DEVIATING T-DNA TRANSFER FROM AGROBACTERIUM-TUMEFACIENS TO PLANTS

We analyzed 29 T-DNA inserts in transgenic Arabidopsis thaliana plants for the junction of the right border sequences and the flanking plant DNA. DNA sequencing showed that in most lines the right border sequen ces transferred had been preserved during integration, corroborating l iterature data. Surprisingly, in four independent transgenic lines a c omplete right border repeat was present followed by binary vector sequ ences. Cloning of two of these T-DNA inserts by plasmid rescue showed that in these lines the transferred DNA consisted of the complete bina ry vector sequences in addition to the T-region. On the basis of the s tructure of the transferred DNA we propose that in these lines T-DNA t ransfer started at the left-border repeat, continued through the vecto r part, passed the right border repeat, and ended only after reaching again this left-border repeat.