Abstract

Growth and form in plant, fungal, and bacterial cells is achieved with two complementary processes: the deposition of new wall material at the cell surface and the mechanical deformation of this material by forces developed within the cell.  To understand how these two processes contribute to cell growth, we have undertaken a biophysical analysis of one major mode of cell morphogenesis called tip growth; whichrevealed that a few basic biophysical principles can explain all essential features of tip growth.  We first showed that the seemingly obscure surface expansion in these cells can be accounted for by the dissipation of elastic energy in the wall.  We also showed that a simple force balance at the cell surface explains the striking ability of these cells to penetrate stiff environments.  Finally, recent experiments suggest that tip-growing cells regulate their shape by controlling the spatial distribution of wall deposition.