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  • 1 University of Ottawa Agricultural Biotechnology Laboratories, Department of Biochemistry, Microbiology and Immunology 451 Smyth Rd. Ottawa ON K1H 8M5 Canada
  • 2 Syngenta Biotechnology, Inc. P.O. Box 12257 3054 Cornwallis Rd Research Triangle Park NC 27709-2257 USA
  • 3 Proteins Easy Corp. 950 Weston Drive, Elmvale Acres Ottawa ON K1G 1X2 Canada
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To understand the molecular details of T-DNA integration, the left border (LB) sequences and flanking plant DNA of 16 independent T-DNA insertions in transgenic cry1Ab rice were analyzed by an inverse PCR approach. DNA sequencing indicated that five of the 16 fragments (31%) were found to have simple or rearranged tandem repeats of right border sequences in a head to tail fashion. Mirror truncations of LB of the T-DNA, as well as mirror rearrangements, such as point mutations, small deletions and inversions were found in the region close to the LB breakpoints in some inserts. Host plant DNA flanking the T-DNA endpoints were also sequenced. The A+T contents in the plant DNA within 50 bp adjacent to the T-DNA endpoints were between 30–76% (average 52.5%), not different from the average genome value. Despite minor mutations and some rearrangements, it appears that T-DNA, harbouring a synthetic cry1Ab coding sequence of 49% GC (as well as uidA and hph ), still carries such a foreign gene into ‘transcriptionally active regions’ of the rice genome, which are 55.8% GC on average as predicted from the rice genome sequence.

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