To explore an effective and reliable karyotyping method in Brassica crop plants

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t-1 DNA was isolated from Brassica oleracea genome

labeled as probe with Biotin-Nick Translation Mix kit

in situ hybridized to mitotic spreads

specific fluorescent bands were showed on each chromosome pairs.25S and 5S rDNA were labeled as probes with DIG-Nick Translation Mix kit and Biotin-Nick Translation Mix kit

respectively

in situ hybridized to mitotic preparations

25S rDNA could be detected on two chromosome pairs

and 5S rDNA only one.C

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t-1 DNA contains rDNA

chromosome sites identity between C

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t-1 DNA and 25S rDNA was determined by dual-colour fluorescence in situ hybridization.All these showed that the karyotyping technique based on a combination of rDNA and C

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t-1 DNA chromosome landmarks is superior to alone one. A more exact karyotype of B.oleracea have been analysed based on a combination of rDNA sites

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t-1 DNA fluorescent bands

chromosome lengths and arm ratios.