Nopaline Ti-plasmid, pTiT37, T-DNA insertions into a flax genome

Abstract

The FT37/1 plant tumor line induced on flax epicotyls by T37, a nopaline strain of Agrobacterium tumefaciens, contains multiple copies of the pTiT37, T-DNA. There are three to four distinct full-length insertions and one tandem insertion. Allowing for the different copy numbers of the inserts, this amounts to seven to eight T-DNA copies per genome unit. The genome unit in this case is the haploid DNA value (7 X 10(8) bp) which predicts a T-DNA copy number of 14-16 per diploid cell. Three novel types of abnormal insertion are also present. FIL (one copy per basic genome) comprises 3.04-4.47 kb of T-DNA derived from the left end, with a normal left border and an abnormal right border. FIR (four copies per basic genome) comprises 5.88-6.47 kb of T-DNA derived from the right end, with a normal right border and an abnormal left border. The third abnormality is represented by fragment "X," a HindIII fragment of 4.90 kb which contains homology with several noncontiguous regions of the T-DNA and which may derive from a tandem insertion. Of the two possible left-border sites (primary and secondary) in which fusion with plant DNA sequences has been observed, only the primary is used.