Identification of different chromatin classes in wheat using in situ hybridization with simple sequence repeat oligonucleotides |
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Authors: | A Cuadrado T Schwarzacher N Jouve |
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Institution: | (1) Department of Cell Biology and Genetics, University of Alcala, 28871 Alcala de Henares, Madrid, Spain e-mail: bcjouve@gene.alcala.es Tel.: +34-91-885 4750, Fax: +34-91-885 4799, ES;(2) John Innes Centre, Norwich Research Park, Colney, Norwich NR4 7UH, UK, GB |
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Abstract: | Clusters of four simple sequence repeats (SSRs), AAC, AAG, AG and CAT, have been mapped physically to hexaploid wheat chromosomes;
15—24-bp synthetic oligonucleotides were labelled by random-primer labelling and used as probes for fluorescent in situ hybridization
with standard formamide and low-salt conditions. AAC hybridized strongly to the pericentromeric regions and several intercalary
sites of all seven chromosomes of the B-genome corresponding to N bands and enabling their identification. Most of the AAC
sites also co-localize with AAG, although the strength of the AAC and AAG signal was often different at the same location.
Not all heterochromatic bands showed AAC signals and a few AAC sites were detected that are neither AAG nor N band positive,
revealing the complex and heterogeneous genome organization of wheat and identifying the four most frequent classes of banded
chromatin. Clusters characterised by a high concentration of AG repeats were detected on chromosome arms 3BS, 4BL, 5BS and
5BL, adjacent to AAG sites. The only detectable CAT cluster was found on chromosome arm 3BL, making this oligonucleotide valuable
in identifying this particular chromosome. SSR in situ hybridization is useful as a diagnostic tool in cytogenetics and for
understanding genome organization in wheat.
Received: 21 September 1999 / Accepted: 19 March 2000 |
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Keywords: | Triticum aestivum L Microsatellites C banding N banding Genome organization |
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