Integration of growth and patterning during vascular tissue formation in Arabidopsis
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ABSTRACT:
ORGANISM(S): Arabidopsis thaliana
PROVIDER: GSE56868 | GEO | 2014/08/15
SECONDARY ACCESSION(S): PRJNA244835
REPOSITORIES: GEO
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Project description:Coordination of cell division and pattern formation is central to tissue and organ development, and is particularly important in plants where walls prevent cell migration. Auxin and cytokinin are both critical for division and patterning, but it is unknown how these hormones converge to control tissue development. Here, we identify a genetic network that reinforces an early embryonic bias in auxin distribution to create a local, non-responding cytokinin source within the root vascular tissue. We provide experimental and theoretical evidence that these cells act as a local tissue organizer by positioning the domain of oriented cell divisions. We further demonstrate that the auxin-cytokinin interaction acts as a spatial incoherent feed forward loop, which is essential to generate distinct hormonal response zones, thus establishing a stable pattern within a growing vascular tissue. 4-day-old plants grown on MS were treated with the indicated compounds for the indicated time, whereafter roots were harvested and total RNA was isolated. Alternatively, roots were protoplasted and cell sorted for GFP+ cells followed by total RNA extraction.
2014-08-15 | E-GEOD-56868 | biostudies-arrayexpress
Project description:This model is from the article:
The influence of cytokinin-auxin cross-regulation on cell-fate determination in Arabidopsis thaliana root development
Muraro D, Byrne H, King J, Voss U, Kieber J, Bennett M.
J Theor Biol.2011 Aug 21;283(1):152-67.
PMID: 21640126,
Abstract:
Root growth and development in Arabidopsis thaliana are sustained by a specialised zone termed the meristem, which contains a population of dividing and differentiating cells that are functionally analogous to a stem cell niche in animals. The hormones auxin and cytokinin control meristem size antagonistically. Local accumulation of auxin promotes cell division and the initiation of a lateral root primordium. By contrast, high cytokinin concentrations disrupt the regular pattern of divisions that characterises lateral root development, and promote differentiation. The way in which the hormones interact is controlled by a genetic regulatory network. In this paper, we propose a deterministic mathematical model to describe this network and present model simulations that reproduce the experimentally observed effects of cytokinin on the expression of auxin regulated genes. We show how auxin response genes and auxin efflux transporters may be affected by the presence of cytokinin. We also analyse and compare the responses of the hormones auxin and cytokinin to changes in their supply with the responses obtained by genetic mutations of SHY2, which encodes a protein that plays a key role in balancing cytokinin and auxin regulation of meristem size. We show that although shy2 mutations can qualitatively reproduce the effect of varying auxin and cytokinin supply on their response genes, some elements of the network respond differently to changes in hormonal supply and to genetic mutations, implying a different, general response of the network. We conclude that an analysis based on the ratio between these two hormones may be misleading and that a mathematical model can serve as a useful tool for stimulate further experimental work by predicting the response of the network to changes in hormone levels and to other genetic mutations.
2024-09-02 | BIOMD0000000416 | BioModels
Project description:Muraro2014 - Vascular patterning in Arabidopsis roots
Using a multicellular model, maintanence of vascular patterning in Arabidopsis roots has been studied. The model that is provided here is the single-cell version of the model. The two-cell and multicellular models described in the paper can be downloaded as python scripts (follow the curation tab to get these files).
This model is described in the article:
Integration of hormonal signaling networks and mobile microRNAs is required for vascular patterning in Arabidopsis roots.
Muraro D, Mellor N, Pound MP, Help H, Lucas M, Chopard J, Byrne HM, Godin C, Hodgman TC, King JR, Pridmore TP, Helariutta Y, Bennett MJ, Bishopp A.
Proc Natl Acad Sci U S A. 2014 Jan 14;111(2):857-62.
Abstract:
As multicellular organisms grow, positional information is continually needed to regulate the pattern in which cells are arranged. In the Arabidopsis root, most cell types are organized in a radially symmetric pattern; however, a symmetry-breaking event generates bisymmetric auxin and cytokinin signaling domains in the stele. Bidirectional cross-talk between the stele and the surrounding tissues involving a mobile transcription factor, SHORT ROOT (SHR), and mobile microRNA species also determines vascular pattern, but it is currently unclear how these signals integrate. We use a multicellular model to determine a minimal set of components necessary for maintaining a stable vascular pattern. Simulations perturbing the signaling network show that, in addition to the mutually inhibitory interaction between auxin and cytokinin, signaling through SHR, microRNA165/6, and PHABULOSA is required to maintain a stable bisymmetric pattern. We have verified this prediction by observing loss of bisymmetry in shr mutants. The model reveals the importance of several features of the network, namely the mutual degradation of microRNA165/6 and PHABULOSA and the existence of an additional negative regulator of cytokinin signaling. These components form a plausible mechanism capable of patterning vascular tissues in the absence of positional inputs provided by the transport of hormones from the shoot.
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2024-09-02 | BIOMD0000000522 | BioModels
Project description:During plant development, a precise balance of cytokinin is crucial for correct growth and patterning, but it remains unclear how this is achieved across different cell types and in the context of a growing organ. Here we show that in the root apical meristem, the TMO5/LHW complex increases active cytokinin levels via two cooperatively acting enzymes. By profiling the transcriptomic changes of increased cytokinin at single-cell level, we further show that this effect is counteracted by a tissue-specific increase in CYTOKININ OXIDASE 3 expression via direct activation of the mobile transcription factor SHORTROOT. In summary, we show that within the root meristem, xylem cells act as a local organizer of vascular development by non-autonomously regulating cytokinin levels in neighbouring procambium cells via sequential induction and repression modules.
2021-10-10 | GSE179820 | GEO
Project description:As plant cells are fixed within their tissue context, a precise control of cell division orientation is crucial to generate complex three-dimensional organs. The transcription factor complex formed by TARGET OF MONOPTEROS5 (TMO5) and LONESOME HIGHWAY (LHW) triggers a change in cell division orientation leading to radial expansion, at least in part by activating local cytokinin biosynthesis. However, it remains unclear how cytokinin controls these oriented cell divisions. Here, we analyzed the transcriptional responses upon simultaneous induction of both TMO5 and LHW in detail. Using inferred network analysis, we identify AT2G28510/DOF2.1 as a cytokinin-dependent downstream target gene of the TMO5/LHW heterodimer complex. We further show that DOF2.1 is specifically required and sufficient for vascular cell proliferation without inducing other cytokinin-dependent effects such as the inhibition of vascular differentiation. In summary, we have identified DOF2.1 as a TMO5/LHW target gene, specifically responsible for controlling vascular cell proliferation leading to radial expansion.
2019-01-24 | GSE116858 | GEO
Project description:The formation of vascular tissue occurs when cellulose, hemicellulose, lignin and other wall components are deposited within the primary cell wall. These secondary thickened cells then undergo programmed cell death producing a network of empty cells with which water and ions can be transported throughout the plant. The hormones auxin and cytokinin are the principle signals for vascular tissue initiation. As a consequence cells cultured in-vitro can be converted into vascular tissue with the addition of exogenous auxin and cytokinin. We have created an in-vitro cell system, using callus produced from leaves that can be induced to form vascular tissue. Leaves are callused on induction media for two weeks. The callus is then transferred to liquid media and incubated under optimum conditions resulting in an increase in vascular tissue formation. Approximately 20% of cells will differentiate during the incubation period. The alteration of cytokinin concentration affects the ability of the cultured cells to undergo differentiation. Consequently callus incubated in liquid media, containing lower cytokinin concentrations, will undertake relatively little differentiation. Samples have been isolated from cell cultures at different time points and different hormone concentrations during incubation. Quantitative PCR using the marker AtCesA7, which encodes a cellulose synthase subunit specific to secondary wall deposition, was used as a guide to determine periods of high and low vascular differentiation. This system provides an opportunity to compare gene expression between differentiating and non differentiating cells and allow the identification of genes up regulated during vascular tissue formation.
2022-11-21 | E-NASC-15 | biostudies-arrayexpress
Project description:The formation of vascular tissue occurs when cellulose, hemicellulose, lignin and other wall components are deposited within the primary cell wall. These secondary thickened cells then undergo programmed cell death producing a network of empty cells with which water and ions can be transported throughout the plant. The hormones auxin and cytokinin are the principle signals for vascular tissue initiation. As a consequence cells cultured in-vitro can be converted into vascular tissue with the addition of exogenous auxin and cytokinin. We have created an in-vitro cell system, using callus produced from leaves that can be induced to form vascular tissue. Leaves are callused on induction media for two weeks. The callus is then transferred to liquid media and incubated under optimum conditions resulting in an increase in vascular tissue formation. Approximately 20% of cells will differentiate during the incubation period. The alteration of cytokinin concentration affects the ability of the cultured cells to undergo differentiation. Consequently callus incubated in liquid media, containing lower cytokinin concentrations, will undertake relatively little differentiation. Samples have been isolated from cell cultures at different time points and different hormone concentrations during incubation. Quantitative PCR using the marker AtCesA7, which encodes a cellulose synthase subunit specific to secondary wall deposition, was used as a guide to determine periods of high and low vascular differentiation. This system provides an opportunity to compare gene expression between differentiating and non differentiating cells and allow the identification of genes up regulated during vascular tissue formation. Experiment Overall Design: 6 samples
2008-06-14 | E-GEOD-6148 | biostudies-arrayexpress
Project description:Successful floral meristem (FM) determinacy is critical for the subsequent reproductive development and life cycle. Although phytohormones cytokinin and auxin interact to coordinately regulate many aspects of plant development, whether, if so how, cytokinin and auxin function in FM determinacy remain unclear. Here we show that the homeostasis of cytokinin is critical for the FM determinacy. Auxin promotes the expression of AUXIN RESPONSE FACTOR3 (ARF3) to repress cytokinin activity in FM determinacy. We found that ARF3 represses the expression of the ISOPENTENYLTRANSFERASE (IPT) family genes directly and the LONELY GUY (LOG) family genes indirectly, whose products are enzymes required for cytokinin biosynthesis. Furthermore, ARF3 directly inhibits the expression of ARABIDOPSIS HISTIDINE KINASE4 (AHK4), one of cytokinin receptor genes, to depress cytokinin activity. Genome-Wide Transcriptional Profiling reveals multiple functions of ARF3 in flower development. Consequently, ARF3 controls cell division by regulating cell cycle genes expression through cytokinin. Eventually, we show that AGAMOUS (AG) dynamically regulates the expression of ARF3 and IPTs resulting in coordinated regulation of FM maintenance and termination through cell division. Therefore, our findings reveal the molecular linkage between phytohormones auxin/cytokinin and AG in FM determinacy and shed light on the mechanisms of FM maintenance and termination.
2018-08-24 | GSE103054 | GEO
Project description:The formation of vascular tissue occurs when cellulose, hemicellulose, lignin and other wall components are deposited within the primary cell wall. These secondary thickened cells then undergo programmed cell death producing a network of empty cells with which water and ions can be transported throughout the plant. The hormones auxin and cytokinin are the principle signals for vascular tissue initiation. As a consequence cells cultured in-vitro can be converted into vascular tissue with the addition of exogenous auxin and cytokinin. We have created an in-vitro cell system, using callus produced from leaves that can be induced to form vascular tissue. Leaves are callused on induction media for two weeks. The callus is then transferred to liquid media and incubated under optimum conditions resulting in an increase in vascular tissue formation. Approximately 20% of cells will differentiate during the incubation period. The alteration of cytokinin concentration affects the ability of the cultured cells to undergo differentiation. Consequently callus incubated in liquid media, containing lower cytokinin concentrations, will undertake relatively little differentiation. Samples have been isolated from cell cultures at different time points and different hormone concentrations during incubation. Quantitative PCR using the marker AtCesA7, which encodes a cellulose synthase subunit specific to secondary wall deposition, was used as a guide to determine periods of high and low vascular differentiation. This system provides an opportunity to compare gene expression between differentiating and non differentiating cells and allow the identification of genes up regulated during vascular tissue formation. Keywords: time_series_design; compound_treatment_design
2007-01-22 | GSE6148 | GEO
Project description:An optimal size of postembryonic root apical meristem (RAM) is achieved by a balance between cell division and differentiation. Despite extensive research, molecular mechanisms underlying the spatiotemporal coordination of cell division and differentiation remain largely unknown. Here, we report that ORESARA 15 (ORE15), an Arabidopsis PLATZ transcription factor preferentially expressed in the RAM, determines RAM size. The primary root length, RAM size, cell division rate, and stem cell niche activity were reduced in an ore15 loss-of-function mutant but enhanced in an activation-tagged line overexpressing ORE15 compared with the wild type. We further demonstrate that ORE15 regulates auxin transport and distribution, at least partly, by modulating the expression and localization of the auxin importer AUXIN RESISTANT 1 (AUX1). ORE15 forms mutually positive and negative feedback loops with auxin and cytokinin signaling, respectively. Collectively, our findings imply that ORE15 controls the RAM size by mediating the antagonistic interaction between auxin and cytokinin.
2024-03-08 | GSE171143 | GEO