Annu. Rev. Plant Physiol. Plant Mol. Biol. 1998. 49:427–51 Copyright c 1998 by Annual Reviews. All rights reserved
BRASSINOSTEROIDS: Essential Regulators of Plant Growth and Development
Steven D. Clouse
Department of Horticultural Science, North Carolina State University, Raleigh, North Carolina 27695
Jenneth M. Sasse
School of Forestry and Resource Conservation, University of Melbourne, Parkville, Victoria 3052, Australia
KEY WORDS: steroid biosynthesis, cell elongation, signal transduction, hormone-insensitive mutant, hormone-deﬁcient mutant
Brassinosteroids (BRs) are growth-promoting natural products found at low levels in pollen, seeds, and young vegetative tissues throughout the plant kingdom. Detailed studies of BR biosynthesis and metabolism, coupled with the recent identiﬁcation of BR-insensitive and BR-deﬁcient mutants, has greatly expanded our view of steroids as signals controlling plant growth and development. This review examines the microchemical and molecular genetic analyses that have provided convincing evidence for an essential role of BRs in diverse developmental programs, including cell expansion, vascular differentiation, etiolation, and reproductive development. Recent advances relevant to the molecular mechanisms of BR-regulated gene expression and BR signal transduction are also discussed.