Research - Plant Vascular Development
Phloem conduits are essential inter-organ communication systems that enable the plants to respond to environmental and developmental cues. During the last decades, Arabidopsis thaliana seedlings roots have been proved to be an excellent system to study vascular development as their being rather transparent enabled their most inner cell layers to be imaged. Within the root meristem, differentiating protophloem strands can be unequivocally identified when root is stained with propidium iodide and imaged using confocal microscopy due to their enhanced cell wall staining. During protophloem differentiation, nucleus breaks down, cell wall gets thicker and callose deposition takes place in the cell walls of adjacent cells.
Remarkably, a tight balance of a lipid compound, phosphatidylinositol-4,5-biphosphate (PIP2) is essential for protophloem differentiation, as shown by the presence of some undifferentiated cells in the protophloem strands of mutants with disturbed levels of PIP2. Additionally, a perturbed progression of protophloem development leads to a reduced meristematic activity associated with a higher density of lateral roots. Thus, elucidating the molecular mechanisms by which PIP2 regulates protophloem differentiation will bring us closer to understand how to shape root architecture.