Identifying Quantitative Trait Loci for Resistance to Sclerotinia Head Rot in Two USDA Sunflower Germplasms

• Published in: Phytopathology 2008-08, Vol.98 (8), p.926-931
• Main Authors: Yue, B, Radi, S.A, Vick, B.A, Cai, X, Tang, S, Knapp, S.J, Gulya, T.J, Miller, J.F, Hu, J
• Format: Article
• Language: English
• Subjects: Ascomycota - physiology; Biological and medical sciences; Chromosome Mapping; Chromosomes, Plant; disease resistance; Fundamental and applied biological sciences. Psychology; fungal diseases of plants; Fungal plant pathogens; Genetic Markers; genetic polymorphism; Genetic Predisposition to Disease; genetic resistance; Genetic Variation; germplasm; Helianthus; Helianthus - genetics; Helianthus - microbiology; Helianthus annuus; microsatellite repeats; molecular sequence data; Phytopathology. Animal pests. Plant and forest protection; plant breeding; Plant Diseases - genetics; Plant Diseases - microbiology; Quantitative Trait Loci - genetics; resistance genes; Sclerotinia; Sclerotinia sclerotiorum; United States; United States Department of Agriculture
• ISSN: 0031-949X; 1943-7684
• DOI: 10.1094/PHYTO-98-8-0926

Sclerotinia head rot is a major disease of sunflower in the world, and quantitative trait loci (QTL) mapping could facilitate understanding of the genetic basis of head rot resistance and breeding in sunflower. One hundred twenty-three F2:3 and F2:4 families from a cross between HA 441 and RHA 439 were studied. The mapping population was evaluated for disease resistance in three field experiments in a randomized complete block design with two replicates. Disease incidence (DI) and disease severity (DS) were assessed. A genetic map with 180 target region amplification polymorphism, 32 simple sequence repeats, 11 insertion-deletion, and 2 morphological markers was constructed. Nine DI and seven DS QTL were identified with each QTL explaining 8.4 to 34.5% of phenotypic variance, suggesting the polygenic basis of the resistance to head rot. Five of these QTL were identified in more than one experiment, and each QTL explained more than 12.9% of phenotypic variance. These QTL could be useful in sunflower breeding. Although a positive correlation existed between the two disease indices, most of the respective QTL were located in different chromosomal regions, suggesting a different genetic basis for the two indices.