title: Alkoxy-auxins are selective inhibitors of auxin transport mediated by PIN, ABCB, and AUX1 transporters.
abstract: Polar auxin movement is a primary regulator of programmed and plastic plant development. Auxin transport is highly regulated at the cellular level and is mediated by coordinated transport activity of plasma membrane-localized PIN, ABCB, and AUX1/LAX transporters. The activity of these transporters has been extensively analyzed using a combination of pharmacological inhibitors, synthetic auxins, and knock-out mutants in Arabidopsis. However, efforts to analyze auxin-dependent growth in other species that are less tractable to genetic manipulation require more selective inhibitors than are currently available. In this report, we characterize the inhibitory activity of 5-alkoxy derivatives of indole 3-acetic acid and 7-alkoxy derivatives of naphthalene 1-acetic acid, finding that the hexyloxy and benzyloxy derivatives act as potent inhibitors of auxin action in plants. These alkoxy-auxin analogs inhibit polar auxin transport and tropic responses associated with asymmetric auxin distribution in Arabidopsis and maize. The alkoxy-auxin analogs inhibit auxin transport mediated by AUX1, PIN, and ABCB proteins expressed in yeast. However, these analogs did not inhibit or activate SCF(TIR1) auxin signaling and had no effect on the subcellular trafficking of PIN proteins. Together these results indicate that alkoxy-auxins are inactive auxin analogs for auxin signaling, but are recognized by PIN, ABCB, and AUX1 auxin transport proteins. Alkoxy-auxins are powerful new tools for analyses of auxin-dependent development.
authors.affiliation: Department of Biochemistry, Okayama University of Science, 1-1 Ridai-cho, Okayama 700-0005, Japan.
authors.forename: Etsuko
authors.initials: E
authors.lastname: Tsuda
authors.forename: Haibing
authors.initials: H
authors.lastname: Yang
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nishimura
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Uehara
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Sakai
authors.forename: Masahiko
authors.initials: M
authors.lastname: Furutani
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Koshiba
authors.forename: Masakazu
authors.initials: M
authors.lastname: Hirose
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nozaki
authors.forename: Angus S
authors.initials: AS
authors.lastname: Murphy
authors.forename: Ken-ichiro
authors.initials: K
authors.lastname: Hayashi
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D044783:F-Box Proteins / Q000235:genetics / Q000378:metabolism; D007210:Indoleacetic Acids / Q000037:antagonists & inhibitors* / Q000378:metabolism* / Q000494:pharmacology; D009281:Naphthalenes / Q000494:pharmacology*; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D003313:Zea mays / Q000235:genetics / Q000378:metabolism*
chemical_list: C100794:AUX1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D044783:F-Box Proteins; D007210:Indoleacetic Acids; D009281:Naphthalenes; D011956:Receptors, Cell Surface; C501405:TIR1 protein, Arabidopsis; C030737:indoleacetic acid