Genetic transformation of the sugar beet plastome

It is very important for the application of chloroplast engineering to extend the range of species in which this technology can be achieved. Here, we describe the development of a chloroplast transfor- mation system for the sugar beet (Beta vulgaris L. ssp. vulgaris, Sugar Beet Group) by biolistic bom- bardment of leaf petioles. Homoplasmic plastid- transformed plants of breeding line Z025 were obtained. Transformation was achieved using a vector that targets genes to the rrn16/rps12 intergenic region of the sugar beet plastome, employing the aadA gene as a selectable marker against spectino- mycin and the gfp gene for visual screening of plastid transformants. gfp gene transcription and protein expression were shown in transplastomic plants. Detection of GFP in Comassie blue-stained gels suggested high GFP levels. Microscopy revealed GFP fluorescence within the chloroplasts. Our results demonstrate the feasibility of engineering the sugar beet chloroplast genome; this technology provides new opportunities for the genetic improvement of this crop and for social acceptance of genetically modi- fied sugar beet plants.