title: Propiconazole is a specific and accessible brassinosteroid (BR) biosynthesis inhibitor for Arabidopsis and maize.
abstract: Brassinosteroids (BRs) are steroidal hormones that play pivotal roles during plant development. In addition to the characterization of BR deficient mutants, specific BR biosynthesis inhibitors played an essential role in the elucidation of BR function in plants. However, high costs and limited availability of common BR biosynthetic inhibitors constrain their key advantage as a species-independent tool to investigate BR function. We studied propiconazole (Pcz) as an alternative to the BR inhibitor brassinazole (Brz). Arabidopsis seedlings treated with Pcz phenocopied BR biosynthetic mutants. The steady state mRNA levels of BR, but not gibberellic acid (GA), regulated genes increased proportional to the concentrations of Pcz. Moreover, root inhibition and Pcz-induced expression of BR biosynthetic genes were rescued by 24epi-brassinolide, but not by GA(3) co-applications. Maize seedlings treated with Pcz showed impaired mesocotyl, coleoptile, and true leaf elongation. Interestingly, the genetic background strongly impacted the tissue specific sensitivity towards Pcz. Based on these findings we conclude that Pcz is a potent and specific inhibitor of BR biosynthesis and an alternative to Brz. The reduced cost and increased availability of Pcz, compared to Brz, opens new possibilities to study BR function in larger crop species.
authors.affiliation: Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana, United States of America.
authors.forename: Thomas
authors.initials: T
authors.lastname: Hartwig
authors.forename: Claudia
authors.initials: C
authors.lastname: Corvalan
authors.forename: Norman B
authors.initials: NB
authors.lastname: Best
authors.forename: Joshua S
authors.initials: JS
authors.lastname: Budka
authors.forename: Jia-Ying
authors.initials: JY
authors.lastname: Zhu
authors.forename: Sunghwa
authors.initials: S
authors.lastname: Choe
authors.forename: Burkhard
authors.initials: B
authors.lastname: Schulz
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D060406:Brassinosteroids / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D009154:Mutation; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D018749:RNA, Plant / Q000096:biosynthesis / Q000235:genetics; D036226:Seedlings / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D014230:Triazoles / Q000494:pharmacology*; D003313:Zea mays / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
chemical_list: D060406:Brassinosteroids; D012333:RNA, Messenger; D018749:RNA, Plant; D014230:Triazoles; C045950:propiconazole; C412342:brassinazole