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Sequence organization of barley centromeres
S Hudakova1, W Michalek, G G Presting
1Institut für Pflanzengenetik und Kulturpflanzenforschung (IPK), Corrensstrasse 3, D-06466 Gatersleben, Germany.
Nucleic Acids Research
|January 29, 2002
Summary
Barley centromeres contain densely packed, complete Ty3/gypsy-like retroelements called cereba. These elements, along with G+C-rich satellite sequences, form the primary structure of barley centromeric DNA.
Area of Science:
- Molecular Biology
- Genetics
- Plant Science
Background:
- Centromeric DNA organization is crucial for chromosome segregation and understanding plant genome evolution.
- Previous studies on cereal centromeres revealed diverse repetitive elements, but barley centromere structure remained less understood.
Purpose of the Study:
- To elucidate the sequence organization of barley centromeric DNA.
- To characterize the repetitive elements within barley centromeres.
Main Methods:
- Sequencing of a centromere-specific large insert clone (BAC 7).
- Fingerprinting and in situ hybridization techniques were employed.
- Analysis of retroelement structure and organization within the BAC insert.
Main Results:
- Identified three copies of the Ty3/gypsy-like retroelement cereba within a 23 kb region of BAC 7.
- Two tandemly arranged cereba elements (approx. 7 kb each) contain intact long terminal repeats (LTRs), coding regions, and polypurine tracts.
- Barley centromeres exhibit a high density (approx. 200 elements/centromere) of complete cereba elements, differing from other cereals by lacking internally deleted elements and solo LTRs.
Conclusions:
- Conserved cereba elements and barley-specific G+C-rich satellite sequences are the major components of barley centromeric DNA.
- The unique organization of cereba elements in barley centromeres offers insights into centromere evolution in cereals.