Identification of Quantitative Trait Loci (QTLs) Associated with Maintenance of Bread Making Quality under Heat Stress in Wheat (Triticum aestivum)
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The aim of this study was to identify QTLs associated with the maintenance of grain quality following post-anthesis heat stress. A population of 64 F6Halberd X Cutter recombinant inbred lines (RILs) was exposed to either heat stress or control conditions in the greenhouse, starting ten days after anthesis. Grain quality was determined using the sodium dodecyl sulfate (SDS) sedimentation test, a significant predictor of bread baking quality. The percent change in SDS sedimentation test scores between the heat and control populations was used to identify QTLs associated with quality stability. Four QTLs were identified, located one each on chromosomes 1B, 1D, 4A, and 7A. Three of the QTLs, those on 1B, 1D, and 4A, were associated with variations in SDS sedimentation level. The QTL on chromosome 7A was associated with the percent change in SDS sedimentation scores between heat-stressed and control conditions. This indicated a relationship between the identified QTL and quality stability. To confirm the detected QTLs, eighty advanced lines grown at three Texas nurseries were genotyped and tested for relationships between QTL-associated markers, quality traits, and stability of the quality traits. Quality trait stability was estimated using the coefficient of variability (CV%) of quality traits between growing sites. Quality characters analyzed in the advanced lines included kernel hardness, mixograph peak time, kernel weight, flour yield, SDS sedimentation, and grain yield. The analysis showed support for the effect of the QTLs on chromosomes 1B, 1D, and 4A. Further analysis will be needed to confirm the QTL on 7A, in particular. The mapping of additional markers will be necessary. However, the potential importance of this QTL and the abundance of other QTLs detected in this region make it worth investigating.
Beecher, Francis Ward (2009). Identification of Quantitative Trait Loci (QTLs) Associated with Maintenance of Bread Making Quality under Heat Stress in Wheat (Triticum aestivum). Master's thesis, Texas A&M University. Available electronically from