title: Analysis of the competence to respond to KNOTTED1 activity in Arabidopsis leaves using a steroid induction system.
abstract: Expression of KNOX (KNOTTED1-like homeobox) genes in the shoot apical meristem of Arabidopsis is required for maintenance of a functional meristem, whereas exclusion of KNOX gene expression from leaf primordia is required for the elaboration of normal leaf morphology. We have constructed a steroid-inducible system to regulate both the amount and timing of KN1 (KNOTTED1) misexpression in Arabidopsis leaves. We demonstrate that lobed leaf morphology is produced in a dose-dependent manner, indicating that the amount of KN1 quantitatively affects the severity of lobing. The KN1-glucocorticoid receptor fusion protein is not detected in leaves in the absence of steroid induction, suggesting that it is only stable when associated with steroid in an active state. By using a second inducible fusion protein to mark exposure of leaf primordia to the steroid, we determined the stage of leaf development that produces lobed leaves in response to KN1. Primordia as old as plastochron 7 and as young as plastochron 2 were competent to respond to KN1.
authors.affiliation: Plant and Microbial Biology Department, University of California, Berkeley 94720, USA.
authors.forename: Angela
authors.initials: A
authors.lastname: Hay
authors.forename: David
authors.initials: D
authors.lastname: Jackson
authors.forename: Naomi
authors.initials: N
authors.lastname: Ori
authors.forename: Sarah
authors.initials: S
authors.lastname: Hake
mesh_terms: D017360:Arabidopsis / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D003907:Dexamethasone / Q000494:pharmacology*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018398:Homeodomain Proteins / Q000378:metabolism*; D010641:Phenotype; D018515:Plant Leaves / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism*; D036226:Seedlings
chemical_list: D018398:Homeodomain Proteins; C095848:Kn1 protein, plant; D010940:Plant Proteins; D003907:Dexamethasone