title: Brassinosteroid signals control expression of the AXR3/IAA17 gene in the cross-talk point with auxin in root development.
abstract: Transgenic plants overexpressing AXR3/IAA17 were impaired in root growth. Specifically, they exhibited severe defects in lateral root and root hair development similar to the root phenotypes of epi-brassinolide (epiBL)-treated wild-type plants. Here, we investigated the involvement of AXR3/IAA17 gene expression in brassinosteroid (BR)-regulated root development. Exogenous epiBL application significantly induced expression of the AXR3/IAA17 gene as well as several Aux/IAA genes, such as AXR2/IAA7, SLR/IAA14, and IAA28. We analyzed the transcription levels of several Aux/IAA genes related to root development in the BR signaling mutant bri1 and the BR biosynthesis mutant det2. AXR3/IAA17 gene expression was significantly decreased in bri1 plants. In det2 plants, expression of AXR3/IAA17 slightly decreased. This in turn suggests that epiBL induced these Aux/IAA genes, and that these induced gene products might function as factors in root development. Furthermore, AXR3/IAA17 might be involved in the BR signaling pathway, suggesting an intersection node of BR-auxin signaling in root development.
authors.affiliation: Department of Biological Sciences, Seoul National University, Republic of Korea.
authors.forename: Hoyeun
authors.initials: H
authors.lastname: Kim
authors.forename: Pil-Joon
authors.initials: PJ
authors.lastname: Park
authors.forename: Hyun-Ju
authors.initials: HJ
authors.lastname: Hwang
authors.forename: So-Young
authors.initials: SY
authors.lastname: Lee
authors.forename: Man-Ho
authors.initials: MH
authors.lastname: Oh
authors.forename: Sang-Gu
authors.initials: SG
authors.lastname: Kim
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics*; D060406:Brassinosteroids; D002777:Cholestanols / Q000494:pharmacology*; D004268:DNA-Binding Proteins / Q000235:genetics*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D009154:Mutation / Q000235:genetics; D009687:Nuclear Proteins / Q000235:genetics*; D010641:Phenotype; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D030821:Plants, Genetically Modified; D036226:Seedlings / Q000235:genetics; D013260:Steroids, Heterocyclic / Q000494:pharmacology*; D014157:Transcription Factors
chemical_list: C110728:AXR3 protein, Arabidopsis; D029681:Arabidopsis Proteins; D060406:Brassinosteroids; D002777:Cholestanols; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D013260:Steroids, Heterocyclic; D014157:Transcription Factors; C023623:brassinolide