Seminar Doron Grossman

Plant morphogenesis is the results of intricate relates between mechanics and biological regulatory process (omics), from cellular level to tissue and organ level. In this talk I will discuss some of the stochastic mechanical effects relevant to morphogenesis. Specifically, how mechanical frustration (residual stress, self-avoidance) plays a role in shape development. Time permitting, I will focus on two projects: First, the geometrical and statistical effects on packing of long semi-flexible filaments in ellipsoidal containers. This problem can be considered as model for cortical microtubules in plant cells, where we take into account the geometry (rather than the stresses) of cell. Specifically, we show that by geometry alone, we can explain why microtubules may arrange along the long axis (which will then promote reshaping of cell towards isotropic). By including self-avoidance, we uncover a complex configurationnel phase space in which, in some cases, microtubules may pack along the shorter dimension of the cell. This may explain, why some cells in plant tissue (fibers) may grow long in contrast with the typical regulation toward isotropy. Time permitting, the second project to be discussed is the exact derivation of a general continuum elastic theory, that can be residually stresses (as often is the case in the natural world). The importance of this work is twofold - from a theoretical/modelling point of view, this project shows how unique macroscopic properties arise from microscopic rules and can help bridge the scale gap between molecular and cellular or cellular and tissue levels. From the basic scientific point of view, this derivation is currently the only general derivation of any elastic model (that can describe a system of any shape, curvature, and residual stresses), answering a 200 years old problem since the days of Cauchy, Poisson and Sophie Germain.

Doron Grossman, Institut de génomique fonctionnelle de Lyon IGFL, ENS de Lyon

Invitation : Philippe Andrey, "Modeling and Digital Imaging" MiN team


In connection with the research developed at the Institute Jean-Pierre Bourgin for Plant Sciences.