ARS | Publication request: EXPRESSION AND INHERITANCE OF TRANSGENES IN GENETICALLY ENGINEERED OAT

Submitted to: Oat International Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: August 6, 1996
Publication Date: N/A

Technical Abstract: For practical application of transgenic plants to crop improvement, stable integration and inheritance of introduced transgenes are essential. We are conducting analyses of integration, expression, and inheritance of transgenes for clues on how to enhance transgene stability and assure consistent, high levels of transgene expression in genetically engineered plants. Transgenic oat tissue cultures and regenerated transgenic plant lines representing 27 independent transformation events were studied. Analysis of transgene integration patterns revealed extensive rearrangements of transgenic DNA sequences integrated into the oat genome. There were, on average, four copies of the marker gene, Escherichia coli udi, which encodes B-glucuronidase (GUS), and three copies of the herbicide resistance selectable gene, Streptomyces hygroscopicus bar, per haploid genome. Both transgenes, uidA and bar, always cosegregated at the DNA level. Some transgenic oat lines exhibited stable expression of the analyzed transgene phenotypes and Mendelian transgene inheritance consistent with the presence of one transgenic locus. Stable transgene expression and Mendelian inheritance were consistent across several generations showing that the oat transformation technology can be applied for crop improvement. However, about one-half of the analyzed lines exhibited distorted GUS inheritance ratios and 70% of lines showed lack of coexpression of the two transgene phenotypes even though the corresponding genes were always present together in the plant genome. High frequency of transgene silencing in oat indicates a need for a system stabilizing transgene expression to be used in future transformation endeavors.