Conserved functional control, but distinct regulation, of cell proliferation in rice and leaves revealed by comparative analysis of orthologs.

Regulation of cell proliferation is crucial for establishing the shape of plant leaves. We have identified (), a loss-of-function mutant of which exhibits a narrowed- and rolled-leaf phenotype in rice. was found to be an ortholog of (), which positively regulates cell proliferation. The reduced leaf size of plants with enlarged cells and the increased size of overexpressing leaves with normal-sized cells indicate that is a positive regulator of leaf proliferation and that mutation triggers a compensation syndrome, as does Expression analysis revealed that is predominantly expressed on the epidermis of leaf primordia, which is different from the location of A protein movement assay demonstrated that MKB3 moves from an expressing domain to a non-expressing domain, which is required for normal leaf development. Our results suggest that rice and have conserved functions and effects on leaf development. However, the expression pattern of and direction of protein movement are different between rice and , which might reflect differences in leaf primordia development in these two species.