Identification and Validation of Novel Quantitative Trait Loci for Grain Hardness in Bread Wheat (<scp><i>Triticum aestivum</i></scp> L.)

ABSTRACT Grain hardness (GH) plays an important role in wheat quality evaluation. Identification of new genes or quantitative trait loci (QTL) for GH is an effective strategy for wheat quality breeding. Here, we used a recombinant inbred line (RIL) population derived from a cross between two hard wheat Yangmai 4 (YM4) and Yanzhan 1 (YZ1) to identify QTL for GH. No QTL was detected on 5D chromosome, as parents YM4 and YZ1 possessed the two hard alleles Pinb‐D1b and Pinb‐D1p at the Hardness‐5D ( Ha‐5D ) locus, respectively. A total of three GH QTL were identified, among which QGh.yaas‐4B and QGh.yaas‐7D could be detected in all experiments and for mean value, explaining 8.69%–15.07% of the phenotypic variances. QGh.yaas‐4D , co‐located with Rht‐D1 , was detected in one experiment and for mean value, explaining 9.94%–11.39% of the phenotypic variances. We were not able to precisely validate QGh.yaas‐4B due to its large mapping interval. Kompetitive allele‐specific PCR (KASP) markers for QGh.yaas‐7D were successfully developed, and then QGh.yaas‐4D and QGh.yaas‐7D were validated in a panel of 101 wheat cultivars/lines (all carrying Pina‐D1a and Pinb‐D1a alleles). Cultivars/lines harbouring the positive alleles of QGh.yaas‐4D and QGh.yaas‐7D increased GH by 85.16% relative to the ones without any positive allele. These results provide new loci and resources in molecular breeding for wheat hardness.