AN EFFICIENT PARTICLE BOMBARDMENT SYSTEM FOR THE GENETIC-TRANSFORMATION OF ASPARAGUS (ASPARAGUS-OFFICINALIS-L)

The microprojectile bombardment method was used to transfer DNA into e mbryogenic callus of asparagus (Asparagus officcinalis L.) and to prod uce stably transformed asparagus plants. Embryogenic callus, derived f rom UC157 and UC72 asparagus cultivars, was bombarded with tungsten pa rticles coated with plasmid DNA that contained genes encoding hygromyc in phosphotransferase, phosphinothricin acetyl transferase and beta-gl ucuronidase. Putatively transformed calli were identified from the bom barded tissue after 4 months selection on 25 mg/L hygromycin B plus 4 mg/L phosphinothricin (PPT). By selecting embryogenic callus on hygrom ycin plus PPT the overall transformation and selection efficiencies we re substantially improved over selection with hygromycin or PPT alone, where no transgenic clones were recovered. The transgenic nature of t he selected material was demonstrated by GUS histochemical assays and Southern blot hybridization analysis. Transgenic asparagus plants were found to withstand the prescribed levels of the PPT-based herbicide B ASTATM for weed control.