Browsing by Subject "Quantitative trait loci QTL"

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    Characterization and quantitative trait loci (QTL) mapping of Fusarium head blight resistance-related traits in the Japanese wheat landrace, PI 81791 (Sapporo Haru Komugi Jugo)
    (2010-04) Quirin, Edmund Andrew
    Fusarium head blight (FHB) is a destructive disease of wheat (Triticum aestivum L.). Infection by Fusarium graminearum affects yield and grain quality traits that can lead to substantial economic losses. Developing resistant cultivars has been a major objective of plant breeders for controlling FHB. The objective of this study was to assess FHB resistance in the Japanese landrace, PI 81791 (Sapporo Haru Komugi Jugo), a line that does not possess the widely used Fhb1 QTL for type II resistance. A population of 150 recombinant inbred lines (RILs) was developed from a cross between this genotype and the susceptible variety, Wheaton, and was assessed for several resistance-related traits, including type I and II resistance, post-harvest grain traits, and agronomic traits in four field environments in Minnesota. Type II resistance was also assessed in two greenhouse environments. The RILs were genotyped using 377 microsatellite markers. Composite interval mapping detected QTL for resistance traits on chromosomes 2B, 3A, 3B, 3D, 4A, 4D, 5A, 5B and 6A and for heading date and height on 1B, 2D, 3B and 4D. The resistance QTL on chromosomes 2B, 3B, and 3D explain the largest amount of variation observed for many of the resistance traits analyzed with alleles being inherited from PI 81791. The QTL on chromosome 3B in the interval of Xbarc229 – Xgwm383b appears to be a major novel resistance locus that explains 7 – 21% of the variation observed for various resistance traits. Similar QTL regions to those on chromosome 2B in the interval of Xgwm639b – Xwmc339 and chromosome 3D in the interval of Xwmc533a – Xwmc656 have been previously reported, supporting their use for FHB resistance breeding. Major resistance QTL were also identified on chromosomes 4A, associated with Xbarc233, and 4D, which is associated with the semi-dwarfing gene, Rht-D1. However, these QTL are likely associated with increased susceptibility from PI 81791 and Wheaton, respectively. Additional type II resistance QTL were identified on 3A in greenhouse environments, explaining as much as 23.2 and 15.8% of the phenotypic variation observed.