Evaluation of rye (Secale cereale L.) inbred lines and their crosses for tissue culture response and stable genetic transformation of homozygous rye inbred line L22 by biolistic gene transfer.

The efficient and reproducible production of stably expressing transgenic rye plants is described. Analysis of the genotype-specific callus culture-response of 21 rye inbred lines, single crosses and a population variety resulted in the identification of the highly responsive inbred line L22. Biolistic transformation experiments were performed using line L22 and the impact of different selection agents on the regeneration capacity was analyzed. Using the selectable marker gene nptII and corresponding paromomycin selection resulted in transformation efficiencies of up to 4.0% of the bombarded explants. A total of 17 independent transgenic rye plants were produced, and their stability and level of transgene expression was analyzed. The majority of these lines showed stable transgene expression. In contrast a few transgenic lines with multiple transgene inserts, provided evidence of transcriptional and post-transcriptional gene silencing.