Isolation, characterization and chromosome localization of repetitive DNA sequences in bananas (Musa spp.) |
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Authors: | M Valárik H Šimková E Hřibová J Šafář M Doleželová J Doležel |
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Institution: | (1) Laboratory of Molecular Cytogenetics and Cytometry, Institute of Experimental Botany, Sokolovská 6, CZ-77200 Olomouc, Czech Republic |
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Abstract: | Partial genomic DNA libraries were constructed in Musa acuminata and M. balbisiana and screened for clones carrying repeated sequences, and sequences carrying rDNA. Isolated clones were characterized in terms
of copy number, genomic distribution in M. acuminata and M. balbisiana, and sequence similarity to known DNA sequences. Ribosomal RNA genes have been the most abundant sequences recovered. FISH
with probes for DNA clones Radka1 and Radka7, which carry different fragments of Musa 26S rDNA, and Radka14, for which no homology with known DNA sequences has been found, resulted in clear signals at secondary constrictions. Only
one clone carrying 5S rDNA, named Radka2, has been recovered. All remaining DNA clones exhibited more or less pronounced clustering at centromeric regions. The study
revealed small differences in genomic distribution of repetitive DNA sequences between M. acuminata and M. balbisiana, the only exception being the 5S rDNA where the two Musa clones under study differed in the number of sites. All repetitive sequences were more abundant in M. acuminata whose genome is about 12% larger than that of M. balbisiana. While, for some sequences, the differences in copy number between the species were relatively small, for some of them, e.g.
Radka5, the difference was almost thirty-fold. These observations suggest that repetitive DNA sequences contribute to the difference
in genome size between both species, albeit to different extents. Isolation and characterization of new repetitive DNA sequences
improves the knowledge of long-range organization of chromosomes in Musa.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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Keywords: | chromosome structure genome size in-situ hybridization Musa repetitive DNA |
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