Location: Sunflower and Plant Biology Research2011 Annual Report
1a. Objectives (from AD-416)
The new objectives of this follow-on project are to 1) continue construction of a recombinant inbred line population (RIL) derived from a cross between HA 441 and RHA 439 for future confirmation of the quantitative trait loci (QTL) for head rot, and 2) evaluate some lines that performed well for Sclerotinia head rot or stalk rot resistance in the 2007 field trials.
1b. Approach (from AD-416)
The primary objective of the original Specific Cooperative Agreement 58-5442-3-277 was to employ advanced molecular technology using marker-assisted selection to accelerate the process of creating sunflower germplasm with higher levels of tolerance to Sclerotinia disease. During the last two years of the project, we completed mapping of the quantitative trait loci (QTL) for Sclerotinia head rot resistance in HA 441and RHA 439, both of which are USDA sunflower lines. We accomplished this by constructing a genetic map of 18 linkage groups with 249 markers, and located nine QTL for disease incidence and seven QTL for disease severity on 10 of the linkage groups. Promising data was also obtained for Sclerotinia stalk rot tolerance. To complete the studies of the original agreement, it is now necessary to complete the construction of the RIL population from the cross of HA 441 and RHA 439. We have completed construction through the F4 generation and need to complete two more generations to obtain a usable RIL population. A new objective of this follow-on agreement will be to evaluate some of the best Sclerotinia tolerant lines we identified in the original project for release to the public. In 2008, we will 1) advance four lines derived from a cross of HA 441/RHA 439 which performed well and consistently for head rot resistance in the F5 generation in greenhouse. Head rot resistance of the four lines together with their hybrids from a cross with cmsHA 89, along with two checks will be evaluated in the field with three replicates; 2) four RIL lines from the RHA 208/RHA 801 RIL population resistant to stalk rot together with their hybrids with cmsHA89 and two checks will be re-evaluated under field conditions with three replicates; and 3) continue construction of the HA 441/RHA 439 RIL population by single seed descent method. We will sow the seeds we bagged in the field in 2007, one row for one head, bagging one head before flowering, and harvesting them for advancing to the next generation in the following year.
3. Progress Report
During FY-2010, Recombinant inbred lines (RILs) from the cross HA 441 x RHA 439 were advanced to the F7 generation by the single seed descent method. The parental line HA 441 was previously selected for tolerance to Sclerotinia head rot and also showed tolerance to stalk rot in the inoculated field nursery in 2008 and 2009. A total of 106 RILs will be evaluated for the reaction to stalk rot in the 2011 field nursery. Four head rot resistant lines derived from the cross of HA 441 and RHA 439, together with their testcrosses and the original parents, HA 441 and RHA 439, were re-evaluated for the reaction to head rot in the 2010 field nursery (second year). All selected resistant lines showed low disease severity and incidence compared to the parents and their testcrosses. Four stalk rot resistant lines selected from the RHA208 x RHA801 RIL population, together with their testcrosses and the original parents, RHA 208 and RHA 801, were re-evaluated for the reaction to stalk rot in the 2010 field nursery (second year). Disease incidence in the 2010 field trials was very low, thus disease test was conducted twice in the greenhouse in 2010-2011. All selected resistant lines except the line RIL 293 exhibited low disease incidence compared to the parents. The ADODR monitors research progress by semiannual meetings with the Cooperator's personnel and by site visits to field plot locations.