Introduction

This is an auspicious time for plant cell biology. We have the recent genome sequence of the model plant Arabidopsis, together with powerful new sets of tools that include functional genomics and the dynamic imaging of green fluorescent protein (GFP)–conjugated proteins by confocal microscopy. We are well placed indeed for uncovering the ways in which all genes act out their roles within individual cells. It is the combinatorial properties of these individual cells that underpin both the higherorder processes of plant growth and development and of plant evolution. At a crucial level in the hierarchy of explanations and structures, between the linear DNA sequence at one extreme and whole plant phenomena at the other, lies the cell. It is to this cellular level, to the irreducible unit of life, that this collection of papers is addressed, literally ‘between genome and plant’. Most of the major conceptual advances in our understanding of cell biology have come from work with animal and fungal systems. The ways in which membranes create dynamic compartments within cells and the role of the cytoskeleton in providing an ordering framework are familiar from the textbooks. But plant cells have special features.