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1.
Development ; 2024 May 16.
Article in English | MEDLINE | ID: mdl-38752444

ABSTRACT

Stem cell homeostasis in the shoot apical meristem involves a core regulatory feedback loop between the signalling peptide CLAVATA3, produced in stem cells, and the transcription factor WUSCHEL, expressed in the underlying organising centre. clavata mutant meristems display massive overgrowth, which is thought to be caused by stem cell overproliferation, although it is unknown how uncontrolled stem cell divisions lead to this altered morphology. Here we reveal local buckling defects in mutant meristems, and use analytical models to show how mechanical properties and growth rates may contribute to the phenotype. Indeed, clavata meristems are mechanically more heterogeneous than the wild type, and also display regional growth heterogeneities. Furthermore, stereotypical wild-type meristem organisation is lost in mutants, in which cells simultaneously express distinct fate markers. Finally, cells in mutant meristems are auxin responsive, suggesting that they are functionally distinguishable from wild-type stem cells. Thus all benchmarks show that clavata meristem cells are different from wild-type stem cells, suggesting that overgrowth is caused by the disruption of a more complex regulatory framework that maintains distinct genetic and functional domains in the meristem.

2.
Proc Natl Acad Sci U S A ; 121(23): e2318481121, 2024 Jun 04.
Article in English | MEDLINE | ID: mdl-38814869

ABSTRACT

Living tissues display fluctuations-random spatial and temporal variations of tissue properties around their reference values-at multiple scales. It is believed that such fluctuations may enable tissues to sense their state or their size. Recent theoretical studies developed specific models of fluctuations in growing tissues and predicted that fluctuations of growth show long-range correlations. Here, we elaborated upon these predictions and we tested them using experimental data. We first introduced a minimal model for the fluctuations of any quantity that has some level of temporal persistence or memory, such as concentration of a molecule, local growth rate, or mechanical property. We found that long-range correlations are generic, applying to any such quantity, and that growth couples temporal and spatial fluctuations, through a mechanism that we call "fluctuation stretching"-growth enlarges the length scale of variation of this quantity. We then analyzed growth data from sepals of the model plant Arabidopsis and we quantified spatial and temporal fluctuations of cell growth using the previously developed cellular Fourier transform. Growth appears to have long-range correlations. We compared different genotypes and growth conditions: mutants with lower or higher response to mechanical stress have lower temporal correlations and longer-range spatial correlations than wild-type plants. Finally, we used theoretical predictions to merge experimental data from all conditions and developmental stages into a unifying curve, validating the notion that temporal and spatial fluctuations are coupled by growth. Altogether, our work reveals kinematic constraints on spatiotemporal fluctuations that have an impact on the robustness of morphogenesis.


Subject(s)
Arabidopsis , Models, Biological , Morphogenesis , Arabidopsis/growth & development , Arabidopsis/genetics , Arabidopsis/metabolism , Arabidopsis/physiology , Flowers/growth & development , Flowers/genetics
3.
J R Soc Interface ; 21(214): 20240008, 2024 May.
Article in English | MEDLINE | ID: mdl-38715319

ABSTRACT

Multicellular organisms grow and acquire their shapes through the differential expansion and deformation of their cells. Recent research has addressed the role of cell and tissue mechanical properties in these processes. In plants, it is believed that growth rate is a function of the mechanical stress exerted on the cell wall, the thin polymeric layer surrounding cells, involving an effective viscosity. Nevertheless, recent studies have questioned this view, suggesting that cell wall elasticity sets the growth rate or that uptake of water is limiting for plant growth. To assess these issues, we developed a microfluidic device to quantify the growth rates, elastic properties and hydraulic conductivity of individual Marchantia polymorpha plants in a controlled environment with a high throughput. We characterized the effect of osmotic treatment and abscisic acid on growth and hydromechanical properties. Overall, the instantaneous growth rate of individuals is correlated with both bulk elastic modulus and hydraulic conductivity. Our results are consistent with a framework in which the growth rate is determined primarily by the elasticity of the wall and its remodelling, and secondarily by hydraulic conductivity. Accordingly, the coupling between the chemistry of the cell wall and the hydromechanics of the cell appears as key to set growth patterns during morphogenesis.


Subject(s)
Cell Wall , Cell Wall/physiology , Marchantia/growth & development , Marchantia/physiology , Abscisic Acid/metabolism , Models, Biological , Biomechanical Phenomena , Plant Development/physiology
4.
Plant Cell Physiol ; 65(2): 301-318, 2024 Feb 15.
Article in English | MEDLINE | ID: mdl-38190549

ABSTRACT

Pectin methylesterases (PMEs) modify homogalacturonan's chemistry and play a key role in regulating primary cell wall mechanical properties. Here, we report on Arabidopsis AtPME2, which we found to be highly expressed during lateral root emergence and dark-grown hypocotyl elongation. We showed that dark-grown hypocotyl elongation was reduced in knock-out mutant lines as compared to the control. The latter was related to the decreased total PME activity as well as increased stiffness of the cell wall in the apical part of the hypocotyl. To relate phenotypic analyses to the biochemical specificity of the enzyme, we produced the mature active enzyme using heterologous expression in Pichia pastoris and characterized it through the use of a generic plant PME antiserum. AtPME2 is more active at neutral compared to acidic pH, on pectins with a degree of 55-70% methylesterification. We further showed that the mode of action of AtPME2 can vary according to pH, from high processivity (at pH8) to low processivity (at pH5), and relate these observations to the differences in electrostatic potential of the protein. Our study brings insights into how the pH-dependent regulation by PME activity could affect the pectin structure and associated cell wall mechanical properties.


Subject(s)
Arabidopsis , Carboxylic Ester Hydrolases , Hypocotyl , Hypocotyl/genetics , Hypocotyl/metabolism , Arabidopsis/metabolism , Cell Wall/metabolism , Mutation/genetics , Pectins/metabolism , Hydrogen-Ion Concentration
5.
bioRxiv ; 2024 Apr 08.
Article in English | MEDLINE | ID: mdl-37546730

ABSTRACT

From smooth to buckled, nature exhibits organs of various shapes and forms. How cellular growth patterns produce smooth organ shapes such as leaves and sepals remains unclear. Here we show that unidirectional growth and comparable stiffness across both epidermal layers of Arabidopsis sepals are essential for smoothness. We identified a mutant with ectopic ASYMMETRIC LEAVES 2 (AS2) expression on the outer epidermis. Our analysis reveals that ectopic AS2 expression causes outer epidermal buckling at early stages of sepal development, due to conflicting growth directions and unequal epidermal stiffnesses. Aligning growth direction and increasing stiffness of the outer epidermis restores smoothness. Furthermore, buckling influences auxin efflux transporter protein PIN-FORMED 1 polarity to generate outgrowth in the later stages, suggesting that buckling is sufficient to initiate outgrowths. Our findings suggest that in addition to molecular cues influencing tissue mechanics, tissue mechanics can also modulate molecular signals, giving rise to well-defined shapes.

6.
bioRxiv ; 2023 Oct 25.
Article in English | MEDLINE | ID: mdl-37961547

ABSTRACT

Living tissues display fluctuations - random spatial and temporal variations of tissue properties around their reference values - at multiple scales. It is believed that such fluctuations may enable tissues to sense their state or their size. Recent theoretical studies developed specific models of fluctuations in growing tissues and predicted that fluctuations of growth show long-range correlations. Here we elaborated upon these predictions and we tested them using experimental data. We first introduced a minimal model for the fluctuations of any quantity that has some level of temporal persistence or memory, such as concentration of a molecule, local growth rate, or mechanical properties. We found that long-range correlations are generic, applying to to any such quantity, and that growth couples temporal and spatial fluctuations. We then analysed growth data from sepals of the model plant Arabidopsis and we quantified spatial and temporal fluctuations of cell growth using the previously developed Cellular Fourier Transform. Growth appears to have long-range correlations. We compared different genotypes and growth conditions: mutants with altered response to mechanical stress have lower temporal correlations and longer-range spatial correlations than wild-type plants. Finally, we used a theoretical prediction to collapse experimental data from all conditions and developmental stages, validating the notion that temporal and spatial fluctuations are coupled by growth. Altogether, our work reveals kinematic constraints on spatiotemporal fluctuations that have an impact on the robustness of morphogenesis.

7.
Cell Rep ; 42(7): 112689, 2023 07 25.
Article in English | MEDLINE | ID: mdl-37352099

ABSTRACT

Extracellular matrices contain fibril-like polymers often organized in parallel arrays. Although their role in morphogenesis has been long recognized, it remains unclear how the subcellular control of fibril synthesis translates into organ shape. We address this question using the Arabidopsis sepal as a model organ. In plants, cell growth is restrained by the cell wall (extracellular matrix). Cellulose microfibrils are the main load-bearing wall component, thought to channel growth perpendicularly to their main orientation. Given the key function of CELLULOSE SYNTHASE INTERACTIVE1 (CSI1) in guidance of cellulose synthesis, we investigate the role of CSI1 in sepal morphogenesis. We observe that sepals from csi1 mutants are shorter, although their newest cellulose microfibrils are more aligned compared to wild-type. Surprisingly, cell growth anisotropy is similar in csi1 and wild-type plants. We resolve this apparent paradox by showing that CSI1 is required for spatial consistency of growth direction across the sepal.


Subject(s)
Arabidopsis Proteins , Arabidopsis , Arabidopsis Proteins/genetics , Arabidopsis Proteins/metabolism , Carrier Proteins , Microtubules/metabolism , Cellulose/metabolism , Arabidopsis/metabolism , Cell Wall/metabolism , Morphogenesis
8.
Phys Rev Lett ; 130(6): 064001, 2023 Feb 10.
Article in English | MEDLINE | ID: mdl-36827557

ABSTRACT

The capture of a soft spherical particle in a rectangular slit leads to a nonmonotonic pressure-flow rate relation at low Reynolds number. Simulations reveal that the flow induced deformations of the trapped particle focus the streamlines and pressure drop to a small region. This increases the resistance to flow by several orders of magnitude as the driving pressure is increased. As a result, two regimes are observed in experiments and simulations: a flow-dominated regime for small particle deformations, where flow rate increases with pressure, and an elastic-dominated regime in which solid deformations block the flow.

9.
PLoS Biol ; 21(1): e3001981, 2023 01.
Article in English | MEDLINE | ID: mdl-36649360

ABSTRACT

Hyphal tip growth allows filamentous fungi to colonize space, reproduce, or infect. It features remarkable morphogenetic plasticity including unusually fast elongation rates, tip turning, branching, or bulging. These shape changes are all driven from the expansion of a protective cell wall (CW) secreted from apical pools of exocytic vesicles. How CW secretion, remodeling, and deformation are modulated in concert to support rapid tip growth and morphogenesis while ensuring surface integrity remains poorly understood. We implemented subresolution imaging to map the dynamics of CW thickness and secretory vesicles in Aspergillus nidulans. We found that tip growth is associated with balanced rates of CW secretion and expansion, which limit temporal fluctuations in CW thickness, elongation speed, and vesicle amount, to less than 10% to 20%. Affecting this balance through modulations of growth or trafficking yield to near-immediate changes in CW thickness, mechanics, and shape. We developed a model with mechanical feedback that accounts for steady states of hyphal growth as well as rapid adaptation of CW mechanics and vesicle recruitment to different perturbations. These data provide unprecedented details on how CW dynamics emerges from material secretion and expansion, to stabilize fungal tip growth as well as promote its morphogenetic plasticity.


Subject(s)
Aspergillus nidulans , Hyphae , Secretory Vesicles/metabolism , Aspergillus nidulans/metabolism , Cell Wall
10.
J Cell Sci ; 135(21)2022 11 01.
Article in English | MEDLINE | ID: mdl-36326245

ABSTRACT

The cell wall (CW) is a thin and rigid layer encasing the membrane of all plant and fungal cells. It ensures mechanical integrity by bearing mechanical stresses derived from large cytoplasmic turgor pressure, contacts with growing neighbors or growth within restricted spaces. The CW is made of polysaccharides and proteins, but is dynamic in nature, changing composition and geometry during growth, reproduction or infection. Such continuous and often rapid remodeling entails risks of enhanced stress and consequent damages or fractures, raising the question of how the CW detects and measures surface mechanical stress and how it strengthens to ensure surface integrity? Although early studies in model fungal and plant cells have identified homeostatic pathways required for CW integrity, recent methodologies are now allowing the measurement of pressure and local mechanical properties of CWs in live cells, as well as addressing how forces and stresses can be detected at the CW surface, fostering the emergence of the field of CW mechanobiology. Here, using tip-growing cells of plants and fungi as case study models, we review recent progress on CW mechanosensation and mechanical regulation, and their implications for the control of cell growth, morphogenesis and survival.


Subject(s)
Cell Wall , Plant Cells , Cell Wall/physiology , Morphogenesis , Stress, Mechanical , Biophysics
11.
Nat Commun ; 13(1): 2498, 2022 05 06.
Article in English | MEDLINE | ID: mdl-35523798

ABSTRACT

Plants generate motion by absorbing and releasing water. Many Asteraceae plants, such as the dandelion, have a hairy pappus that can close depending on moisture levels to modify dispersal. Here we demonstrate the relationship between structure and function of the underlying hygroscopic actuator. By investigating the structure and properties of the actuator cell walls, we identify the mechanism by which the dandelion pappus closes. We developed a structural computational model that can capture observed pappus closing and used it to explore the critical design features. We find that the actuator relies on the radial arrangement of vascular bundles and surrounding tissues around a central cavity. This allows heterogeneous swelling in a radially symmetric manner to co-ordinate movements of the hairs attached at the upper flank. This actuator is a derivative of bilayer structures, which is radial and can synchronise the movement of a planar or lateral attachment. The simple, material-based mechanism presents a promising biomimetic potential in robotics and functional materials.


Subject(s)
Robotics , Taraxacum , Biomimetics , Motion , Plants
12.
Plant Cell ; 34(5): 2019-2037, 2022 04 26.
Article in English | MEDLINE | ID: mdl-35157082

ABSTRACT

Stomata optimize land plants' photosynthetic requirements and limit water vapor loss. So far, all of the molecular and electrical components identified as regulating stomatal aperture are produced, and operate, directly within the guard cells. However, a completely autonomous function of guard cells is inconsistent with anatomical and biophysical observations hinting at mechanical contributions of epidermal origins. Here, potassium (K+) assays, membrane potential measurements, microindentation, and plasmolysis experiments provide evidence that disruption of the Arabidopsis thaliana K+ channel subunit gene AtKC1 reduces pavement cell turgor, due to decreased K+ accumulation, without affecting guard cell turgor. This results in an impaired back pressure of pavement cells onto guard cells, leading to larger stomatal apertures. Poorly rectifying membrane conductances to K+ were consistently observed in pavement cells. This plasmalemma property is likely to play an essential role in K+ shuttling within the epidermis. Functional complementation reveals that restoration of the wild-type stomatal functioning requires the expression of the transgenic AtKC1 at least in the pavement cells and trichomes. Altogether, the data suggest that AtKC1 activity contributes to the building of the back pressure that pavement cells exert onto guard cells by tuning K+ distribution throughout the leaf epidermis.


Subject(s)
Arabidopsis Proteins , Arabidopsis , Arabidopsis/metabolism , Arabidopsis Proteins/genetics , Arabidopsis Proteins/metabolism , Photosynthesis , Plant Leaves/metabolism , Plant Stomata/metabolism
13.
Eur Phys J E Soft Matter ; 45(2): 13, 2022 Feb 14.
Article in English | MEDLINE | ID: mdl-35157173

ABSTRACT

Measuring the mechanical properties of cells and tissues often involves indentation with a sphere or compression between two plates. Different theoretical approaches have been developed to retrieve material parameters (e.g., elastic modulus) or state variables (e.g., pressure) from such experiments. Here, we extend previous theoretical work on indentation of a spherical pressurized shell by a point force to cover indentation by a spherical probe or a plate. We provide formulae that enable the modulus or pressure to be deduced from experimental results with realistic contact geometries, giving different results that are applicable depending on pressure level. We expect our results to be broadly useful when investigating biomechanics or mechanobiology of cells and tissues.


Subject(s)
Elasticity , Biomechanical Phenomena , Elastic Modulus , Pressure
14.
Plant Cell ; 34(1): 72-102, 2022 01 20.
Article in English | MEDLINE | ID: mdl-34529074

ABSTRACT

As scientists, we are at least as excited about the open questions-the things we do not know-as the discoveries. Here, we asked 15 experts to describe the most compelling open questions in plant cell biology. These are their questions: How are organelle identity, domains, and boundaries maintained under the continuous flux of vesicle trafficking and membrane remodeling? Is the plant cortical microtubule cytoskeleton a mechanosensory apparatus? How are the cellular pathways of cell wall synthesis, assembly, modification, and integrity sensing linked in plants? Why do plasmodesmata open and close? Is there retrograde signaling from vacuoles to the nucleus? How do root cells accommodate fungal endosymbionts? What is the role of cell edges in plant morphogenesis? How is the cell division site determined? What are the emergent effects of polyploidy on the biology of the cell, and how are any such "rules" conditioned by cell type? Can mechanical forces trigger new cell fates in plants? How does a single differentiated somatic cell reprogram and gain pluripotency? How does polarity develop de-novo in isolated plant cells? What is the spectrum of cellular functions for membraneless organelles and intrinsically disordered proteins? How do plants deal with internal noise? How does order emerge in cells and propagate to organs and organisms from complex dynamical processes? We hope you find the discussions of these questions thought provoking and inspiring.


Subject(s)
Plant Cells/physiology , Plant Physiological Phenomena , Cell Biology , Plant Development
15.
Methods Mol Biol ; 2395: 97-106, 2022.
Article in English | MEDLINE | ID: mdl-34822151

ABSTRACT

Growth and morphogenesis in plants depend on cell wall mechanics and on turgor pressure. Nanoindentation methods, such as atomic force microscopy (AFM), enable measurements of mechanical properties of a tissue at subcellular resolution, while confocal microscopy of tissues expressing fluorescent reporters indicates cell identity. Associating mechanical data with specific cells is essential to reveal the links between cell identity and cell mechanics. Here we describe an image analysis protocol that allows us to segment AFM scans containing information on tissue topography and/or mechanics, to stitch several scans in order to reconstitute an entire region of the tissue investigated, to segment the scans and label cells, and to associate labeled cells to the projection of confocal images. Thus all mechanical data can be mapped to the corresponding cells and to their identity. This protocol is implemented using NanoIndentation, a plugin that we are developing in the Fiji distribution of ImageJ.


Subject(s)
Image Processing, Computer-Assisted , Cell Wall , Microscopy, Atomic Force , Microscopy, Confocal
16.
Cells ; 10(10)2021 10 06.
Article in English | MEDLINE | ID: mdl-34685657

ABSTRACT

Flax (Linum usitatissimum L.) seed oil, which accumulates in the embryo, and mucilage, which is synthesized in the seed coat, are of great economic importance for food, pharmaceutical as well as chemical industries. Theories on the link between oil and mucilage production in seeds consist in the spatio-temporal competition of both compounds for photosynthates during the very early stages of seed development. In this study, we demonstrate a positive relationship between seed oil production and seed coat mucilage extrusion in the agronomic model, flax. Three recombinant inbred lines were selected for low, medium and high mucilage and seed oil contents. Metabolite and transcript profiling (1H NMR and DNA oligo-microarrays) was performed on the seeds during seed development. These analyses showed main changes in the seed coat transcriptome during the mid-phase of seed development (25 Days Post-Anthesis), once the mucilage biosynthesis and modification processes are thought to be finished. These transcriptome changes comprised genes that are putatively involved in mucilage chemical modification and oil synthesis, as well as gibberellic acid (GA) metabolism. The results of this integrative biology approach suggest that transcriptional regulations of seed oil and fatty acid (FA) metabolism could occur in the seed coat during the mid-stage of seed development, once the seed coat carbon supplies have been used for mucilage biosynthesis and mechanochemical properties of the mucilage secretory cells.


Subject(s)
Flax/growth & development , Flax/genetics , Gene Expression Regulation, Developmental , Gene Expression Regulation, Plant , Plant Mucilage/metabolism , Seeds/growth & development , Seeds/genetics , Transcription, Genetic , Cell Wall/metabolism , Endosperm/metabolism , Fatty Acids/metabolism , Flax/ultrastructure , Gibberellins/metabolism , Glucose/metabolism , Inbreeding , Kinetics , Metabolomics , Phenotype , Plant Mucilage/ultrastructure , Plant Oils/metabolism , Principal Component Analysis , Recombination, Genetic/genetics , Seeds/ultrastructure , Starch/metabolism , Sucrose/metabolism , Transcriptome/genetics
17.
Elife ; 102021 05 07.
Article in English | MEDLINE | ID: mdl-33960300

ABSTRACT

In multicellular organisms, sexual reproduction requires the separation of the germline from the soma. In flowering plants, the female germline precursor differentiates as a single spore mother cell (SMC) as the ovule primordium forms. Here, we explored how organ growth contributes to SMC differentiation. We generated 92 annotated 3D images at cellular resolution in Arabidopsis. We identified the spatio-temporal pattern of cell division that acts in a domain-specific manner as the primordium forms. Tissue growth models uncovered plausible morphogenetic principles involving a spatially confined growth signal, differential mechanical properties, and cell growth anisotropy. Our analysis revealed that SMC characteristics first arise in more than one cell but SMC fate becomes progressively restricted to a single cell during organ growth. Altered primordium geometry coincided with a delay in the fate restriction process in katanin mutants. Altogether, our study suggests that tissue geometry channels reproductive cell fate in the Arabidopsis ovule primordium.


Subject(s)
Arabidopsis/genetics , Arabidopsis/physiology , Cell Division , Ovule/physiology , Arabidopsis/growth & development , Cell Cycle , Cell Differentiation , Cell Proliferation , Mutation , Ovule/genetics
18.
Phys Biol ; 18(4)2021 04 14.
Article in English | MEDLINE | ID: mdl-33276350

ABSTRACT

The way in which interactions between mechanics and biochemistry lead to the emergence of complex cell and tissue organization is an old question that has recently attracted renewed interest from biologists, physicists, mathematicians and computer scientists. Rapid advances in optical physics, microscopy and computational image analysis have greatly enhanced our ability to observe and quantify spatiotemporal patterns of signalling, force generation, deformation, and flow in living cells and tissues. Powerful new tools for genetic, biophysical and optogenetic manipulation are allowing us to perturb the underlying machinery that generates these patterns in increasingly sophisticated ways. Rapid advances in theory and computing have made it possible to construct predictive models that describe how cell and tissue organization and dynamics emerge from the local coupling of biochemistry and mechanics. Together, these advances have opened up a wealth of new opportunities to explore how mechanochemical patterning shapes organismal development. In this roadmap, we present a series of forward-looking case studies on mechanochemical patterning in development, written by scientists working at the interface between the physical and biological sciences, and covering a wide range of spatial and temporal scales, organisms, and modes of development. Together, these contributions highlight the many ways in which the dynamic coupling of mechanics and biochemistry shapes biological dynamics: from mechanoenzymes that sense force to tune their activity and motor output, to collectives of cells in tissues that flow and redistribute biochemical signals during development.


Subject(s)
Biomechanical Phenomena , Morphogenesis , Signal Transduction , Models, Biological
19.
PLoS Biol ; 18(11): e3000940, 2020 11.
Article in English | MEDLINE | ID: mdl-33253165

ABSTRACT

It is unknown how growth in one tissue impacts morphogenesis in a neighboring tissue. To address this, we used the Drosophila ovarian follicle, in which a cluster of 15 nurse cells and a posteriorly located oocyte are surrounded by a layer of epithelial cells. It is known that as the nurse cells grow, the overlying epithelial cells flatten in a wave that begins in the anterior. Here, we demonstrate that an anterior to posterior gradient of decreasing cytoplasmic pressure is present across the nurse cells and that this gradient acts through TGFß to control both the triggering and the progression of the wave of epithelial cell flattening. Our data indicate that intrinsic nurse cell growth is important to control proper nurse cell pressure. Finally, we reveal that nurse cell pressure and subsequent TGFß activity in the stretched cells combine to increase follicle elongation in the anterior, which is crucial for allowing nurse cell growth and pressure control. More generally, our results reveal that during development, inner cytoplasmic pressure in individual cells has an important role in shaping their neighbors.


Subject(s)
Drosophila melanogaster/cytology , Drosophila melanogaster/metabolism , Ovarian Follicle/cytology , Ovarian Follicle/metabolism , Animals , Biomechanical Phenomena , Cell Differentiation , Cell Polarity , Cell Shape , Cytoplasm/metabolism , Drosophila Proteins/metabolism , Epithelial Cells/cytology , Epithelial Cells/metabolism , Female , Microscopy, Atomic Force , Models, Biological , Oocytes/cytology , Oocytes/metabolism , Oogenesis , Pressure , Signal Transduction , Transforming Growth Factor beta/metabolism
20.
Nat Plants ; 6(6): 686-698, 2020 06.
Article in English | MEDLINE | ID: mdl-32451448

ABSTRACT

Organ size and shape are precisely regulated to ensure proper function. The four sepals in each Arabidopsis thaliana flower must maintain the same size throughout their growth to continuously enclose and protect the developing bud. Here we show that DEVELOPMENT RELATED MYB-LIKE 1 (DRMY1) is required for both timing of organ initiation and proper growth, leading to robust sepal size in Arabidopsis. Within each drmy1 flower, the initiation of some sepals is variably delayed. Late-initiating sepals in drmy1 mutants remain smaller throughout development, resulting in variability in sepal size. DRMY1 focuses the spatiotemporal signalling patterns of the plant hormones auxin and cytokinin, which jointly control the timing of sepal initiation. Our findings demonstrate that timing of organ initiation, together with growth and maturation, contribute to robust organ size.


Subject(s)
Arabidopsis Proteins/genetics , Arabidopsis/growth & development , Cytokinins/metabolism , DNA-Binding Proteins/genetics , Indoleacetic Acids/metabolism , Organogenesis, Plant/genetics , Signal Transduction/genetics , Arabidopsis/genetics , Arabidopsis/metabolism , Arabidopsis Proteins/metabolism , DNA-Binding Proteins/metabolism , Flowers/genetics , Flowers/growth & development
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