Optimization and transformation of garden balsam, impatiens balsamina, mediated by microprojectile bombardment

Abstract

In this study, a transformation system was developed by initially optimizing the microprojectile bombardment parameters for cotyledonous explants. The parameters optimized were combination of distance from stopping screen to target tissue and helium pressure, number of bombardment, preculture duration prior to bombardment, DNA amount, osmoticum treatment and post-bombardment incubation time. Determination of minimal inhibitory concentration for efficient selection of transformants was also carried out for hygromycin. Different concentrations of hygromycin (25. 50, 75 and 100 mg L-1) were tested against different ages of explants (0, 1, 3 and 5 weeks) for efficient selection of transformants. Using the optimized parameters, transformation of cotyledons was carried out followed by selection on 75 mg L-1 hygromycin at different weeks of post-bombardment. Transgenic plants were successfully regenerated from bombarded explants and confirmed via histochemical GUS assay and PCR analysis.