Brassinosteroids are steroidal phytohormones required for the growth and development of plants and are widely used in agriculture to improve crop yields. They are synthesized in the cell interior, but they bind their receptors at the cell surface. While brassinosteroids were discovered over 50 years ago, research on the mechanisms exporting them out of the cell lagged for decades. Researchers have now uncovered a role for the Arabidopsis ABC transporter ABCB19, formerly known as an auxin transporter, in brassinosteroid export. Future research will unravel the mechanisms regulating the ABCB19 activation and substrate preference and hopefully identify additional brassinosteroid exporters. Such mechanisms will help design more effective strategies to improve plant productivity and resilience via modulating endogenous brassinosteroid amounts and distribution.
