title: Insertion DNA Accelerates Meiotic Interchromosomal Recombination in Arabidopsis thaliana.
abstract: Nucleotide insertions/deletions are ubiquitous in eukaryotic genomes, and the resulting hemizygous (unpaired) DNA has significant, heritable effects on adjacent DNA. However, little is known about the genetic behavior of insertion DNA. Here, we describe a binary transgenic system to study the behavior of insertion DNA during meiosis. Transgenic Arabidopsis lines were generated to carry two different defective reporter genes on nonhomologous chromosomes, designated as "recipient" and "donor" lines. Double hemizygous plants (harboring unpaired DNA) were produced by crossing between the recipient and the donor, and double homozygous lines (harboring paired DNA) via self-pollination. The transfer of the donor's unmutated sequence to the recipient generated a functional β-glucuronidase gene, which could be visualized by histochemical staining and corroborated by polymerase chain reaction amplification and sequencing. More than 673 million seedlings were screened, and the results showed that meiotic ectopic recombination in the hemizygous lines occurred at a frequency  >6.49-fold higher than that in the homozygous lines. Gene conversion might have been exclusively or predominantly responsible for the gene correction events. The direct measurement of ectopic recombination events provided evidence that an insertion, in the absence of an allelic counterpart, could scan the entire genome for homologous counterparts with which to pair. Furthermore, the unpaired (hemizygous) architectures could accelerate ectopic recombination between itself and interchromosomal counterparts. We suggest that the ectopic recombination accelerated by hemizygous architectures may be a general mechanism for interchromosomal recombination through ubiquitously dispersed repeat sequences in plants, ultimately contributing to genetic renovation and eukaryotic evolution.
authors.affiliation: Jiangsu Key Laboratory for the Research and Uti1ization of Plant Resources, Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, China hangyueyu@cnbg.net.
authors.forename: Xiao-Qin
authors.initials: XQ
authors.lastname: Sun
authors.affiliation: Jiangsu Key Laboratory for the Research and Uti1ization of Plant Resources, Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, China.
authors.forename: Ding-Hong
authors.initials: DH
authors.lastname: Li
authors.affiliation: Jiangsu Key Laboratory for the Research and Uti1ization of Plant Resources, Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, China.
authors.forename: Jia-Yu
authors.initials: JY
authors.lastname: Xue
authors.affiliation: State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China.
authors.forename: Si-Hai
authors.initials: SH
authors.lastname: Yang
authors.affiliation: Jiangsu Key Laboratory for the Research and Uti1ization of Plant Resources, Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, China.
authors.forename: Yan-Mei
authors.initials: YM
authors.lastname: Zhang
authors.affiliation: Jiangsu Key Laboratory for the Research and Uti1ization of Plant Resources, Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, China.
authors.forename: Mi-Mi
authors.initials: MM
authors.lastname: Li
authors.affiliation: Jiangsu Key Laboratory for the Research and Uti1ization of Plant Resources, Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, China hangyueyu@cnbg.net.
authors.forename: Yue-Yu
authors.initials: YY
authors.lastname: Hang
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D002875:Chromosomes; D003434:Crossing Over, Genetic; D018744:DNA, Plant / Q000235:genetics*; D005785:Gene Conversion; D057898:Hemizygote; D059765:Homologous Recombination; D006720:Homozygote; D008540:Meiosis / Q000235:genetics; D016254:Mutagenesis, Insertional; D030821:Plants, Genetically Modified; D011995:Recombination, Genetic; D036226:Seedlings
chemical_list: D018744:DNA, Plant
keywords: insertion; interchromosomal recombination; meiotic recombination.; unpaired DNA