Abstract: cDNA encoding (-)-4S-limonene synthase from spearmint has been isolated and sequenced, and the corresponding amino acid sequence has been determined. Accordingly, isolated DNA sequences are provided which code for the expression of limonene synthase, such as the sequence designated SEQ ID No:11 which encodes limonene synthase from spearmint (Mentha spicata). In other aspects, replicable recombinant cloning vehicles are provided which code for limonene synthase or for a base sequence sufficiently complementary to at least a portion of the limonene synthase DNA or RNA to enable hybridization therewith (e.g., antisense limonene synthase RNA or fragments of complementary limonene synthase DNA which are useful as polymerase chain reaction primers or as probes for limonene synthase or related genes). In yet other aspects, modified host cells are provided that have been transformed, transfected, infected and/or injected with a recombinant cloning vehicle and/or DNA sequence encoding limonene synthase.