 11% for SISs, and RMSE of less than 5% and RRMSE of less than 35% for RISs. The proposed PPS-SPC method can be potentially applied in plant breeding and precision agriculture to balance accuracy requirement and UAV flight height in the limited battery life and operation time.
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Affiliation(s)
- Pengcheng Hu
- CSIRO Agriculture and Food, Queensland Biosciences Precinct 306 Carmody Road, St Lucia 4067, Qld, Australia
| | - Scott C Chapman
- CSIRO Agriculture and Food, Queensland Biosciences Precinct 306 Carmody Road, St Lucia 4067, Qld, Australia; and School of Food and Agricultural Sciences, The University of Queensland, via Warrego Highway, Gatton 4343, Qld, Australia
| | - Bangyou Zheng
- CSIRO Agriculture and Food, Queensland Biosciences Precinct 306 Carmody Road, St Lucia 4067, Qld, Australia; and Corresponding author.
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11
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Amarteifio S, Fallesen T, Pruessner G, Sena G. A random-sampling approach to track cell divisions in time-lapse fluorescence microscopy. PLANT METHODS 2021; 17:25. [PMID: 33685468 PMCID: PMC7941913 DOI: 10.1186/s13007-021-00723-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 02/22/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND Particle-tracking in 3D is an indispensable computational tool to extract critical information on dynamical processes from raw time-lapse imaging. This is particularly true with in vivo time-lapse fluorescence imaging in cell and developmental biology, where complex dynamics are observed at high temporal resolution. Common tracking algorithms used with time-lapse data in fluorescence microscopy typically assume a continuous signal where background, recognisable keypoints and independently moving objects of interest are permanently visible. Under these conditions, simple registration and identity management algorithms can track the objects of interest over time. In contrast, here we consider the case of transient signals and objects whose movements are constrained within a tissue, where standard algorithms fail to provide robust tracking. RESULTS To optimize 3D tracking in these conditions, we propose the merging of registration and tracking tasks into a registration algorithm that uses random sampling to solve the identity management problem. We describe the design and application of such an algorithm, illustrated in the domain of plant biology, and make it available as an open-source software implementation. The algorithm is tested on mitotic events in 4D data-sets obtained with light-sheet fluorescence microscopy on growing Arabidopsis thaliana roots expressing CYCB::GFP. We validate the method by comparing the algorithm performance against both surrogate data and manual tracking. CONCLUSION This method fills a gap in existing tracking techniques, following mitotic events in challenging data-sets using transient fluorescent markers in unregistered images.
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Affiliation(s)
| | - Todd Fallesen
- Department of Life Sciences, Imperial College London, London, UK
- Crick Advanced Light Microscopy, Francis Crick Institute, London, UK
| | | | - Giovanni Sena
- Department of Life Sciences, Imperial College London, London, UK.
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12
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Okumura T, Nomoto Y, Kobayashi K, Suzuki T, Takatsuka H, Ito M. MYB3R-mediated active repression of cell cycle and growth under salt stress in Arabidopsis thaliana. JOURNAL OF PLANT RESEARCH 2021; 134:261-277. [PMID: 33580347 DOI: 10.1007/s10265-020-01250-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 12/23/2020] [Indexed: 06/12/2023]
Abstract
Under environmental stress, plants are believed to actively repress their growth to save resource and alter its allocation to acquire tolerance against the stress. Although a lot of studies have uncovered precise mechanisms for responding to stress and acquiring tolerance, the mechanisms for regulating growth repression under stress are not as well understood. It is especially unclear which particular genes related to cell cycle control are involved in active growth repression. Here, we showed that decreased growth in plants exposed to moderate salt stress is mediated by MYB3R transcription factors that have been known to positively and negatively regulate the transcription of G2/M-specific genes. Our genome-wide gene expression analysis revealed occurrences of general downregulation of G2/M-specific genes in Arabidopsis under salt stress. Importantly, this downregulation is significantly and universally mitigated by the loss of MYB3R repressors by mutations. Accordingly, the growth performance of Arabidopsis plants under salt stress is significantly recovered in mutants lacking MYB3R repressors. This growth recovery involves improved cell proliferation that is possibly due to prolonging and accelerating cell proliferation, which were partly suggested by enlarged root meristem and increased number of cells positive for CYCB1;1-GUS. Our ploidy analysis further suggested that cell cycle progression at the G2 phase was delayed under salt stress, and this delay was recovered by loss of MYB3R repressors. Under salt stress, the changes in expression of MYB3R activators and repressors at both the mRNA and protein levels were not significant. This observation suggests novel mechanisms underlying MYB3R-mediated growth repression under salt stress that are different from the mechanisms operating under other stress conditions such as DNA damage and high temperature.
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Affiliation(s)
- Toru Okumura
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Chikusa, 464-8601, Japan
| | - Yuji Nomoto
- School of Biological Science and Technology, College of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan
| | - Kosuke Kobayashi
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Chikusa, 464-8601, Japan
| | - Takamasa Suzuki
- Department of Biological Chemistry, College of Bioscience and Biotechnology, Chubu University, 1200 Matsumoto-cho, Kasugai, Aichi, 487-8501, Japan
| | - Hirotomo Takatsuka
- School of Biological Science and Technology, College of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan
| | - Masaki Ito
- School of Biological Science and Technology, College of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan.
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13
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Kang H, Wu D, Fan T, Zhu Y. Activities of Chromatin Remodeling Factors and Histone Chaperones and Their Effects in Root Apical Meristem Development. Int J Mol Sci 2020; 21:ijms21030771. [PMID: 31991579 PMCID: PMC7038114 DOI: 10.3390/ijms21030771] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 01/22/2020] [Accepted: 01/23/2020] [Indexed: 01/01/2023] Open
Abstract
Eukaryotic genes are packaged into dynamic but stable chromatin structures to deal with transcriptional reprogramming and inheritance during development. Chromatin remodeling factors and histone chaperones are epigenetic factors that target nucleosomes and/or histones to establish and maintain proper chromatin structures during critical physiological processes such as DNA replication and transcriptional modulation. Root apical meristems are vital for plant root development. Regarding the well-characterized transcription factors involved in stem cell proliferation and differentiation, there is increasing evidence of the functional implications of epigenetic regulation in root apical meristem development. In this review, we focus on the activities of chromatin remodeling factors and histone chaperones in the root apical meristems of the model plant species Arabidopsis and rice.
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14
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Dumur T, Duncan S, Graumann K, Desset S, Randall RS, Scheid OM, Prodanov D, Tatout C, Baroux C. Probing the 3D architecture of the plant nucleus with microscopy approaches: challenges and solutions. Nucleus 2019; 10:181-212. [PMID: 31362571 PMCID: PMC6682351 DOI: 10.1080/19491034.2019.1644592] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 06/24/2019] [Accepted: 07/01/2019] [Indexed: 12/18/2022] Open
Abstract
The eukaryotic cell nucleus is a central organelle whose architecture determines genome function at multiple levels. Deciphering nuclear organizing principles influencing cellular responses and identity is a timely challenge. Despite many similarities between plant and animal nuclei, plant nuclei present intriguing specificities. Complementary to molecular and biochemical approaches, 3D microscopy is indispensable for resolving nuclear architecture. However, novel solutions are required for capturing cell-specific, sub-nuclear and dynamic processes. We provide a pointer for utilising high-to-super-resolution microscopy and image processing to probe plant nuclear architecture in 3D at the best possible spatial and temporal resolution and at quantitative and cell-specific levels. High-end imaging and image-processing solutions allow the community now to transcend conventional practices and benefit from continuously improving approaches. These promise to deliver a comprehensive, 3D view of plant nuclear architecture and to capture spatial dynamics of the nuclear compartment in relation to cellular states and responses. Abbreviations: 3D and 4D: Three and Four dimensional; AI: Artificial Intelligence; ant: antipodal nuclei (ant); CLSM: Confocal Laser Scanning Microscopy; CTs: Chromosome Territories; DL: Deep Learning; DLIm: Dynamic Live Imaging; ecn: egg nucleus; FACS: Fluorescence-Activated Cell Sorting; FISH: Fluorescent In Situ Hybridization; FP: Fluorescent Proteins (GFP, RFP, CFP, YFP, mCherry); FRAP: Fluorescence Recovery After Photobleaching; GPU: Graphics Processing Unit; KEEs: KNOT Engaged Elements; INTACT: Isolation of Nuclei TAgged in specific Cell Types; LADs: Lamin-Associated Domains; ML: Machine Learning; NA: Numerical Aperture; NADs: Nucleolar Associated Domains; PALM: Photo-Activated Localization Microscopy; Pixel: Picture element; pn: polar nuclei; PSF: Point Spread Function; RHF: Relative Heterochromatin Fraction; SIM: Structured Illumination Microscopy; SLIm: Static Live Imaging; SMC: Spore Mother Cell; SNR: Signal to Noise Ratio; SRM: Super-Resolution Microscopy; STED: STimulated Emission Depletion; STORM: STochastic Optical Reconstruction Microscopy; syn: synergid nuclei; TADs: Topologically Associating Domains; Voxel: Volumetric pixel.
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Affiliation(s)
- Tao Dumur
- Gregor Mendel Institute (GMI) of Molecular Plant Biology, Austrian Academy of Sciences, Vienna Biocenter (VBC), Vienna, Austria
| | - Susan Duncan
- Norwich Research Park, Earlham Institute, Norwich, UK
| | - Katja Graumann
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, UK
| | - Sophie Desset
- GReD, Université Clermont Auvergne, CNRS, INSERM, Clermont–Ferrand, France
| | - Ricardo S Randall
- Department of Plant and Microbial Biology, Zürich-Basel Plant Science Center, University of Zürich, Zürich, Switzerland
| | - Ortrun Mittelsten Scheid
- Gregor Mendel Institute (GMI) of Molecular Plant Biology, Austrian Academy of Sciences, Vienna Biocenter (VBC), Vienna, Austria
| | - Dimiter Prodanov
- Environment, Health and Safety, Neuroscience Research Flanders, Leuven, Belgium
| | - Christophe Tatout
- GReD, Université Clermont Auvergne, CNRS, INSERM, Clermont–Ferrand, France
| | - Célia Baroux
- Department of Plant and Microbial Biology, Zürich-Basel Plant Science Center, University of Zürich, Zürich, Switzerland
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15
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Rahni R, Birnbaum KD. Week-long imaging of cell divisions in the Arabidopsis root meristem. PLANT METHODS 2019; 15:30. [PMID: 30988691 PMCID: PMC6446972 DOI: 10.1186/s13007-019-0417-9] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 03/19/2019] [Indexed: 05/25/2023]
Abstract
BACKGROUND Characterizing the behaviors of dynamic systems requires capturing them with high temporal and spatial resolution. Owing to its transparency and genetic tractability, the Arabidopsis thaliana root lends itself well to live imaging when combined with cell and tissue-specific fluorescent reporters. We developed a novel 4D imaging method that utilizes simple confocal microscopy and readily available components to track cell divisions in the root stem cell niche and surrounding region for up to 1 week. RESULTS Using this method, we performed a direct measurement of cell division intervals within and around the root stem cell niche. The results reveal a short, steep gradient of cell division rates in proximal stem cells, with progressively more rapid cell division rates from quiescent center (QC), to cells in direct contact with the QC (initials), to their immediate daughters, after which division rates appear to become more homogeneous. CONCLUSIONS These results provide a baseline to study how perturbations in signaling could affect cell division patterns in the root meristem. This new setup further allows us to finely analyze meristematic cell division rates that lead to patterning.
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Affiliation(s)
- Ramin Rahni
- Department of Biology, Center for Genomics and Systems Biology, New York University, 12 Waverly Place, New York, NY 10003 USA
| | - Kenneth D. Birnbaum
- Department of Biology, Center for Genomics and Systems Biology, New York University, 12 Waverly Place, New York, NY 10003 USA
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16
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Höwing T, Dann M, Müller B, Helm M, Scholz S, Schneitz K, Hammes UZ, Gietl C. The role of KDEL-tailed cysteine endopeptidases of Arabidopsis (AtCEP2 and AtCEP1) in root development. PLoS One 2018; 13:e0209407. [PMID: 30576358 PMCID: PMC6303060 DOI: 10.1371/journal.pone.0209407] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 12/05/2018] [Indexed: 12/17/2022] Open
Abstract
Plants encode a unique group of papain-type cysteine endopeptidases (CysEP) characterized by a C-terminal KDEL endoplasmic reticulum retention signal (KDEL-CysEP) and an unusually broad substrate specificity. The three Arabidopsis KDEL-CysEPs (AtCEP1, AtCEP2, and AtCEP3) are differentially expressed in vegetative and generative tissues undergoing programmed cell death (PCD). While KDEL-CysEPs have been shown to be implicated in the collapse of tissues during PCD, roles of these peptidases in processes other than PCD are unknown. Using mCherry-AtCEP2 and EGFP-AtCEP1 reporter proteins in wild type versus atcep2 or atcep1 mutant plants, we explored the participation of AtCEP in young root development. Loss of AtCEP2, but not AtCEP1 resulted in shorter primary roots due to a decrease in cell length in the lateral root (LR) cap, and impairs extension of primary root epidermis cells such as trichoblasts in the elongation zone. AtCEP2 was localized to root cap corpses adherent to epidermal cells in the rapid elongation zone. AtCEP1 and AtCEP2 are expressed in root epidermis cells that are separated for LR emergence. Loss of AtCEP1 or AtCEP2 caused delayed emergence of LR primordia. KDEL-CysEPs might be involved in developmental tissue remodeling by supporting cell wall elongation and cell separation.
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Affiliation(s)
- Timo Höwing
- Lehrstuhl für Botanik, Center of Life and Food Sciences Weihenstephan, Technische Universitaet Muenchen, Freising, Germany
| | - Marcel Dann
- Lehrstuhl für Botanik, Center of Life and Food Sciences Weihenstephan, Technische Universitaet Muenchen, Freising, Germany
| | - Benedikt Müller
- Cell Biology and Plant Biochemistry, Biochemie-Zentrum Regensburg, University of Regensburg, Regensburg, Germany
| | - Michael Helm
- Lehrstuhl für Botanik, Center of Life and Food Sciences Weihenstephan, Technische Universitaet Muenchen, Freising, Germany
| | - Sebastian Scholz
- Plant Developmental Biology, Center of Life and Food Sciences Weihenstephan, Technische Universitaet Muenchen, Freising, Germany
| | - Kay Schneitz
- Plant Developmental Biology, Center of Life and Food Sciences Weihenstephan, Technische Universitaet Muenchen, Freising, Germany
| | - Ulrich Z. Hammes
- Cell Biology and Plant Biochemistry, Biochemie-Zentrum Regensburg, University of Regensburg, Regensburg, Germany
| | - Christine Gietl
- Lehrstuhl für Botanik, Center of Life and Food Sciences Weihenstephan, Technische Universitaet Muenchen, Freising, Germany
- * E-mail:
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17
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Zhukovskaya NV, Bystrova EI, Dubrovsky JG, Ivanov VB. Global analysis of an exponential model of cell proliferation for estimation of cell cycle duration in the root apical meristem of angiosperms. ANNALS OF BOTANY 2018; 122:811-822. [PMID: 29425277 PMCID: PMC6215031 DOI: 10.1093/aob/mcx216] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 12/26/2017] [Indexed: 05/13/2023]
Abstract
Background and Aims Information on cell cycle duration (T) in the root apical meristem (RAM) provides insight into root growth, development and evolution. We have previously proposed a simple method for evaluating T based on the dynamics of root growth (V), the number of cells in the RAM (Nm) and the length of fully elongated cells (l), which we named the rate-of-cell-production (RCP) method. Here, a global analysis was performed to confirm the reliability of this method in a range of angiosperm species and to assess the advantages of this approach. Methods We measured V, Nm and l from live or fixed cleared primary roots of seedlings or adventitious roots of bulbs and used this information to estimate the average T values in 73 angiosperm species via the RCP method. The results were then compared with published data obtained using the classical but laborious and time-consuming 3H-thymidine method. Key Results In most species examined, the T values obtained by the RCP method were nearly identical to those obtained by the 3H-thymidine method. Conclusions The global analysis demonstrated that the relationship between the variables V, Nm and l in roots in the steady state of growth is correctly described by the equation T = (ln2 Nm l)V-1. Thus, the RCP method enables cell cycle duration in the RAM to be rapidly and accurately determined. This method can be performed using live or fixed roots for each individual cell type. The simplicity of the approach suggests that it will be widely used in phenomics, evolutionary ecology and other plant biology studies.
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Affiliation(s)
- Natalia V Zhukovskaya
- Department of Root Physiology, Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia
| | - Elena I Bystrova
- Department of Root Physiology, Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia
| | - Joseph G Dubrovsky
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Victor B Ivanov
- Department of Root Physiology, Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia
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18
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Bureau C, Lanau N, Ingouff M, Hassan B, Meunier AC, Divol F, Sevilla R, Mieulet D, Dievart A, Périn C. A protocol combining multiphoton microscopy and propidium iodide for deep 3D root meristem imaging in rice: application for the screening and identification of tissue-specific enhancer trap lines. PLANT METHODS 2018; 14:96. [PMID: 30386414 PMCID: PMC6206838 DOI: 10.1186/s13007-018-0364-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 10/21/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND The clear visualization of 3D organization at the cellular level in plant tissues is needed to fully understand plant development processes. Imaging tools allow the visualization of the main fluorophores and in vivo growth monitoring. Confocal microscopy coupled with the use of propidium iodide (PI) counter-staining is one of the most popular tools used to characterize the structure of root meristems in A. thaliana. However, such an approach is relatively ineffective in species with more complex and thicker root systems. RESULTS We adapted a PI counter-staining protocol to visualize the internal 3D architecture of rice root meristems using multiphoton microscopy. This protocol is simple and compatible with the main fluorophores (CFP, GFP and mCherry). The efficiency and applicability of this protocol were demonstrated by screening a population of 57 enhancer trap lines. We successfully characterized GFP expression in all of the lines and identified 5 lines with tissue-specific expression. CONCLUSIONS All of these resources are now available for the rice community and represent critical tools for future studies of root development.
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Affiliation(s)
- Charlotte Bureau
- CIRAD, UMR-AGAP, Université de Montpellier, Avenue Agropolis, 34398 Montpellier Cedex 5, France
| | - Nadège Lanau
- CIRAD, UMR-AGAP, Université de Montpellier, Avenue Agropolis, 34398 Montpellier Cedex 5, France
| | - Mathieu Ingouff
- UMR DIADE, Université de Montpellier, 911 Avenue Agropolis, 34394 Montpellier Cedex 5, France
| | - Boukhaddaoui Hassan
- INSERM U1051, Institut des Neurosciences de Montpellier, 34095 Montpellier, France
| | - Anne-Cécile Meunier
- CIRAD, UMR-AGAP, Université de Montpellier, Avenue Agropolis, 34398 Montpellier Cedex 5, France
| | - Fanchon Divol
- UMR Biochimie et Physiologie Moléculaire des Plantes, INRA, Campus INRA/SupAgro, 2 Place Viala, 34060 Montpellier Cedex 2, France
| | - Rosie Sevilla
- CIRAD, UMR-AGAP, Université de Montpellier, Avenue Agropolis, 34398 Montpellier Cedex 5, France
| | - Delphine Mieulet
- CIRAD, UMR-AGAP, Université de Montpellier, Avenue Agropolis, 34398 Montpellier Cedex 5, France
| | - Anne Dievart
- CIRAD, UMR-AGAP, Université de Montpellier, Avenue Agropolis, 34398 Montpellier Cedex 5, France
| | - Christophe Périn
- CIRAD, UMR-AGAP, Université de Montpellier, Avenue Agropolis, 34398 Montpellier Cedex 5, France
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19
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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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20
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A Plausible Microtubule-Based Mechanism for Cell Division Orientation in Plant Embryogenesis. Curr Biol 2018; 28:3031-3043.e2. [PMID: 30245102 DOI: 10.1016/j.cub.2018.07.025] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 05/18/2018] [Accepted: 07/09/2018] [Indexed: 01/27/2023]
Abstract
Oriented cell divisions are significant in plant morphogenesis because plant cells are embedded in cell walls and cannot relocate. Cell divisions follow various regular orientations, but the underlying mechanisms have not been clarified. We propose that cell-shape-dependent self-organization of cortical microtubule arrays is able to provide a mechanism for determining planes of early tissue-generating divisions and may form the basis for robust control of cell division orientation in the embryo. To show this, we simulate microtubules on actual cell surface shapes, from which we derive a minimal set of three rules for proper array orientation. The first rule captures the effects of cell shape alone on microtubule organization, the second rule describes the regulation of microtubule stability at cell edges, and the third rule includes the differential effect of auxin on local microtubule stability. These rules generate early embryonic division plane orientations and potentially offer a framework for understanding patterned cell divisions in plant morphogenesis.
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21
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Radhakrishnan D, Kareem A, Durgaprasad K, Sreeraj E, Sugimoto K, Prasad K. Shoot regeneration: a journey from acquisition of competence to completion. CURRENT OPINION IN PLANT BIOLOGY 2018; 41:23-31. [PMID: 28843861 DOI: 10.1016/j.pbi.2017.08.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Revised: 08/07/2017] [Accepted: 08/08/2017] [Indexed: 05/12/2023]
Abstract
Plants display an extraordinary ability to regenerate complete shoot systems from a tissue fragment or even from a single cell. Upregulation of the determinants of pluripotency during a precise window of time in response to external inductive cues is a key decisive factor for shoot regeneration. A burst of recent studies has begun to provide an understanding of signaling molecules that are instrumental in the making of the regenerative mass, as well as the developmental regulators that are seminal in shaping the pluripotent state. Here, we discuss how signaling molecules, waves of mutually exclusive stem cell regulators and epigenetic modifiers could contribute to cellular heterogeneity in an island of regenerative mass, thus leading to de novo shoot regeneration.
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Affiliation(s)
- Dhanya Radhakrishnan
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695016, India
| | - Abdul Kareem
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695016, India
| | - Kavya Durgaprasad
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695016, India
| | - E Sreeraj
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695016, India
| | - Kaoru Sugimoto
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Kalika Prasad
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695016, India.
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22
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von Wangenheim D, Hauschild R, Fendrych M, Barone V, Benková E, Friml J. Live tracking of moving samples in confocal microscopy for vertically grown roots. eLife 2017. [PMID: 28628006 PMCID: PMC5498147 DOI: 10.7554/elife.26792] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Roots navigate through soil integrating environmental signals to orient their growth. The Arabidopsis root is a widely used model for developmental, physiological and cell biological studies. Live imaging greatly aids these efforts, but the horizontal sample position and continuous root tip displacement present significant difficulties. Here, we develop a confocal microscope setup for vertical sample mounting and integrated directional illumination. We present TipTracker - a custom software for automatic tracking of diverse moving objects usable on various microscope setups. Combined, this enables observation of root tips growing along the natural gravity vector over prolonged periods of time, as well as the ability to induce rapid gravity or light stimulation. We also track migrating cells in the developing zebrafish embryo, demonstrating the utility of this system in the acquisition of high-resolution data sets of dynamic samples. We provide detailed descriptions of the tools enabling the easy implementation on other microscopes.
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Affiliation(s)
| | - Robert Hauschild
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Matyáš Fendrych
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Vanessa Barone
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Eva Benková
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Jiří Friml
- Institute of Science and Technology Austria, Klosterneuburg, Austria
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23
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García-Gómez ML, Azpeitia E, Álvarez-Buylla ER. A dynamic genetic-hormonal regulatory network model explains multiple cellular behaviors of the root apical meristem of Arabidopsis thaliana. PLoS Comput Biol 2017; 13:e1005488. [PMID: 28426669 PMCID: PMC5417714 DOI: 10.1371/journal.pcbi.1005488] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 05/04/2017] [Accepted: 03/30/2017] [Indexed: 11/18/2022] Open
Abstract
The study of the concerted action of hormones and transcription factors is fundamental to understand cell differentiation and pattern formation during organ development. The root apical meristem of Arabidopsis thaliana is a useful model to address this. It has a stem cell niche near its tip conformed of a quiescent organizer and stem or initial cells around it, then a proliferation domain followed by a transition domain, where cells diminish division rate before transiting to the elongation zone; here, cells grow anisotropically prior to their final differentiation towards the plant base. A minimal model of the gene regulatory network that underlies cell-fate specification and patterning at the root stem cell niche was proposed before. In this study, we update and couple such network with both the auxin and cytokinin hormone signaling pathways to address how they collectively give rise to attractors that correspond to the genetic and hormonal activity profiles that are characteristic of different cell types along A. thaliana root apical meristem. We used a Boolean model of the genetic-hormonal regulatory network to integrate known and predicted regulatory interactions into alternative models. Our analyses show that, after adding some putative missing interactions, the model includes the necessary and sufficient components and regulatory interactions to recover attractors characteristic of the root cell types, including the auxin and cytokinin activity profiles that correlate with different cellular behaviors along the root apical meristem. Furthermore, the model predicts the existence of activity configurations that could correspond to the transition domain. The model also provides a possible explanation for apparently paradoxical cellular behaviors in the root meristem. For example, how auxin may induce and at the same time inhibit WOX5 expression. According to the model proposed here the hormonal regulation of WOX5 might depend on the cell type. Our results illustrate how non-linear multi-stable qualitative network models can aid at understanding how transcriptional regulators and hormonal signaling pathways are dynamically coupled and may underlie both the acquisition of cell fate and the emergence of hormonal activity profiles that arise during complex organ development.
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Affiliation(s)
- Mónica L. García-Gómez
- Departamento de Ecología Funcional, Instituto de Ecología, Universidad Nacional Autónoma de México, Coyoacán, Ciudad de México, México
- Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, Coyoacán, Ciudad de México, México
| | - Eugenio Azpeitia
- INRIA project-team Virtual Plants, joint with CIRAD and INRA, Montpellier, France
| | - Elena R. Álvarez-Buylla
- Departamento de Ecología Funcional, Instituto de Ecología, Universidad Nacional Autónoma de México, Coyoacán, Ciudad de México, México
- Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, Coyoacán, Ciudad de México, México
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24
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Vyplelová P, Ovečka M, Šamaj J. Alfalfa Root Growth Rate Correlates with Progression of Microtubules during Mitosis and Cytokinesis as Revealed by Environmental Light-Sheet Microscopy. FRONTIERS IN PLANT SCIENCE 2017; 8:1870. [PMID: 29163595 PMCID: PMC5670501 DOI: 10.3389/fpls.2017.01870] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 10/13/2017] [Indexed: 05/04/2023]
Abstract
Cell division and expansion are two fundamental biological processes supporting indeterminate root growth and development of plants. Quantitative evaluations of cell divisions related to root growth analyses have been performed in several model crop and non-crop plant species, but not in important legume plant Medicago sativa. Light-sheet fluorescence microscopy (LSFM) is an advanced imaging technique widely used in animal developmental biology, providing efficient fast optical sectioning under physiological conditions with considerably reduced phototoxicity and photobleaching. Long-term 4D imaging of living plants offers advantages for developmental cell biology not available in other microscopy approaches. Recently, LSFM was implemented in plant developmental biology studies, however, it is largely restricted to the model plant Arabidopsis thaliana. Cellular and subcellular events in crop species and robust plant samples have not been studied by this method yet. Therefore we performed LSFM long-term live imaging of growing root tips of transgenic alfalfa plants expressing the fluorescent molecular marker for the microtubule-binding domain (GFP-MBD), in order to study dynamic patterns of microtubule arrays during mitotic cell division. Quantitative evaluations of cell division progress in the two root tissues (epidermis and cortex) clearly indicate that root growth rate is correlated with duration of cell division in alfalfa roots. Our results favor non-invasive environmental LSFM as one of the most suitable methods for qualitative and quantitative cellular and developmental imaging of living transgenic legume crops.
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25
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Lee SA, Jang S, Yoon EK, Heo JO, Chang KS, Choi JW, Dhar S, Kim G, Choe JE, Heo JB, Kwon C, Ko JH, Hwang YS, Lim J. Interplay between ABA and GA Modulates the Timing of Asymmetric Cell Divisions in the Arabidopsis Root Ground Tissue. MOLECULAR PLANT 2016; 9:870-84. [PMID: 26970019 DOI: 10.1016/j.molp.2016.02.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 02/14/2016] [Accepted: 02/23/2016] [Indexed: 05/21/2023]
Abstract
In multicellular organisms, controlling the timing and extent of asymmetric cell divisions (ACDs) is crucial for correct patterning. During post-embryonic root development in Arabidopsis thaliana, ground tissue (GT) maturation involves an additional ACD of the endodermis, which generates two different tissues: the endodermis (inner) and the middle cortex (outer). It has been reported that the abscisic acid (ABA) and gibberellin (GA) pathways are involved in middle cortex (MC) formation. However, the molecular mechanisms underlying the interaction between ABA and GA during GT maturation remain largely unknown. Through transcriptome analyses, we identified a previously uncharacterized C2H2-type zinc finger gene, whose expression is regulated by GA and ABA, thus named GAZ (GA- AND ABA-RESPONSIVE ZINC FINGER). Seedlings ectopically overexpressing GAZ (GAZ-OX) were sensitive to ABA and GA during MC formation, whereas GAZ-SRDX and RNAi seedlings displayed opposite phenotypes. In addition, our results indicated that GAZ was involved in the transcriptional regulation of ABA and GA homeostasis. In agreement with previous studies that ABA and GA coordinate to control the timing of MC formation, we also confirmed the unique interplay between ABA and GA and identified factors and regulatory networks bridging the two hormone pathways during GT maturation of the Arabidopsis root.
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Affiliation(s)
- Shin Ae Lee
- Department of Systems Biotechnology, Konkuk University, Seoul 05029, Korea
| | - Sejeong Jang
- Department of Systems Biotechnology, Konkuk University, Seoul 05029, Korea
| | - Eun Kyung Yoon
- Department of Systems Biotechnology, Konkuk University, Seoul 05029, Korea
| | - Jung-Ok Heo
- Department of Systems Biotechnology, Konkuk University, Seoul 05029, Korea
| | - Kwang Suk Chang
- Department of Systems Biotechnology, Konkuk University, Seoul 05029, Korea
| | - Ji Won Choi
- Department of Systems Biotechnology, Konkuk University, Seoul 05029, Korea
| | - Souvik Dhar
- Department of Systems Biotechnology, Konkuk University, Seoul 05029, Korea
| | - Gyuree Kim
- Department of Systems Biotechnology, Konkuk University, Seoul 05029, Korea
| | - Jeong-Eun Choe
- Department of Systems Biotechnology, Konkuk University, Seoul 05029, Korea
| | - Jae Bok Heo
- Department of Molecular Biotechnology, Dong-A University, Busan 49201, Korea
| | - Chian Kwon
- Department of Molecular Biology, Dankook University, Yongin 16890, Korea
| | - Jae-Heung Ko
- Department of Plant and Environmental New Resources, Kyung Hee University, Yongin 17104, Korea
| | - Yong-Sic Hwang
- Department of Systems Biotechnology, Konkuk University, Seoul 05029, Korea
| | - Jun Lim
- Department of Systems Biotechnology, Konkuk University, Seoul 05029, Korea.
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26
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Kumpf RP, Nowack MK. The root cap: a short story of life and death. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:5651-62. [PMID: 26068468 DOI: 10.1093/jxb/erv295] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Over 130 years ago, Charles Darwin recognized that sensory functions in the root tip influence directional root growth. Modern plant biology has unravelled that many of the functions that Darwin attributed to the root tip are actually accomplished by a particular organ-the root cap. The root cap surrounds and protects the meristematic stem cells at the growing root tip. Due to this vanguard position, the root cap is predisposed to receive and transmit environmental information to the root proper. In contrast to other plant organs, the root cap shows a rapid turnover of short-lived cells regulated by an intricate balance of cell generation, differentiation, and degeneration. Thanks to these particular features, the root cap is an excellent developmental model system, in which generation, differentiation, and degeneration of cells can be investigated in a conveniently compact spatial and temporal frame. In this review, we give an overview of the current knowledge and concepts of root cap biology, focusing on the model plant Arabidopsis thaliana.
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Affiliation(s)
- Robert P Kumpf
- Department of Plant Systems Biology, Vlaams Instituut voor Biotechnologie, B-9052 Ghent, Belgium Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium
| | - Moritz K Nowack
- Department of Plant Systems Biology, Vlaams Instituut voor Biotechnologie, B-9052 Ghent, Belgium Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium
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27
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Ikeuchi M, Iwase A, Rymen B, Harashima H, Shibata M, Ohnuma M, Breuer C, Morao AK, de Lucas M, De Veylder L, Goodrich J, Brady SM, Roudier F, Sugimoto K. PRC2 represses dedifferentiation of mature somatic cells in Arabidopsis. NATURE PLANTS 2015; 1:15089. [PMID: 27250255 DOI: 10.1038/nplants.2015.89] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 05/29/2015] [Indexed: 05/18/2023]
Abstract
Plant somatic cells are generally acknowledged to retain totipotency, the potential to develop into any cell type within an organism. This astonishing plasticity may contribute to a high regenerative capacity on severe damage, but how plants control this potential during normal post-embryonic development remains largely unknown(1,2). Here we show that POLYCOMB REPRESSIVE COMPLEX 2 (PRC2), a chromatin regulator that maintains gene repression through histone modification, prevents dedifferentiation of mature somatic cells in Arabidopsis thaliana roots. Loss-of-function mutants in PRC2 subunits initially develop unicellular root hairs indistinguishable from those in wild type but fail to retain the differentiated state, ultimately resulting in the generation of an unorganized cell mass and somatic embryos from a single root hair. Strikingly, mutant root hairs complete the normal endoreduplication programme, increasing their nuclear ploidy, but subsequently reinitiate mitotic division coupled with successive DNA replication. Our data show that the WOUND INDUCED DEDIFFERENTIATION3 (WIND3) and LEAFY COTYLEDON2 (LEC2) genes are among the PRC2 targets involved in this reprogramming, as their ectopic overexpression partly phenocopies the dedifferentiation phenotype of PRC2 mutants. These findings unveil the pivotal role of PRC2-mediated gene repression in preventing unscheduled reprogramming of fully differentiated plant cells.
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Affiliation(s)
- Momoko Ikeuchi
- RIKEN Centre for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
| | - Akira Iwase
- RIKEN Centre for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
| | - Bart Rymen
- RIKEN Centre for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
| | - Hirofumi Harashima
- RIKEN Centre for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
| | - Michitaro Shibata
- RIKEN Centre for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
| | - Mariko Ohnuma
- RIKEN Centre for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
| | - Christian Breuer
- RIKEN Centre for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
| | - Ana Karina Morao
- Institut de Biologie de l'Ecole Normale Supérieure, CNRS UMR8197, INSERM U1024, 46 rue d'Ulm, Paris Cedex 05 75230, France
| | - Miguel de Lucas
- Department of Plant Biology and Genome Center, University of California, Davis, 1002 Life Sciences, One Shields Avenue, Davis, California 95616, USA
| | - Lieven De Veylder
- Department of Plant Systems Biology, VIB, Gent B-9052, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Gent B-9052, Belgium
| | - Justin Goodrich
- Institute of Molecular Plant Sciences, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JR, UK
| | - Siobhan M Brady
- Department of Plant Biology and Genome Center, University of California, Davis, 1002 Life Sciences, One Shields Avenue, Davis, California 95616, USA
| | - François Roudier
- Institut de Biologie de l'Ecole Normale Supérieure, CNRS UMR8197, INSERM U1024, 46 rue d'Ulm, Paris Cedex 05 75230, France
| | - Keiko Sugimoto
- RIKEN Centre for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
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28
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Berry S, Hartley M, Olsson TSG, Dean C, Howard M. Local chromatin environment of a Polycomb target gene instructs its own epigenetic inheritance. eLife 2015; 4:e07205. [PMID: 25955967 PMCID: PMC4450441 DOI: 10.7554/elife.07205] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 05/07/2015] [Indexed: 01/10/2023] Open
Abstract
Inheritance of gene expression states is fundamental for cells to 'remember' past events, such as environmental or developmental cues. The conserved Polycomb Repressive Complex 2 (PRC2) maintains epigenetic repression of many genes in animals and plants and modifies chromatin at its targets. Histones modified by PRC2 can be inherited through cell division. However, it remains unclear whether this inheritance can direct long-term memory of individual gene expression states (cis memory) or instead if local chromatin states are dictated by the concentrations of diffusible factors (trans memory). By monitoring the expression of two copies of the Arabidopsis Polycomb target gene FLOWERING LOCUS C (FLC) in the same plants, we show that one copy can be repressed while the other is active. Furthermore, this 'mixed' expression state is inherited through many cell divisions as plants develop. These data demonstrate that epigenetic memory of FLC expression is stored not in trans but in cis.
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29
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Bizet F, Hummel I, Bogeat-Triboulot MB. Length and activity of the root apical meristem revealed in vivo by infrared imaging. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:1387-95. [PMID: 25540436 PMCID: PMC4339598 DOI: 10.1093/jxb/eru488] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Understanding how cell division and cell elongation influence organ growth and development is a long-standing issue in plant biology. In plant roots, most of the cell divisions occur in a short and specialized region, the root apical meristem (RAM). Although RAM activity has been suggested to be of high importance to understand how roots grow and how the cell cycle is regulated, few experimental and numeric data are currently available. The characterization of the RAM is difficult and essentially based upon cell length measurements through destructive and time-consuming microscopy approaches. Here, a new non-invasive method is described that couples infrared light imaging and kinematic analyses and that allows in vivo measurements of the RAM length. This study provides a detailed description of the RAM activity, especially in terms of cell flux and cell division rate. We focused on roots of hydroponic grown poplars and confirmed our method on maize roots. How the RAM affects root growth rate is studied by taking advantage of the high inter-individual variability of poplar root growth. An osmotic stress was applied and did not significantly affect the RAM length, highlighting its homeostasis in short to middle-term responses. The methodology described here simplifies a lot experimental procedures, allows an increase in the number of individuals that can be taken into account in experiments, and means new experiments can be formulated that allow temporal monitoring of the RAM length.
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Affiliation(s)
- François Bizet
- INRA, UMR Ecologie et Ecophysiologie Forestière, F-25420 Champenoux, France Université de Lorraine, UMR Ecologie et Ecophysiologie Forestière, BP 239, F-54506 Vandoeuvre, France
| | - Irène Hummel
- INRA, UMR Ecologie et Ecophysiologie Forestière, F-25420 Champenoux, France Université de Lorraine, UMR Ecologie et Ecophysiologie Forestière, BP 239, F-54506 Vandoeuvre, France
| | - Marie-Béatrice Bogeat-Triboulot
- INRA, UMR Ecologie et Ecophysiologie Forestière, F-25420 Champenoux, France Université de Lorraine, UMR Ecologie et Ecophysiologie Forestière, BP 239, F-54506 Vandoeuvre, France
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30
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Jerominek M, Bull-Hereñu K, Arndt M, Claßen-Bockhoff R. Live imaging of developmental processes in a living meristem of Davidia involucrata (Nyssaceae). FRONTIERS IN PLANT SCIENCE 2014; 5:613. [PMID: 25431576 PMCID: PMC4230046 DOI: 10.3389/fpls.2014.00613] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 10/20/2014] [Indexed: 05/26/2023]
Abstract
Morphogenesis in plants is usually reconstructed by scanning electron microscopy and histology of meristematic structures. These techniques are destructive and require many samples to obtain a consecutive series of states. Unfortunately, using this methodology the absolute timing of growth and complete relative initiation of organs remain obscure. To overcome this limitation, an in vivo observational method based on Epi-Illumination Light Microscopy (ELM) was developed and tested with a male inflorescence meristem (floral unit) of the handkerchief tree Davidia involucrata Baill. (Nyssaceae). We asked whether the most basal flowers of this floral unit arise in a basipetal sequence or, alternatively, are delayed in their development. The growing meristem was observed for 30 days, the longest live observation of a meristem achieved to date. The sequence of primordium initiation indicates a later initiation of the most basal flowers and not earlier or simultaneously as SEM images could suggest. D. involucrata exemplarily shows that live-ELM gives new insights into developmental processes of plants. In addition to morphogenetic questions such as the transition from vegetative to reproductive meristems or the absolute timing of ontogenetic processes, this method may also help to quantify cellular growth processes in the context of molecular physiology and developmental genetics studies.
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Affiliation(s)
- Markus Jerominek
- Institut für Spezielle Botanik, Johannes Gutenberg-UniversitätMainz, Germany
| | - Kester Bull-Hereñu
- Escuela de Pedagogía en Biología y Ciencias, Universidad Central de ChileSantiago de Chile, Chile
- Facultad de Ciencias Biológicas, Pontificia Universidad Católica de ChileSantiago de Chile, Chile
| | - Melanie Arndt
- Institut für Spezielle Botanik, Johannes Gutenberg-UniversitätMainz, Germany
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31
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Yin K, Ueda M, Takagi H, Kajihara T, Sugamata Aki S, Nobusawa T, Umeda-Hara C, Umeda M. A dual-color marker system for in vivo visualization of cell cycle progression in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 80:541-52. [PMID: 25158977 DOI: 10.1111/tpj.12652] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Revised: 08/18/2014] [Accepted: 08/20/2014] [Indexed: 05/08/2023]
Abstract
Visualization of the spatiotemporal pattern of cell division is crucial to understand how multicellular organisms develop and how they modify their growth in response to varying environmental conditions. The mitotic cell cycle consists of four phases: S (DNA replication), M (mitosis and cytokinesis), and the intervening G1 and G2 phases; however, only G2/M-specific markers are currently available in plants, making it difficult to measure cell cycle duration and to analyze changes in cell cycle progression in living tissues. Here, we developed another cell cycle marker that labels S-phase cells by manipulating Arabidopsis CDT1a, which functions in DNA replication origin licensing. Truncations of the CDT1a coding sequence revealed that its carboxy-terminal region is responsible for proteasome-mediated degradation at late G2 or in early mitosis. We therefore expressed this region as a red fluorescent protein fusion protein under the S-specific promoter of a histone 3.1-type gene, HISTONE THREE RELATED2 (HTR2), to generate an S/G2 marker. Combining this marker with the G2/M-specific CYCB1-GFP marker enabled us to visualize both S to G2 and G2 to M cell cycle stages, and thus yielded an essential tool for time-lapse imaging of cell cycle progression. The resultant dual-color marker system, Cell Cycle Tracking in Plant Cells (Cytrap), also allowed us to identify root cells in the last mitotic cell cycle before they entered the endocycle. Our results demonstrate that Cytrap is a powerful tool for in vivo monitoring of the plant cell cycle, and thus for deepening our understanding of cell cycle regulation in particular cell types during organ development.
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Affiliation(s)
- Ke Yin
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Takayama 8916-5, Ikoma, Nara, 630-0192, Japan
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32
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Bennett T, van den Toorn A, Willemsen V, Scheres B. Precise control of plant stem cell activity through parallel regulatory inputs. Development 2014; 141:4055-64. [PMID: 25256342 DOI: 10.1242/dev.110148] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The regulation of columella stem cell activity in the Arabidopsis root cap by a nearby organizing centre, the quiescent centre, has been a key example of the stem cell niche paradigm in plants. Here, we investigate interactions between transcription factors that have been shown to regulate columella stem cells using a simple quantification method for stem cell activity in the root cap. Genetic and expression analyses reveal that the RETINOBLASTOMA-RELATED protein, the FEZ and SOMBRERO NAC-domain transcription factors, the ARF10 and ARF16 auxin response factors and the quiescent centre-expressed WOX5 homeodomain protein each provide independent inputs to regulate the number of columella stem cells. Given the tight control of columella development, we found that these inputs act in a surprisingly parallel manner. Nevertheless, important points of interaction exist; for example, we demonstrate the repression of SMB activity by non-autonomous action of WOX5. Our results suggest that the developmental progression of columella stem cells may be quantitatively regulated by several more broadly acting transcription factors rather than by a single intrinsic stem cell factor, which raises questions about the special nature of the stem cell state in plants.
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Affiliation(s)
- Tom Bennett
- Department of Molecular Genetics, University of Utrecht, Padualaan 8, Utrecht 3584 CH, The Netherlands
| | - Albert van den Toorn
- Department of Molecular Genetics, University of Utrecht, Padualaan 8, Utrecht 3584 CH, The Netherlands Plant Developmental Biology, Wageningen University Research, Wageningen 6708 PB, The Netherlands
| | - Viola Willemsen
- Department of Molecular Genetics, University of Utrecht, Padualaan 8, Utrecht 3584 CH, The Netherlands Plant Developmental Biology, Wageningen University Research, Wageningen 6708 PB, The Netherlands
| | - Ben Scheres
- Department of Molecular Genetics, University of Utrecht, Padualaan 8, Utrecht 3584 CH, The Netherlands Plant Developmental Biology, Wageningen University Research, Wageningen 6708 PB, The Netherlands
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33
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A quiescent path to plant longevity. Trends Cell Biol 2014; 24:443-8. [DOI: 10.1016/j.tcb.2014.03.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 03/06/2014] [Accepted: 03/07/2014] [Indexed: 01/17/2023]
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34
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Sozzani R, Busch W, Spalding EP, Benfey PN. Advanced imaging techniques for the study of plant growth and development. TRENDS IN PLANT SCIENCE 2014; 19:304-10. [PMID: 24434036 PMCID: PMC4008707 DOI: 10.1016/j.tplants.2013.12.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 11/29/2013] [Accepted: 12/11/2013] [Indexed: 05/07/2023]
Abstract
A variety of imaging methodologies are being used to collect data for quantitative studies of plant growth and development from living plants. Multi-level data, from macroscopic to molecular, and from weeks to seconds, can be acquired. Furthermore, advances in parallelized and automated image acquisition enable the throughput to capture images from large populations of plants under specific growth conditions. Image-processing capabilities allow for 3D or 4D reconstruction of image data and automated quantification of biological features. These advances facilitate the integration of imaging data with genome-wide molecular data to enable systems-level modeling.
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Affiliation(s)
- Rosangela Sozzani
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
| | - Wolfgang Busch
- Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, 1030 Vienna, Austria
| | - Edgar P Spalding
- Department of Botany, University of Wisconsin, Madison, WI 53706 USA
| | - Philip N Benfey
- Department of Biology, Duke Center for Systems Biology, and Howard Hughes Medical Institute, Duke University, Durham, NC 27708, USA.
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35
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Marcos D, Berleth T. Dynamic auxin transport patterns preceding vein formation revealed by live-imaging of Arabidopsis leaf primordia. FRONTIERS IN PLANT SCIENCE 2014; 5:235. [PMID: 24966861 PMCID: PMC4052221 DOI: 10.3389/fpls.2014.00235] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2014] [Accepted: 05/11/2014] [Indexed: 05/18/2023]
Abstract
Self-regulatory patterning mechanisms capable of generating biologically meaningful, yet unpredictable cellular patterns offer unique opportunities for obtaining mathematical descriptions of underlying patterning systems properties. The networks of higher-order veins in leaf primordia constitute such a self-regulatory system. During the formation of higher-order veins, vascular precursors are selected from a homogenous field of subepidermal cells in unpredictable positions to eventually connect in complex cellular networks. Auxin transport routes have been implicated in this selection process, but understanding of their role in vascular patterning has been limited by our inability to monitor early auxin transport dynamics in vivo. Here we describe a live-imaging system in emerging Arabidopsis thaliana leaves that uses a PIN1:GFP reporter to visualize auxin transport routes and an Athb8:YFP reporter as a marker for vascular commitment. Live-imaging revealed common features initiating the formation of all higher-order veins. The formation of broad PIN1 expression domains is followed by their restriction, leading to sustained, elevated PIN1 expression in incipient procambial cells files, which then express Athb8. Higher-order PIN1 expression domains (hPEDs) are initiated as freely ending domains that extend toward each other and sometimes fuse with them, creating connected domains. During the restriction and specification phase, cells in wider hPEDs are partitioned into vascular and non-vascular fates: Central cells acquire a coordinated cell axis and express elevated PIN1 levels as well as the pre-procambial marker Athb8, while edge cells downregulate PIN1 and remain isodiametric. The dynamic nature of the early selection process is underscored by the instability of early hPEDs, which can result in dramatic changes in vascular network architecture prior to Athb8 expression, which is correlated with the promotion onto vascular cell fate.
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Affiliation(s)
| | - Thomas Berleth
- *Correspondence: Thomas Berleth, Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, ON M5S 3B2, Canada e-mail:
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36
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Nakielski J, Lipowczan M. Spatial and directional variation of growth rates in Arabidopsis root apex: a modelling study. PLoS One 2013; 8:e84337. [PMID: 24367654 PMCID: PMC3867472 DOI: 10.1371/journal.pone.0084337] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Accepted: 11/21/2013] [Indexed: 11/18/2022] Open
Abstract
Growth and cellular organization of the Arabidopsis root apex are investigated in various aspects, but still little is known about spatial and directional variation of growth rates in very apical part of the apex, especially in 3D. The present paper aims to fill this gap with the aid of a computer modelling based on the growth tensor method. The root apex with a typical shape and cellular pattern is considered. Previously, on the basis of two types of empirical data: the published velocity profile along the root axis and dimensions of cell packets formed in the lateral part of the root cap, the displacement velocity field for the root apex was determined. Here this field is adopted to calculate the linear growth rate in different points and directions. The results are interpreted taking principal growth directions into account. The root apex manifests a significant anisotropy of the linear growth rate. The directional preferences depend on a position within the root apex. In the root proper the rate in the periclinal direction predominates everywhere, while in the root cap the predominating direction varies with distance from the quiescent centre. The rhizodermis is distinguished from the neighbouring tissues (cortex, root cap) by relatively high contribution of the growth rate in the anticlinal direction. The degree of growth anisotropy calculated for planes defined by principal growth directions and exemplary cell walls may be as high as 25. The changes in the growth rate variation are modelled.
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Affiliation(s)
- Jerzy Nakielski
- Department of Biophysics and Morphogenesis of Plants, University of Silesia, Katowice, Poland
- * E-mail:
| | - Marcin Lipowczan
- Department of Biophysics and Morphogenesis of Plants, University of Silesia, Katowice, Poland
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37
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Racolta A, Bryan AC, Tax FE. The receptor-like kinases GSO1 and GSO2 together regulate root growth in Arabidopsis through control of cell division and cell fate specification. Dev Dyn 2013; 243:257-78. [PMID: 24123341 DOI: 10.1002/dvdy.24066] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2013] [Revised: 09/19/2013] [Accepted: 09/19/2013] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND The root apical meristem of Arabidopsis is established post-embryonically as the main source of root cells, and its activity is maintained by complex bidirectional signaling between stem cells and mature cells. The receptor-like kinases GASSHO1 (GSO1) and GSO2 have been shown to regulate aerial epidermal function and seedling growth in Arabidopsis. RESULTS Here we show that gso1; gso2 seedlings also have root growth and patterning defects. Analyses of mutant root morphology indicate abnormal numbers of cells in longitudinal files and radial cell layers, as well as aberrant stem cell division planes. gso1; gso2 double mutants misexpress markers for stem cells and differentiated root cell types. In addition, gso1; gso2 root growth defects, but not marker missexpression or patterning phenotypes, are rescued by growth on media containing metabolizable sugars. CONCLUSIONS We conclude that GSO1 and GSO2 function together in intercellular signaling to positively regulate cell proliferation, differentiation of root cell types, and stem cell identity. In addition, GSO1 and GSO2 control seedling root growth by modulating sucrose response after germination.
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Affiliation(s)
- Adriana Racolta
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona
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38
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Perilli S, Perez-Perez JM, Di Mambro R, Peris CL, Díaz-Triviño S, Del Bianco M, Pierdonati E, Moubayidin L, Cruz-Ramírez A, Costantino P, Scheres B, Sabatini S. RETINOBLASTOMA-RELATED protein stimulates cell differentiation in the Arabidopsis root meristem by interacting with cytokinin signaling. THE PLANT CELL 2013; 25:4469-78. [PMID: 24285791 PMCID: PMC3875730 DOI: 10.1105/tpc.113.116632] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 11/04/2013] [Accepted: 11/14/2013] [Indexed: 05/23/2023]
Abstract
Maintenance of mitotic cell clusters such as meristematic cells depends on their capacity to maintain the balance between cell division and cell differentiation necessary to control organ growth. In the Arabidopsis thaliana root meristem, the antagonistic interaction of two hormones, auxin and cytokinin, regulates this balance by positioning the transition zone, where mitotically active cells lose their capacity to divide and initiate their differentiation programs. In animals, a major regulator of both cell division and cell differentiation is the tumor suppressor protein RETINOBLASTOMA. Here, we show that similarly to its homolog in animal systems, the plant RETINOBLASTOMA-RELATED (RBR) protein regulates the differentiation of meristematic cells at the transition zone by allowing mRNA accumulation of AUXIN RESPONSE FACTOR19 (ARF19), a transcription factor involved in cell differentiation. We show that both RBR and the cytokinin-dependent transcription factor ARABIDOPSIS RESPONSE REGULATOR12 are required to activate the transcription of ARF19, which is involved in promoting cell differentiation and thus root growth.
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Affiliation(s)
- Serena Perilli
- Department of Biology and Biotechnology, Laboratories of Functional Genomics and Proteomics of Model Systems, University of Rome Sapienza, 00185 Rome, Italy
| | - José Manuel Perez-Perez
- Molecular Genetics, Department of Biology, University of Utrecht, 3584 CH Utrecht, The Netherlands
| | - Riccardo Di Mambro
- Department of Biology and Biotechnology, Laboratories of Functional Genomics and Proteomics of Model Systems, University of Rome Sapienza, 00185 Rome, Italy
| | - Cristina Llavata Peris
- Department of Biology and Biotechnology, Laboratories of Functional Genomics and Proteomics of Model Systems, University of Rome Sapienza, 00185 Rome, Italy
| | - Sara Díaz-Triviño
- Molecular Genetics, Department of Biology, University of Utrecht, 3584 CH Utrecht, The Netherlands
| | - Marta Del Bianco
- Department of Biology and Biotechnology, Laboratories of Functional Genomics and Proteomics of Model Systems, University of Rome Sapienza, 00185 Rome, Italy
| | - Emanuela Pierdonati
- Department of Biology and Biotechnology, Laboratories of Functional Genomics and Proteomics of Model Systems, University of Rome Sapienza, 00185 Rome, Italy
| | - Laila Moubayidin
- Department of Biology and Biotechnology, Laboratories of Functional Genomics and Proteomics of Model Systems, University of Rome Sapienza, 00185 Rome, Italy
| | - Alfredo Cruz-Ramírez
- Molecular Genetics, Department of Biology, University of Utrecht, 3584 CH Utrecht, The Netherlands
| | - Paolo Costantino
- Department of Biology and Biotechnology, Laboratories of Functional Genomics and Proteomics of Model Systems, University of Rome Sapienza, 00185 Rome, Italy
| | - Ben Scheres
- Molecular Genetics, Department of Biology, University of Utrecht, 3584 CH Utrecht, The Netherlands
| | - Sabrina Sabatini
- Department of Biology and Biotechnology, Laboratories of Functional Genomics and Proteomics of Model Systems, University of Rome Sapienza, 00185 Rome, Italy
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39
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Hayashi K, Hasegawa J, Matsunaga S. The boundary of the meristematic and elongation zones in roots: endoreduplication precedes rapid cell expansion. Sci Rep 2013; 3:2723. [PMID: 24121463 PMCID: PMC3796303 DOI: 10.1038/srep02723] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Accepted: 09/04/2013] [Indexed: 01/01/2023] Open
Abstract
Plant roots consist of a meristematic zone of mitotic cells and an elongation zone of rapidly expanding cells, in which DNA replication often occurs without cell division, a process known as endoreduplication. The duration of the cell cycle and DNA replication, as measured by 5-ethynyl-2'-deoxy-uridine (EdU) incorporation, differed between the two regions (17 h in the meristematic zone, 30 h in the elongation zone). Two distinct subnuclear patterns of EdU signals, whole and speckled, marked nuclei undergoing DNA replication at early and late S phase, respectively. The boundary region between the meristematic and elongation zones was analysed by a combination of DNA replication imaging and optical estimation of the amount of DNA in each nucleus (C-value). We found a boundary cell with 4C nuclei exhibiting the whole pattern of EdU signals. Analyses of cells in the boundary region revealed that endoreduplication precedes rapid cell elongation in roots.
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Affiliation(s)
- Kohma Hayashi
- Department of Applied Biological Science Faculty of Science and Technology Tokyo University of Science 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Junko Hasegawa
- Department of Applied Biological Science Faculty of Science and Technology Tokyo University of Science 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Sachihiro Matsunaga
- Department of Applied Biological Science Faculty of Science and Technology Tokyo University of Science 2641 Yamazaki, Noda, Chiba 278-8510, Japan
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40
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Dhondt S, Wuyts N, Inzé D. Cell to whole-plant phenotyping: the best is yet to come. TRENDS IN PLANT SCIENCE 2013; 18:428-39. [PMID: 23706697 DOI: 10.1016/j.tplants.2013.04.008] [Citation(s) in RCA: 155] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 04/18/2013] [Accepted: 04/22/2013] [Indexed: 05/18/2023]
Abstract
Imaging and image processing have revolutionized plant phenotyping and are now a major tool for phenotypic trait measurement. Here we review plant phenotyping systems by examining three important characteristics: throughput, dimensionality, and resolution. First, whole-plant phenotyping systems are highlighted together with advances in automation that enable significant throughput increases. Organ and cellular level phenotyping and its tools, often operating at a lower throughput, are then discussed as a means to obtain high-dimensional phenotypic data at elevated spatial and temporal resolution. The significance of recent developments in sensor technologies that give access to plant morphology and physiology-related traits is shown. Overall, attention is focused on spatial and temporal resolution because these are crucial aspects of imaging procedures in plant phenotyping systems.
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Affiliation(s)
- Stijn Dhondt
- Department of Plant Systems Biology, VIB, Technologiepark 927, 9052 Gent, Belgium
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41
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Noir S, Bömer M, Takahashi N, Ishida T, Tsui TL, Balbi V, Shanahan H, Sugimoto K, Devoto A. Jasmonate controls leaf growth by repressing cell proliferation and the onset of endoreduplication while maintaining a potential stand-by mode. PLANT PHYSIOLOGY 2013; 161:1930-51. [PMID: 23439917 PMCID: PMC3613466 DOI: 10.1104/pp.113.214908] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Phytohormones regulate plant growth from cell division to organ development. Jasmonates (JAs) are signaling molecules that have been implicated in stress-induced responses. However, they have also been shown to inhibit plant growth, but the mechanisms are not well understood. The effects of methyl jasmonate (MeJA) on leaf growth regulation were investigated in Arabidopsis (Arabidopsis thaliana) mutants altered in JA synthesis and perception, allene oxide synthase and coi1-16B (for coronatine insensitive1), respectively. We show that MeJA inhibits leaf growth through the JA receptor COI1 by reducing both cell number and size. Further investigations using flow cytometry analyses allowed us to evaluate ploidy levels and to monitor cell cycle progression in leaves and cotyledons of Arabidopsis and/or Nicotiana benthamiana at different stages of development. Additionally, a novel global transcription profiling analysis involving continuous treatment with MeJA was carried out to identify the molecular players whose expression is regulated during leaf development by this hormone and COI1. The results of these studies revealed that MeJA delays the switch from the mitotic cell cycle to the endoreduplication cycle, which accompanies cell expansion, in a COI1-dependent manner and inhibits the mitotic cycle itself, arresting cells in G1 phase prior to the S-phase transition. Significantly, we show that MeJA activates critical regulators of endoreduplication and affects the expression of key determinants of DNA replication. Our discoveries also suggest that MeJA may contribute to the maintenance of a cellular "stand-by mode" by keeping the expression of ribosomal genes at an elevated level. Finally, we propose a novel model for MeJA-regulated COI1-dependent leaf growth inhibition.
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42
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Peterson KM, Torii KU. Long-term, high-resolution confocal time lapse imaging of Arabidopsis cotyledon epidermis during germination. J Vis Exp 2012:4426. [PMID: 23299369 DOI: 10.3791/4426] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Imaging in vivo dynamics of cellular behavior throughout a developmental sequence can be a powerful technique for understanding the mechanics of tissue patterning. During animal development, key cell proliferation and patterning events occur very quickly. For instance, in Caenorhabditis elegans all cell divisions required for the larval body plan are completed within six hours after fertilization, with seven mitotic cycles(1); the sixteen or more mitoses of Drosophila embryogenesis occur in less than 24 hr(2). In contrast, cell divisions during plant development are slow, typically on the order of a day (3,4,5) . This imposes a unique challenge and a need for long-term live imaging for documenting dynamic behaviors of cell division and differentiation events during plant organogenesis. Arabidopsis epidermis is an excellent model system for investigating signaling, cell fate, and development in plants. In the cotyledon, this tissue consists of air- and water-resistant pavement cells interspersed with evenly distributed stomata, valves that open and close to control gas exchange and water loss. Proper spacing of these stomata is critical to their function, and their development follows a sequence of asymmetric division and cell differentiation steps to produce the organized epidermis (Fig. 1). This protocol allows observation of cells and proteins in the epidermis over several days of development. This time frame enables precise documentation of stem-cell divisions and differentiation of epidermal cells, including stomata and epidermal pavement cells. Fluorescent proteins can be fused to proteins of interest to assess their dynamics during cell division and differentiation processes. This technique allows us to understand the localization of a novel protein, POLAR(6), during the proliferation stage of stomatal-lineage cells in the Arabidopsis cotyledon epidermis, where it is expressed in cells preceding asymmetric division events and moves to a characteristic area of the cell cortex shortly before division occurs. Images can be registered and streamlined video easily produced using public domain software to visualize dynamic protein localization and cell types as they change over time.
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Affiliation(s)
- Kylee M Peterson
- Department of Biology, University of Washington, Washington, USA
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43
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Smolarkiewicz M, Dhonukshe P. Formative Cell Divisions: Principal Determinants of Plant Morphogenesis. ACTA ACUST UNITED AC 2012; 54:333-42. [DOI: 10.1093/pcp/pcs175] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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44
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Nakielski J, Lipowczan M. A method to determine the displacement velocity field in the apical region of the Arabidopsis root. PLANTA 2012; 236:1547-57. [PMID: 22828709 PMCID: PMC3481058 DOI: 10.1007/s00425-012-1707-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 07/02/2012] [Indexed: 05/26/2023]
Abstract
In angiosperms, growth of the root apex is determined by the quiescent centre. All tissues of the root proper and the root cap are derived from initial cells that surround this zone. The diversity of cell lineages originated from these initials suggests an interesting variation of the displacement velocity within the root apex. However, little is known about this variation, especially in the most apical region including the root cap. This paper shows a method of determination of velocity field for this region taking the Arabidopsis root apex as example. Assuming the symplastic growth without a rotation around the root axis, the method combines mathematical modelling and two types of empirical data: the published velocity profile along the root axis above the quiescent centre, and dimensions of cell packet originated from the initials of epidermis and lateral root cap. The velocities, calculated for points of the axial section, vary in length and direction. Their length increases with distance from the quiescent centre, in the root cap at least twice slower than in the root proper, if points at similar distance from the quiescent centre are compared. The vector orientation depends on the position of a calculation point, the widest range of angular changes, reaching almost 90°, in the lateral root cap. It is demonstrated how the velocity field is related to both distribution of growth rates and growth-resulted deformation of the cell wall system. Also changes in the field due to cell pattern asymmetry and differences in slope of the velocity profile are modelled.
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Affiliation(s)
- Jerzy Nakielski
- Department of Biophysics and Morphogenesis of Plants, University of Silesia, Katowice, Poland.
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45
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RETRACTED: A PLETHORA-Auxin Transcription Module Controls Cell Division Plane Rotation through MAP65 and CLASP. Cell 2012; 149:383-96. [DOI: 10.1016/j.cell.2012.02.051] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 11/15/2011] [Accepted: 02/28/2012] [Indexed: 11/19/2022]
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46
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Pauluzzi G, Divol F, Puig J, Guiderdoni E, Dievart A, Périn C. Surfing along the root ground tissue gene network. Dev Biol 2012; 365:14-22. [PMID: 22349629 DOI: 10.1016/j.ydbio.2012.02.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Revised: 01/31/2012] [Accepted: 02/06/2012] [Indexed: 11/19/2022]
Abstract
Organization of tissues in Arabidopsis thaliana root is made of, from outside in, epidermis, cortex, middle cortex, endodermis, pericycle and vascular tissues. Cortex, middle cortex and endodermis form the ground tissue (GT) system. Functional and molecular characterization of GT patterning mutants' properties has greatly increased our understanding of fundamental processes of plant root development. These studies have demonstrated GT is an elegant model that can be used to study how different cell types and cell fates are specified. This review analyzes GT mutants to provide a detailed account of the molecular network that regulates GT formation in A. thaliana. The most recent results indicate an unexpectedly complex network of transcription factors, epigenetic and hormonal controls that play crucial roles in GT development. Major differences exist between GT formation in dicots and monocots, particularly in the model plant rice, opening the way for evo-devo of GT formation in angiosperm. In rice, adaptation to submergence relies on a multilayered cortex. Moreover, variation in the number of cortex cell layers is also observed between the five root types. A mechanism of control for cortical cell number should then exist in rice and it remains to be determined if any of the Arabidopsis thaliana identified GT network members are also involved in this process in rice. Alternatively, a totally different network may have been invented. However, first available results suggest functional conservation in rice of at least two transcription factors, SHORT ROOT (SHR) and SCARECROW (SCR), involved in ground tissue formation in Arabidopsis.
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Affiliation(s)
- G Pauluzzi
- CIRAD, UMR AGAP, F-34398 Montpellier, France
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47
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Curtis MJ, Hays JB. Cooperative responses of DNA-damage-activated protein kinases ATR and ATM and DNA translesion polymerases to replication-blocking DNA damage in a stem-cell niche. DNA Repair (Amst) 2011; 10:1272-81. [PMID: 22018494 DOI: 10.1016/j.dnarep.2011.10.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2011] [Revised: 09/28/2011] [Accepted: 10/02/2011] [Indexed: 01/27/2023]
Abstract
Conserved DNA-damage responses (DDRs) efficiently cope with replication blocks and double-strand breaks (DSBs) in cultured eukaryotic cells; DDRs in tissues remain poorly understood. DDR-inactivating mutations lethal in animals are tolerated in Arabidopsis, whose root meristem provides a powerful stem-cell-niche model. We imaged UVB-induced death of specific meristem cells in single and double Arabidopsis mutants to elucidate cooperation among DNA translesion synthesis (TLS) polymerases (Polη, Polζ) and DNA-damage-activated protein kinases (ATR, ATM). Death was 100-fold higher in stem and progenitor (StPr) cells than in transiently amplifying cells. Quantitative analyses of dose-response plots showed that Polη and Polζ act redundantly to tolerate replication blocks and that Polζ-mediated TLS requires ATR. Deficient TLS resulted in ATM-signaled death, which first appeared 10-14h post-UVB. Although ssDNA downstream of blocks was likely cleaved into DSBs throughout S phase, death pathways appeared to initiate late in S. In atm mutants death appeared much later, likely signaled by a slow ATR-dependent pathway. To bypass replication blocks, tissues may use TLS rather than error-free pathways that could generate genomic aberrations. Dynamic balances among ATR and ATM death-avoidance and death-signaling functions determine how many DSB-burdened StPr cells are killed. Their replacement by less-burdened quiescent-center cells then restores growth homeostasis.
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Affiliation(s)
- Marc J Curtis
- Department of Environmental and Molecular Toxicology, Oregon State University, 1007 ALS, Campus Way, Corvallis, OR 97331, United States
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48
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Wuyts N, Bengough AG, Roberts TJ, Du C, Bransby MF, McKenna SJ, Valentine TA. Automated motion estimation of root responses to sucrose in two Arabidopsis thaliana genotypes using confocal microscopy. PLANTA 2011; 234:769-784. [PMID: 21630041 DOI: 10.1007/s00425-011-1435-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Accepted: 05/08/2011] [Indexed: 05/30/2023]
Abstract
Root growth is a highly dynamic process influenced by genetic background and environment. This paper reports the development of R scripts that enable root growth kinematic analysis that complements a new motion analysis tool: PlantVis. Root growth of Arabidopsis thaliana expressing a plasma membrane targeted GFP (C24 and Columbia 35S:LTI6b-EGFP) was imaged using time-lapse confocal laser scanning microscopy. Displacement of individual pixels in the time-lapse sequences was estimated automatically by PlantVis, producing dense motion vector fields. R scripts were developed to extract kinematic growth parameters and report displacement to ± 0.1 pixel. In contrast to other currently available tools, Plantvis-R delivered root velocity profiles without interpolation or averaging across the root surface and also estimated the uncertainty associated with tracking each pixel. The PlantVis-R analysis tool has a range of potential applications in root physiology and gene expression studies, including linking motion to specific cell boundaries and analysis of curvature. The potential for quantifying genotype × environment interactions was examined by applying PlantVis-R in a kinematic analysis of root growth of C24 and Columbia, under contrasting carbon supply. Large genotype-dependent effects of sucrose were recorded. C24 exhibited negligible differences in elongation zone length and elongation rate but doubled the density of lateral roots in the presence of sucrose. Columbia, in contrast, increased its elongation zone length and doubled its elongation rate and the density of lateral roots.
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49
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Ckurshumova W, Caragea AE, Goldstein RS, Berleth T. Glow in the dark: fluorescent proteins as cell and tissue-specific markers in plants. MOLECULAR PLANT 2011; 4:794-804. [PMID: 21772029 DOI: 10.1093/mp/ssr059] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Since the hallmark discovery of Aequorea victoria's Green Fluorescent Protein (GFP) and its adaptation for efficient use in plants, fluorescent protein tags marking expression profiles or genuine proteins of interest have been used to recognize plant tissues and cell types, to monitor dynamic cell fate selection processes, and to obtain cell type-specific transcriptomes. Fluorescent tagging enabled visualization in living tissues and the precise recordings of dynamic expression pattern changes. The resulting accurate recording of cell fate acquisition kinetics in space and time has strongly stimulated mathematical modeling of self-organizing feedback mechanisms. In developmental studies, the use of fluorescent proteins has become critical, where morphological markers of tissues, cell types, or differentiation stages are either not known or not easily recognizable. In this review, we focus on the use of fluorescent markers to identify and illuminate otherwise invisible cell states in plant development.
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Affiliation(s)
- Wenzislava Ckurshumova
- Department of Cell and Systems Biology, University of Toronto, 25 Willcocks St, Toronto, ON M5S 3B2, Canada.
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50
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Asl LK, Dhondt S, Boudolf V, Beemster GT, Beeckman T, Inzé D, Govaerts W, De Veylder L. Model-based analysis of Arabidopsis leaf epidermal cells reveals distinct division and expansion patterns for pavement and guard cells. PLANT PHYSIOLOGY 2011; 156:2172-83. [PMID: 21693673 PMCID: PMC3149966 DOI: 10.1104/pp.111.181180] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Accepted: 06/21/2011] [Indexed: 05/18/2023]
Abstract
To efficiently capture sunlight for photosynthesis, leaves typically develop into a flat and thin structure. This development is driven by cell division and expansion, but the individual contribution of these processes is currently unknown, mainly because of the experimental difficulties to disentangle them in a developing organ, due to their tight interconnection. To circumvent this problem, we built a mathematic model that describes the possible division patterns and expansion rates for individual epidermal cells. This model was used to fit experimental data on cell numbers and sizes obtained over time intervals of 1 d throughout the development of the first leaf pair of Arabidopsis (Arabidopsis thaliana). The parameters were obtained by a derivative-free optimization method that minimizes the differences between the predicted and experimentally observed cell size distributions. The model allowed us to calculate probabilities for a cell to divide into guard or pavement cells, the maximum size at which it can divide, and its average cell division and expansion rates at each point during the leaf developmental process. Surprisingly, average cell cycle duration remained constant throughout leaf development, whereas no evidence for a maximum cell size threshold for cell division of pavement cells was found. Furthermore, the model predicted that neighboring cells of different sizes within the epidermis expand at distinctly different relative rates, which could be verified by direct observations. We conclude that cell division seems to occur independently from the status of cell expansion, whereas the cell cycle might act as a timer rather than as a size-regulated machinery.
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