BIOCHEMICAL AND GENETIC-ANALYSIS OF BRASSINOSTEROID METABOLISM AND FUNCTION IN ARABIDOPSIS

Recent analysis of several constitutive photomorphogenic Arabidopsis m utants, defective in brassinosteroid biosynthesis or signaling, provid ed unequivocal evidence for the essential phytohormone function of bra ssinosteroids. From earlier studies a wealth of information is availab le regarding the occurrence of these steroids and their potential inte raction with regulatory mechanisms controlled by other plant hormones. In addition, the major pathways of brassinosteroid biosynthesis and m etabolism have been clarified in the past couple of years and signific ant efforts have been made to characterize structure-function relation ships. This knowledge is now being confronted with data emerging from genetic and molecular analysis of the gene mutations and functions aff ecting brassinosteroid synthesis and signaling. Future progress in thi s field is expected to give insight into the evolution of steroid horm one regulation in eukaryotes, as well as the mechanisms by which brass inosteroids control basic functions, such as cell elongation, morphoge nesis and stress responses. (C) Elsevier, Paris.