MBE Advance Access originally published online on July 18, 2008
Molecular Biology and Evolution 2008 25(10):2079-2083; doi:10.1093/molbev/msn158
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Letter |
Insertion DNA Promotes Ectopic Recombination during Meiosis in Arabidopsis
* State Key Laboratory of Pharmaceutical Biotechnology, Plant Molecular Institute, Nanjing University, Nanjing, China
Friedrich Miescher Institute, Basel, Switzerland
E-mail: dtian{at}nju.edu.cn.
Accepted for publication July 10, 2008.
Nucleotide insertion/deletions are common polymorphisms in living organisms; however, little is known about their genetic behavior during meiosis. Here, the recombination frequency (RF) of isogenic strains of transgenic Arabidopsis thaliana, that differ in the presence or absence of an insertion, was compared. We screened over 6 million seedlings and found that during meiosis the unpaired DNA insertions paired with ectopic homologues demonstrated a 13.8 times higher RF than that of noninsertion DNA. The direct measurement of recombination events provided the first evidence that a large piece of insertion DNA had a unique genetic behavior during meiosis. This pattern was consistently observed in different lines varying in overlapping sequence, construct orientation, chromosome location, and crossing direction. We suggest that higher ectopic recombination is promoted by DNA insertions and that this mechanism exists commonly in plants. Therefore, insertion DNA plays a nontrivial role in shaping genetic variation, chromosome instability, and genome evolution.
Key Words: insertion/deletion • ectopic recombination • genetic variation • Arabidopsis
1 These authors contributed equally to this work.