Looping Network Meetings

#43 June 2, 2023

Monday, 15:00 CET

Camille Le Scao

Leaf Morphogenesis

Abstract:
Evolutionary developmental biology (or "evo-devo") is a field that compares the developmental processes of different organisms to infer how developmental processes evolved. In this talk, we will first discuss leaf evolution and development, and make a parallel between "evo-devo" approaches and the modelling of leaf venation patterns. We will then focus on the case of the leaf central vein. Leaves are photosynthetic organs with a diversity of shapes and complex vascular networks, often featuring a central vein with very stable oscillations. In order to explain the development of this central vein, we propose a numerical model of growth by interface propagation describing the dynamics of the vascular network as a function of the initial shape of the front and the spacing of the veins. We make the assumption that veins can be used as a marker of revious growth zones, as they develop around morphogen auxin flux, and includeregular vein spacing and symmetrical bifurcations as they correspond to the more primitive leaves. During morphogenesis, two modes of growth are distinguished, peripheral and global. A front propagation model corresponds to a peripheral mode of growth. We find a leaf-like object with a stable central vein, with two lobes by edge effect. We base our growth function on gaussians centered on the position of veins, and introduce an initial pre-factor on the vein closest to the center, making the central vein stable. In the absence of this pre-factor, the dynamic of the central vein can be modelled by an iterated function whose geometry explains its instability.

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