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United States Department of Agriculture

Agricultural Research Service

Research Project: GENETIC CHARACTERIZATION AND UTILIZATION OF DISEASE RESISTANCE GENES IN TETRAPLOID WHEAT
2012 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 identified four T. dicoccum (e.g., PI 41025, PI 254188, PI 254193, and PI 272527) and two T. carthlicum (e.g., PI 61102 and PI 94748) accessions and a hexaploid wheat line (PI 277012) with FHB resistance. They were previously crossed and backcrossed with durum wheat cultivars ‘Ben’, ‘Divide’, ‘Lebsock’, and ‘Maier’. Twenty-nine durum lines from the backcrosses in advanced generations (BC1F7 to BC1F10) and a double haploid with improved FHB resistance were previously selected based on evaluation in the greenhouse in multiple seasons and field nurseries in multiple locations. These lines were further evaluated using a randomized complete block design with three replications in greenhouse in the fall of 2011 and spring of 2012. They were also evaluated in the field nurseries in three locations (Fargo, Langdon, and Prosper) during the summer in 2012.

To further improve the agronomic characteristics and quality of the selected lines with improved FHB resistance, seven BC1-derived advanced lines (10FAR2627 and 10FAR2891 from Divide/PI 272527//Divide, 08F285, 08G33, and 08G105 from Ben/PI 41025//Maier, 07F459 from Lebsock/PI 94748//Lebsock, and 10FAR2778 from Lebsock/PI 277012//Lebsock), and one double haploid (LP102-14 from Lebsock/PI 61102) have been crossed and backcrossed with the new ND durum cultivar ‘Tioga’ and two elite durum lines (D03028 and D04581). Approximately 2,000 BC1F1 plants were evaluated for Type II resistance in the greenhouse in the fall of 2011. The BC1F2 progeny from 170 BC1F1 plants were selected and evaluated in greenhouse and field nurseries in three locations (Fargo, Langdon, and Prosper) during the summer of 2012. In addition, the BC1F2 progeny from additional 402 BC1F1 plants were evaluated in field nurseries in two locations (Fargo and Langdon) during the summer of 2012.

To map the FHB resistance in T. dicoccum PI 41025, the population BP025 (durum Ben/PI 41025) of 200 F2:7 recombinant inbred (RI) lines have been evaluated for Type II resistance in the greenhouse for three seasons using a randomized complete block design with three replications. The population will be genotyped with 90K wheat SNP makers for QTL analysis in the coming season. For preparing molecular mapping of the FHB resistance derived from T. dicoccum PI 272527, a new RI population derived from the crosses between 10FAR2891 (Divide/PI 272527//Divide) and durum line D03028 is being developed. Approximately 300 F2 plants from the cross have been grown to produce F3 seed.


Last Modified: 10/25/2014
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