Location: Sunflower and Plant Biology Research2008 Annual Report
1a. Objectives (from AD-416)
The objectives of our proposed research are threefold: (1) To evaluate cultivated sunflower and wild Helianthus species for insect and disease resistance, concentrating on those diseases and insects which are of greatest impact to the U.S. sunflower industry, (2) to develop and phenotype segregating populations for DNA marker discovery, which will be used to supplement classical breeding methods to identify breeding material with improved agronomic, disease and insect resistance traits, and (3) to develop advanced germplasm which carry genes for insect and disease resistance.
1b. Approach (from AD-416)
To identify new sources of insect and disease resistance in sunflower we will evaluate, either under natural infestations (insects) or with artificial inoculations (diseases) a diverse selection of sunflower germplasm, including breeding populations, USDA Plant Introductions, and wild species (obtained from a companion research project 5442-21000-034-00D). For diseases, we will focus on Sclerotinia, downy mildew, and rust. The major insect pests in our studies are the sunflower stem weevil, sunflower moth, and banded sunflower moth. We have developed segregating populations for some insect and diseases, and are developing others. These populations will be used by the project molecular geneticist to identify markers for these traits. Phenotyping will be done at several locations, using either natural insect infestations or artificial inoculations for diseases. Finally, using field plots with natural insect infestations or artificial disease inoculations, and supplemented by marker-assisted selection, we will evaluate the new sources for resistance to the major insect pest species and disease pathogens and transfer that resistance into genetic stocks or advanced USDA germplasm for release to the public.
3. Progress Report
Two hundred sixty cultivated sunflower accessions from the USDA Plant Introduction collection and elite inbreds were tested in inoculated field trials at three locations for resistance to Sclerotinia stalk rot. The most resistant material will be retested in 2009 for stalk rot and in separate trials for head rot. Breeding material from three other unit scientists was evaluated for head rot and stalk rot in separate inoculated nurseries in Minnesota and North Dakota. Transfer of downy mildew resistance into multiple genetic backgrounds was initiated, effectively combining this resistance with IMI herbicide resistance, Sclerotinia resistance, and altered fatty acid profiles. Rust resistant populations are in the early stages of development, and this resistance will be placed in an elite genetic background combined with other important traits. The effect of root exudates of six different crops on the mode of sclerotial germination was studied in a Fargo field trial. Downy mildew samples were collected for race identification and to monitor the possible development of fungicide resistance. Evaluation was conducted on over 432 germplasm sources including accessions, S1 lines, F2:3 lines, and interspecific crosses for resistance to the principal insect pests of sunflower, including the sunflower moth and sunflower stem weevil in Kansas, the red sunflower seed weevil in South Dakota, and the banded sunflower moth in North Dakota. Several different populations are under various stages of development for resistance to the four major insect pests. Most noteworthy this year was the advancement of an F2-derived set of lines that consistently showed insect resistance over two years of trials. We plan to begin testing F3-derived versions of these lines next year. Studies also were conducted to evaluate selected commercial sunflower hybrids for tolerance to damage by the sunflower midge. We developed a network of cooperators to monitor flight activity of the sunflower moth from southern Texas to Canada using pheromone traps to provide a system to alert consultants and growers when moths are active in the area and the information is plotted weekly on a map available on university and industry websites. We conducted research to develop a degree-day model for banded sunflower moth emergence and flight activity using pheromone traps in North Dakota, South Dakota, Minnesota, and Manitoba. A study was initiated to investigate the biology and management of the sunflower seed maggot in North Dakota, including field studies of maggot biology, impact of planting date, determination of economic injury levels, insecticide efficacy and timing, and evaluation of commercial sunflower hybrids for resistance to maggot damage. (This research addresses National Program 301 Action Plan Component 3, Genetic Improvement of Crops, Problem Statement 3B, Capitalizing on Untapped Genetic Diversity, and Problem Statement 3C, Germplasm Enhancement/Release of Improved Genetic Resources and Varieties).
5. Significant Activities that Support Special Target Populations