STABLE TRANSFORMATION VIA PARTICLE BOMBARDMENT IN 2 DIFFERENT SOYBEANREGENERATION SYSTEMS

The Biolistics(R) particle delivery system for the transformation of s oybean (Glycine max L. (Merr.) was evaluated in two different regenera tion systems. The first system was multiple shoot proliferation from s hoot tips obtained from immature zygotic embryos of the cultivar Willi ams 82, and the second was somatic embryogenesis from a long term prol iferative suspension culture of the cultivar Fayette. Bombardment of s hoot tips with tungsten particles, coated with precipitated DNA contai ning the gene for beta-glucuronidase (GUS), produced GUS-positive sect ors in 30% of the regenerated shoots. However, none of the regenerants which developed into plants continued to produce GUS positive tissue. Bombardment of embryogenic suspension cultures produced GUS positive globular somatic embryos which proliferated into GUS positive somatic embryos and plants. An average of 4 independent transgenic lines were generated per bombarded flask of an embryogenic suspension. Particle b ombardment delivered particles into the first two cell layers of eithe r shoot tips or somatic embryos. Histological analysis indicated that shoot organogenesis appeared to involve more than the first two superf icial cell layers of a shoot tip, while somatic embryo proliferation o ccurred from the first cell layer of existing somatic embryos. The dif ferent transformation results obtained with these two systems appeared to be directly related to differences in the cell types which were re sponsible for regeneration and their accessibility to particle penetra tion.