The present disclosure relates to a new class of cytokinin biosynthetic enzymes, cytokinin synthases, which have two domains: an isopentenyl transfer (IPT)-like domain and a cytokinin nucleotide phosphoribohydrolase (PRH)-like domain. The invention provides compositions and methods for the recombinant production of cytokinin synthase, host cells and transformants that include the cytokinin synthases, as well as compositions and formulations that include the disclosed cytokinin synthase.