Identification of three QTLs that additively affect heading time in bread wheat (Triticum aestivum L.) by QTL-seq approach

Optimizing the timing of heading is crucial for achieving stable production in bread wheat ( Triticum aestivum L.). We analyzed a breeding line, ‘B1-0393’, that headed 5 days earlier than the Japanese elite cultivar ‘Kitahonami’. To identify quantitative trait loci (QTLs) responsible for this difference, we conducted QTL-seq using F ₃ progeny of a cross between ‘Kitahonami’ and ‘B1-0393’. We detected QTLs on chromosomes 2D ( QDth.kupg-2D ), 3D ( QDth.kupg-3D ), and 4A ( QDth.kupg-4A ), explaining 10.25%, 2.00%, and 8.24%, respectively, of phenotypic variance. The QDth.kupg-2D locus corresponded to the major photoperiod-regulating gene Photoperiod-D1 ( Ppd-D1 ). ‘Kitahonami’ had the photoperiod-sensitive Ppd-D1b allele and ‘B1-0393’ had the insensitive Ppd-D1a allele. QDth.kupg-4A overlapped with previously reported QTLs, while QDth.kupg-3D was a novel QTL. Segregation analysis using F ₂ and F ₃ plants confirmed that alleles from ‘B1-0393’ at all three loci accelerated heading and that the three QTLs had additive effects on days to heading. Our findings could be valuable for regulating heading time to optimize wheat yield.