As the major sites of photosynthesis, leaves are crucial organs of higher plants. Young leaves originate from the
flank of shoot apical meristem and undergo various developmental events; i.e., axis determination, cell proliferation,
cell elongation, cell differentiation, and tissue differentiation. Various aspects of leaf development have
been studied, and the mechanisms of spatiotemporal control of cell proliferation and cell differentiation at key
events. The genetic mechanism underlying the transition from cell proliferation to cell differentiation during leaf
development has been the subject of intensive study