Instability of the gene nptII expression in transgenic tobacco (Nicotiana tabacum L.) plants during inbreeding

The expression persistence and inheritance of the marker gene nptII were investigated in inbred transgenic tobacco (Nicotiana tabacum) plants. The inheritance of nptII in most examined plants corresponded to mono- and dihybrid segregation. Two successive self-pollinations of the plant T-0-5 resulted in the silencing of the marker gene with a frequency of 33.3%. The silencing persisted in the subsequent self-pollinating generations. Reversions of the nptII gene expression were found in crosses between Km-sensitive transgenic tobacco plants (2 x 10(-4)) and in plants regenerated from explants of Km-sensitive genotypes (about 50%).