MOLECULAR AND GENETIC-CHARACTERIZATION OF ELITE TRANSGENIC RICE PLANTS PRODUCED BY ELECTRIC-DISCHARGE PARTICLE-ACCELERATION

The recovery of transgenic rice plants expressing a number of exogenou s genes was reported previously. Using immature embryo explants as the target tissue, plasmids containing both selectable and screenable mar ker genes were introduced into elite rice varieties via electric-disch arge particle acceleration. Co-integration, copy number, expression, a nd inheritance of these genes were analyzed. A 100% co-integration fre quency was confirmed by Southern-blot analyses of R0 plants. The major ity of transgenic plants contained between one and ten copies of exoge nous DNA and molecular and genetic analyses of progeny indicated that all copies in almost all RO plants were inherited as a single dominant hemizygous locus. Co-expression of unselected genes ranged from 30-66 % for gus/hmr constructs, depending on the promotor used, and up to 90 % for bar/hmr constructs. The integrative structures of two unlinked t ransgenic loci of a rare R0 plant were analyzed in detail by Southern- blot analysis of its progeny.