Association of a lipoxygenase locus, Lpx-B1, with variation in lipoxygenase activity in durum wheat seeds

Lipoxygenases constitute a family of enzymes that catalyze the breakdown of lipids, resulting in products that may have undesirable effects. These enzymes can affect pasta color and cause off-flavors. The purpose of this study was to map the loci associated with lipoxygenase activity in seeds of a durum wheat (Triticum turgidum ssp. durum) population to determine if lipoxygenase activity is associated with flour color. Seed of the parents, Jennah Khetifa and Cham 1, and the recombinant inbred population consisting of 113 progeny lines were used to assay lipoxygenase activity and flour color. A saturated molecular-marker linkage map for this population was previously constructed. Allele specific primers targeting the wheat homolog to barley LoxA were designed, and a fragment length polymorphism resulting from a miniature inverted-repeat transposable element (MITE) insertion in an intron of the durum wheat LoxA homolog allowed mapping of the locus to chromosome 4BS. To measure lipoxygenase activity, spectrophotometric changes were recorded. Chain I had a change in absorbance of 0.284 units of absorbance over I min compared with 0.752 units for Jennah Khetifa. Quantitative trait locus analysis of these data indicated that most of the lipoxygenase activity was associated with the wheat lipoxygenase gene (Lpx) on chromosome 4BS. A quantitative trait locus, for vitreous appearance of seeds also was associated with this locus. Flour color was not correlated with lipoxygenase activity in this population. With this knowledge, marker-assisted selection can be used to select genotypes with lower lipoxygenase activity in durum wheat populations.