Signals involved in control of polarity, cell fate and developmental pattern in plants

The plant extracellular matrix has multiple roles in determining pattern during plant development. These include provision of anchorage sites for focal adhesion-like structures which may play a direct signalling role and provide a reference for cytoskeletal elements involved in nuclear rotation and orientation of the cell division plane. The activity of mechanosensitive ion channels in the plasma membrane can also be regulated by the mechanical properties of the cell wall. Moreover, there is increasing evidence from a variety of systems suggesting that the cell wall may be a direct source of factors which specify cell fate in response to position. These may be inserted into the wall by differentiating cells and may act by providing signals to adjacent cells or by providing positive feedback to the protoplast contained therein, maintaining its fate according to its position.