title: hca: an Arabidopsis mutant exhibiting unusual cambial activity and altered vascular patterning.
abstract: By screening a T-DNA population of Arabidopsis mutants for alterations in inflorescence stem vasculature, we have isolated a mutant with a dramatic increase in vascular tissue development, characterized by a continuous ring of xylem/phloem. This phenotype is the consequence of premature and numerous cambial cell divisions in both the fascicular and interfascicular regions that result in the loss of the alternate vascular bundle/fiber organization typically observed in Arabidopsis stems. The mutant was therefore designated high cambial activity (hca). The hca mutation also resulted in pleiotropic effects including stunting and a delay in developmental events such as flowering and senescence. The physiological characterization of hca seedlings in vitro revealed an altered auxin and cytokinin response and, most strikingly, an enhanced sensitivity to cytokinin. These results were substantiated by comparative microarray analysis between hca and wild-type plants. The genetic analysis of hca indicated that the mutant phenotype was not tagged by the T-DNA and that the hca mutation segregated as a single recessive locus, mapping to the long arm of chromosome 4. We propose that hca is involved in mechanisms controlling the arrangement of vascular bundles throughout the plant by regulating the auxin-cytokinin sensitivity of vascular cambial cells. Thus, the hca mutant is a useful model for examining the genetic and hormonal control of cambial growth and differentiation.
authors.affiliation: Surfaces Cellulaires et Signalisation chez les Végétaux, Unité Mixte de Recherche, Centre National de la Recherche Scientifique - Université Paul Sabatier 5546, Pôle de Biotechnologie Végétale, 31326 Castanet Tolosan, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Pineau
authors.forename: Amandine
authors.initials: A
authors.lastname: Freydier
authors.forename: Philippe
authors.initials: P
authors.lastname: Ranocha
authors.forename: Alain
authors.initials: A
authors.lastname: Jauneau
authors.forename: Simon
authors.initials: S
authors.lastname: Turner
authors.forename: Gaëtan
authors.initials: G
authors.lastname: Lemonnier
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Renou
authors.forename: Petr
authors.initials: P
authors.lastname: Tarkowski
authors.forename: Göran
authors.initials: G
authors.lastname: Sandberg
authors.forename: Lise
authors.initials: L
authors.lastname: Jouanin
authors.forename: Björn
authors.initials: B
authors.lastname: Sundberg
authors.forename: Alain-Michel
authors.initials: AM
authors.lastname: Boudet
authors.forename: Deborah
authors.initials: D
authors.lastname: Goffner
authors.forename: Magalie
authors.initials: M
authors.lastname: Pichon
mesh_terms: D017360:Arabidopsis / Q000033:anatomy & histology* / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D002874:Chromosome Mapping; D032461:Chromosomes, Plant / Q000235:genetics; D003583:Cytokinins / Q000494:pharmacology; D004269:DNA, Bacterial / Q000235:genetics; D018398:Homeodomain Proteins / Q000378:metabolism; D007210:Indoleacetic Acids / Q000494:pharmacology; D009024:Morphogenesis; D009154:Mutation / Q000235:genetics*; D010641:Phenotype; D018515:Plant Leaves / Q000033:anatomy & histology / Q000235:genetics; D018517:Plant Roots / Q000033:anatomy & histology / Q000235:genetics; D018547:Plant Stems / Q000033:anatomy & histology / Q000235:genetics; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development; D014157:Transcription Factors / Q000378:metabolism; D015854:Up-Regulation
chemical_list: C098015:ATHB-8 protein, Arabidopsis; D029681:Arabidopsis Proteins; D003583:Cytokinins; D004269:DNA, Bacterial; D018398:Homeodomain Proteins; D007210:Indoleacetic Acids; C036483:T-DNA; D014157:Transcription Factors