Molecular and cytogenetic analyses of stably and unstably expressed transgene loci in tobacco

摘要: To study the influence of genomic context on transgene expression, we have determined T-DNA structure, flanking DNA sequences, and chromosomal location four independent loci in tobacco. Two these were stably expressed homozygous condition over many generations, whereas other two became unstable after several generations homozygosity. The comprised relatively simple arrangements that flanked at least one side by plant containing AT-rich regions bind to nuclear matrices vitro. Of unstably loci, consisted multiple incomplete copies, second contained a single intact T-DNA; both cases, however, binary vector sequences directly contiguous right border. Fluorescence situ hybridization demonstrated inserts present vicinity telomeres. occupied intercalary paracentromeric locations, respectively. Results stability expression F1 progeny obtained intercrossing lines sensitivity inactivation presence an unlinked "trans-silencing" locus are also presented. findings discussed repetitive allotetraploid nature tobacco genome.