Inheritance and expression of foreign genes in transgenic soybean plants

DNA-coated gold particles were introduced into meristems of immature soybean seeds using electric discharge particle acceleration to produce transgenic fertile soybean plants. The lineages of integrated foreign DNA in two independently transformed plants were followed in the first (R(1)) and second (R(2)) generation of self-pollinated progeny. One plant (4615) was transformed with the Escherichia coli genes for beta-glucuronidase and neomycin phosphotransferase II; the other (3993) was transformed only with the gene for beta-glucuronidase. Segregation ratios for the introduced gene(s) were approximately 3:1 for plant 4615 and 1:1 for plant 3993 in the R(1) generation. DNA analysis showed 100% concordance between presence of the foreign gene sequences and enzyme activity. Moreover, all copies of the foreign genes are inherited as a unit in each plant. Plant 3993 segregated in a 1:1 ratio in the R(2) generation. R(1) plants derived from plant 4615, which expressed both genes, gave either 100% or 3:1 expression of both genes in the R(2) generation, demonstrating recovery of both homozygous and heterozygous R(1) plants. Our results show that foreign DNA introduced into soybean plants using electric discharge particle acceleration can be inherited in a Mendelian manner. Results also demonstrate cotransformation of tandem markers and show that both markers are inherited as closely linked genes in subsequent generations. These results indicate that whole plants can be derived from single transformed cells by a de novo organogenic pathway.