title: High-frequency gene transfer from the chloroplast genome to the nucleus.
abstract: Eukaryotic cells arose through endosymbiotic uptake of free-living bacteria followed by massive gene transfer from the genome of the endosymbiont to the host nuclear genome. Because this gene transfer took place over a time scale of hundreds of millions of years, direct observation and analysis of primary transfer events has remained difficult. Hence, very little is known about the evolutionary frequency of gene transfer events, the size of transferred genome fragments, the molecular mechanisms of the transfer process, or the environmental conditions favoring its occurrence. We describe here a genetic system based on transgenic chloroplasts carrying a nuclear selectable marker gene that allows the efficient selection of plants with a nuclear genome that carries pieces transferred from the chloroplast genome. We can select such gene transfer events from a surprisingly small population of plant cells, indicating that the escape of genetic material from the chloroplast to the nuclear genome occurs much more frequently than generally believed and thus may contribute significantly to intraspecific and intraorganismic genetic variation.
authors.affiliation: Westfälische Wilhelms-Universität Münster, Institut für Biochemie und Biotechnologie der Pflanzen, Hindenburgplatz 55, D-48143 Münster, Germany.
authors.forename: Sandra
authors.initials: S
authors.lastname: Stegemann
authors.forename: Stefanie
authors.initials: S
authors.lastname: Hartmann
authors.forename: Stephanie
authors.initials: S
authors.lastname: Ruf
authors.forename: Ralph
authors.initials: R
authors.lastname: Bock
mesh_terms: D001483:Base Sequence; D002467:Cell Nucleus / Q000235:genetics; D002736:Chloroplasts / Q000235:genetics*; D003433:Crosses, Genetic; D018742:DNA, Chloroplast / Q000235:genetics; D019143:Evolution, Molecular; D022761:Gene Transfer, Horizontal; D005819:Genetic Markers; D014644:Genetic Variation; D018745:Genome, Plant; D007613:Kanamycin Resistance / Q000235:genetics; D008957:Models, Genetic; D030821:Plants, Genetically Modified; D013559:Symbiosis; D014026:Nicotiana / Q000235:genetics / Q000382:microbiology
chemical_list: D018742:DNA, Chloroplast; D005819:Genetic Markers