In vitro characterization of a (E)-β-farnesene synthase from Matricaria recutita L. and its up-regulation by methyl jasmonate

• A full-length cDNA of Mr-βFS was cloned and characterized for the first time.
• Recombinant Mr-βFS protein displays (E)-β-farnesene synthase activity.
• Tissue distribution of Mr-βFS mRNA was investigated.
• The expression profile of Mr-βFS was up-regulated after MeJA treatment.
• The (E)-β-farnesene content was up-regulated after MeJA treatment.

(E)-β-farnesene is a sesquiterpene semiochemical that is used extensively by both plants and animals for communication. This acyclic olefin is found in the essential oil of chamomile (Matricaria recutita) and was demonstrated that it could attract natural enemies to reduce cabbage aphids in the Chinese cabbage fields. However, little is known regarding the sequence and function of (E)-β-farnesene synthase in M. recutita. In this study, we reported a new full-length cDNA encoding (E)-β-farnesene synthase from M. recutita (Mr-βFS). The cDNA of Mr-βFS consisted of 2010 bp including 1725 bp of coding sequence encoding a protein of 574 amino acids with a molecular weight of 67 kDa. The deduced amino acid sequence exhibits a considerably higher homology to βFS from Artemisia annua (about 92% identity) than to βFSs from other plants (about 20–40% identity). The recombinant enzyme, produced in Escherichia coli, catalyzed the formation of a single product, (E)-β-farnesene, from farnesyl diphosphate. Real-time quantitative PCR (qRT-PCR) analysis showed that Mr-βFS expression was highest in leaves and lowest in disk florets. The treatment of M. recutita with methyl jasmonate (MeJA) significantly enhanced the transcriptional level of βFS gene and the content of (E)-β-farnesene in M. recutita. The transcriptional level of βFS gene was approximately 11.5-fold higher than the control sample and the (E)-β-farnesene emission level ranged from approximately from 0.082 to 0.695 μg/g after 24 h induction. Our results laid a solid foundation for later improving crop aphid resistance by transgenic technology and provided an important basic data for the regulation of valuable products from M. recutita.