title: hoc: An Arabidopsis mutant overproducing cytokinins and expressing high in vitro organogenic capacity.
abstract: A novel Arabidopsis thaliana mutant, named hoc, was found to have an high organogenic capacity for shoot regeneration. The HOC locus may be involved in cytokinin metabolism leading to cytokinin-overproduction. In vitro, hoc root explants develop many shoots in the absence of exogenous growth regulators. The mutant displays a bushy phenotype with supernumerary rosettes and with normal phyllotaxy, resulting from precocious axillary meristem development. Genetic and molecular analyses show that the high shoot regeneration and the bushy phenotype are controlled by a recessive single gene, located on chromosome I, next to the GAPB CAPS marker. The mapping data and allelism tests reveal that the hoc mutant is not allelic to other reported Arabidopsis growth-regulator mutants. In darkness the hoc mutant is de-etiolated, with a short hypocotyl, opened cotyledons and true leaves. Growth regulator assays reveal that the mutant accumulates cytokinins at about two- and sevenfold the cytokinin level of wild-type plants in its aerial parts and roots, respectively. Consequently, the elevated amounts of endogenous cytokinins in hoc plants are associated with high organogenic capacity and hence bushy phenotype. Thus hoc is the first cytokinin-overproducing Arabidopsis mutant capable of auto-regenerating shoots without exogenous growth regulators.
authors: Laboratoire Androgenèse et Biotechnologie, Université de Picardie Jules Verne, Faculté des Sciences, 33 rue Saint-Leu, 80039 Amiens Cedex 1, France.
authors: Manuella
authors: M
authors: Catterou
authors: Frédéric
authors: F
authors: Dubois
authors: Raphael
authors: R
authors: Smets
authors: Sébastien
authors: S
authors: Vaniet
authors: Thomas
authors: T
authors: Kichey
authors: Harry
authors: H
authors: Van Onckelen
authors: Brigitte S
authors: BS
authors: Sangwan-Norreel
authors: Rajbir S
authors: RS
authors: Sangwan
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D002874:Chromosome Mapping; D003583:Cytokinins / Q000378:metabolism* / Q000494:pharmacology; D003624:Darkness; D004305:Dose-Response Relationship, Drug; D005030:Ethylenes / Q000378:metabolism / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005875:Gibberellins / Q000378:metabolism / Q000494:pharmacology; D007210:Indoleacetic Acids / Q000378:metabolism / Q000494:pharmacology; D008027:Light; D018519:Meristem / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D009154:Mutation; D010641:Phenotype; D010937:Plant Growth Regulators / Q000378:metabolism / Q000494:pharmacology; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism
chemical_list: D003583:Cytokinins; D005030:Ethylenes; D005875:Gibberellins; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; C036216:ethylene