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Horizontal Gene Transfer from Genus Agrobacterium to the Plant Linaria in Nature

December 2012 , Volume 25 , Number  12
Pages  1,542 - 1,551

Tatiana V. Matveeva,1 Denis I. Bogomaz,1 Olga A. Pavlova,1 Eugene W. Nester,2 and Ludmila A. Lutova1

1Department of Genetics, St. Petersburg State University, 7/9, Universitetskaya emb., St. Petersburg, 199034, Russia; 2Department of Microbiology, University of Washington, Box 357735, Seattle 98195, U.S.A.

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Accepted 12 August 2012.

Genes can be transferred horizontally between prokaryotes and eukaryotes in nature. The best-studied examples occur between Agrobacterium rhizogenes and certain Nicotiana spp. To investigate possible additional cases of horizontal gene transfer in nature between Agrobacterium and plants, a real-time polymerase chain reaction-based approach was employed to screen 127 plant species, belonging to 38 families of Dicotyledones, for the presence of oncogenes homologous to the transfer DNA fragments (T-DNA) from both A. tumefaciens and A. rhizogenes. Among all of the analyzed plant species, we found that only Linaria vulgaris contained sequences homologous to the T-DNA of A. rhizogenes. All screened L. vulgaris plants from various parts of Russia contained the same homologous sequences, including rolB, rolC, ORF13, ORF14, and mis genes. The same opine gene is found in the species of Nicotiana which contain genes of A. rhizogenes. In L. vulgaris, there are two copies of T-DNA organized as a single tandem imperfect direct repeat. The plant DNA sequence of the site of integration shows similarity to a retrotransposon. This site is most likely silent, suggesting that the T-DNA is not expressed. Attempts to demonstrate expression of the T-DNA genes were negative. Our study indicates that the frequency of gene transfer and fixation in the germline from Agrobacterium to plant hosts is rare in the natural environment.

© 2012 The American Phytopathological Society