|Gulya Jr, Thomas|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/14/2007
Publication Date: 1/23/2008
Citation: Yue, B., Radi, S.A., Vick, B.A., Cai, X., Tang, S., Knapp, S.J., Gulya, T.J., Miller, J.F., Hu, J. 2008. Progress in Mapping QTL for Sclerotinia Stalk Rot Tolerance in a Sunflower Recombinant Inbred Population [abstract]. 6th Annual Sclerotinia Initiative Meeting, January 23-25, 2008, Bloomington, MN. p. 33.
Technical Abstract: The stalk rot caused by Sclerotinia sclerotiorum (Lib.) de Bary is a serious disease of sunflower (Helianthus annuus L.), and mapping quantitative trait loci (QTL) for resistance to Sclerotinia should facilitate the development of marker-assisted selection strategies for enhancing resistance. In this study QTL mapping for tolerance to Sclerotinia stalk rot was conducted in a recombinant inbred line (RIL) population developed from a cross between RHA280 and RHA801. The RILs were artificially inoculated using mycelium-bearing millet seeds in both greenhouse and field conditions. In 2006, disease severity, on a scale from 0 (highly resistant) to 9 (susceptible), ranged from 1.7 to 8.3 among RILs in the two greenhouse tests. Disease incidence was used to evaluate the stalk rot tolerance in field tests, and it ranged from 0 to 27.5% and 0 to 52.5% in the two field tests (Fargo and Grandin, ND), respectively. In 2007, we repeated the same tests. Unfortunately, the field tests did not produce useful data for an extremely low disease incidence at both locations due to unfavorable weather condition after inoculation. However, the greenhouse test was successful and the disease severity scores ranged from 1.2 to 8.7 among the RILs, very close to that of the previous year. In general, phenotypic correlations for RIL disease tolerance traits between tests were positive and significant. Three QTL for disease severity were identified in greenhouse tests and two QTL for disease incidence were identified in field tests. Individual QTL explained 9.1% to 15.4% of the phenotypic variation, and different QTL were detected in different tests, indicating strong environmental effects. More tests are needed to confirm the location of these QTL.