High-Density Linkage Map Construction and Mapping of Mutant Low Phytate QTLs in Winter Wheat (Triticum aestivum L.) Using Genotyping-By-Sequencing (GBS).

The phytate molecule in grains and legumes reduces the bioavailability and absorption of minerals in the gut due to its capacity to chelate divalent elements such as iron and zinc. In wheat (Triticum aestivum L.), a low phytate mutant (lpa1-1) is now available and has been reported to reduce phytate in wheat kernels up to 35%. However, little is known about the genetic control of this trait and its location in the wheat genome. Our objective was to construct a high-density linkage map to identify quantitative trait loci (QTLs) associated with the low phytate trait in wheat kernels. To do this, 171 hexaploid winter wheat recombinant inbred lines (RILs), developed from a single cross between ‘Danby’ (a Kansas elite variety) and ‘AO2568WS-A-12-10’ (low phytate donor parent), were phenotyped for inorganic phosphate and sequenced using Genotyping-by-Sequencing (GBS). Inorganic phosphate is inversely correlated with phytate levels in the wheat kernel. A total of 158,174 raw SNPs were discovered. After stringent filtering, 2,509 high quality SNPs were obtained and then used to construct a saturated intra-specific genetic linkage map of winter wheat. This linkage map had 21 linkage groups spanning 3,067 cM with an average distance of 1.22 cM between adjacent markers. The linkage map was used to identify two major QTLs associated with the inorganic phosphate trait. The two QTLs, located in chromosomes 4D and 5A, accounted for 43% of the phenotypic variation. For future approaches, the SNP markers associated to these major QTLs can be converted to Kompetitive Allele Specific PCR (KASP) makers that will support breeding efforts to reduce phytate in wheat populations containing lpa1-1 background.