Brassinosteroid signal transduction: still casting the actors

Significant advances in the genetic dissection of brassinosteroid biosynthe sis and signaling have been made during the past few years. Genetic and bio chemical data have helped to elucidate the pathways of biosynthesis of bras sinolide, the most active brassinosteroid. In addition, several models have been put forward for the perception of brassinolide by its putative recept or, BRI1, a ubiquitously expressed plasma membrane localized protein kinase . These studies provide the basic framework for future analysis of brassino steroid signaling.