Plants respond to various external and internal stimuli by activating signal transduction pathways. The plasma membrane, acting as the cell boundary, provides a platform for various signaling components. These include cell surface receptor-like kinases, intrinsic transporters, membrane-anchored proteins, and cytosolic signaling components attached to the membrane from its cytosolic side. Phosphorylation is one of the most sensitive and essential post-translational modifications. To identify the sequential kinase-target relationships and understand the triggers for downstream regulatory complexes, we employed a phosphoproteomic approach. By subjecting plants to brassinolide and/or sucrose, we aim to identify the BR-BRI1 downstream substrates and investigate the possible impact of sucrose on this signaling pathway.