2012 Annual Report 1a.Objectives (from AD-416): 1) Identify resistant wild Helianthus species populations. 2) Transfer resistance genes into a cultivated background. 3) Study the inheritance of resistance. 1b.Approach (from AD-416): The head rot evaluation misting facility at Carrington, ND, will be used as the primary site for field Sclerotinia head rot evaluation of wild Helianthus interspecific hybrids and early generation progenies when materials become available. Backcrossed progenies of interspecific hybrids or from amphiploids will be evaluated in replicated field plots as soon as the plants reach 2n=34 chromosomes and have sufficient seeds from either self-pollination or further backcrosses. The field evaluation will be conducted every year as more progeny families are produced. Five cross combinations between amphiploids, head rot resistant wild sunflower, or stalk rot resistant wild sunflower will be made with HA 441 or HA 410, followed by backcrossing to obtain new resistant lines. For inheritance studies, these new resistant lines will be crossed with susceptible inbred line HA 234, and disease evaluations will be conducted on F1, F2, and F3 progeny families. Due to the quantitative nature of Sclerotinia resistance and low probability of obtaining the resistant recombinant, the number of 2n=34 progeny families for field test will be continuously increased throughout the years of the project. In addition, 2n=36 plants from selfed 2n=35 plants, expected to be disomic additions, will be tested in the field to identify major resistance QTLs associated with specific chromosomes. If major resistance QTLs are found, their transfer into lines HA 410 or HA 441 will be followed and the disomics will be located to specific linkage groups of the sunflower RFLP map. 3.Progress Report: Backcross BC4F3/BC4F4 progenies of stalk rot resistant hexaploid perennial H. californicus crossed with HA 410 were evaluated in replicated field trials in 2011. Backcross progenies of five stalk and head rot resistant interspecific amphiploids crossed with HA 410 were established in the field, and BC2F4/BC3F3 families were evaluated in replicated field trials in 2011. Crosses between NMS HA89 and head rot resistant diploid perennials H. maximiliani and H. nuttallii were advanced to BC1F4 and BC2F4 families for replicated field trials in 2011. Stalk rot resistant diploid perennials H. maximiliani, H. giganteus, and H. grosseserratus were crossed with HA 410 in 2007, and their BC1F4/ BC2F3 families evaluated in replicated field trials in 2009-2011. Replicated field tests in 2011 for head and stalk rot resistance indicated moderate to good resistance indicating successful gene introgression. Progeny families susceptible after two years of field testing were eliminated and those resistant for two years will be further tested. Field trials in 2011 for stalk rot resistance failed due to hail damage and an extremely wet growing season at Carrington, ND. New perennials of H. salicifolius, H. hirsutus, H. occidentalis, H. divaricatus, and H. resinosus were crossed with HA410 or HA451 to further diversify the resistance genes and to increase the probability of identifying useful major resistance QTLs. Fifty-nine alien addition progeny plants from backcrosses of interspecific amphiploids with HA 410 have been produced and will be characterized in 2012. The addition lines will provide materials for identifying major QTLs for Sclerotinia resistance on specific chromosomes. Over 200 advanced backcross progeny families were grown in Fargo, ND, for seed increase for the 2012 replicated field tests.