1
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Moore S, Jervis G, Topping JF, Chen C, Liu J, Lindsey K. A predictive model for ethylene-mediated auxin and cytokinin patterning in the Arabidopsis root. PLANT COMMUNICATIONS 2024; 5:100886. [PMID: 38504522 DOI: 10.1016/j.xplc.2024.100886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 02/25/2024] [Accepted: 03/18/2024] [Indexed: 03/21/2024]
Abstract
The interaction between auxin and cytokinin is important in many aspects of plant development. Experimental measurements of both auxin and cytokinin concentration and reporter gene expression clearly show the coexistence of auxin and cytokinin concentration patterning in Arabidopsis root development. However, in the context of crosstalk among auxin, cytokinin, and ethylene, little is known about how auxin and cytokinin concentration patterns simultaneously emerge and how they regulate each other in the Arabidopsis root. This work utilizes a wide range of experimental observations to propose a mechanism for simultaneous patterning of auxin and cytokinin concentrations. In addition to revealing the regulatory relationships between auxin and cytokinin, this mechanism shows that ethylene signaling is an important factor in achieving simultaneous auxin and cytokinin patterning, while also predicting other experimental observations. Combining the mechanism with a realistic in silico root model reproduces experimental observations of both auxin and cytokinin patterning. Predictions made by the mechanism can be compared with a variety of experimental observations, including those obtained by our group and other independent experiments reported by other groups. Examples of these predictions include patterning of auxin biosynthesis rate, changes in PIN1 and PIN2 patterns in pin3,4,7 mutants, changes in cytokinin patterning in the pls mutant, PLS patterning, and various trends in different mutants. This research reveals a plausible mechanism for simultaneous patterning of auxin and cytokinin concentrations in Arabidopsis root development and suggests a key role for ethylene pattern integration.
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Affiliation(s)
- Simon Moore
- Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK; Hubei Hongshan Laboratory, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - George Jervis
- Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK
| | - Jennifer F Topping
- Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK
| | - Chunli Chen
- Hubei Hongshan Laboratory, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China; National Key Laboratory for Germplasm Innovation and Utilization for Fruit and Vegetable Horticultural Crops, Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Junli Liu
- Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK.
| | - Keith Lindsey
- Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK.
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2
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Sessa G, Carabelli M, Sassi M. The Ins and Outs of Homeodomain-Leucine Zipper/Hormone Networks in the Regulation of Plant Development. Int J Mol Sci 2024; 25:5657. [PMID: 38891845 PMCID: PMC11171833 DOI: 10.3390/ijms25115657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Revised: 05/20/2024] [Accepted: 05/21/2024] [Indexed: 06/21/2024] Open
Abstract
The generation of complex plant architectures depends on the interactions among different molecular regulatory networks that control the growth of cells within tissues, ultimately shaping the final morphological features of each structure. The regulatory networks underlying tissue growth and overall plant shapes are composed of intricate webs of transcriptional regulators which synergize or compete to regulate the expression of downstream targets. Transcriptional regulation is intimately linked to phytohormone networks as transcription factors (TFs) might act as effectors or regulators of hormone signaling pathways, further enhancing the capacity and flexibility of molecular networks in shaping plant architectures. Here, we focus on homeodomain-leucine zipper (HD-ZIP) proteins, a class of plant-specific transcriptional regulators, and review their molecular connections with hormonal networks in different developmental contexts. We discuss how HD-ZIP proteins emerge as key regulators of hormone action in plants and further highlight the fundamental role that HD-ZIP/hormone networks play in the control of the body plan and plant growth.
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Affiliation(s)
| | | | - Massimiliano Sassi
- Istituto di Biologia e Patologia Molecolari, Consiglio Nazionale delle Ricerche, 00185 Rome, Italy; (G.S.); (M.C.)
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3
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Sun Y, Yang B, De Rybel B. Hormonal control of the molecular networks guiding vascular tissue development in the primary root meristem of Arabidopsis. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:6964-6974. [PMID: 37343122 PMCID: PMC7615341 DOI: 10.1093/jxb/erad232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 06/16/2023] [Indexed: 06/23/2023]
Abstract
Vascular tissues serve a dual function in plants, both providing physical support and controlling the transport of nutrients, water, hormones, and other small signaling molecules. Xylem tissues transport water from root to shoot; phloem tissues transfer photosynthates from shoot to root; while divisions of the (pro)cambium increase the number of xylem and phloem cells. Although vascular development constitutes a continuous process from primary growth in the early embryo and meristem regions to secondary growth in the mature plant organs, it can be artificially separated into distinct processes including cell type specification, proliferation, patterning, and differentiation. In this review, we focus on how hormonal signals orchestrate the molecular regulation of vascular development in the Arabidopsis primary root meristem. Although auxin and cytokinin have taken center stage in this aspect since their discovery, other hormones including brassinosteroids, abscisic acid, and jasmonic acid also take leading roles during vascular development. All these hormonal cues synergistically or antagonistically participate in the development of vascular tissues, forming a complex hormonal control network.
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Affiliation(s)
- Yanbiao Sun
- Ghent University, Department of Plant Biotechnology and Bioinformatics, Technologiepark 71, 9052 Ghent, Belgium
- VIB Centre for Plant Systems Biology, Technologiepark 71, 9052 Ghent, Belgium
| | - Baojun Yang
- Ghent University, Department of Plant Biotechnology and Bioinformatics, Technologiepark 71, 9052 Ghent, Belgium
- VIB Centre for Plant Systems Biology, Technologiepark 71, 9052 Ghent, Belgium
| | - Bert De Rybel
- Ghent University, Department of Plant Biotechnology and Bioinformatics, Technologiepark 71, 9052 Ghent, Belgium
- VIB Centre for Plant Systems Biology, Technologiepark 71, 9052 Ghent, Belgium
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4
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Wang X, Mäkilä R, Mähönen AP. From procambium patterning to cambium activation and maintenance in the Arabidopsis root. CURRENT OPINION IN PLANT BIOLOGY 2023; 75:102404. [PMID: 37352651 DOI: 10.1016/j.pbi.2023.102404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 05/08/2023] [Accepted: 05/20/2023] [Indexed: 06/25/2023]
Abstract
In addition to primary growth, which elongates the plant body, many plant species also undergo secondary growth to thicken their body. During primary vascular development, a subset of the vascular cells, called procambium and pericycle, remain undifferentiated to later gain vascular cambium and cork cambium identity, respectively. These two cambia are the lateral meristems providing secondary growth. The vascular cambium produces secondary xylem and phloem, which give plants mechanical support and transport capacity. Cork cambium produces a protective layer called cork. In this review, we focus on recent advances in understanding the formation of procambium and its gradual maturation to active cambium in the Arabidopsis thaliana root.
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Affiliation(s)
- Xin Wang
- Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences and Viikki Plant Science Centre, University of Helsinki, Helsinki, Finland
| | - Riikka Mäkilä
- Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences and Viikki Plant Science Centre, University of Helsinki, Helsinki, Finland
| | - Ari Pekka Mähönen
- Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences and Viikki Plant Science Centre, University of Helsinki, Helsinki, Finland.
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5
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Kiradjiev KB, Band LR. Multiscale Asymptotic Analysis Reveals How Cell Growth and Subcellular Compartments Affect Tissue-Scale Hormone Transport. Bull Math Biol 2023; 85:101. [PMID: 37702758 PMCID: PMC10499980 DOI: 10.1007/s11538-023-01199-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 08/14/2023] [Indexed: 09/14/2023]
Abstract
Determining how cell-scale processes lead to tissue-scale patterns is key to understanding how hormones and morphogens are distributed within biological tissues and control developmental processes. In this article, we use multiscale asymptotic analysis to derive a continuum approximation for hormone transport in a long file of cells to determine how subcellular compartments and cell growth and division affect tissue-scale hormone transport. Focusing our study on plant tissues, we begin by presenting a discrete multicellular ODE model tracking the hormone concentration in each cell's cytoplasm, subcellular vacuole, and surrounding apoplast, represented by separate compartments in the cell-file geometry. We allow the cells to grow at a rate that can depend both on space and time, accounting for both cytoplasmic and vacuolar expansion. Multiscale asymptotic analysis enables us to systematically derive the corresponding continuum model, obtaining an effective reaction-advection-diffusion equation and revealing how the effective diffusivity, effective advective velocity, and the effective sink term depend on the parameters in the cell-scale model. The continuum approximation reveals how subcellular compartments, such as vacuoles, can act as storage vessels, that significantly alter the effective properties of hormone transport, such as the effective diffusivity and the induced effective velocity. Furthermore, we show how cell growth and spatial variance across cell lengths affect the effective diffusivity and the induced effective velocity, and how these affect the tissue-scale hormone distribution. In particular, we find that cell growth naturally induces an effective velocity in the direction of growth, whereas spatial variance across cell lengths induces effective velocity due to the presence of an extra compartment, such as the apoplast and the vacuole, and variations in the relative sizes between the compartments across the file of cells. It is revealed that hormone transport is faster across cells of decreasing lengths than cells with increasing lengths. We also investigate the effect of cell division on transport dynamics, assuming that each cell divides as soon as it doubles in size, and find that increasing the time between successive cell divisions decreases the growth rate, which enhances the effect of cell division in slowing hormone transport. Motivated by recent experimental discoveries, we discuss particular applications for transport of gibberellic acid (GA), an important growth hormone, within the Arabidopsis root. The model reveals precisely how membrane proteins that mediate facilitated GA transport affect the effective tissue-scale transport. However, the results are general enough to be relevant to other plant hormones, or other substances that are transported in a similar way in any type of cells.
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Affiliation(s)
- K B Kiradjiev
- School of Mathematical Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD, UK.
| | - L R Band
- School of Mathematical Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UK
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6
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Hardtke CS. Phloem development. THE NEW PHYTOLOGIST 2023. [PMID: 37243530 DOI: 10.1111/nph.19003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Accepted: 04/13/2023] [Indexed: 05/29/2023]
Abstract
The evolution of the plant vascular system is a key process in Earth history because it enabled plants to conquer land and transform the terrestrial surface. Among the vascular tissues, the phloem is particularly intriguing because of its complex functionality. In angiosperms, its principal components are the sieve elements, which transport phloem sap, and their neighboring companion cells. Together, they form a functional unit that sustains sap loading, transport, and unloading. The developmental trajectory of sieve elements is unique among plant cell types because it entails selective organelle degradation including enucleation. Meticulous analyses of primary, so-called protophloem in the Arabidopsis thaliana root meristem have revealed key steps in protophloem sieve element formation at single-cell resolution. A transcription factor cascade connects specification with differentiation and also orchestrates phloem pole patterning via noncell-autonomous action of sieve element-derived effectors. Reminiscent of vascular tissue patterning in secondary growth, these involve receptor kinase pathways, whose antagonists guide the progression of sieve element differentiation. Receptor kinase pathways may also safeguard phloem formation by maintaining the developmental plasticity of neighboring cell files. Our current understanding of protophloem development in the A. thaliana root has reached sufficient detail to instruct molecular-level investigation of phloem formation in other organs.
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Affiliation(s)
- Christian S Hardtke
- Department of Plant Molecular Biology, University of Lausanne, CH-1015, Lausanne, Switzerland
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7
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Sidhu JS, Ajmera I, Arya S, Lynch JP. RootSlice-A novel functional-structural model for root anatomical phenotypes. PLANT, CELL & ENVIRONMENT 2023; 46:1671-1690. [PMID: 36708192 DOI: 10.1111/pce.14552] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 01/18/2023] [Accepted: 01/23/2023] [Indexed: 06/18/2023]
Abstract
Root anatomy is an important determinant of root metabolic costs, soil exploration, and soil resource capture. Root anatomy varies substantially within and among plant species. RootSlice is a multicellular functional-structural model of root anatomy developed to facilitate the analysis and understanding of root anatomical phenotypes. RootSlice can capture phenotypically accurate root anatomy in three dimensions of different root classes and developmental zones, of both monocotyledonous and dicotyledonous species. Several case studies are presented illustrating the capabilities of the model. For maize nodal roots, the model illustrated the role of vacuole expansion in cell elongation; and confirmed the individual and synergistic role of increasing root cortical aerenchyma and reducing the number of cortical cell files in reducing root metabolic costs. Integration of RootSlice for different root zones as the temporal properties of the nodal roots in the whole-plant and soil model OpenSimRoot/maize enabled the multiscale evaluation of root anatomical phenotypes, highlighting the role of aerenchyma formation in enhancing the utility of cortical cell files for improving plant performance over varying soil nitrogen supply. Such integrative in silico approaches present avenues for exploring the fitness landscape of root anatomical phenotypes.
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Affiliation(s)
- Jagdeep Singh Sidhu
- Department of Plant Science, The Pennsylvania State University, University Park, State College, Pennsylvania, USA
| | - Ishan Ajmera
- Department of Plant Science, The Pennsylvania State University, University Park, State College, Pennsylvania, USA
| | - Sankalp Arya
- Department of Plant Science, The Pennsylvania State University, University Park, State College, Pennsylvania, USA
| | - Jonathan P Lynch
- Department of Plant Science, The Pennsylvania State University, University Park, State College, Pennsylvania, USA
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8
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Fujiwara M, Imamura M, Matsushita K, Roszak P, Yamashino T, Hosokawa Y, Nakajima K, Fujimoto K, Miyashima S. Patterned proliferation orients tissue-wide stress to control root vascular symmetry in Arabidopsis. Curr Biol 2023; 33:886-898.e8. [PMID: 36787744 DOI: 10.1016/j.cub.2023.01.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 11/24/2022] [Accepted: 01/18/2023] [Indexed: 02/16/2023]
Abstract
Symmetric tissue alignment is pivotal to the functions of plant vascular tissue, such as long-distance molecular transport and lateral organ formation. During the vascular development of the Arabidopsis roots, cytokinins initially determine cell-type boundaries among vascular stem cells and subsequently promote cell proliferation to establish vascular tissue symmetry. Although it is unknown whether and how the symmetry of initially defined boundaries is progressively refined under tissue growth in plants, such boundary shapes in animal tissues are regulated by cell fluidity, e.g., cell migration and intercalation, lacking in plant tissues. Here, we uncover that cell proliferation during vascular development produces anisotropic compressive stress, smoothing, and symmetrizing cell arrangement of the vascular-cell-type boundary. Mechanistically, the GATA transcription factor HANABA-TARANU cooperates with the type-B Arabidopsis response regulators to form an incoherent feedforward loop in cytokinin signaling. The incoherent feedforward loop fine-tunes the position and frequency of vascular cell proliferation, which in turn restricts the source of mechanical stress to the position distal and symmetric to the boundary. By combinatorial analyses of mechanical simulations and laser cell ablation, we show that the spatially constrained environment of vascular tissue efficiently entrains the stress orientation among the cells to produce a tissue-wide stress field. Together, our data indicate that the localized proliferation regulated by the cytokinin signaling circuit is decoded into a globally oriented mechanical stress to shape the vascular tissue symmetry, representing a reasonable mechanism controlling the boundary alignment and symmetry in tissue lacking cell fluidity.
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Affiliation(s)
- Motohiro Fujiwara
- Department of Biological Sciences, Graduate School of Science, Osaka University, Machikaneyama-cho, Toyonaka 560-0043, Japan
| | - Miyu Imamura
- Laboratory of Molecular and Functional Genomics, Graduate School of Bioagricultural Sciences, Nagoya University, Furocho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Katsuyoshi Matsushita
- Department of Biological Sciences, Graduate School of Science, Osaka University, Machikaneyama-cho, Toyonaka 560-0043, Japan
| | - Pawel Roszak
- Sainsbury Laboratory, University of Cambridge, 47 Bateman Street, Cambridge CB2 1LR, United Kingdom; Faculty of Biological and Environmental Sciences, University of Helsinki 00014, Helsinki, Finland
| | - Takafumi Yamashino
- Laboratory of Molecular and Functional Genomics, Graduate School of Bioagricultural Sciences, Nagoya University, Furocho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Yoichiroh Hosokawa
- Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
| | - Keiji Nakajima
- Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
| | - Koichi Fujimoto
- Department of Biological Sciences, Graduate School of Science, Osaka University, Machikaneyama-cho, Toyonaka 560-0043, Japan.
| | - Shunsuke Miyashima
- Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan.
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9
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Santos Teixeira J, van den Berg T, ten Tusscher K. Complementary roles for auxin and auxin signalling revealed by reverse engineering lateral root stable prebranch site formation. Development 2022; 149:279332. [PMID: 36314783 PMCID: PMC9793420 DOI: 10.1242/dev.200927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 10/24/2022] [Indexed: 11/22/2022]
Abstract
Priming is the process through which periodic elevations in auxin signalling prepattern future sites for lateral root formation, called prebranch sites. Thus far, the extent to which elevations in auxin concentration and/or auxin signalling are required for priming and prebranch site formation has remained a matter of debate. Recently, we discovered a reflux-and-growth mechanism for priming generating periodic elevations in auxin concentration that subsequently dissipate. Here, we reverse engineer a mechanism for prebranch site formation that translates these transient elevations into a persistent increase in auxin signalling, resolving the prior debate into a two-step process of auxin concentration-mediated initial signal and auxin signalling capacity-mediated memorization. A crucial aspect of the prebranch site formation mechanism is its activation in response to time-integrated rather than instantaneous auxin signalling. The proposed mechanism is demonstrated to be consistent with prebranch site auxin signalling dynamics, lateral inhibition, and symmetry-breaking mechanisms and perturbations in auxin homeostasis.
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Affiliation(s)
- Joana Santos Teixeira
- Computational Developmental Biology Group, Faculty of Science, Utrecht University, Utrecht 3584 CH, The Netherlands
| | - Thea van den Berg
- Computational Developmental Biology Group, Faculty of Science, Utrecht University, Utrecht 3584 CH, The Netherlands
| | - Kirsten ten Tusscher
- Computational Developmental Biology Group, Faculty of Science, Utrecht University, Utrecht 3584 CH, The Netherlands,Author for correspondence ()
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10
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Rutten J, van den Berg T, Tusscher KT. Modeling Auxin Signaling in Roots: Auxin Computations. Cold Spring Harb Perspect Biol 2022; 14:a040089. [PMID: 34001532 PMCID: PMC8805645 DOI: 10.1101/cshperspect.a040089] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Auxin signaling and patterning is an inherently complex process, involving polarized auxin transport, metabolism, and signaling, its effect on developmental zones, as well as growth rates, and the feedback between all these different aspects. This complexity has led to an important role for computational modeling in unraveling the multifactorial roles of auxin in plant developmental and adaptive processes. Here we discuss the basic ingredients of auxin signaling and patterning models for root development as well as a series of key modeling studies in this area. These modeling studies have helped elucidate how plants use auxin signaling to compute the size of their root meristem, the direction in which to grow, and when and where to form lateral roots. Importantly, these models highlight how auxin, through patterning of and collaborating with other factors, can fulfill all these roles simultaneously.
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Affiliation(s)
- Jaap Rutten
- Computational Developmental Biology Group, Utrecht University, Utrecht 3584 CH, The Netherlands
| | - Thea van den Berg
- Computational Developmental Biology Group, Utrecht University, Utrecht 3584 CH, The Netherlands
| | - Kirsten Ten Tusscher
- Computational Developmental Biology Group, Utrecht University, Utrecht 3584 CH, The Netherlands
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11
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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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12
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Cytokinins initiate secondary growth in the Arabidopsis root through a set of LBD genes. Curr Biol 2021; 31:3365-3373.e7. [PMID: 34129827 PMCID: PMC8360765 DOI: 10.1016/j.cub.2021.05.036] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 03/24/2021] [Accepted: 05/07/2021] [Indexed: 12/13/2022]
Abstract
During primary growth, plant tissues increase their length, and as these tissues mature, they initiate secondary growth to increase thickness.1 It is not known what activates this transition to secondary growth. Cytokinins are key plant hormones regulating vascular development during both primary and secondary growth. During primary growth of Arabidopsis roots, cytokinins promote procambial cell proliferation2,3 and vascular patterning together with the hormone auxin.4-7 In the absence of cytokinins, secondary growth fails to initiate.8 Enhanced cytokinin levels, in turn, promote secondary growth.8,9 Despite the importance of cytokinins, little is known about the downstream signaling events in this process. Here, we show that cytokinins and a few downstream LATERAL ORGAN BOUNDARIES DOMAIN (LBD) family of transcription factors are rate-limiting components in activating and further promoting secondary growth in Arabidopsis roots. Cytokinins directly activate transcription of two homologous LBD genes, LBD3 and LBD4. Two other homologous LBDs, LBD1 and LBD11, are induced only after prolonged cytokinin treatment. Our genetic studies revealed a two-stage mechanism downstream of cytokinin signaling: while LBD3 and LBD4 regulate activation of secondary growth, LBD1, LBD3, LBD4, and LBD11 together promote further radial growth and maintenance of cambial stem cells. LBD overexpression promoted rapid cell growth followed by accelerated cell divisions, thus leading to enhanced secondary growth. Finally, we show that LBDs rapidly inhibit cytokinin signaling. Together, our data suggest that the cambium-promoting LBDs negatively feed back into cytokinin signaling to keep root secondary growth in balance.
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13
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Nedvěd D, Hošek P, Klíma P, Hoyerová K. Differential Subcellular Distribution of Cytokinins: How Does Membrane Transport Fit into the Big Picture? Int J Mol Sci 2021; 22:3428. [PMID: 33810428 PMCID: PMC8037549 DOI: 10.3390/ijms22073428] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 03/02/2021] [Accepted: 03/22/2021] [Indexed: 12/17/2022] Open
Abstract
Cytokinins are a class of phytohormones, signalling molecules specific to plants. They act as regulators of diverse physiological processes in complex signalling pathways. It is necessary for plants to continuously regulate cytokinin distribution among different organs, tissues, cells, and compartments. Such regulatory mechanisms include cytokinin biosynthesis, metabolic conversions and degradation, as well as cytokinin membrane transport. In our review, we aim to provide a thorough picture of the latter. We begin by summarizing cytokinin structures and physicochemical properties. Then, we revise the elementary thermodynamic and kinetic aspects of cytokinin membrane transport. Next, we review which membrane-bound carrier proteins and protein families recognize cytokinins as their substrates. Namely, we discuss the families of "equilibrative nucleoside transporters" and "purine permeases", which translocate diverse purine-related compounds, and proteins AtPUP14, AtABCG14, AtAZG1, and AtAZG2, which are specific to cytokinins. We also address long-distance cytokinin transport. Putting all these pieces together, we finally discuss cytokinin distribution as a net result of these processes, diverse in their physicochemical nature but acting together to promote plant fitness.
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Affiliation(s)
- Daniel Nedvěd
- The Czech Academy of Sciences, Institute of Experimental Botany, 165 02 Prague, Czech Republic; (D.N.); (P.H.)
- Department of Biochemistry, Faculty of Science, Charles University, 128 00 Prague, Czech Republic
| | - Petr Hošek
- The Czech Academy of Sciences, Institute of Experimental Botany, 165 02 Prague, Czech Republic; (D.N.); (P.H.)
| | - Petr Klíma
- The Czech Academy of Sciences, Institute of Experimental Botany, 165 02 Prague, Czech Republic; (D.N.); (P.H.)
| | - Klára Hoyerová
- The Czech Academy of Sciences, Institute of Experimental Botany, 165 02 Prague, Czech Republic; (D.N.); (P.H.)
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14
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Hartmann FP, Rathgeber CBK, Badel É, Fournier M, Moulia B. Modelling the spatial crosstalk between two biochemical signals explains wood formation dynamics and tree-ring structure. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:1727-1737. [PMID: 33247732 DOI: 10.1093/jxb/eraa558] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 11/23/2020] [Indexed: 06/12/2023]
Abstract
In conifers, xylogenesis during a growing season produces a very characteristic tree-ring structure: large, thin-walled earlywood cells followed by narrow, thick-walled latewood cells. Although many factors influence the dynamics of differentiation and the final dimensions of xylem cells, the associated patterns of variation remain very stable from one year to the next. While radial growth is characterized by an S-shaped curve, the widths of xylem differentiation zones exhibit characteristic skewed bell-shaped curves. These elements suggest a strong internal control of xylogenesis. It has long been hypothesized that much of this regulation relies on a morphogenetic gradient of auxin. However, recent modelling studies have shown that while this hypothesis could account for the dynamics of stem radial growth and the zonation of the developing xylem, it failed to reproduce the characteristic tree-ring structure. Here, we investigated the hypothesis of regulation by a crosstalk between auxin and a second biochemical signal, by using computational morphodynamics. We found that, in conifers, such a crosstalk is sufficient to simulate the characteristic features of wood formation dynamics, as well as the resulting tree-ring structure. In this model, auxin controls cell enlargement rates while another signal (e.g. cytokinin, tracheary element differentiation inhibitory factor) drives cell division and auxin polar transport.
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Affiliation(s)
- Félix P Hartmann
- Université Clermont Auvergne, INRAE, PIAF, Clermont-Ferrand, France
| | | | - Éric Badel
- Université Clermont Auvergne, INRAE, PIAF, Clermont-Ferrand, France
| | - Meriem Fournier
- Université de Lorraine, AgroParisTech, INRAE, Silva, Nancy, France
| | - Bruno Moulia
- Université Clermont Auvergne, INRAE, PIAF, Clermont-Ferrand, France
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15
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Atif MJ, Ahanger MA, Amin B, Ghani MI, Ali M, Cheng Z. Mechanism of Allium Crops Bulb Enlargement in Response to Photoperiod: A Review. Int J Mol Sci 2020; 21:E1325. [PMID: 32079095 PMCID: PMC7072895 DOI: 10.3390/ijms21041325] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 02/07/2020] [Accepted: 02/13/2020] [Indexed: 12/17/2022] Open
Abstract
The photoperiod marks a varied set of behaviors in plants, including bulbing. Bulbing is controlled by inner signals, which can be stimulated or subdued by the ecological environment. It had been broadly stated that phytohormones control the plant development, and they are considered to play a significant part in the bulb formation. The past decade has witnessed significant progress in understanding and advancement about the photoperiodic initiation of bulbing in plants. A noticeable query is to what degree the mechanisms discovered in bulb crops are also shared by other species and what other qualities are also dependent on photoperiod. The FLOWERING LOCUS T (FT) protein has a role in flowering; however, the FT genes were afterward reported to play further functions in other biological developments (e.g., bulbing). This is predominantly applicable in photoperiodic regulation, where the FT genes seem to have experienced significant development at the practical level and play a novel part in the switch of bulb formation in Alliums. The neofunctionalization of FT homologs in the photoperiodic environments detects these proteins as a new class of primary signaling mechanisms that control the growth and organogenesis in these agronomic-related species. In the present review, we report the underlying mechanisms regulating the photoperiodic-mediated bulb enlargement in Allium species. Therefore, the present review aims to systematically review the published literature on the bulbing mechanism of Allium crops in response to photoperiod. We also provide evidence showing that the bulbing transitions are controlled by phytohormones signaling and FT-like paralogues that respond to independent environmental cues (photoperiod), and we also show that an autorelay mechanism involving FT modulates the expression of the bulbing-control gene. Although a large number of studies have been conducted, several limitations and research gaps have been identified that need to be addressed in future studies.
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Affiliation(s)
- Muhammad Jawaad Atif
- Department of Vegetable Science, College of Horticulture, Northwest A&F University, Yangling 712100, China; (M.J.A.); (B.A.); (M.I.G.); (M.A.)
- Vegetable Crops Program, National Agricultural Research Centre, Islamabad 44000, Pakistan
| | | | - Bakht Amin
- Department of Vegetable Science, College of Horticulture, Northwest A&F University, Yangling 712100, China; (M.J.A.); (B.A.); (M.I.G.); (M.A.)
| | - Muhammad Imran Ghani
- Department of Vegetable Science, College of Horticulture, Northwest A&F University, Yangling 712100, China; (M.J.A.); (B.A.); (M.I.G.); (M.A.)
- College of Natural Resource and Environment, Northwest A&F University, Yangling 712100, China
| | - Muhammad Ali
- Department of Vegetable Science, College of Horticulture, Northwest A&F University, Yangling 712100, China; (M.J.A.); (B.A.); (M.I.G.); (M.A.)
| | - Zhihui Cheng
- Department of Vegetable Science, College of Horticulture, Northwest A&F University, Yangling 712100, China; (M.J.A.); (B.A.); (M.I.G.); (M.A.)
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16
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Santos Teixeira JA, Ten Tusscher KH. The Systems Biology of Lateral Root Formation: Connecting the Dots. MOLECULAR PLANT 2019; 12:784-803. [PMID: 30953788 DOI: 10.1016/j.molp.2019.03.015] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 03/20/2019] [Accepted: 03/26/2019] [Indexed: 05/29/2023]
Abstract
The root system is a major determinant of a plant's access to water and nutrients. The architecture of the root system to a large extent depends on the repeated formation of new lateral roots. In this review, we discuss lateral root development from a systems biology perspective. We focus on studies combining experiments with computational modeling that have advanced our understanding of how the auxin-centered regulatory modules involved in different stages of lateral root development exert their specific functions. Moreover, we discuss how these regulatory networks may enable robust transitions from one developmental stage to the next, a subject that thus far has received limited attention. In addition, we analyze how environmental factors impinge on these modules, and the different manners in which these environmental signals are being integrated to enable coordinated developmental decision making. Finally, we provide some suggestions for extending current models of lateral root development to incorporate multiple processes and stages. Only through more comprehensive models we can fully elucidate the cooperative effects of multiple processes on later root formation, and how one stage drives the transition to the next.
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Affiliation(s)
- J A Santos Teixeira
- Computational Developmental Biology Group, Department of Biology, Utrecht University, Utrecht, the Netherlands
| | - K H Ten Tusscher
- Computational Developmental Biology Group, Department of Biology, Utrecht University, Utrecht, the Netherlands.
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17
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Li XR, Vroomans RMA, Fox S, Grieneisen VA, Østergaard L, Marée AFM. Systems Biology Approach Pinpoints Minimum Requirements for Auxin Distribution during Fruit Opening. MOLECULAR PLANT 2019; 12:863-878. [PMID: 31128274 PMCID: PMC6557309 DOI: 10.1016/j.molp.2019.05.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 05/01/2019] [Accepted: 05/03/2019] [Indexed: 06/09/2023]
Abstract
The phytohormone auxin is implied in steering various developmental decisions during plant morphogenesis in a concentration-dependent manner. Auxin maxima have been shown to maintain meristematic activity, for example, of the root apical meristem, and position new sites of outgrowth, such as during lateral root initiation and phyllotaxis. More recently, it has been demonstrated that sites of auxin minima also provide positional information. In the developing Arabidopsis fruit, auxin minima are required for correct differentiation of the valve margin. It remains unclear, however, how this auxin minimum is generated and maintained. Here, we employ a systems biology approach to model auxin transport based on experimental observations. This allows us to determine the minimal requirements for its establishment. Our simulations reveal that two alternative processes-which we coin "flux-barrier" and "flux-passage"-are both able to generate an auxin minimum, but under different parameter settings. Both models are in principle able to yield similar auxin profiles but present qualitatively distinct patterns of auxin flux. The models were tested by tissue-specific inducible ablation, revealing that the auxin minimum in the fruit is most likely generated by a flux-passage process. Model predictions were further supported through 3D PIN localization imaging and implementing experimentally observed transporter localization. Through such an experimental-modeling cycle, we predict how the auxin minimum gradually matures during fruit development to ensure timely fruit opening and seed dispersal.
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Affiliation(s)
- Xin-Ran Li
- Crop Genetics, John Innes Centre, Norwich NR4 7UH, UK
| | - Renske M A Vroomans
- Computational and Systems Biology, John Innes Centre, Norwich NR4 7UH, UK; Centre of Excellence in Computational and Experimental Developmental Biology, Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
| | - Samantha Fox
- Cell and Developmental Biology, John Innes Centre, Norwich NR4 7UH, UK
| | - Verônica A Grieneisen
- Computational and Systems Biology, John Innes Centre, Norwich NR4 7UH, UK; School of Biosciences, Cardiff University, Cardiff CF10 3AX, Wales, UK
| | | | - Athanasius F M Marée
- Computational and Systems Biology, John Innes Centre, Norwich NR4 7UH, UK; School of Biosciences, Cardiff University, Cardiff CF10 3AX, Wales, UK.
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18
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Mellor N, Vaughan-Hirsch J, Kümpers BMC, Help-Rinta-Rahko H, Miyashima S, Mähönen AP, Campilho A, King JR, Bishopp A. A core mechanism for specifying root vascular patterning can replicate the anatomical variation seen in diverse plant species. Development 2019; 146:dev.172411. [PMID: 30858228 PMCID: PMC6451317 DOI: 10.1242/dev.172411] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 02/18/2019] [Indexed: 01/06/2023]
Abstract
Pattern formation is typically controlled through the interaction between molecular signals within a given tissue. During early embryonic development, roots of the model plant Arabidopsis thaliana have a radially symmetric pattern, but a heterogeneous input of the hormone auxin from the two cotyledons forces the vascular cylinder to develop a diarch pattern with two xylem poles. Molecular analyses and mathematical approaches have uncovered the regulatory circuit that propagates this initial auxin signal into a stable cellular pattern. The diarch pattern seen in Arabidopsis is relatively uncommon among flowering plants, with most species having between three and eight xylem poles. Here, we have used multiscale mathematical modelling to demonstrate that this regulatory module does not require a heterogeneous auxin input to specify the vascular pattern. Instead, the pattern can emerge dynamically, with its final form dependent upon spatial constraints and growth. The predictions of our simulations compare to experimental observations of xylem pole number across a range of species, as well as in transgenic systems in Arabidopsis in which we manipulate the size of the vascular cylinder. By considering the spatial constraints, our model is able to explain much of the diversity seen in different flowering plant species.
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Affiliation(s)
- Nathan Mellor
- Centre for Plant Integrative Biology/School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
| | - John Vaughan-Hirsch
- Centre for Plant Integrative Biology/School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
| | - Britta M C Kümpers
- Centre for Plant Integrative Biology/School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
| | - Hanna Help-Rinta-Rahko
- Institute of Biotechnology, HiLIFE/Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki 00014, Finland
| | - Shunsuke Miyashima
- Graduate School of Science and Technology, Nara Institute of Science and Technology, Nara 630-0192, Japan
| | - Ari Pekka Mähönen
- Institute of Biotechnology, HiLIFE/Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki 00014, Finland
| | - Ana Campilho
- Research Center in Biodiversity and Genetic Resources, Department of Biology, Faculty of Sciences, University of Porto, 4485-661 Vairão, Portugal
| | - John R King
- School of Mathematical Sciences/Centre for Plant Integrative Biology, University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Anthony Bishopp
- Centre for Plant Integrative Biology/School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
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19
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Wybouw B, De Rybel B. Cytokinin - A Developing Story. TRENDS IN PLANT SCIENCE 2019; 24:177-185. [PMID: 30446307 DOI: 10.1016/j.tplants.2018.10.012] [Citation(s) in RCA: 95] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 10/15/2018] [Accepted: 10/18/2018] [Indexed: 05/21/2023]
Abstract
In the past decade tremendous advances have been made in understanding the biosynthesis, perception, and signaling pathways of the plant hormone cytokinin. It also became clear that interfering with any of these steps greatly impacts all on stages of growth and development. This has recently spurted renewed effort to understand how cytokinin signaling affects developmental processes. As a result, new insights on the role of cytokinin signaling and the downstream targets during, for example, shoot apical meristem, flower, female gametophyte, stomata and vascular development are being unraveled. In this review we aim to give a comprehensive overview of recent findings on how cytokinin influences growth and development in plants, and highlight areas for future research.
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Affiliation(s)
- Brecht Wybouw
- Ghent University, Department of Plant Biotechnology and Bioinformatics, 9052 Ghent, Belgium; VIB Center for Plant Systems Biology, 9052 Ghent, Belgium
| | - Bert De Rybel
- Ghent University, Department of Plant Biotechnology and Bioinformatics, 9052 Ghent, Belgium; VIB Center for Plant Systems Biology, 9052 Ghent, Belgium.
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20
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21
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22
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Vaughan-Hirsch J, Goodall B, Bishopp A. North, East, South, West: mapping vascular tissues onto the Arabidopsis root. CURRENT OPINION IN PLANT BIOLOGY 2018; 41:16-22. [PMID: 28837854 DOI: 10.1016/j.pbi.2017.07.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 07/24/2017] [Accepted: 07/29/2017] [Indexed: 05/27/2023]
Abstract
The Arabidopsis root has provided an excellent model for understanding patterning processes and cell fate specification. Vascular patterning represents an especially interesting process, as new positional information must be generated to transform an approximately radially symmetric root pole into a bisymmetric structure with a single xylem axis. This process requires both growth of the embryonic tissue alongside the subsequent patterning. Recently researchers have identified a series of transcription factors that modulate cell divisions to control vascular tissues growth. Spatial regulation in the signalling of two hormones, auxin and cytokinin, combine with other transcription factors to pattern the xylem axis. We are now witnessing the discovery of increasingly complex interactions between these hormones that can be interpreted through the use of mathematical models.
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Affiliation(s)
- John Vaughan-Hirsch
- Centre for Plant Integrative Biology and School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
| | - Benjamin Goodall
- Centre for Plant Integrative Biology and School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
| | - Anthony Bishopp
- Centre for Plant Integrative Biology and School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK.
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23
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Liu J, Moore S, Chen C, Lindsey K. Crosstalk Complexities between Auxin, Cytokinin, and Ethylene in Arabidopsis Root Development: From Experiments to Systems Modeling, and Back Again. MOLECULAR PLANT 2017; 10:1480-1496. [PMID: 29162416 DOI: 10.1016/j.molp.2017.11.002] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Revised: 11/06/2017] [Accepted: 11/07/2017] [Indexed: 05/23/2023]
Abstract
Understanding how hormones and genes interact to coordinate plant growth in a changing environment is a major challenge in plant developmental biology. Auxin, cytokinin, and ethylene are three important hormones that regulate many aspects of plant development. This review critically evaluates the crosstalk between the three hormones in Arabidopsis root development. We integrate a variety of experimental data into a crosstalk network, which reveals multiple layers of complexity in auxin, cytokinin, and ethylene crosstalk. In particular, data integration reveals an additional, largely overlooked link between the ethylene and cytokinin pathways, which acts through a phosphorelay mechanism. This proposed link addresses outstanding questions on whether ethylene application promotes or inhibits receptor kinase activity of the ethylene receptors. Elucidating the complexity in auxin, cytokinin, and ethylene crosstalk requires a combined experimental and systems modeling approach. We evaluate important modeling efforts for establishing how crosstalk between auxin, cytokinin, and ethylene regulates patterning in root development. We discuss how a novel methodology that iteratively combines experiments with systems modeling analysis is essential for elucidating the complexity in crosstalk of auxin, cytokinin, and ethylene in root development. Finally, we discuss the future challenges from a combined experimental and modeling perspective.
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Affiliation(s)
- Junli Liu
- Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK
| | - Simon Moore
- Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK
| | - Chunli Chen
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
| | - Keith Lindsey
- Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK.
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24
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Affiliation(s)
- Raili Ruonala
- Institute of Biotechnology and Department of Biosciences, University of Helsinki, 00014 Helsinki, Finland
- The Sainsbury Laboratory, University of Cambridge, Cambridge CB2 1LR, United Kingdom;, ,
| | - Donghwi Ko
- The Sainsbury Laboratory, University of Cambridge, Cambridge CB2 1LR, United Kingdom;, ,
| | - Ykä Helariutta
- Institute of Biotechnology and Department of Biosciences, University of Helsinki, 00014 Helsinki, Finland
- The Sainsbury Laboratory, University of Cambridge, Cambridge CB2 1LR, United Kingdom;, ,
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25
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Laskowski M, Ten Tusscher KH. Periodic Lateral Root Priming: What Makes It Tick? THE PLANT CELL 2017; 29:432-444. [PMID: 28223442 PMCID: PMC5385950 DOI: 10.1105/tpc.16.00638] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 02/17/2017] [Accepted: 02/18/2017] [Indexed: 05/02/2023]
Abstract
Conditioning small groups of root pericycle cells for future lateral root formation has a major impact on overall plant root architecture. This priming of lateral roots occurs rhythmically, involving temporal oscillations in auxin response in the root tip. During growth, this process generates a spatial pattern of prebranch sites, an early stage in lateral root formation characterized by a stably maintained high auxin response. To date, the molecular mechanism behind this rhythmicity has remained elusive. Some data implicate a cell-autonomous oscillation in gene expression, while others strongly support the importance of tissue-level modulations in auxin fluxes. Here, we summarize the experimental data on periodic lateral root priming. We present a theoretical framework that distinguishes between a priming signal and its subsequent memorization and show how major roles for auxin fluxes and gene expression naturally emerge from this framework. We then discuss three mechanisms that could potentially induce oscillations of auxin response: cell-autonomous oscillations, Turing-type patterning, and tissue-level oscillations in auxin fluxes, along with specific properties of lateral root priming that may be used to discern which type of mechanism is most likely to drive lateral root patterning. We conclude with suggestions for future experiments and modeling studies.
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Affiliation(s)
| | - Kirsten H Ten Tusscher
- Theoretical Biology Group, Faculty of Science, Utrecht University, 3584CH Utrecht, The Netherlands
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26
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Root branching plasticity: collective decision-making results from local and global signalling. Curr Opin Cell Biol 2017; 44:51-58. [DOI: 10.1016/j.ceb.2017.03.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 03/01/2017] [Accepted: 03/02/2017] [Indexed: 11/30/2022]
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Ramachandran P, Carlsbecker A, Etchells JP. Class III HD-ZIPs govern vascular cell fate: an HD view on patterning and differentiation. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:55-69. [PMID: 27794018 DOI: 10.1093/jxb/erw370] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Plant vasculature is required for the transport of water and solutes throughout the plant body. It is constituted of xylem, specialized for transport of water, and phloem, that transports photosynthates. These two differentiated tissues are specified early in development and arise from divisions in the procambium, which is the vascular meristem during primary growth. During secondary growth, the xylem and phloem are further expanded via differentiation of cells derived from divisions in the cambium. Almost all of the developmental fate decisions in this process, including vascular specification, patterning, and differentiation, are regulated by transcription factors belonging to the class III homeodomain-leucine zipper (HD-ZIP III) family. This review draws together the literature describing the roles that these genes play in vascular development, looking at how HD-ZIP IIIs are regulated, and how they in turn influence other regulators of vascular development. Themes covered vary, from interactions between HD-ZIP IIIs and auxin, cytokinin, and brassinosteroids, to the requirement for exquisite spatial and temporal regulation of HD-ZIP III expression through miRNA-mediated post-transcriptional regulation, and interactions with other transcription factors. The literature described places the HD-ZIP III family at the centre of a complex network required for initiating and maintaining plant vascular tissues.
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Affiliation(s)
- Prashanth Ramachandran
- Physiological Botany, Department of Organismal Biology and Linnean Centre for Plant Biology in Uppsala, Uppsala University, Ulls väg 24E, SE-756 51 Uppsala, Sweden
| | - Annelie Carlsbecker
- Physiological Botany, Department of Organismal Biology and Linnean Centre for Plant Biology in Uppsala, Uppsala University, Ulls väg 24E, SE-756 51 Uppsala, Sweden
| | - J Peter Etchells
- Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK
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28
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Etchells JP, Turner SR. Realizing pipe dreams - a detailed picture of vascular development. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:1-4. [PMID: 28013229 PMCID: PMC5183087 DOI: 10.1093/jxb/erw482] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Affiliation(s)
- J Peter Etchells
- Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK,
| | - Simon R Turner
- Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester M13 9PT, UK
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29
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Mellor N, Adibi M, El-Showk S, De Rybel B, King J, Mähönen AP, Weijers D, Bishopp A. Theoretical approaches to understanding root vascular patterning: a consensus between recent models. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:5-16. [PMID: 27837006 DOI: 10.1093/jxb/erw410] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The root vascular tissues provide an excellent system for studying organ patterning, as the specification of these tissues signals a transition from radial symmetry to bisymmetric patterns. The patterning process is controlled by the combined action of hormonal signaling/transport pathways, transcription factors, and miRNA that operate through a series of non-linear pathways to drive pattern formation collectively. With the discovery of multiple components and feedback loops controlling patterning, it has become increasingly difficult to understand how these interactions act in unison to determine pattern formation in multicellular tissues. Three independent mathematical models of root vascular patterning have been formulated in the last few years, providing an excellent example of how theoretical approaches can complement experimental studies to provide new insights into complex systems. In many aspects these models support each other; however, each study also provides its own novel findings and unique viewpoints. Here we reconcile these models by identifying the commonalities and exploring the differences between them by testing how transferable findings are between models. New simulations herein support the hypothesis that an asymmetry in auxin input can direct the formation of vascular pattern. We show that the xylem axis can act as a sole source of cytokinin and specify the correct pattern, but also that broader patterns of cytokinin production are also able to pattern the root. By comparing the three modeling approaches, we gain further insight into vascular patterning and identify several key areas for experimental investigation.
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Affiliation(s)
- Nathan Mellor
- Centre for Plant Integrative Biology, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
| | - Milad Adibi
- Department of Comparative Development and Genetics, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany
| | - Sedeer El-Showk
- Institute of Biotechnology, University of Helsinki, Helsinki FIN-00014, Finland
- Department of Biosciences, Viikki Plant Science Centre, University of Helsinki, Helsinki FIN-00014, Finland
| | - Bert De Rybel
- Laboratory of Biochemistry, Wageningen University, Stippeneng 4, 6708WE Wageningen, The Netherlands
- Department of Plant Systems Biology, VIB, Technologiepark 927, B-9052, Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, VIB, Technologiepark 927, B-9052, Ghent, Belgium
| | - John King
- Centre for Plant Integrative Biology, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
- School of Mathematical Sciences, University of Nottingham, Nottingham NG7 2RD, UK
- Synthetic Biology Research Centre, The University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Ari Pekka Mähönen
- Institute of Biotechnology, University of Helsinki, Helsinki FIN-00014, Finland
- Department of Biosciences, Viikki Plant Science Centre, University of Helsinki, Helsinki FIN-00014, Finland
| | - Dolf Weijers
- Laboratory of Biochemistry, Wageningen University, Stippeneng 4, 6708WE Wageningen, The Netherlands
| | - Anthony Bishopp
- Centre for Plant Integrative Biology, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
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30
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Morales-Tapia A, Cruz-Ramírez A. Computational Modeling of Auxin: A Foundation for Plant Engineering. FRONTIERS IN PLANT SCIENCE 2016; 7:1881. [PMID: 28066453 PMCID: PMC5168462 DOI: 10.3389/fpls.2016.01881] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 11/29/2016] [Indexed: 05/29/2023]
Abstract
Since the development of agriculture, humans have relied on the cultivation of plants to satisfy our increasing demand for food, natural products, and other raw materials. As we understand more about plant development, we can better manipulate plants to fulfill our particular needs. Auxins are a class of simple metabolites that coordinate many developmental activities like growth and the appearance of functional structures in plants. Computational modeling of auxin has proven to be an excellent tool in elucidating many mechanisms that underlie these developmental events. Due to the complexity of these mechanisms, current modeling efforts are concerned only with single phenomena focused on narrow spatial and developmental contexts; but a general model of plant development could be assembled by integrating the insights from all of them. In this perspective, we summarize the current collection of auxin-driven computational models, focusing on how they could come together into a single model for plant development. A model of this nature would allow researchers to test hypotheses in silico and yield accurate predictions about the behavior of a plant under a given set of physical and biochemical constraints. It would also provide a solid foundation toward the establishment of plant engineering, a proposed discipline intended to enable the design and production of plants that exhibit an arbitrarily defined set of features.
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Ohashi-Ito K, Fukuda H. Functional mechanism of bHLH complexes during early vascular development. CURRENT OPINION IN PLANT BIOLOGY 2016; 33:42-47. [PMID: 27314622 DOI: 10.1016/j.pbi.2016.06.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 06/01/2016] [Accepted: 06/01/2016] [Indexed: 05/27/2023]
Abstract
The vascular system spreads throughout the plant body. This highly organized network contains several types of cells. Vascular cell development is initiated during embryogenesis, and then vascular cells proliferate, form a vascular pattern, and commit to specific cell fates. Recent molecular genetics and modeling approaches have increased our understanding of the molecular mechanisms underlying early vascular development. Early events during vascular development are tightly linked and controlled by transcriptional complexes consisting of LONESOME HIGHWAY (LHW) and TARGET OF MONOPTEROS5 (TMO5) families. The role of LHW-TMO5 is tightly coupled with biosynthesis and/or signaling of phytohormones such as auxin and cytokinin. In this review, we discuss the regulatory network mediated by LHW-TMO5 during early vascular development.
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Affiliation(s)
- Kyoko Ohashi-Ito
- Department Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-0033, Japan.
| | - Hiroo Fukuda
- Department Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-0033, Japan.
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Palovaara J, de Zeeuw T, Weijers D. Tissue and Organ Initiation in the Plant Embryo: A First Time for Everything. Annu Rev Cell Dev Biol 2016; 32:47-75. [PMID: 27576120 DOI: 10.1146/annurev-cellbio-111315-124929] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Land plants can grow to tremendous body sizes, yet even the most complex architectures are the result of iterations of the same developmental processes: organ initiation, growth, and pattern formation. A central question in plant biology is how these processes are regulated and coordinated to allow for the formation of ordered, 3D structures. All these elementary processes first occur in early embryogenesis, during which, from a fertilized egg cell, precursors for all major tissues and stem cells are initiated, followed by tissue growth and patterning. Here we discuss recent progress in our understanding of this phase of plant life. We consider the cellular basis for multicellular development in 3D and focus on the genetic regulatory mechanisms that direct specific steps during early embryogenesis.
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Affiliation(s)
- Joakim Palovaara
- Laboratory of Biochemistry, Wageningen University, 6703 HA Wageningen, The Netherlands;
| | - Thijs de Zeeuw
- Laboratory of Biochemistry, Wageningen University, 6703 HA Wageningen, The Netherlands;
| | - Dolf Weijers
- Laboratory of Biochemistry, Wageningen University, 6703 HA Wageningen, The Netherlands;
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Taylor-Teeples M, Lanctot A, Nemhauser JL. As above, so below: Auxin's role in lateral organ development. Dev Biol 2016; 419:156-164. [PMID: 26994944 DOI: 10.1016/j.ydbio.2016.03.020] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 03/14/2016] [Accepted: 03/15/2016] [Indexed: 02/02/2023]
Abstract
Organogenesis requires the coordination of many highly-regulated developmental processes, including cell fate determination, cell division and growth, and cell-cell communication. For tissue- and organ-scale coordination, a network of regulators enables molecular events in individual cells to translate into multicellular changes in structure and functional capacity. One recurrent theme in plant developmental networks is a central role for plant hormones, especially auxin. Here, we focus first on describing recent advances in understanding lateral root development, one of the best-studied examples of auxin-mediated organogenesis. We then use this framework to examine the parallel process of emergence of lateral organs in the shoot-a process called phyllotaxy. This comparison reveals a high degree of conservation, highlighting auxin's pivotal role determining overall plant architecture.
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Affiliation(s)
| | - Amy Lanctot
- Department of Biology, University of Washington, Seattle, WA 98195, USA.
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