Spatio temporal control of cell growth by CUC3 shapes leaf margins

Abstract

How a shape arises from the coordinated behavior of cells is one of the most fascinating questions in developmental biology. In plants, fine spatial and temporal controls of cell proliferation and cell expansion sustain differential growth defining organ shape and size. At the leaf margin of Arabidopsis thaliana, interplay between auxin transport and transcription factors named CUP SHAPED COTYLEDON (CUCs), involved in the establishment of boundary domain identity, were reported to trigger differential growth, leading to serration. Cellular behaviors behind these differential growths remain scarcely described. Here, we used 3D and time lapse imaging on young leaves at different stages of development to determine the sequence of cellular events resulting in leaf serrations. In addition, we showed that CUC3 TF is a negative regulator of cell growth and that its expression dynamics in very few cells at the leaf margin is tightly associated with the control of differential growth.