Transformation and regeneration of French bean plants by the particle bombardment process

Stable transformation of French bean (Phaseolus vulgaris L. cv. Goldstar) plants has been achieved using gold particles coated with plasmid pSOG-1016 carrying a chimeric gene encoding beta-glucuronidase (GUS) under the control of concanavalin A (Con A) promoter. The bombardment conditions were optimized by the observation of transient expression of the GUS reporter gene bombarded to the shoot apexes of embryonic axes. After bombardment of embryonic axes, many particles were detectable at 20-80 mu m of depth from the top of the shoot apex by anatomic observation. The bombarded embryonic axes were cultured for 3 weeks on MS or N6 medium without plant hormones. Regenerated plantlets were transferred to soil and kept in a growth chamber where they subsequently flowered and produced seeds. PCR and Southern blot analysis showed the integration of the Con A::GUS gene. The expression of the GUS activity was observed in the cotyledons and seed coats of the transgenic plants by histochemical staining.