ARS | Publication request: New Sources of Sclerotinia Stalk Rot in Cultivated USDA Sunflower Plant Introductions

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: January 4, 2010
Publication Date: January 15, 2010
Citation: Gulya, T.J., Hulke, B.S. 2010. New Sources of Sclerotinia Stalk Rot in Cultivated USDA Sunflower Plant Introductions. 8th Annual Sclerotinia Initiative Meeting, January 20-22, 2010, Bloomington, MN. p. 20.

Technical Abstract: In a two-year study, 250 cultivated sunflower genotypes from the USDA sunflower collection (maintained and distributed by the North Central Regional Plant Introduction Station, Ames, Iowa) were evaluated in multiple field trials for their reaction to stalk rot incited by Sclerotinia sclerotiorum. Three locations were planted in 2008 and again in 2009; one location each year flooded and thus only four datasets were usable. Due to the large experiment size, the study was designed as a randomized complete block design with sets in reps. Artificial inoculation was done using Sclerotinia grown on millet (mycelium without sclerotia) which was deposited in furrows mid-season using a granular chemical applicator mounted on a tractor. In addition to the 250 Plant Introductions (PIs), twelve USDA inbreds were also included for comparison with germplasm developed specifically for disease resistance. Averaged over four locations, stalk rot ratings ranged from 3.5% (USDA inbred HA 441) to 84% for PI 650710 (confection type from Spain). The entries which were rated in the top 10% of the study included six USDA inbred lines, plus a very diverse group of international germplasm originating from eleven countries (Argentina, Canada, Czech Republic, France, Hungary, Mexico, Paraguay, Poland, Russia, Spain, Zambia). This group of stalk rot resistant germplasm will form the basis of both improving our USDA breeding material and will help to diversify its overall genetic foundation. The data produced in this study will be used in association mapping by a companion project. Future plans call for testing either the elite stalk rot material, or the entire collection of 250 Plant Introductions in inoculated trials for head rot resistance, in an attempt to select for germplasm with high levels of resistance to both diseases.