Analysis of Brassinosteroid Signaling Mutant bil(brz-insensitive-long hypocotyl)

Abstract

In order to analyze the mechanism of brassinosteroid signal transduction in detail, we screened for mutants that showed resistance to brassinosteroid biosynthesis inhibitor Brz220 effects. At first, we identified a semidominant mutant, bil1-1D from EMS-lines. In the Brz 3mM medium, that wild-type plant showed a quite short hypocotyl, but the mutant showed a hypocotyl length as long as the wild type grown on the Brz-unsupplemented medium. The genomic walking results of bzr1-1D(brz-resistant1) revealed that the bil1-1D gene is the just same gene with bzr1-1D, and shared the 88 % identity with bes1(bri1-EMS-suppressor). GFP fusion protein analysis revealed that the plant specific new gene family BZR1/BES1/BIL1 is a key component of the brassinosteroid signaling from the cytosol to nucleus. Analysis of a recessive mutant bil5 was also in progress.