Abstract
Brassinosteroids (BRs) are steroid hormones of plants that regulate plant growth and development. BRs are perceived by a plasma membrane receptor kinase BRI1, and then various components are predicted to be involved to transduce the BR signal in the cell. To identify additional components involved in BR signal, we had analyzed various dwarf and semidwarf mutants from Arabidopsis mutant, which is insensitive to the BR synthetic inhibitor Brz. Brz causes deetiolation and dwarf phenotype similar to those of BR-deficient mutants. We had tried to screen mutants that showed to etiolate on medium containing Brz. Here we identify a bil4 (Brz-insensitive-long hypocotyl 4) mutant from activation tagging line. bil4 mutant showed slender dwarf phenotype which small and twisted leaves, and short and thin inflorescences. From genetic and functional analyses to bil4 mutant, we would like to clarify in detail the mechanism of brassinosteroid signaling transduction.
