Co-integration, co-expression and co-segregation of an unlinked selectablemarker gene and NtFAD3 gene in transgenic rice plants produced by particlebombardment

Using the scutellar tissue of rice mature embryos as a target tissue, a sel ectable marker gene, bar, and an unselectable gene, fatty acid desaturase g ene from tobacco (NtFAD3), on separate plasmids, were introduced by particl e bombardment. Cointegration, co-expression and inheritance of these genes were analyzed as well as seed fertility of the transgenic plants. Twenty-th ree out of 32 bialaphos-resistant plants integrated the NtFAD3 gene, which was confirmed by Southern-blot analysis of Ro plants, and showed one to mor e than 20 hybridizing bands of exogenous DNA, indicating a 72% (23/32) co-i ntegration frequency. However, the frequency of the transgenic plants conta ining the 1.4-kb fragment of NtFAD3 gene was 34% (11/32). Northern-blot ana lysis revealed that seven out of ten fertile transgenic rice plants which h ad a 1.4-kb fragment of NtFAD3 cDNA expressed NtFAD3 mRNA. The NtFAD3 gene under the control of CaMV35S promoter stably expressed in the transgenic ri ce plants and modified the proportions of linoleic acid (18:2) and linoleni c acid (18:3) in fatty acids; the content of 18:2 decreased and that of 18: 3 increased. Fourteen out of 32 (44%) transgenic plants set seeds and 18 (5 6%) showed low fertility or sterility. Molecular analysis of the selfed pro geny indicated that all copies in almost all Ro plants were inherited as a- single dominant hemizygous locus.