ISHS Acta Horticulturae 484: Eucarpia Symposium on Fruit Breeding and Genetics
THE APPLICATION OF GENOME ‘PAINTING’ IN POLYPLOID RUBUS |
| Authors: | K.Y. Lim, A.M. Hadonou, V.H. Knight, M.D. Bennett, I.J. Leitch |
| Keywords: | GISH, FISH |
| Abstract:
An EU-funded Rubus breeding project, in which HRI-East Malling is participating, has generated a range of allopolyploid hybrids between raspberry and blackberry providing ideal material for investigating the application in Rubus of the cytogenetic technique non-isotope in situ hybridization using genomic and cloned probes. Genomic in situ hybridization (GISH) was tested on metaphase chromosomes of allotetraploids and allopentaploids by probing with labelled total genomic DNA from raspberry and unlabelled total genomic DNA from blackberry as a block. This approach clearly labelled the raspberry chromosomes although the labelling was restricted predominantly to the centromeric regions. These Rubus hybrids are the smallest genomes (1C = c. 0.3 pg) to be discriminated in this way using GISH. Fluorescent in situ hybridization (FISH), with a cloned probe for the ribosomal RNA genes 18S-5.8S-26S (pTa71), was used to detect the location of the rDNA sequences on the chromosomes, which may represent the nucleolar organiser regions. Four fluorescent sites were identified in a colchicine-doubled tetraploid raspberry and four, five and six sites in an allotetraploid, allopentaploid and allohexaploid respectively. Our results indicate the potential of these genome ‘painting’ techniques for chromosome identification and physical mapping in rosaceous fruit crops. | |
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