biolistic device that accelerates the microprojectiles to speeds of 300 to 600 m s which is sufficient to penetrate plant cell walls and membranes sanford et al part sci technol 5 27 1987 sanford trends biotech 6 299 1988 sanford physiol plant 79 206 1990 and klein et al biotechnology 10 268 1992 expression vectors are also introduced into plant tissues via direct infection or co cultivation of plant tissue with agrobacterium tumefaciens horsch et al science 227 1229 1985 descriptions of agrobacterium vector systems and methods for agrobacterium mediated gene transfer are provided by gruber et al u201c vectors for plant transformation u201d in methods in plant molecular biology and biotechnology glick et al eds pages 89 119 crc press 1993 miki et al supra and moloney et al plant cell reports 8 238 1989 additionally expression vectors may be introduced into the plant chloroplast genome by methods well known to the skilled artisan see u s pat nos 5 451 513 and 5 693 507 foreign genes introduced into the chloroplast genome are maternally inherited transcription of the foreign gene may be controlled by a plant promoter or by a viral promoter such as a cauliflower mosaic virus camv 35s promoter and its derivative the enhanced 35s version u201c e35s u201d a figwort mosaic virus promoter and the like gruber et al supra odell et al nature 313 810 1985 kay et al science 236 1299 1987 the polyubiquitin gene promoters from arabidopsis thaliana ubq3 and ubq10 norris et al plant mol biol 21 895 1993 are also useful for directing gene expression in transgenic impatiens additional useful promoters from arabidopsis include the tefa 1 gene promoter from the arabidopsis translation elongation factor 1 gene and two additional polyubiquitin gene promoters from arabidopsis ubq11.