|Yue, Bing - NORTH DAKOTA STATE UNIV|
|Cai, Xiwen - NORTH DAKOTA STATE UNIV|
|Gulya Jr, Thomas|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: October 3, 2006
Publication Date: January 13, 2007
Citation: Yue, B., Radi, S.A., Miller, J.F., Vick, B.A., Cai, X., Gulya, T.J., Hu, J. 2007. Dissecting quantitative trait loci for head rot tolerance in two sunflower lines with partial tolerance. Plant and Animal Genome XV Conference, January 13-17, 2007, San Diego, CA. P667. p. 268. Technical Abstract: One hundred and twenty-three F3 lines derived from a cross between HA 441 and RHA 439 were used for the current study. Both parental lines showed partial tolerance to Sclerotinia head rot caused by Sclerotinia sclerotiorum. A genetic map with 236 TRAP, 11 SSR, and 2 morphological markers was constructed in a F2 population with 123 individuals. This map has 18 linkage groups and spans 2328.3 cM. The F3 families (20-25 plants each) were planted in Carrington, ND, with a randomized complete block field design with two replications. At flowering stage each head was inoculated with a suspension containing 5000 ascospores per milliliter and kept under mist irrigation for three weeks to create an effective microenvironment for disease development. Five weeks after the inoculation, disease on individual heads was scored in a scale of 0 (no symptoms) through 5 (100% of head rotted). Disease tolerance was evaluated by disease incidence (DI) being calculated as the percentage of plants infected within a row and disease severity (DS) being measured by the mean disease score of the infected plants within each row. Although a positive correlation existed between the two indexes, the respective QTLs were located in different chromosomal regions, suggesting a different genetic basis for the two indexes. Six and nine QTLs were detected for DI and DS, respectively. These QTLs, each with LOD scores ranging from 2.1 to 18.1, were distributed in 11 of the 18 linkage groups.