Figure 1.

Generalized schematic representation of the processes and factors necessary for correct positioning of division planes during (asymmetrical) plant cell division. (A) For a parental cell to polarize, positional information is required. Positional information is generated by both cell-intrinsic factors (left) and extrinsic factors from surrounding tissues (right). Cell-intrinsic factors chiefly act at the cell cortex, where they can establish polarized signaling domains (red). Extrinsic signaling occurs via (unequal) exposure to cues, examples of which are provided. (B) As the parental cell is about to undergo mitosis, specific structures arise that will instruct the prospective division apparatus on the position and orientation of the desired division plane. The most prominent structure is the cortical division zone (CDZ; light green) that marks the partitioning plane (left). Additionally, polarized microtubule structures that are associated with the nucleus affect the axis along which division will take place (right). (C) As mitosis is executed, continuous control over the position and orientation of the division apparatus is required for proper division plane control (right). Final guidance of the division apparatus constructing the nascent dividing wall towards the CDZ is achieved by physical and/or biochemical communication between these two structures (left).