Agrobacterium tumefaciens-mediated transformation of the aromatic shrub Lavandula latifolia

Transgenic plants of the aromatic shrub Lavandula latifolia (Lamiaceae) wer e produced using Agrobacterium tumefaciens-mediated gene transfer. Leaf and hypocotyl explants from 35-40-day old lavender seedlings were inoculated w ith the EHA105 strain carrying the nptII gene, as selectable marker, and th e reporter gusA gene with an intron. Some of the factors influencing T-DNA transfer to L. latifolia explants were assessed. Optimal transformation rat es (6.0 +/- 1.6% in three different experiments) were obtained when leaf ex plants precultured for 1 day on regeneration medium were subcultured on sel ection medium after a 24 h co-cultivation with Agrobacterium. Evidence for stable integration was obtained by GUS assay, PCR and Southern hybridisatio n. More than 250 transgenic plants were obtained from 37 independent transf ormation events. Twenty-four transgenic plants from 7 of those events were successfully established in soil. beta -glucuronidase activity and kanamyci n resistance assays in greenhouse-grown plants from two independent transge nic lines confirmed the stable expression of both gusA and nptII genes two years after the initial transformation. Evidence from PCR data, GUS assays and regeneration in the presence of kanamycin demonstrated a 1:15 Mendelian segregation of both transgenes among seedlings of the T1 progeny of two pl ants from one transgenic L. latifolia line.