Phylogenetic tree of terpene synthases from the Asteraceae showing relationships among the isolated chamomile TPS genes. Clusters corresponding to two TPS subfamilies (TPS a and TPS b) are apparent. As an outgroup, a diterpene synthase from primary metabolism was chosen. New terpene synthases from chamomile are written in bold. The alignment was accomplished with the ClustalX algorithm. Trees were inferred with the neighbor-joining method and n = 1000 replicates for bootstrapping. Accession numbers are provided in Additional file 2: Table S2.