title: p-Chlorophenoxyisobutyric acid impairs auxin response in Arabidopsis root.
abstract: p-Chlorophenoxyisobutyric acid (PCIB) is known as a putative antiauxin and is widely used to inhibit auxin action, although the mechanism of PCIB-mediated inhibition of auxin action is not characterized very well at the molecular level. In the present work, we showed that PCIB inhibited BA::beta-glucuronidase (GUS) expression induced by indole-3-acetic acid (IAA), 2,4-dichlorophenoxyacetic acid, and 1-naphthaleneacetic acid. PCIB also inhibited auxin-dependent DR5::GUS expression. RNA hybridization and quantitative reverse transcriptase-polymerase chain reaction analyses suggested that PCIB reduced auxin-induced accumulation of transcripts of Aux/IAA genes. In addition, PCIB relieved the reduction of GUS activity in HS::AXR3NT-GUS transgenic line in which auxin inhibits GUS activity by promoting degradation of the AXR3NT-GUS fusion protein. Physiological analysis revealed that PCIB inhibited lateral root production, gravitropic response of roots, and growth of primary roots. These results suggest that PCIB impairs auxin-signaling pathway by regulating Aux/IAA protein stability and thereby affects the auxin-regulated Arabidopsis root physiology.
authors.affiliation: Department of Ion-beam-applied Biology, Japan Atomic Energy Research Institute, Takasaki 370-1292, Japan. yoono@taka.jaeri.go.jp
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Oono
authors.forename: Chiharu
authors.initials: C
authors.lastname: Ooura
authors.forename: Abidur
authors.initials: A
authors.lastname: Rahman
authors.forename: Evalour T
authors.initials: ET
authors.lastname: Aspuria
authors.forename: Ken-ichiro
authors.initials: K
authors.lastname: Hayashi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Tanaka
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Uchimiya
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D002995:Clofibric Acid / Q000494:pharmacology*; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005966:Glucuronidase / Q000187:drug effects / Q000378:metabolism; D007210:Indoleacetic Acids / Q000494:pharmacology*; D009280:Naphthaleneacetic Acids / Q000494:pharmacology; D010937:Plant Growth Regulators / Q000494:pharmacology; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
chemical_list: D007210:Indoleacetic Acids; D009280:Naphthaleneacetic Acids; D010937:Plant Growth Regulators; D015084:2,4-Dichlorophenoxyacetic Acid; C034182:1-naphthaleneacetic acid; D002995:Clofibric Acid; C030737:indoleacetic acid; D005966:Glucuronidase