Location: Cereal Disease Laboratory
Project Number: 3640-22000-024-05
Start Date: Sep 18, 2013
End Date: Aug 30, 2014
Objective 1) The Tun108 lines will be screened for FHB resistance in both greenhouse and field. Our current data clearly indicates a segregation for and a number of highly resistant lines based on greenhouse and field screening. Although there are obvious discrepancies between the two set of data because of environmental effect, on the average, 53 out of 173 (30.64%) and 57 out of 170 (33.53%) lines showed less than 20% infection in the two Tun108 populations. Both populations were genotyped using DArT clones and resulted in 553 polymorphic loci that mapped on the A and B genomes. Additional SSR markers are being added to these populations to anchor the DArT map and saturate the regions of critical importance. Objective 2) The major limitation will be the type of marker identified to be associated with important FHB resistance loci. The system we plan to use for SSR and SNP marker detection is relatively easy to apply and can be directly incorporated into the durum wheat breeding program. The DArT markers would require conversion into an easily scored marker system to become part of the routine selection protocol. The majority of DArT markers have been or are being sequenced. Therefore, we can take that information and identify flanking regions to use in developing either a sequence tagged site (STS) or cleaved amplified product (CAP) marker for the locus of interest. Objective 3) We plan to initiate a project that involves the use of gamma radiation and chemical mutagens and search for resistance in cultivated durum lines. The use of gamma ray irradiation has not only been effective in high-resolution physical mapping and BAC contig alignment to the genome but also in high resolution map based cloning in wheat. We will utilize this approach to derive about 1-5 Mb deletions lacking different parts of chromosome 2A in durum wheat to map the exact location of the suppressor gene(s). Seeds of a susceptible durum wheat cultivar carrying many of the major QTL regions for FHB resistance will be irradiated to produce M1 plants. Objective 4) To pyramid FHB resistance regions on chromosomes 5BL and 3BS, identified in Tunisian derived lines into, durum cultivars we plan to initiate a traditional crossing strategy utilizing closely associated markers for selection. We have identified a number of lines in the current study that show excellent levels of resistance and carry the major QTL regions identified by association mapping. These lines will be intercrossed to develop lines that pyramid all of the important regions. Backcrossing this source to advance durum breeding lines and selection with molecular markers will allow us to identify lines that potentially carry the major QTLs.