A comparison of sequence resolution on plant chromosomes: PRINS versus FISH

The resolution of the chromosomal positions of six high- and one low-copy s equences by oligonucleotide-primed in situ (PRINS) labelling was compared w ith corresponding data obtained after fluorescent in situ hybridization (FI SH) on field-bean and barley chromosomes. While PRINS proved to be suitable for the rapid detection of high-copy tandem repeats: at the same loci as t hose revealed by FISH, no clear PRINS signal was obtained for the low-copy family of vicilin genes at their locus on field-bean chromosome II. This in dicates that localization of short target sequences by primer extension via Taq polymerase in situ does not yet provide a resolution equal, or superio r, to FISH on plant chromosomes. Therefore, the use of a cocktail of chromo some-specific single-copy sequences as primers for PRINS is no alternative for the not as yet feasible chromosome painting in plants.