How Plants Grow: New Principles of Development from Live Imaging and Computational Modelling

Plants grow from meristems, collections of stem cells found at the apical tip of each shoot, and at the base of each root. The shoot apical meristem of flowering plants is the source all of the parts of the plant found above ground, and therefore is responsible for most of our food, fiber, and even atmospheric oxygen. How this collection of a few hundred stem cells makes, over time, a highly patterned plant, with dozens of cell types, is under study. Recent investigations directed to understanding the origin of the pattern of leaves around each stem in the laboratory plant Arabidopsis thaliana have involved live imaging using laser scanning confocal microscopy, and computational modelling of cell-cell interactions. These studies have led to a detailed model of pattern formation at the shoot apex, and to some surprises: a new class of developmental model, and the discovery that leaf pattern results from feedbacks between chemical signals and physical forces in growing tissues.