DEVELOPMENT AND CHARACTERIZATION OF A WHOLE GENOME RADIATION HYBRID PANEL FOR TETRAPLOID WHEAT

The recent release of high-quality sequence information from hexaploid wheat (IWGSC 2014) coupled with the availability of high-density consensus maps for tetraploid wheat (Maccaferri et al. 2014) has accelerated marker and gene discovery in durum wheat (Triticum durum), thus facilitating the genetic dissection of agronomic traits (Tuberosa and Pozniak 2014). This notwithstanding, the construction of genetic maps remains a bottleneck for the investigation of the durum wheat genome. In this context, the development of physical mapping resources to facilitate the assembly of BAC contigs in future sequencing projects of durum wheat is becoming a primary necessity. Radiation hybrid (RH) mapping is a promising recombination-independent mapping approach, which involves the use of radiation-induced chromosomal breakage and marker segregation to reconstruct marker order (Tiwari et al. 2016). In this study, for the first time, a RH panel for tetraploid wheat was developed for reference durum genotype Svevo (Sv-WGRH panel). The Sv-WGRH panel was developed at Kansas State University (USA), according to the protocol reported by Tiwari et al. 2016. Freshly dehiscing pollen of Svevo was irradiated with γ-rays (10-Gy) and this was used to pollinate ~150 emasculated spikes of Senatore Cappelli (used as the female parent), which produced ~1000 RH1 seeds, each representing an independent RH event. Greenhouse planting of these 1000 RH1 seeds resulted in ~730 RH1 plants, each representing a RH line of Sv-WGRH panel. Initial assessment of Sv-WGRH panel was performed based on 19 SSR markers. Results indicated that average marker retention of Sv-WGRH panel is ~85%. Work is in progress to select most informative 188 RH lines and these selected lines will be genotyped on a high-density marker platform. This RH panel is an important resource contributing towards the assembly of the genome sequence of durum wheat and other tetraploid wheats.