Gene insertion into strawberry leaf disk regeneration system using particle bombardment

Strawberry has previously been transformed using Agrobacterium-mediated DNA transfer. In this paper, we present a process for delivering foreign genes into strawberry leaf disks using particle bombardment. Expression of foreign DNA into strawberry leaf disks (Fragaria X ananassa Duch.) was detected - using in situ GUS assay-following bombardment with tungsten particles coated with plasmid DNA (pBI221.23) that coded for the selectable (hygromycin phosphotransferase [hpt] and the screenable (β-glucuronidase [GUS]) marker genes. Both genes are under the control of the Cauliflower Mosaic Virus (CaMV) 35S promoter. The criteria of stability of phenotypes after the removal of selective pressure, Southern blot hybridization and segregation analysis were used to confirm the mitotic stability of the foreign gene and its stable integration into the strawberry genome progeny. The relative simplicity of this system recommends its future use for the production of genetically modified strawberry.