High-efficiency Agrobacterium rhizogenes-mediated genetic transformation in Artemisia vulgaris: Hairy root production and essential oil analysis

Abstract

Agrobacterium rhizogenes-mediated genetic transformation of Artemisia vulgaris was investigated using four bacterial strains: A4GUS, R1000, R1601and ATCC15834 and three explant types: shoot tip, leaf and node. The A4GUS proved to be more competent than other strains and the highest transformation rates were observed in leaf explant (92.6%). Among 92 hairy root clones acquired, clones AV1 and AV2 exhibited the highest growth. Growth of hairy roots was assessed on the basis of total root elongation, lateral root density and biomass accumulation. Out of four media composition, the ½ MS medium was found to be most suitable for biomass production. Biomass accumulation was the highest when the medium was supplemented with 40 g L−1 sucrose. PCR and Southern hybridization analysis revealed both the TL- and TR-DNA integration in the root clones AV1 and AV2. Hairy roots showed higher growth rate and accumulated substantial amount of essential oils than non-transformed roots. Eighty-seven compounds were identified from transformed root essential oils, whereas 77 compounds were identified from non-transformed root essential oils. The main compounds identified were camphor, camphene, α-thujone, germacrene D, 1,8-cineole and β-caryophyllene.