Brassinosteroids Brassinosteroids (BRs) are
steroid hormones ubiquitously found in plants but first purified from
Brassica. BRs contribute to growth, vascular differentiation,
reproductive development, and stress responses. In the 1990s BR
biosynthesis and response mutants were identified, allowing the complete
pathway from synthesis to response to be assembled. BRs are remarkable
in the diversity of their actions, and have potential applications
ranging from improving plant stress tolerances to increasing grain
yields. First posted September 30, 2010, revised November 26, 2014 by John Chandler ( and Mary Williams.