Abstract

One of the defining features of plant development is the way in which morphology is determined by differential growth. Two essential aspects controlling differential growth are the orientation of cell division and the direction of p cell expansion. We have been taking different approaches to examine both these aspects of plant development. We have been using plant vascular tissue as a means of understanding what regulates the orientation of plant cell divisions. In the vascular meristem cell divisions occur down the long axis of the cell and must be highly orientated to generate the highly aligned files of cells generated during vascular development. Identification of the pxy mutants have allowed us to identify a receptor kinase and its corresponding peptide ligand, a member of the CLE gene family, which are essential in regulating this process. We are currently analysing the PXY /Cle signalling network that appears to regulate the orientation and rate of cell division as well as the differentiation of xylem cells. In to understand the control of cell expansion we have been looking at the organization of cortical microtubule array that are essential in organizing cell wall. In order to undergo directions cell expansion the microtubule array must change from an essentially net-like array to an aligned array in which all microtubules are essentially parallel. In particular we have been examining the role of the microtubule severing protein katanin in this process and demonstrate that essential of the proper regulation severing in determining aligned MT arrays.