Arabidopsis embryogenesis. Radicle development(s)

Cell walls: structures and signals

Cell walls harbor proteins and polysaccharides able to condition the development of a plant. In the past year, genes and enzymes modulating the composition and physical properties of walls have been characterized, and wall composition has been linked to the way a cell interacts with another cell, and to the way in which it differentiates. The sum of the signaling and physical activities of a cell wall may explain much about the control of development.

Cell-cell interactions: taking cues from the neighbors

Three lines of inquiry indicate that inductive interactions play a major role in the acquisition of cell identity during plant development.

Plant development: pulled up by the roots

Recent advances in the study of root development in Arabidopsis have begun to yield mechanistic insights into the processes that underpin morphogenesis, pattern formation and cell differentiation in plants. The most exciting feature of these advances is that, as a consequence of the simple and largely invariant cellular architecture of the root, the processes can be studied at a cellular level. Nevertheless, it is clear that although the cell lineages of the root are relatively invariant, we have no evidence that lineage per se is an important regulator of development. Instead, all the evidence indicates that the positional regulation of inductive cues is of primary importance. The availability of new root mutants is alerting us to the complexity of the contribution of cell size and cell expansion to plant development.