DETECTION AND CHARACTERIZATION OF 1B/1R TRANSLOCATIONS IN HEXAPLOID WHEAT

Total genomic DNA from rye was labelled with biotin and used as a probe for in situ hybridization to show the sizes and translocation points of the rye chromosome segments in five wheat varieties which carry a translocation between wheat chromosome 1B and the short arm of rye chromosome 1R (1B/1R). All the translocation breakpoints were at, or very near to, the centromere. Using genomic DNA to block some cross-hybridization, little signal from hybridization between the rye probe and wheat chromosomes was observed despite the 78 per cent sequence homology between the species. The translocation was identified in cells at all stages of the cell cycle. Total genomic rye DNA used as a probe was also able to distinguish rye, triticale and wheat varieties carrying the translocations, by Southern hybridization. The techniques using genomic probes are useful for detecting, characterizing and following alien chromosomes or chromosome segments through breeding programmes, by both in situ and Southern hybridization.