Genetic and molecular characterization of barley chromosome telomeres

Previously, we cloned telomere-associated sequences using Vectorette-PCR and mapped the most telomeric regions of barley chromosome arms 1S (7HS), 2S (2HS), and 4S (4HS) (Kilian and Kleinhofs 1992). Here we report mapping 33 different telomere-associated markers (21 RFLPs and 12 PCR-based) identifying the most telomeric region of 10 out of the 14 barley chromosome arms. Other telomere-associated markers mapped very close, but not at the telomere, or were interstitial. Four markers mapped at centromeric regions. Two markers, generated by PCR using a single primer based on the sequence of the barley telomere repeats, mapped to the end of barley chromosome 7L (5HL) and internally on chromosome 3L (3HL). Cloning and sequencing of PCR products from the 3L (3HL) interstitial location revealed homology to the HvRT family. Several low copy number sequences physically linked to HvRTs were also cloned and used as RFLP probes. These probes often mapped close to the ends of linkage groups. A few RFLPs mapped at centromeric regions in agreement with the result of in situ hybridization of HvRT clones showing positive signal at the ends and around centromeres of barley chromosomes.