hca: an Arabidopsis mutant exhibiting unusual cambial activity and altered vascular patterning.
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.
Pineau
Christophe
C
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.
Freydier
Amandine
A
Ranocha
Philippe
P
Jauneau
Alain
A
Turner
Simon
S
Lemonnier
Gaëtan
G
Renou
Jean-Pierre
JP
Tarkowski
Petr
P
Sandberg
Göran
G
Jouanin
Lise
L
Sundberg
Björn
B
Boudet
Alain-Michel
AM
Goffner
Deborah
D
Pichon
Magalie
M
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
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