Screening and characterization of brassinosteroid signaling mutant [I]bil[/I] ([I]Brz-insensitive-long hypocotyl[/I]) as a plant chemical genetics using brassinosteroid biosynthesis inhibitior, Brz.

Abstract

Brassinosteriods are sterol-derived plant growth regulators with important biological activities, including promotion of cell elongation, negative regulation of chloroplast development and so on. Brz (brassinazole) was synthesized as the first specific inhibitor of brassinosteroid biosynthesis by Asami et al. Target of Brz220 is the cytochrome P450 enzyme encoded by [I]DWF4[/I]. We screened for mutants that showed longer hypocotyls than wild type when grown with Brz220 in the dark, and designated [I]bil[/I] mutants ([I]Brz-insensitive-long hypocotyl[/I]). The working hypothesis for mutants screening by chemicals is going to be called as chemical genetics. Our trials for [I]bil[/I] screening could be remarked as the pioneer research for plant chemical genetics.
At this symposium, we will introduce [I]bzr1-D/bil1-D[/I] that showed longest hypocotyl in the dark with Brz and the gene encoded an protein imported from cytosol to nuclei, a semi-dominant mutant [I]bil5[/I] that showes pale green, thin stems, and thin leaves.