The Formation of Shapes: Interplay of Genes during Leaf Development Processes

Leaf shape, as one of the clearest manifestations of plant morphology, shows considerable variation owing to genetics and the environment. Leaf initiation occurs in the peripheral zone of the SAM and goes through the three overlapping phases of leaf primordium initiation, leaf dorsiventral development, and leaf marginal meristem establishment. Transcription factors, such as KNOX, WOX, and CUC; hormone-regulating genes, such as GA2ox, GA20ox, and PIN1; and miRNAs such as miR164/165 are tightly involved in leaf shaping through the generation of intricate cooperative networks in different temporal phases and specific tissue zones. Here, we briefly discuss the critical interplay occurring between certain genes and the pivotal role these play in the leaf developmental network and phytohormone regulation, including AS1/AS2-KNOX-GA20ox-GA, miR164-NAM/CUC-PIN1-auxin, and CUC-BAS1/CYP734A-BR, and we attempt to summarize several basic insights into the mechanisms of leaf shape regulation.