A new hyperrecombinogenic mutant of Nicotiana tabacum

Abstract

SummaryWe have isolated a hyperrecombinogenic Nicotiana tabacum mutant. The mutation, Hyrec, is dominant and segregates in a Mendelian fashion. In the mutant, the level of mitotic recombination between homologous chromosomes is increased by more than three orders of magnitude. Recombination between extrachromosomal substrates is increased six-to ninefold, and intrachromosomal recombination is not affected. Hyrec plants were found to perform non-homologous end joining as ef®ciently as the wild type, ruling out the possibility that the increase in homologous recombination is due to a defect in end joining. In addition, Hyrec plants show signi®cant resistance to gammairradiation, whereas UV resistance is not different from the wild type. This suggests that homologous recombination can be strongly up-regulated in plants. Moreover, Hyrec constitutes a novel type of mutation: no similar mutant was reported in plants and hyperrecombinogenic mutants from other organisms usually show sensitivity to DNA damaging agents. We discuss the insight that this mutant provides into understanding the mechanisms of recombination plus the potential application for gene targeting in plants.

CENTRIN2 Modulates Homologous Recombination and Nucleotide Excision Repair in Arabidopsis[W]

“…To address this question, a genetic screen for Arabidopsis mutants in which the frequency of HR is upregulated was undertaken. Although recombination mutants have been isolated previously, the nature of most of the affected genes has not been studied (Masson and Paszkowski, 1997;Gorbunova et al, 2000;Lucht et al, 2002).…”

Excision and Episomal Replication of Cauliflower mosaic virus Integrated into a Plant Genome

“…The potential for homologous recombination has been evaluated in plants by using a transgene cassette that consists of two nonfunctional copies of the luciferase gene that contained 1,146 bp of overlapping sequence (Gorbunova et al, 2000;Kovalchuk et al, 2003). The restoration of luciferase function was visualized as bright spots on the leaves and indicated that a homologous recombination event had led to the excision of the duplicated portion of the luciferase gene.…”

Reevaluation of the Reliability and Usefulness of the Somatic Homologous Recombination Reporter Lines

“…For example, Yao et al (2011) reported that they employed a 500 bp noncoding DNA fragment as linker. However, after consulting the references cited, we found that the linker sequence used in their study in fact appears to be much larger and contains the bar gene cassette providing resistance to phosphinothricin (Gorbunova et al, 2000). Van der Auwera et al (2008) used mannopine synthase promoter and enhancer elements as the linker sequence but they considered this information and sequence details irrelevant to their study (Van der Auwera et al, 2008).…”

“…sequences having 29 amino acids of the open reading frame V of CaMV (Swoboda et al, 1994) or the omega (V) enhancer of Tobacco mosaic virus (Gorbunova et al, 2000) (Figure 1). These fragments are believed to enhance transgene protein production up to a level necessary to visualize clonal GUS (Schultze et al, 1990) or LUC spots.…”