Intercellular alignments of the plant cytoskeleton

The cytoskeleton orchestrates many processes in plant development, includin g division and control of the direction of cell expansion, and is therefore central in the coordination of plant growth. There are a number of situati ons in which there is a precise alignment of the cytoskeleton, in particula r microtubules, between neighboring cells. However, it is not known how the se intercellular alignments are brought about. We discuss the possibility t hat the intercellular alignments are due to individual cells each respondin g in turn to an external orienting vector, without a need for direct commun ication between cells. Alternatively, there may be information exchange bet ween the cells about the orientation of the cytoskeleton to allow for coord ination. This exchange could take place directly via the plasmodesmata or m ore indirectly through the intervening cell wall. The final possibility, di scussed here, is that orientation of the cytoskeleton in neighboring cells is coordinated via direct continuity of the cytoskeleton between neighborin g cells, presumably via the plasmodesmata.