Involved in strigolactone signaling pathway. Functions downstream of strigolactone synthesis, as a component of hormone signaling and as an enzyme that participates in the conversion of strigolactones to the bioactive form. Binds and hydrolyzes the synthetic strigolactone analog GR24 and its enantiomers in vitro. Forms a stable covalent complex with the D-ring of strigolactone, which is essential for hormone bioactivity. The D-ring is attached to His-247 of the catalytic triad. The hydrolysis of strigolactone into a covalently linked intermediate molecule is required to trigger strigolactone signaling. This mechanism defines RMS3 as a non-canonical hormone receptor with dual functions to generate and sense the active form of strigolactone (PubMed:27479744). Strigolactones are hormones that inhibit tillering and shoot branching through the MAX-dependent pathway, contribute to the regulation of shoot architectural response to phosphate-limiting conditions and function as rhizosphere signal that stimulates hyphal branching of arbuscular mycorrhizal fungi and trigger seed germination of root parasitic weeds (Probable). Reduced plant height and extensive vegetative branching from both basal and aerial nodes. Belongs to the AB hydrolase superfamily.