Plant cell shape: modulators and measurements

Abstract

Plant cell shape, seen as an integrative output, is of considerable interest in various fields, such as cell wall research, cytoskeleton dynamics and biomechanics. In this review we summarize the current state of knowledge on cell shape formation in plants focusing on shape of simple cylindrical cells, as well as in complex multipolar cells such as leaf pavement cells and trichomes. We summarize established concepts as well as recent additions to the understanding of how cells construct cell walls of a given shape and the underlying processes. These processes include cell wall synthesis, activity of the actin and microtubule cytoskeletons, in particular their regulation by microtubule associated proteins, actin-related proteins, GTP'ases and their effectors, as well as the recently-elucidated roles of plant hormone signaling and vesicular membrane trafficking. We discuss some of the challenges in cell shape research with a particular emphasis on quantitative imaging and statistical analysis of shape in 2D and 3D, as well as novel developments in this area. Finally, we review recent examples of the use of novel imaging techniques and how they have contributed to our understanding of cell shape formation.

Keywords: Arabidopsis; Microtubules; actin; auxin; hypocotyl; pavement cell; shape tools.

Figure 1

Leaf epidermal pavement cells on the abaxial surface (underside) of an Arabidopsis cotyledon. Image is reproduced with permission from Dolan and Langdale (2004). Scale bar: 50 μm.

Figure 2

Organization of cortical microtubules in leaf epidermal pavement cells. Typical organization of microtubules in wild-type (left panel), rop6-1 (mid panel) and ROP6-3 over-expressor (right panel) leaf epidermal pavement cells visualized by an anti-tubulin antibody. Arrows indicate ordered transverse microtubules in the neck regions of wild-type cells. Image is reproduced with permission from Fu et al. (2009). Scale bar: 30 μm.