Adaxial-abaxial polarity: The developmental basis of leaf shape diversity

Abstract

Leaves of flowering plants are diverse in shape. Part of this morphological diversity can be attributed to differences in spatiotemporal regulation of polarity in the upper (adaxial) and lower (abaxial) sides of developing leaves. In a leaf primordium, antagonistic interactions between polarity determinants specify the adaxial and abaxial domains in a mutually exclusive manner. The patterning of those domains is critical for leaf morphogenesis. In this review, we first summarize the gene networks regulating adaxial-abaxial polarity in conventional bifacial leaves and then discuss how patterning is modified in different leaf type categories. © 2013 Wiley Periodicals, Inc.