Curruption in India

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

ABSTRACT
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.

CONTENTS
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OCCURRENCE AND LOCALIZATION OF BRs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Distribution and Endogenous Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Methods of Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BIOSYNTHESIS AND METABOLISM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Early and Late C6 Oxidation Pathways . . . . ....