Location: Cereal Crops Research2011 Annual Report
1a. Objectives (from AD-416)
The objectives of this cooperative research project are: 1) Characterize the genes/QTLs controlling resistance to three fungal diseases, including Fusarium head blight (FHB), tan spot, and Stagonospora nodorum blotch (SNB), in domesticated emmer wheat, and 2) to exploit the novel resistance genes for developing durum wheat germplasm adapted to the Northern Great Plains.
1b. Approach (from AD-416)
We previously identified a number of Persian wheat (Triticum turgidum L. subsp. carthlicum) and cultivated emmer wheat (T. dicoccum) accessions with resistance to FHB, tan spot, and SNB. We are currently transferring the resistance from some of these accessions into ND durum cultivars using the backcross method coupled with doubled haploid (DH) and single-seed descent (SSD). We have developed approximately 500 DH and 591 BC1-derived lines from crosses of five T. carthlicum and four T. dicoccum accessions with four durum cultivars (Lebsock, Ben, Mountrail, and Maier). In this project, we will evaluate the DH and BC1F1-derived (BC1F4 and BC1F5) lines for resistance to the three diseases in greenhouse and field nurseries. The 10 DH and BC1F5-derived lines with the highest level of resistance will be used as donors for the second cycle of introgression. In addition, we will initiate the introgression of the resistance from additional 10 T. carthlicum and T. dicoccum accessions with potential novel genes for a high level of resistance to the three diseases at the tetraploid level. The selected DH and BC1-derived lines and the T. carthlicum and T. dicoccum accessions first will be crossed with the durum cultivars Maier and Divide. The F1 hybrids will be backcrossed with their durum parents to produce BC1 seeds. All the BC1F1 plants will be evaluated for Type II FHB resistance in the greenhouse. The BC1F2 plants derived from the BC1F1 plants with low infection will be advanced to the BC1F5 through evaluation and selection. The resistance in the BC1F5-derived lines will be validated by evaluating the lines using a randomized complete block design (RCBD) with three replications in greenhouse and field nurseries in two locations. The BC1F5-derived lines with a high level of FHB resistance will be further evaluated for resistance to tan spot and SNB. The elite lines with multiple resistances will be used for further introgression and durum wheat breeding. To characterize the genes/QTLs controlling the resistance to FHB and SNB in tetraploid wheat, we have developed a population (LP749) consisting of 146 DH lines from a cross between the durum cultivar Lebsock and T. carthlicum accession PI 94749, which is resistant to FHB and SNB. The population will be used for developing linkage maps of all 14 chromosomes consisting of about 300 SSR markers, and then it will be evaluated for reaction to FHB and SNB. SNB evaluation will be conducted in three replicated experiments under controlled conditions. FHB evaluation will be performed for at least three seasons in greenhouse. The FHB and SNB phenotypic values will then be regressed on the marker data using single-factor regression, simple interval mapping, and composite interval mapping to identify QTLs associated with FHB and SNB resistance. In addition, we will initiate the development of a tetraploid recombinant inbred (RI) population derived from a cross between the emmer wheat accession PI41025 (with resistance to the three diseases) and the susceptible durum variety Ben. Approximately 150 RI lines will be developed from this cross using the SSD method and advanced to the F6:7 generation.
3. Progress Report
Introgression of the FHB resistance from T. carthlicum and T. dicoccum into ND durum cultivars was continued. We previously produced over 6,000 BC1F1 plants by crossing and backcrossing four doubled haploid (DH) lines (BP888-7, BP281-13, BP025-3, and MC085-1), six BC1F4-derived lines (07F48, 07F217, 08F130, 08F275, 08F286, and 07F468), and 19 T. dicoccum accessions (PI191390, PI254188, PI254193, PI272527, PI275998, PI276005, PI276007, PI276014, PI276018, PI276021, PI289603, PI330544, PI352337, PI352338, PI352342, PI352361, PI355460, PI355461, and PI355489) with the durum cultivars Alkabo, Grenora, Maier, and Divide. About 150 BC1F4-5 lines with improved FHB resistance were evaluated in field nurseries in Fargo and Langdon during the summer of 2010. Based on the field evaluation, 44 BC1F5-6 lines were selected and evaluated in the greenhouse in the winter of 2010 and their derived BC1F6-7 lines are currently being evaluated in greenhouse and field nurseries in Fargo and Prosper during the summer of 2011. To further improve the agronomic traits, six BC1-derived advanced lines (10FAR2627 and 10FAR2891 from Divide/PI 272527//Divide, 08F285, 08G33, and 08G105 from Ben/PI 41025//Maier, and 07F459 from Lebstock/T. carthlicum PI 94748//Lebstock) and one doubled haploid (LP102-14 from Lebsock/ T. carthlicum PI 61102) have been crossed and backcrossed with the new ND durum cultivar ‘Tioga’ and two elite durum lines (D03028 and D04581). For mapping the resistance QTL in T. dicoccum PI 41025, a population BP025 (Ben/PI 41025) of 200 F2:7 recombinant inbred lines has been evaluated for Type II resistance in the greenhouse for two seasons. In addition, we identified a “T. dicoccum” accession (PI 277012) consistently showing a high level of FHB resistance across all environments. PI 277012 is currently classified as T. dicoccum in the National Small Grains Collection, but we verified that PI 277012 is actually a hexaploid wheat line. Using a doubled haploid (‘Grandin’/ PI 277012) population, we mapped two major FHB resistance QTLs on chromosome arms 5AS (Qfhb.rwg-5A.1) and 5AL (Qfhb.rwg-5A.2), respectively, with each explaining up to 20% and 32% of the variation in FHB severity, respectively. The two QTLs also showed major effects on reducing the percentage of Fusarium damaged kernels and DON accumulation in seeds. To transfer FHB resistance QTLs from PI 277012 to durum wheat, we backcrossed PI 277012 to six durum cultivars (Ben, Maier, Divide, Lebsock, Mountrail, and Alkabo). A durum line (10FAR2778) carrying both QTLs, and six durum lines carrying only the 5AS QTL, have been selected in the BC1F5 from the backcrosses of PI 277012 with Lebsock, Ben, Divide, and Mountrail. To further improve agronomics, the durum line carrying the two QTLs has been crossed and backcrossed with Lebsock, Tioga, D03028, and D04581. ADODR monitoring included personal visitation, email correspondence, and telephone discussions.