title: Brassinosteroids interact with auxin to promote lateral root development in Arabidopsis.
abstract: Plant hormone brassinosteroids (BRs) and auxin exert some similar physiological effects likely through their functional interaction, but the mechanism for this interaction is unknown. In this study, we show that BRs are required for lateral root development in Arabidopsis and that BRs act synergistically with auxin to promte lateral root formation. BR perception is required for the transgenic expression of the beta-glucuronidase gene fused to a synthetic auxin-inducible promoter (DR5::GUS) in root tips, while exogenous BR promotes DR5::GUS expression in the root tips and the stele region proximal to the root tip. BR induction of both lateral root formation and DR5::GUS expression is suppressed by the auxin transport inhibitor N-(1-naphthyl) phthalamic acid. Importantly, BRs promote acropetal auxin transport (from the base to the tip) in the root. Our observations indicate that BRs regulate auxin transport, providing a novel mechanism for hormonal interactions in plants and supporting the hypothesis that BRs promote lateral root development by increasing acropetal auxin transport.
authors.affiliation: Department of Botany and Plant Sciences and Center for Plant Cell Biology, University of California, Riverside, California 92521, USA.
authors.forename: Fang
authors.initials: F
authors.lastname: Bao
authors.forename: Junjiang
authors.initials: J
authors.lastname: Shen
authors.forename: Shari R
authors.initials: SR
authors.lastname: Brady
authors.forename: Gloria K
authors.initials: GK
authors.lastname: Muday
authors.forename: Tadao
authors.initials: T
authors.lastname: Asami
authors.forename: Zhenbiao
authors.initials: Z
authors.lastname: Yang
mesh_terms: D017360:Arabidopsis / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D001692:Biological Transport / Q000187:drug effects; D060406:Brassinosteroids; D002777:Cholestanols / Q000494:pharmacology*; D004357:Drug Synergism; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D007210:Indoleacetic Acids / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology*; D010797:Phthalimides / Q000494:pharmacology; D010937:Plant Growth Regulators / Q000494:pharmacology*; D018517:Plant Roots / Q000187:drug effects* / Q000254:growth & development; D013260:Steroids, Heterocyclic / Q000494:pharmacology*
chemical_list: D060406:Brassinosteroids; D002777:Cholestanols; D007210:Indoleacetic Acids; D010797:Phthalimides; D010937:Plant Growth Regulators; D013260:Steroids, Heterocyclic; C002687:alpha-naphthylphthalamic acid; C030737:indoleacetic acid; C023623:brassinolide