title: RecA stimulates sister chromatid exchange and the fidelity of double-strand break repair, but not gene targeting, in plants transformed by Agrobacterium.
abstract: Expression of the bacterial RecA protein in plants stimulates homologous recombination in tobacco. Here we show that RecA plays a direct role in DNA strand exchange in vivo. The number of sister chromatid exchanges (SCEs) was increased 2.4-fold over wild type in transgenic tobacco plants expressing a nuclear-targeted RecA (nt-RecA) protein and could not be increased further by DNA damage, which caused a doubling of the baseline SCE frequency in wild-type plants. Although gene targeting requires homologous recombination, the number of targeted gene replacements was not increased markedly by the presence of nt-RecA by using Agrobacterium-mediated transformation. However, the number of double-strand breaks that were repaired at both sides by homologous recombination was increased 3.3-fold. Stimulation of SCE and fidelity of double-strand break repair by nt-RecA, but not by gene targeting, suggests that the stimulatory activity of RecA is linked to active DNA synthesis. Therefore, nascent replication-associated single strands may be a prerequisite for RecA action in plant cells.
authors.affiliation: Max-Planck-Institut für Züchtungsforschung, Carl-von-Linne-Weg 10, D-50829 Köln, Germany. reiss@mpiz-koeln.mpg.de
authors.forename: B
authors.initials: B
authors.lastname: Reiss
authors.forename: I
authors.initials: I
authors.lastname: Schubert
authors.forename: K
authors.initials: K
authors.lastname: Köpchen
authors.forename: E
authors.initials: E
authors.lastname: Wendeler
authors.forename: J
authors.initials: J
authors.lastname: Schell
authors.forename: H
authors.initials: H
authors.lastname: Puchta
mesh_terms: D001483:Base Sequence; D017931:DNA Primers; D004260:DNA Repair; D018390:Gene Targeting; D010944:Plants / Q000235:genetics*; D011938:Rec A Recombinases / Q000378:metabolism*; D011995:Recombination, Genetic; D012231:Rhizobium / Q000502:physiology*; D012854:Sister Chromatid Exchange; D014170:Transformation, Genetic
chemical_list: D017931:DNA Primers; D011938:Rec A Recombinases