Intercellular alignments of the plant cytoskeleton

The cytoskeleton orchestrates many processes in plant development, including division and control of the direction of cell expansion, and is therefore central in the coordination of plant growth. There are a number of situations in which there is a precise alignment of the cytoskeleton, in particular microtubules, between neighboring cells. However, it is not known how these intercellular alignments are brought about. We discuss the possibility that the intercellular alignments are due to individual cells each responding in turn to an external orienting vector, without a need for direct communication between cells. Alternatively, there may be information exchange between the cells about the orientation of the cytoskeleton to allow for coordination. This exchange could take place directly via the plasmodesmata or more indirectly through the intervening cell wall. The final possibility, discussed here, is that orientation of the cytoskeleton in neighboring cells is coordinated via direct continuity of the cytoskeleton between neighboring cells, presumably via the plasmodesmata.