Increased Leaf Angle1, a Raf-Like MAPKKK That Interacts with a Nuclear Protein Family, Regulates Mechanical Tissue Formation in the Lamina Joint of Rice

摘要: Mitogen-activated protein kinase kinases (MAPKKKs), which function at the top level of mitogen-activated cascades, are clustered into three groups. However, no Group C Raf-like MAPKKKs have yet been functionally identified. We report here characterization a rice (Oryza sativa) mutant, increased leaf angle1 (ila1), resulting from T-DNA insertion in MAPKKK gene. The angle ila1 is caused by abnormal vascular bundle formation and cell wall composition lamina joint, as distinct mechanism observed brassinosteroid-related mutants. Phosphorylation assays revealed that ILA1 functional with Ser/Thr activity. predominantly resident nucleus expressed bundles joints. Yeast two-hybrid screening identified six closely related interacting proteins (IIPs) unknown function. Using representative IIPs, interaction IIPs was confirmed vivo. were localized showed transactivation Furthermore, could phosphorylate IIP4, indicating may be downstream substrates ILA1. Microarray analyses joints provided additional evidence for alterations mechanical strength ila1. thus key factor regulating tissue joint.