Brassinosteroid (BR) is an endogenous steroid hormone in plants, which is considered to play an important role in regulating plant growth and development. Brassinolide guanylate exchange factor (BRI 1) is a membrane receptor protein responsible for mediating brassinolide signal transduction. BRI 1 belongs to the family of membrane receptor kinases, with its N-terminal located outside the cell and its C-terminal connected to the cytoplasm. When brassinolide molecules are bound to the outside of BRI 1 protein, it will cause conformational changes in protein, promote the formation of complexes between BRI 1 and other protein (such as BAK 1), and thus trigger the cascade reaction of downstream signal transduction pathways, thus affecting the process of plant growth and development.