ORE15, a PLATZ transcription factor, determines root meristem size by modulating auxin and cytokinin signaling
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ABSTRACT:
ORGANISM(S): Arabidopsis thaliana
PROVIDER: GSE171143 | GEO | 2024/03/08
REPOSITORIES: GEO
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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.
2012-04-10 | BIOMD0000000416 | BioModels
Project description:Genome wide transcriptome profiling of pericycle cells from roots exposed to auxin, cytokinin and both hormones simultaneously. Lateral root organogenesis in Arabidopsis is governed by a complex network of hormonal regulations. Plant hormones auxin and cytokinin were demonstrated to be the key regulators of this lateral root organogenesis and their mode of interaction is antagonistic. The aim of the project is to understand the role of the auxin - cytokinin signalling pathways in lateral root organogenesis.
2020-03-13 | GSE146778 | GEO
Project description:Myosins are evolutionarily conserved motor proteins that interact with actin filaments to regulate organelle transport, cytoplasmic streaming and cell growth. Plant specific Class XI myosin proteins direct cell division and root organogenesis. However, the roles of Class VIII myosin proteins in plant growth and development are less understood. Here, we investigated the function of an auxin-regulated Class VIII myosin, Arabidopsis thaliana Myosin 1 (ATM1), using genetics and live cell microscopy. ATM1 is a plasmodesmata-localized protein that is enriched in actively dividing cells in the root apical meristem (RAM). Loss of ATM1 function results in impaired primary root growth due to decreased RAM size and reduced cell proliferation in a sugar dependent manner. Examination of stem cell marker line expression in atm1-1 indicated impaired division of the lateral root cap and columella cells and a diminished auxin response. Transcriptome analysis of atm1-1 linked these growth defects to dysregulation of cell cycle and auxin pathway genes. Complementation of ATM1 loss-of- function mutant restored root growth and cell cycle progression in the root meristem. Collectively, these results provide novel evidence that ATM1 functions to influence cell proliferation and differentiation in primary roots in response to auxin and sugar cues.
2023-06-08 | GSE200917 | GEO
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:Adventitious root formation at the base of plant cuttings is an innate de novo organogenesis process that allows massive vegetative propagation of many economically and ecologically important species. The early molecular events following shoot excision are not well understood. Using whole-genome microarrays, we detected significant transcriptome remodeling during 48 hours following shoot removal in Populus softwood cuttings in the absence of exogenous auxin, with 27% and 36% of the gene models showing differential abundance between 0 and 6 hours, and 6 and 24 hours, respectively. During these two time intervals, gene networks involved in protein turnover, protein phosphorylation, molecular transport and translation were among the most significantly regulated. Transgenic lines expressing a constitutively active form of the Populus type-B response regulator PtRR13 (ΔDDKPtRR13) have a delayed rooting phenotype and cause misregulation of COV1, a negative regulator of vascularization; PDR9, an auxin efflux transporter; two AP2/ERF genes with sequence similarity to TINY1. Cytokinin action appeared to disrupt root development 24 hours after shoot excision, when root founder cells are hypothesized to be sensitive to the negative effects of cytokinin. Our results suggest that PtRR13 acts downstream of cytokinin to repress adventitious root formation in intact plants, and that reduced cytokinin signaling after shoot excision enables coordinated expression of ethylene, auxin and vascularization pathways leading to adventitious root development.
2009-03-27 | GSE15049 | GEO
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.
2014-08-15 | GSE56868 | GEO
Project description:Directional transport of auxin is critical for inflorescence and floral development in flowering plants, but the role of auxin influx carriers (AUX1 proteins) has been largely overlooked. Taking advantage of available AUX1 mutants in Setaria viridis and maize, we uncover previously unreported aspects of plant development that are affected by auxin influx, including higher order branches in the inflorescence, stigma branch number, and glume (floral bract) development, and plant fertility. However, disruption of auxin flux does not affect all parts of the plant, with little obvious effect on inflorescence meristem size, time to flowering, and anther morphology. In double mutant studies in maize, disruptions of ZmAUX1 also affect vegetative development. A GFP-tagged construct of SvAUX1 under its native promoter showed that the AUX1 protein localizes to the plasma membrane of outer tissue layers in both roots and inflorescences, and accumulates specifically in inflorescence branch meristems, consistent with the mutant phenotype and expected auxin maxima. RNA-seq analysis finds that most gene expression modules are conserved between mutant and wildtype plants, with only a few hundred genes differentially expressed in spp1 inflorescences. Using CRISPR-Cas9 technology, we disrupted SPP1 and the other four AUX1 homologs in S. viridis. SvAUX1/SPP1 has a larger effect on inflorescence development than the others, although all contribute to plant height, tiller formation, leaf, and root development. The AUX1 importers are thus not fully redundant in S. viridis. Our detailed phenotypic characterization plus a stable GFP-tagged line offer tools for future dissection of the function of auxin influx proteins.
2022-01-13 | GSE193344 | GEO
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:Analysis of calli derived from the wild type (Ler), the ckh1 and ckh2 mutants cultured on media in the absence of cytokinin (control), in the presence of low (25 ng/ml kinetin) or high (200 ng/ml kinetin) levels of cytokinin, or in the presence of Trichostatin A (TSA). In these conditions, a constant 2,4-dichlorophenoxyacetic acid (2,4-D) was included as an auxin.
2011-08-17 | GSE26297 | GEO
Project description:The plant hormone auxin represents an important regulator of growth and development. Significant insight into the mechanisms of auxin action have been obtained from studies of auxin resistant mutants such as aux1 and axr3. The Arabidopsis axr4 mutant was identified in a screen for auxin resistant root growth. In addition to the root growth of axr4 being resistant to exogenous auxin, there is also a 50% reduction in the number of lateral roots that form. The double axr4/aux1 mutant shows an additive effect in reducing lateral root numbers to 10% of wild-type. Gaining further information about the potential interaction between AUX1 and AXR4 may provide important insight into auxin regulated plant growth. Mapping experiments have placed the AXR4 gene on the lower arm of chromosome 1 between the ch1 and le markers (Hobbie and Estelle 1995). However, the AXR4 gene remains to be cloned. Identifying the AXR4 gene will help in elucidating the function of the protein. A transcript analysis of axr4 mutant seedlings will be used in 2 ways. Firstly, the transcription level of genes in the locality of the axr4 map position will be examined to identify those which are absent or significantly reduced in axr4 compared to the Col0 control. If the lesion causing the axr4 mutation results in a highly unstable mRNA or abolishes transcription then the signal will be dramatically reduced. Potential candidate genes identified in this way will be further analysed using a combination of RT-PCR and sequencing to identify the AXR4 gene. Secondly, the transcriptomics data obtained from axr4 and Col0 will be compared to identify genes which show significant transcript level differences and therefore represent targets for either direct or indirect regulation by AXR4. Hobbie, L. and Estelle, M. (1995) The axr4 auxin-resistant mutants of Arabidopsis thaliana define a gene important for root gravitropism and lateral root initiation. Plant J. 7 211-220
2022-11-21 | E-NASC-39 | biostudies-arrayexpress