QTL Mapping of Spike-Related, Agronomic, and Quality Traits in Wheat.

Commonly grown wheat (Triticum aestivum) cultivars are characterized by spikes with fusiform shape, and spikelets evenly distributed. However, landraces and non-adapted genotypes present a broad range of spike-related traits, which could be used as a source of new genes to enrich the germplasm of wheat breeding programs. Most spike morphology QTL mapping studies in wheat are conducted using populations derived from elite x elite crosses where a limited number of polymorphic markers are identified. However, the use of exotic germplasm in mapping studies, in addition to contributing novel alleles of interest, offers an additional advantage of finding more polymorphic markers. In the present study, a RIL population derived from an elite line and an exotic line with Supernumerary Spikelet (SS) was used to identify QTL associated with several traits of economic importance. A total of 163 RILs, seven checks and the two parents were evaluated over four to six environments for a total of 11 spike-related, 10 agronomic, and seven quality traits. A linkage map was generated using a total of 939 DArT markers which covered a total map length of 3,114.2 cM, with an average distance of 4.6 cM between any two marker loci. QTL analysis using composite interval mapping identified several new QTL as well as confirmed several other QTL identified in previous studies. A number of QTL identified during the present study were consistent across all environments and may be used to transfer into other germplasm using marker assisted selection. Some QTL associated with optimal values of agronomic and quality traits were also derived from the exotic line, suggesting the possibility of enriching the breeding germplasm with alleles from exotic genotypes