Transgenic rapeseed plants obtained by the microinjection of DNA into microspore-derived embryoids

A novel method in the field of genetic engineering of higher plants is presented: microinjection into multicellular structures which have a high competence for plant regeneration through embryogenesis. Microspore-derived embryoids of Brassica napus L. were individually selected and microinjected with NPT II gene constructions. High frequency regeneration of haploid plants through embryogenesis was achieved within 8 weeks. Transformation efficiencies between 27% and 51% were determined by DNA dot blot analysis of primary regenerants. Stable integration of fulllength microinjected genes into high molecular weight DNA was proven by Southern analysis of genomic DNA isolated from regenerated plants. Transformed plants were tested for expression of the NPT II gene by enzyme assay. The chimeric nature of the primary regenerants was demonstrated after their in vitro segregation through secondary embryogenesis into pure transformants.