Transgene inheritance, segregation and expression in bread wheat

Transgene integration, inheritance and expression were studied in six transgenic wheat (Triticum aestivum) lines produced by co-bombardment with two plasmids containing marker genes and genes encoding HMW subunits of wheat glutenin, respectively. Transgene insertion number ranged from 1 to approximately 15. Within a transgenic locus the majority of plasmid copies were found at dispersed genomic sites separated by intervening DNA. However, evidence was obtained for the arrangement of introduced plasmid copies as concatamers and for plasmid truncation and rearrangement. Transgenes were frequently located in genetically unlinked chromosome sites, resulting in independent segregation of loci among progeny. In two lines this gave rise to progeny containing only the gene of interest. Transgenes were inherited in the T-1 generation as a dominant trait although Mendelian segregation ratios were not always observed. No evidence of co-suppression of endogenous HMW subunits was observed.