High-resolution mapping of the of the peri-centromeric region on wheat chromosome arm 5AS harboring the Fusarium head blight resistance QTL Qfhs.ifa-5A

3 years ago

High-resolution mapping of the of the peri-centromeric region on wheat chromosome arm 5AS harboring the Fusarium head blight resistance QTL Qfhs.ifa-5A

Christian Wagner, Giampiero Valè, Delfina Barabaschi, Maria Buerstmayr, Petra Schwarz, Luigi Cattivelli, Andrea Volante, Barbara Steiner, Hermann Buerstmayr, Klaus Brugger

The Qfhs.ifa-5A allele, contributing to enhanced Fusarium head blight resistance in wheat, resides in a low recombinogenic region of chromosome 5A close to the centromere. A near isogenic RIL population segregating for the Qfhs.ifa-5A resistance allele was developed and among 3650 lines as few as four recombined within the pericentromeric C-5AS1-0.40 bin, yielding only a single recombination point. Genetic mapping of the pericentromeric region using a recombination dependent approach was thus not successful. To facilitate fine-mapping the physically large Qfhs.ifa-5A interval, two gamma-irradiated deletion panels were generated: (1) Seeds of line NIL3 carrying the Qfhs.ifa-5A resistance allele in an otherwise susceptible background were irradiated and plants thereof were selfed to obtain deletions in homozygous state. (2) A radiation hybrid panel was produced using irradiated pollen of the wheat line Chinese Spring (CS) for pollinating the CS-nullisomic5Atetrasomic5B. In total 5157 radiation selfing and 276 radiation hybrid plants were screened for deletions on 5AS and plants containing deletions were analysed using 102 5AS specific markers. Combining genotypic information of both panels yielded an 817 fold map improvement (cR/cM) for the centromeric bin and was 389 fold increased across the Qfhs.ifa-5A interval compared to the genetic map, with an average map resolution of 0.77 Mb/cR. We successfully proved that the RH mapping technique can effectively resolve marker order in low-recombining regions, including pericentromeric intervals, and simultaneously allow developing an in vivo panel of sister lines differing for induced deletions across the Qfhs.ifa-5A interval that can be used for phenotyping. This article is protected by copyright. All rights reserved.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1111/pbi.12850