Unravelling the biomechanical interactions controlling growth and posture in plant stems

While the genetic control of plant development is well studied, the underlying physical basis behind plant growth remains largely unknown. At the cellular level, the fundamental link between mechanical forces and cell expansion is not fully understood and is still a matter of debate. At the level of tissues and organs, the interactions between cells and their geometric complexity make it difficult to predict the very nature of the physical forces acting locally, and to understand how they affect plant growth. Using the sunflower (H. annuus) as a model species, we aim to elucidate how plant anatomy, which determines the spatial arrangement of cells in organs, affects mechanical interactions between cells. Our primary mechanical testing techniques include microindentations, cellular force microscopy (CFM), extensometry, and osmotic treatments. Combining these with epi-fluorescent microscopy, we are able to obtain live 3D images of the effects of our mechanical tests at the cellular scale. Analysing our data with MorphoGraphX will allow us to extract the growth and geometry of each individual cell, giving us the direct effects of physical constraints with unprecedented accuracy.