Detailed programme - MiLS meeting 21/06/17

10:30 Arrival and coffee

11:00 Dr. Leah Band (University of Nottingham)

Title: Analysing how auxin controls plant root growth

Abstract: TBA

12:00 Dr. Nathan Mellor (University of Nottingham)

Title: The organization of vascular pattern in plant roots

Abstract: In higher plants the root vascular tissue or stele contains the xylem vessels, which transport water and nutrients from root to shoot, and the phloem, which transport photosynthetic products (sugars) from shoot to root. In Arabidopsis there are exactly two xylem vessels and two phloem vessels in every root, arranged in a diarch pattern, and regulated and organised by the two plant hormones, auxin and cytokinin. Mathematical modelling has shown that an embryonic asymmetry in auxin, originating from the two cotyledons, may establish the vascular pattern prior to germination, and that once established this pattern is robust to perturbations in hormone concentrations. However, the models have not yet been able to explain how the patterning of the vascular bundles of monocots, such as cereals that may have ten or more xylem poles, can originate from a single cotyledon auxin source. Furthermore, it can be shown that vascular pattern may be altered in growing roots via experimental manipulation, suggesting some post-embryonic patterning mechanism is present. We use a variety of modelling approaches to investigate how such de-novo patterning with multiple xylem and phloem vessels may occur in plant roots.

12:30 Lunch

14:00 Dr. Mirela Domijan (University of Liverpool)

Title: Modeling insights into the behaviour and function of the Arabidopsis circadian clock

Abstract: TBA

15:00 Dr. Melissa Tomkins (John Innes Centre, Norwich)

Title: The leafhopper effect: how leafhopper-phytoplasma-plant interactions drive large-scale patterns of infection

Abstract: Phytoplasmas are specialised bacteria that colonise a wide range of agriculturally important plants, causing a variety of symptoms ranging from mild yellowing to plant death. They are transmitted by vectors, normally sap-feeding insects such as leafhoppers, which carry the bacteria from plant to plant. Describing the phytoplasma life-cycle therefore requires knowledge about both plant and insect hosts and how they are affected by environmental factors, such as climate change, and changes to farming methods. Building computational models allow researchers to untangle some of this complexity, while developing new hypotheses regarding the dynamics of the spread of the pathogen, which can then be tested in the field.

The current availability of computational power has allowed researchers unparalleled opportunity to build highly complicated models, but it is important to ensure that each additional level of complexity adds value. One method of achieving this, is to start from simple models, and slowly introduce additional components, examining the difference made to the output, and whether it provides an increase in accuracy or understanding. Here, we demonstrate the change in the predicted dynamics of a simple infection model describing a host-vector-pathogen relationship when implemented as a series of ordinary differential equations (ODEs), or as a spatially explicit individual-based model. We prove that the differences are due to the non-uniform distribution of leafhoppers and infection rather than any difference in the method of implementation, by showing that a comparable ‘fully-mixed’ individual-based scenario produces identical results to the ODE model.

15:30 Dr. Yassin Refahi (The Sainsbury Laboratory)

Title: A stochastic multicellular model of phyllotaxis

Abstract: Biological patterns emerge from collective dynamics of individual units at lower levels of organization. Whether pattern irregularities may be instructive on system properties at lower scales is a challenging question. We addressed this question in plants lateral organ patterns called phyllotaxis. The majority of phyllotaxis studies focus on regularity of patterns associated with a deterministic view of organ formation. Recent recurrent observations of irregularities
in phyllotactic patterns have challenged this determinism and led us to revisit in-depth the deterministic view of phyllotaxis. We developed a multi-scale stochastic model of primordia initiation integrating the natural stochasticity in signaling perception and locality in cellular
decision. The model generated both regular and irregular phyllotactic patterns. We then showed that phyllotactic perturbations convey important information about the underlying parameters prescribing system dynamics. Therefore, pattern disorders can include biological watermarks (hidden information) of developmental systems.

16:00 Tea

16:30 Dr. Víctor F. Breña-Medina (Centro de Ciencias Matemáticas, Universidad Nacional Autónoma de México)

Title: A reaction-diffusion model of plant root hair initiation; a long story short from 1D to 2D​.

Abstract: In this talk, we present aspects ​ of pattern formation​ in a ​ ​reaction-diffusion (RD) sub-cellular model ​characterising the effect of a spatial gradient of a plant hormone distribution on a family of G-proteins associated with root-hair (RH) initiation in the plant cell Arabidopsis thaliana ​.​ The activation of these G-proteins, known as the Rho of Plants (ROPs), by the plant hormone, auxin, is known to promote certain protuberances on ​RH cells, which are crucial for both anchorage and the uptake of nutrients from the soil. The mathematical model for the activation of ROPs by the auxin gradient is an extension of the model proposed by Payne and Grierson [PLoS ONE, 12(4), (2009)], and consists of a two-component ​generalised Schnackenberg RD system with spatially ​non-homogeneous coefficients. The nonlinear kinetics in this RD system model the nonlinear ​interactions ​ between the active and inactive forms of ROPs. ​The hybrid analysis ​having as an essential feature a semi-strong theory approach, which together with n umerical bifurcation analysis ​ and time-dependent numerical simulations of the RD system ​,​ ​is ​performed ​ to ​ illustrate ​ 1D and 2D localised patterns in the model​ and their intrinsic dynamics. Possible consequences of either physical as purely genetical interacting features are discussed.

17:00 Dr. Etienne Farcot (University of Nottingham)

Title: Oscillations in models of auxin transport and signalling

Abstract: TBA

17:30 Close