Effect of 1Bx7null on Soft Wheat Cookie Quality Under Different Nitrogen Inputs and Its CAPS Marker Development

The role of HMW-GSs in soft wheat quality remains inadequately understood. In Chinese soft wheat variety Ningmai 9, a nonsense mutation (<i>Glu-B1x</i>, <i>1Bx7null</i>) reduced dough tenacity while enhancing dough extensibility under both low (LN) and high nitrogen (HN) inputs. The improved extensibility in the NIL carrying <i>1Bx7null</i> was primarily due to a reduced glutenin/gliadin ratio, with HN further increasing extensibility compared to LN. Notably, the NIL under HN exhibited better cookie quality than WT under LN without yield loss (<i>p</i> < 0.05). A CAPS marker was developed based on a C-to-T SNP at 514 bp in the CDS of <i>1Bx7null</i>, reliably distinguishing <i>1Bx7</i> and <i>1Bx7null</i> alleles. This allele-marker combination shows promising potential for soft wheat breeding. Future studies should explore the effects of allele <i>1Bx7null</i> across diverse genetic backgrounds and soft wheat products.