Involved in strigolactones biosynthesis by catalyzing the isomerization of the C9-C10 double bond in all-trans-beta-carotene leading to 9-cis-beta-carotene and providing the substrate for CCD7. 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. all-trans-beta-carotene = 9-cis-beta-carotene A number of isoforms are produced. According to EST sequences. Expressed in hypocotyls and shoots. Expressed at low levels in roots. Increased shoot branching.