Fine Mapping of a Quantitative Trait Loci for Wheat Resistance to Pre-Harvest Sprouting Using Genotyping-By-Sequencing (GBS).

Wheat pre-harvest sprouting (PHS), germination of physiologically matured grains in a spike before harvesting, can cause significant reduction in wheat end-use quality and thus in grain sale price. Short or no seed dormancy has been considered as the major component of PHS. A quantitative trait locus (QTL) for seed dormancy and PHS resistance has been previously mapped on wheat chromosome 4AL, but markers linked to the QTL are too far from the QTL, thus not useful for marker-assisted breeding. To fine map this QTL, a F6 population of 155 recombinant inbred lines (RILs) derived from the cross between a PHS-resistant parent Tutoumai A and a PHS-susceptible parent Siyang 936 was analyzed by genotyping-by-sequencing (GBS). A total of 8624 SNPs showed segregation among the RILs, and 9 of them were mapped to the QTL region between Xbarc170 and Xgwm397. The resulting map delimited 4A QTL to a 3.1 cM interval between GBS markers GBS109947 and GBS212432. These two SNPs were converted into KASP markers that can be easily used for marker-assisted selection (MAS) to improve PHS resistance. In addition, this study laid a foundation for map-based cloning of the causal gene of the 4A QTL.