Abstract

Saccharina is a brown marine alga (kelp) that develops a pear-shaped monolayered cell sheet during embryogenesis. Notably, this shape is maintained throughout embryogenesis and, within the sheet, the cells are cuboids arranged in a grid, resulting in the so-called 4-way junctions pattern. Interestingly, this tissue pattern has been described as rare and unstable in land plants (Thompson, 1942; Lloyd, 1991) whereas it is commonly observed in kelp embryos  (Sauvageau, 1918).

Using a 2D-vertex mechanical model, we have studied the cellular parameters that underlie the formation of this grid during growth, while maintaining the initial shape of the embryo. I will show the extent to which Saccharina must control these parameters, especially under stochastic conditions aimed to reflect real-life fluctuations in cell turgor and in cell division time, position and orientation. In particular, I will assess the extent to which this model can account for the diversity of shapes observed in living algal embryos.