title: CINCINNATA in Antirrhinum majus directly modulates genes involved in cytokinin and auxin signaling.
abstract: Mutations in the CINCINNATA (CIN) gene in Antirrhinum majus and its orthologs in Arabidopsis result in crinkly leaves as a result of excess growth towards the leaf margin. CIN homologs code for TCP (TEOSINTE-BRANCHED 1, CYCLOIDEA, PROLIFERATING CELL FACTOR 1 AND 2) transcription factors and are expressed in a broad zone in a growing leaf distal to the proliferation zone where they accelerate cell maturation. Although a few TCP targets are known, the functional basis of CIN-mediated leaf morphogenesis remains unclear. We compared the global transcription profiles of wild-type and the cin mutant of A. majus to identify the targets of CIN. We cloned and studied the direct targets using RNA in situ hybridization, DNA-protein interaction, chromatin immunoprecipitation and reporter gene analysis. Many of the genes involved in the auxin and cytokinin signaling pathways showed altered expression in the cin mutant. Further, we showed that CIN binds to genomic regions and directly promotes the transcription of a cytokinin receptor homolog HISTIDINE KINASE 4 (AmHK4) and an IAA3/SHY2 (INDOLE-3-ACETIC ACID INDUCIBLE 3/SHORT HYPOCOTYL 2) homolog in A. majus. Our results suggest that CIN limits excess cell proliferation and maintains the flatness of the leaf surface by directly modulating the hormone pathways involved in patterning cell proliferation and differentiation during leaf growth.
authors.affiliation: Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, 560 012, India.
authors.forename: Mainak
authors.initials: M
authors.lastname: Das Gupta
authors.forename: Pooja
authors.initials: P
authors.lastname: Aggarwal
authors.forename: Utpal
authors.initials: U
authors.lastname: Nath
mesh_terms: D032161:Antirrhinum / Q000235:genetics* / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics; D049109:Cell Proliferation; D047369:Chromatin Immunoprecipitation; D003583:Cytokinins / Q000235:genetics / Q000378:metabolism*; D020224:Expressed Sequence Tags; D018506:Gene Expression Regulation, Plant; D007210:Indoleacetic Acids / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D018515:Plant Leaves / Q000166:cytology / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic; D015398:Signal Transduction / Q000235:genetics
chemical_list: D003583:Cytokinins; D007210:Indoleacetic Acids; D010940:Plant Proteins
keywords: Antirrhinum; CINCINNATA (CIN)/TCP (TEOSINTE-BRANCHED 1, CYCLOIDEA, PROLIFERATING CELL FACTOR 1 AND 2); hormone signaling; leaf morphogenesis; transcriptional regulation