Terpenoids in genetically transformed cultures of chamomile

Abstract

By naturally occurring gene-transformation Ri-plasmids of Agrobacterium rhizogenes have been integrated into the plant genome of Chamomillo recutita, thereby inducing the formation of hairy roots. Clones with the best biosynthetic potential were multiplied for phytochemical investigations. The amounts of terpenoid and polyene compounds in the genetically transformed cultures were compared with those in in-vivo plants. In Hungary a wild chamomile population was found which contained significant amount of (-)-alpha-bisabolol in the oil from the inflorescence. We used biotechnological methods to preserve the genome of this wild type. Transformed chamomile root cultures were obtained by infection of sterile organized cultures with Agrobacterium rhizogenes strains #A-4,# 15834, and #R-1601. Hairy roots freed from bacteria were cultivated on solid medium and then in liquid, hormone-free, B5 and MS media. The qualitative and quantitative composition of the essential oil was examined by gas chromatography and mass spectrometry. The volatile compounds were identified by comparing their retention times with those of authentic standards and of essential oils of known composition, and by peak enrichment. Confirmation of identity was achieved by comparison of mass spectra with those reported in the literature and those of reference compounds. The amount of each component as a percentage of the total was determined by area normalization. GC and GC-MS studies showed that genetically transformed chamomile cultures generated the terpenoid and polyene compounds most characteristic of the parent plant. The main components of hairy root cultures were trans-beta-farnesene, alpha-farnesene, geranyl isovalerate, and cedrol. We identified beta-selinene as a new component of the genetically transformed cultures.