The John Innes Centre Publications Repository contains details of all publications resulting from our researchers.
The repository also includes Open Access publications, which can be identified by the icons found on search results.
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The creation of this publications repository was funded by BBSRC.
Current Opinion in Cell Biology (44) 51-58
Publisher's version: 10.1016/j.ceb.2017.03.001
ID: 55817read more
Cells within tissues can be regarded as autonomous entities that respond to their local environment and to signals from neighbours. Coordination between cells is particularly important in plants, as the architecture of the plant adapts to environmental cues. To explain the architectural plasticity of the root, we propose to view it as a swarm of coupled multi-cellular structures, rhizomers, rather than a large set of autonomous cells. Each rhizomer contains a primed site with the potential to develop a single lateral root. Rhizomers are spaced through oscillatory genetic events that occur at the basal root tip. The decision whether or not to develop a lateral root primordium results from the interplay between local interactions of the rhizomer with its immediate environment, such as local nutrient availability, long-range interactions between the rhizomers and global cues, such as overall nutrient uptake. It can halt lateral root progression through its developmental stages, resulting in the observed complex root architecture.
Parsimonious Model of Vascular Patterning Links Transverse Hormone Fluxes to Lateral Root Initiation: Auxin Leads the Way, while Cytokinin Levels Out.
PLoS Computational Biology (11) e1004450
Publisher's version: 10.1371/journal.pcbi.1004450
ID: 52019read more
An auxin maximum is positioned along the xylem axis of the Arabidopsis root tip. The pattern depends on mutual feedback between auxin and cytokinins mediated by the PIN class of auxin efflux transporters and AHP6, an inhibitor of cytokinin signalling. This interaction has been proposed to regulate the size and the position of the hormones' respective signalling domains and specify distinct boundaries between them. To understand the dynamics of this regulatory network, we implemented a parsimonious computational model of auxin transport that considers hormonal regulation of the auxin transporters within a spatial context, explicitly taking into account cell shape and polarity and the presence of cell walls. Our analysis reveals that an informative spatial pattern in cytokinin levels generated by diffusion is a theoretically unlikely scenario. Furthermore, our model shows that such a pattern is not required for correct and robust auxin patterning. Instead, auxin-dependent modifications of cytokinin response, rather than variations in cytokinin levels, allow for the necessary feedbacks, which can amplify and stabilise the auxin maximum. Our simulations demonstrate the importance of hormonal regulation of auxin efflux for pattern robustness. While involvement of the PIN proteins in vascular patterning is well established, we predict and experimentally verify a role of AUX1 and LAX1/2 auxin influx transporters in this process. Furthermore, we show that polar localisation of PIN1 generates an auxin flux circuit that not only stabilises the accumulation of auxin within the xylem axis, but also provides a mechanism for auxin to accumulate specifically in the xylem-pole pericycle cells, an important early step in lateral root initiation. The model also revealed that pericycle cells on opposite xylem poles compete for auxin accumulation, consistent with the observation that lateral roots are not initiated opposite to each other.
The biophysical nature of cells: potential cell behaviours revealed by analytical and computational studies of cell surface mechanics
BMC Biophysics ( )
Publisher's version: 10.1186/s13628-015-0022-x
ID: 49527read more
Background: The biophysical characteristics of cells determinethe shape of individual cells and their packing within tissues. Cellscan form regular or irregular epithelial structures, round up andform clusters, or deform and attach to substrates. The acquired shapeof cells and tissues is a consequence of (i) internal cytoskeletalprocesses, such as actin polymerisation and cortical myosin contraction,(ii) adhesion molecules within the cell membrane that interact withsubstrates and neighbouring cells, and (iii) processes that regulatecell volume. Although these processes seem relatively simple, whencombined they unleash a rich variety of cellular behaviour that isnot readily understandable outside a theoretical framework.Results: Here we present a mathematical and computationalanalysis of a commonly used class of model formalisms that describecell surface mechanics using an energy-based approach. The analyticalstudy reveals the complete possible spectrum of single cell behaviourand tissue packing in both 2D and 3D, by taking the typical core elementsof cell surface mechanics into account: adhesion, cortical tensionand volume conservation. We show that from an energy-based description,forces and tensions can be derived, as well as the prediction of cellbehaviour and tissue packing, providing an intuitive and biologicallyrelevant mapping between modelling parameters and experiments. Thesepredictions are confirmed by the computational outcomes of cell-packinggeometries, both in a vertex-model and in 2D and 3D simulations ofthe Cellular Potts Model.Conclusions: The biological insights and qualitative cellularbehaviours agree with the this analytical study, even across differentmodel formalisms. This illustrates the generality of energy-basedapproaches for cell surface mechanics and highlights how meaningfuland quantitative comparisons between models can be established. Moreover,the mathematical analysis yields direct links between known biophysicalproperties and specific parameter settings within the Cellular PottsModel.
Mathematical Modeling and Experimental Validation of the Spatial Distribution of Boron in the Root of Arabidopsis thaliana Identify High Boron Accumulation in the Tip and Predict a Distinct Root Tip Uptake Function.
Plant Cell Physiology (56) 620-30
Publisher's version: 10.1093/pcp/pcv016
ID: 49410read more
Boron, an essential micronutrient, is transported in roots of Arabidopsis thaliana mainly by two different types of transporters, BORs and NIPs (nodulin26-like intrinsic proteins). Both are plasma membrane localized, but have distinct transport properties and patterns of cell type-specific accumulation with different polar localizations, which are likely to affect boron distribution. Here, we used mathematical modeling and an experimental determination to address boron distributions in the root. A computational model of the root is created at the cellular level, describing the boron transporters as observed experimentally. Boron is allowed to diffuse into roots, in cells and cell walls, and to be transported over plasma membranes, reflecting the properties of the different transporters. The model predicts that a region around the quiescent center has a higher concentration of soluble boron than other portions. To evaluate this prediction experimentally, we determined the boron distribution in roots using laser ablation-inductivity coupled plasma-mass spectrometry. The analysis indicated that the boron concentration is highest near the tip and is lower in the more proximal region of the meristem zone, similar to the pattern of soluble boron distribution predicted by the model. Our model also predicts that upward boron flux does not continuously increase from the root tip toward the mature region, indicating that boron taken up in the root tip is not efficiently transported to shoots. This suggests that root tip-absorbed boron is probably used for local root growth, and that instead it is the more mature root regions which have a greater role in transporting boron toward the shoots.
Journal of Integrative Plant Biology (55) 847-63
Publisher's version: 10.1111/jipb.12092
ID: 47419read more
In the past 20-30 years, developmental biologists have made tremendous progress in identifying genes required for the specification of individual cell types of an organ and in describing how they interact in genetic networks. In comparison, very little is known about the mechanisms that regulate tissue polarity and overall organ patterning. Gynoecia and fruits from members of the Brassicaceae family of flowering plants provide excellent model systems to study organ patterning and tissue specification because they become partitioned into distinct domains whose formation is determined by polarity establishment both at a cellular and whole tissue level. Interactions among key regulators of Arabidopsis gynoecium and fruit development have revealed a network of upstream transcription factor activities required for such tissue differentiation. Regulation of the plant hormone auxin is emerging as both an immediate downstream output and input of these activities, and here we aim to provide an overview of the current knowledge regarding the link between auxin and female reproductive development in plants. In this review, we will also demonstrate how available data can be exploited in a mathematical modeling approach to reveal and understand the feedback regulatory circuits that underpin the polarity establishment, necessary to guide auxin flows.
Journal of Integrative Plant Biology
Publisher's version: 10.1111/jipb.12092
ID: 43438read more
Development (140) 2061-74
Publisher's version: 10.1242/dev.062984
ID: 41877read more
Bulletin of Mathematical Biology (74) 2570-99
Publisher's version: 10.1007/s11538-012-9766-5
ID: 41342read more
A bistable circuit involving SCARECROW-RETINOBLASTOMA integrates cues to inform asymmetric stem cell division.
Cell (150) 1002-15
Publisher's version: 10.1016/j.cell.2012.07.017
ID: 41339read more
BMC Systems Biology (6) 37
Publisher's version: 10.1186/1752-0509-6-37
ID: 41338read more
How cells integrate complex stimuli: the effect of feedback from phosphoinositides and cell shape on cell polarization and motility.
PLoS Computing Biology (8) e1002402
Publisher's version: 10.1371/journal.pcbi.1002402
ID: 40529read more