QTLs for agronomic traits detected in recombinant inbred lines derived from a bread wheat × spelt cross

Spelt wheat (Triticum aestivum subsp. spelta), a subspecies of common wheat, is a genetic resource for the breeding of bread wheat (T. aestivum subsp. aestivum); however, genetic analyses of agronomic traits in bread wheat × spelt crosses are insufficient. Here, we conducted QTL analysis in the recombinant inbred lines from a bread wheat × spelt cross. In addition to the major Q locus, QSpd.obu-4D was detected with the spelt allele conferring a higher spikelet density than the bread wheat allele. The effect of QSpd.obu-4D was evident in the presence of the Q allele of bread wheat, suggesting that this variation might be cryptic in spelt wheat with the q allele. Two QTLs with stable effects were identified for grain length, one of which (QGl.obu-1A) has never been detected in a bread wheat × spelt cross. The spelt wheat allele at QHt.obu-7B conferring later heading was identified in the Vrn-B3 region and could be a novel gene source for modifying heading time. Furthermore, QGi.obu-2B, responsible for low grain dormancy of spelt wheat, was detected. Further exploration and identification of useful QTLs could accelerate the utilization of spelt wheat as a genetic resource for bread wheat breeding programs.