Leaf development in Arabidopsis

In this review, we summarize recent research on leaf development in Arabidopsis. Topics include leaf initiation, ontogeny, the acquisition of leaf shape, heteroblasty, and the differentiation of the tissue types that make up a leaf. New data obtained by a molecular genetic approach and advanced microscopy are discussed in relation to existing hypotheses derived from earlier surgical experiments, morphological and anatomical descriptions, and mutational analyses. Molecular markers are providing new tools with which to investigate cell identity and growth patterns. An example is shown in which cell division is monitored during leaf growth. The cloning of the first set of genes critical for leaf development has shown that transcription factors control a number of important switches in developmental programs, such as the transition from indeterminate to determinate growth during leaf initiation, dorsiventral patterning and cell determination during trichome formation. In short, the study of leaf development seems to be about to come of age.