Regulation of leaf maturation by chromatin-mediated modulation of cytokinin responses.

Plant shoots display indeterminate growth, while their evolutionary decedents, the leaves, are determinate. Determinate leaf growth is conditioned by the CIN-TCP transcription factors, which promote leaf maturation and are negatively regulated by miR319 in leaf primordia. Here we show that CIN-TCPs reduce leaf sensitivity to cytokinin (CK), a phytohormone implicated ...
in inhibition of differentiation in the shoot. We identify the SWI/SNF chromatin remodeling ATPase BRAHMA (BRM) as a genetic mediator of CIN-TCP activities and CK responses. An interactome screen further revealed that SWI/SNF complex components including BRM preferentially interacted with basic-helix-loop-helix (bHLH) transcription factors and the bHLH-related CIN-TCPs. Indeed, TCP4 and BRM interacted in planta. Both TCP4 and BRM bound the promoter of an inhibitor of CK responses, ARR16, and induced its expression. Reconstituting ARR16 levels in leaves with reduced CIN-TCP activity restored normal growth. Thus, CIN-TCP and BRM together promote determinate leaf growth by stage-specific modification of CK responses.
Mesh Terms:
Adenosine Triphosphatases, Arabidopsis, Arabidopsis Proteins, Basic Helix-Loop-Helix Transcription Factors, Blotting, Western, Cell Differentiation, Chromatin, Chromatin Immunoprecipitation, Cytokinins, Gene Expression Regulation, Developmental, Gene Expression Regulation, Plant, Mutation, Plant Leaves, Plants, Genetically Modified, Promoter Regions, Genetic, Protein Interaction Maps, RNA, Messenger, Real-Time Polymerase Chain Reaction, Reverse Transcriptase Polymerase Chain Reaction, Trans-Activators, Transcription Factors, Two-Hybrid System Techniques
Dev. Cell
Date: Feb. 25, 2013
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