Efficient male germ line transformation for transgenic tobacco production without selection.

Microspores at late uninucleate/early binucleate stages were isolated from flower buds of tobacco (Nicotiana tabacum L.) and in vitro culture methods optimised for their maturation to fully functional viable pollen which, after application to the stigma of emasculated plants in situ, led to the generation of large numbers of seed. Efficient protocols were established for the biolistic introduction of a construct containing a reporter gene and selectable marker into these microspores and hence, after in vitro maturation and in situ fertilisation, for the generation of transgenic plants. Stable transformants of low copy number were generated by this procedure. The efficiency of transformation achieved allows the production of large numbers of transgenic plants without selection, dispensing with the requirement for a selectable marker in plant transgenesis.