title: The tarani mutation alters surface curvature in Arabidopsis leaves by perturbing the patterns of surface expansion and cell division.
abstract: The leaf surface usually stays flat, maintained by coordinated growth. Growth perturbation can introduce overall surface curvature, which can be negative, giving a saddle-shaped leaf, or positive, giving a cup-like leaf. Little is known about the molecular mechanisms that underlie leaf flatness, primarily because only a few mutants with altered surface curvature have been isolated and studied. Characterization of mutants of the CINCINNATA-like TCP genes in Antirrhinum and Arabidopsis have revealed that their products help maintain flatness by balancing the pattern of cell proliferation and surface expansion between the margin and the central zone during leaf morphogenesis. On the other hand, deletion of two homologous PEAPOD genes causes cup-shaped leaves in Arabidopsis due to excess division of dispersed meristemoid cells. Here, we report the isolation and characterization of an Arabidopsis mutant, tarani (tni), with enlarged, cup-shaped leaves. Morphometric analyses showed that the positive curvature of the tni leaf is linked to excess growth at the centre compared to the margin. By monitoring the dynamic pattern of CYCLIN D3;2 expression, we show that the shape of the primary arrest front is strongly convex in growing tni leaves, leading to excess mitotic expansion synchronized with excess cell proliferation at the centre. Reduction of cell proliferation and of endogenous gibberellic acid levels rescued the tni phenotype. Genetic interactions demonstrated that TNI maintains leaf flatness independent of TCPs and PEAPODs.
authors.affiliation: Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560 012, India.
authors.forename: Premananda
authors.initials: P
authors.lastname: Karidas
authors.affiliation: Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560 012, India.
authors.forename: Krishna Reddy
authors.initials: KR
authors.lastname: Challa
authors.affiliation: Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560 012, India utpal@mcbl.iisc.ernet.in.
authors.forename: Utpal
authors.initials: U
authors.lastname: Nath
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002454:Cell Differentiation; D002455:Cell Division; D049109:Cell Proliferation; D002874:Chromosome Mapping; D018548:Cotyledon / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development; D016213:Cyclins / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D005875:Gibberellins / Q000378:metabolism; D009154:Mutation; D010641:Phenotype; D018515:Plant Leaves / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development; D030821:Plants, Genetically Modified; D036226:Seedlings / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development
chemical_list: D029681:Arabidopsis Proteins; C496944:CycD3 protein, Arabidopsis; D016213:Cyclins; D004268:DNA-Binding Proteins; D005875:Gibberellins; C513798:PEAPOD protein, Arabidopsis; C007842:gibberellic acid
keywords: Arabidopsis thaliana; TARANI.; cell proliferation; gibberellic acid (GA); leaf shape; surface curvature