Involved in carotenoid biosynthesis. Catalyzes the double cyclization reaction which converts lycopene to beta-carotene and neurosporene to beta-zeacarotene (PubMed:8837512). Major lycopene beta-cyclase that does not seem to be involved in neoxanthin synthesis (PubMed:19549928). Involved in salt tolerance improvement by increasing synthesis of carotenoids, which impairs reactive oxygen species (ROS) and protects the photosynthetic system under salt stress (PubMed:21471119). a carotenoid psi-end group = a carotenoid beta-end derivative Carotenoid biosynthesis; beta-carotene biosynthesis. Carotenoid biosynthesis; beta-zeacarotene biosynthesis. Plants overexpressing LYC1 exhibit improved tolerance to salt stress. Belongs to the lycopene cyclase family.