Sobo, a recently amplified satellite repeat of potato, and its implications for the origin of tandemly repeated sequences.
Highly repetitive satellite DNA sequences are main components of heterochromatin in higher eukaryotic genomes. It is well known that satellite repeats can expand and contract dramatically, which may result in significant genome size variation among genetically related species. The origin of satellite repeats, however, is elusive. Here we report a satellite repeat, Sobo, from a diploid potato species, Solanum bulbocastanum. The Sobo repeat is mapped to a single location in the pericentromeric region of chromosome 7. This single Sobo locus spans approximately 360 kb of a 4.7-kb monomer. Sequence analysis revealed that the major part of the Sobo monomer shares significant sequence similarity with the long terminal repeats (LTRs) of a retrotransposon. The Sobo repeat was not detected in other Solanum species and is absent in some S. bulbocastanum accessions. Sobo monomers are highly homogenized and share >99% sequence identity. These results suggest that the Sobo repeat is a recently emerged satellite and possibly originated by a sudden amplification of a genomic region including the LTR of a retrotransposon and its flanking genomic sequences.
Tek
Ahmet L
AL
Department of Horticulture, University of Wisconsin, Madison, Wisconsin 53706, USA.
Song
Junqi
J
Macas
Jiri
J
Jiang
Jiming
J
D001483:Base Sequence; D015139:Blotting, Southern; D004276:DNA, Satellite / Q000235:genetics*; D019143:Evolution, Molecular; D017404:In Situ Hybridization, Fluorescence; D008969:Molecular Sequence Data; D018626:Retroelements / Q000235:genetics; D017422:Sequence Analysis, DNA; D011198:Solanum tuberosum / Q000235:genetics*; D020080:Tandem Repeat Sequences / Q000235:genetics*
D004276:DNA, Satellite; D018626:Retroelements