Brassinosteroids (BRs) collectively refer to the plant steroid hormones, which were first isolated from pollen of rape plants belonging to the Brassicaceae family. The chemical structure of brassinolide, the most active compounds among more than 50 BRs identified to date, was determined in 1979 after X-ray crystallography. However, the importance of these compounds as plant growth-promoting hormones was re-discovered in 1990s after extensive research on Arabidopsis mutants that are defective in either biosynthesis or signaling pathways of BRs.
The primary effects of BRs in plant biology include stimulation of cell division and differentiation. Especially, BR deficient mutants display characteristic phenotypes attributable to retarded elongation of the cells. Furthermore, BRs are central to control xylem tissue development. More recently, their roles in regulation of plant stress responses are being revealed.
We are primarily interested in genetic and biochemical elucidation of the whole biosynthetic pathways of BRs, and their regulation. In addition, we aim to reveal the evolutionary mechanisms of interaction of these pathways with other plant hormones such as auxin, salicylic acid, jasmonic acid, ethylene, gibberellins, cytokinins, and abscisic acid.
Our understanding on BR biology will lead to development of crop plants that possess the novel traits conferring an increase in yield of grain or biomass production.