Characterization of Brassinazole, a Triazole-Type Brassinosteroid Biosynthesis Inhibitor

Screening for brassinosteroid (BR) biosynthesis inhibitors was performed to find chemicals that induce dwarfism in Arabidopsis, mutants that resembled BR biosynthesis mutants that can be rescued by BR. Through this screening experiment, the compound brassinazole was selected as the most potent chemi...

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Bibliographic Details
Published in:Plant physiology (Bethesda) 2000-05, Vol.123 (1), p.93-99
Main Authors: Asami, Tadao, Yong Ki Min, Nagata, Noriko, Kazutoshi Yamagishi, Takatsuto, Suguru, Fujioka, Shozo, Noboru Murofushi, Yamaguchi, Isomaro, Yoshida, Shigeo
Format: Article
Language:English
Subjects:
Arabidopsis - metabolism
Biological and medical sciences
Biosynthesis
Brassinosteroids
Cell growth
Cytochromes
Development and Hormone Action
Dwarfism
Fundamental and applied biological sciences. Psychology
Gibberellins
Growth regulators
Hypocotyls
Metabolism
Plant cells
Plant growth
Plant physiology and development
Plants
Seedlings
Steroids - antagonists & inhibitors
Steroids - biosynthesis
Triazoles - metabolism
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Summary:Screening for brassinosteroid (BR) biosynthesis inhibitors was performed to find chemicals that induce dwarfism in Arabidopsis, mutants that resembled BR biosynthesis mutants that can be rescued by BR. Through this screening experiment, the compound brassinazole was selected as the most potent chemical. In dark-grown Arabidopsis, brassinazole-induced morphological changes were nearly restored to those of wild type by treatment with brassinolide. The structure of brassinazole is similar to pacrobutrazol, a gibberellin biosynthesis inhibitor. However, in assays with cress (Lepidium sativum) plants, brassinazole-treated plants did not show recovery after the addition of gibberellin but showed good recovery after the addition of brassinolide. These data demonstrate that brassinazole is a specific BR biosynthesis inhibitor. Brassinazole-treated cress also showed dwarfism, with altered leaf morphology, including the downward curling and dark green color typical of Arabidopsis BR-deficient mutants, and this dwarfism was reversed by the application of 10 nM brassinolide. This result suggests that BRs are essential for plant growth, and that brassinazole can be used to clarify the function of BRs in plants as a complement to BR-deficient mutants. The brassinazole action site was also investigated by feeding BR biosynthesis intermediates to cress grown in the light.
ISSN:0032-0889
1532-2548
DOI:10.1104/pp.123.1.93