Mechanism of leaf-shape determination.

Biodiversity of plant shape is mainly attributable to biodiversity of leaf shape and the shape of floral organs, the modified leaves. However, the exact mechanisms of leaf-shape determination remain unclear due to the complexity of flat-structure organogenesis that includes the simultaneous cell cycling and cell enlargement in primordia. Recent studies in developmental and molecular genetics have revealed several important aspects of leaf-shape control mechanisms. For example, understanding of polar control in leaf-blade expansion has advanced greatly. A curious phenomenon called "compensated cell enlargement" found in leaf organogenesis studies should also provide interesting clues regarding the mechanisms of multicellular organ development. This paper reviews recent research findings with a focus on leaf development in Arabidopsis thaliana.