Theses and Dissertations Collection

Fusarium head blight (FHB) is one of the most destructive diseases of wheat causing significant yield losses and quality reduction in the humid areas of the world. It is also an emerging wheat disease in Southeastern Idaho of the United States. Resistance to FHB is known to be a quantitatively inherited trait and highly influenced by confounding environmental factors. The objectives of this study were to map and characterize QTL associated with FHB resistance in 151 (F_4:6) recombinant inbred lines (RILs) derived from the cross between a resistant cultivar &lsquoUI Stone&rsquo and a moderately susceptible cultivar &lsquoAlturas&rsquo. The population was evaluated for type II FHB resistance by measuring disease severity expressed as a percentage of infected spikelets (PIS) in four greenhouse experiments over three years. Two major QTL for type II FHB resistance, QFhbuis.ab&ndash2B and QFhbuis.ab&ndash3B, were identified by both single marker and composite interval mapping (CIM) methods and together these QTL explained 23.6 to 24.8% of phenotypic variation. Four additional QTL, QFhbuis.ab&ndash1D, QFhbuis.ab&ndash2D·1, QFhbuis.ab&ndash2D·2, and QFhbalt.ab&ndash4A, were identified by either the single marker or CIM methods and were associated with disease severity in specific experiments. The two major QTL identified in this study have potential application in marker&ndashassisted breeding of FHB resistance. This study also identified 4 lines with better FHB resistance and higher grain yield than UI Stone and these could be used as germplasm and/or released as new resistant cultivars after further testing.