©Crit. Rev. Plant Sci. 18: 527-546 (1999)
Pyke, K. and Lopez-Juez, E.
A focused approach that exploits a single plant species, namely, Arabidopsis thaliana, as a means to understand how leaf cells differentiate and the factors that govern overall leaf morphogenesis has begun to generate a significant body of knowledge in this model plant. Although many studies have concentrated on specific cell types and factors that control their differentiation, some degree of consensus is starting to be reached. However, an understanding of specific mechanisms by which cells differentiate in relation to their position, that appears to be an overriding factor in this process, is not yet in place for cell types in the Arabidopsis leaf. It is clear that perturbations in cellular development within the leaf do not necessarily have a general effect on morphogenesis. Environmental factors, particularly light, have been known to affect leaf cell differentiation and expansion, and endogenous hormones also appear to play an important role, through mechanisms that are beginning to be uncovered. It is likely that continued identification of genes involved in leaf development and their regulation in relation to positional information or other cues will lead to a clearer understanding of the control of differentiation and morphogenesis in the Arabidopsis leaf.