title: No recombination detected in artificial potyvirus mixed infections and between potyvirus derived transgenes and heterologous challenging potyviruses.
abstract: Risk-assessment studies of virus-resistant transgenic plants (VRTPs) focussing on recombination of a plant virus with a transgenic sequence of a different virus should include a comparison of recombination frequencies between viruses in double-infected non-transgenic plants with those observed in singly infected transgenic plants to estimate recombination incidence in VRTPs. In this study, the occurrence of recombination events was investigated in non-transgenic plants double-infected with two different potyviruses, as well as in potyviral genomes in singly infected transgenic plants expressing potyvirus sequences. Different potyviruses, namely Potato virus A (PVA), Tobacco vein mottling virus (TVMV), two strains of Potato virus Y (PVY-O, PVY-H) and two strains of Plum pox virus (PPV-NAT, PPV-SK68), were used in three combinations for double infection of a common host. Furthermore, transgenic plants expressing either potyviral coat protein (CP), helicase (CI) or polymerase (NIb) coding sequences (PPV-NAT-CP, PVY-CI, PVY-NIb) were singly-infected with a heterologous potyvirus, which was not targeted by the respective transgenic resistance. To identify recombinant potyviral sequences, a sensitive RT-PCR was developed to detect up to one recombinant molecule out of 10(6) parental molecules. In 304 mixed infected non-transgenic plants, 92 mixed and 164 single infected transgenic plants screened for recombinant sequences no recombinant potyviral sequence was found. These results indicate that recombination events between different potyviruses in mixed infections and between a potyvirus infecting a potyvirus-resistant transgenic plant are likely to be very infrequent.
authors.affiliation: German Collection of Microorganisms and Cell Cultures, Plant Virus Division, Inhoffenstrasse 7b, 38124 Braunschweig, Germany.
authors.forename: Christof
authors.initials: C
authors.lastname: Dietrich
authors.forename: Jane
authors.initials: J
authors.lastname: Miller
authors.forename: Gaynor
authors.initials: G
authors.lastname: McKenzie
authors.forename: László
authors.initials: L
authors.lastname: Palkovics
authors.forename: Ervin
authors.initials: E
authors.lastname: Balázs
authors.forename: Peter
authors.initials: P
authors.lastname: Palukaitis
authors.forename: Edgar
authors.initials: E
authors.lastname: Maiss
mesh_terms: D004279:DNA, Viral / Q000235:genetics; D010935:Plant Diseases / Q000821:virology*; D030821:Plants, Genetically Modified / Q000821:virology*; D017800:Potyvirus / Q000235:genetics*; D011995:Recombination, Genetic; D014026:Nicotiana / Q000235:genetics* / Q000821:virology*; D019076:Transgenes / Q000235:genetics
chemical_list: D004279:DNA, Viral