Radiation Hybrid Mapping of Wheat Chromosome 7B

The radiation hybrid (RH) mapping is a non-recombination based method that provides a construction of high-resolution physical map.  Distances on a radiation hybrid map are determined by the frequency of radiation-induced breaks between markers. In this study, the radiation hybrid panel of wheat chromosome 7B was produced by crossing irradiated tetraploid Langdon wheat to Langdon 7D (7B) substitution line. Three radiation doses of gamma rays (25, 35 and 45 krad) were used to induce random chromosomal breakage.  A panel of 1200 radiation hybrids was generated and screened with 7B specific retrojunction molecular markers to identify lines carrying breaks. Around 300 radiation hybrid lines with marker retention frequencies from 10 to 90% were selected and will be subsequently tested for high-resolution physical mapping on NimbleGen platform with markers designed from available shotgun contig sequences and BAC contigs.