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Abstract

T-DNA flanking sequences were isolated from 112 Arabidopsis thaliana single-copy T-DNA lines and sequence mapped to the chromosomes. Even though two T-DNA insertions mapped to a heterochromatic domain located in the pericentromeric region of chromosome I, expression of reporter genes was detected in these transgenic lines. T-DNA insertion did not seem to be biased toward any of Arabidopsis' five chromosomes. The observed distribution of T-DNA copies in intergenic sequence versus gene sequence (i.e. 5'-upstream regions, coding sequences and 3'-downstream regions) appeared randomly. An evaluation of T-DNA insertion frequencies within gene sequence revealed that integration into 5'-upstream regions occurred more frequently than expected, whereas insertions in coding sequences (exons and introns) were found less frequently than expected based on random distribution predictions. In the majority of cases, single-copy T-DNA insertions were associated with small or large rearrangements such as deletions and/or duplications of target site sequences, deletions and/or duplications of T-DNA sequences, and gross chromosomal rearrangements such as translocations. The accuracy of integration was similarly high for both left- and right-border sequences. These results may be called upon when making detailed molecular analyses of transgenic plants or T-DNA induced mutants.

Reciprocal chromosome translocation associated with TDNA-insertion mutation in Arabidopsis: genetic and cytological analyses of consequences for gametophyte development and for construction of doubly mutant lines

“…Castle et al (1993) observed rearrangements in 7 out of 41 TDNA-tagged mutants. Forsbach et al (2003) observed translocations in only 2.6% of 112 single-copy T-DNA lines, but chromosomal rearrangements were more frequent in plant lines with more than one T-DNA insertion. Nacry et al (1998) characterized a reciprocal translocation involving chromosome II and III.…”

Agrobacterium tumefaciens-mediated transformation of Aspergillus aculeatus for insertional mutagenesis

“…To isolate one albino mutant with a 95% probability out of 5,500 transformants from the approximately 35-Mb genome of A. aculeatus , it was calculated that the T-DNA must disrupt gene the function in a 19-kb region around the T-DNA integration locus (Krysan et al 1999). The 1,002-bp deletion at the AapksP locus in the alb1 mutant was relatively larger than those reported for M. oryzae and Arabidopsis , in which the majority of deletions ranged from 1 to 35 bp and 11 to 100 bp, respectively (Brunaud et al 2002; Choi et al 2007; Forsbach et al 2003). Furthermore, the coding region of AapksP is relatively large at 6,645 bp; however, it is not large enough to increase the probability of isolating two albino mutants from 11,000 transformants.…”

Why Organic Farming Should Embrace Co-Existence with Cisgenic Late Blight–Resistant Potato

“…However, also, in that case, the number of additional nucleotides that has been introduced is limited to three base pairs from the left T-DNA border and 21 base pairs from the right T-DNA border. In fact, in many cases, the number of base pairs introduced is even lower, with fewer or no T-DNA sequences introduced from the right border, and sometimes also the base pairs from the left T-DNA border are missing [29]. In practice it is often possible to select cisgenic events that contain no T-DNA sequences, resulting in a plant that only differs from the conventional plant in its location of the cisgene.…”