Brassinosteroid biosynthesis and metabolism

Abstract

The sessile nature of plants requires distinctive regulatory mechanisms to meet the demands of development and environmental challenges. Various plant hormones that act alone or in concert underpin these mechanisms. Brassinosteroids (BRs) collectively refers to naturally-occurring 5α cholestane steroids that elicit growth stimulation in nano- or micromolar concentrations (15). BRs that are biosynthesized using sterols as precursors are structurally similar to the cholesterol-derived, human steroid hormones and insect molting hormones. BRs have been known for decades to be effective in plant growth promotion. However, definitive evidence for their roles in growth and development remained unclear until the recent characterization of BR dwarf mutants isolated from Arabidopsis and other plants. This chapter1 aims to provide a cohesive summary of information about progress made in the molecular genetic characterization of mutants that are defective in sterol and BR biosynthetic pathways.