The Allele Increases Wheat Bread-Making Quality by Regulating SPA and SPR.

Common wheat ( L.) is an important food crop with a unique processing quality. The gene positively regulates the processing quality of wheat, but the underlying mechanism remains unclear. Here, a new allele () responsible for compact spikes and good bread performance was identified. Compared with the allele widely distributed in modern common wheat cultivars, had a missense mutation outside the miRNA172-binding site. This missense mutation led to a more compact messenger RNA (mRNA) secondary structure around the miRNA172-binding region, resulting in increased expression during the spike development stage and a consequent increase in spike density. Furthermore, this missense mutation weakened the physical interaction between Q and storage protein activator (SPA) in seeds and suppressed the expression of (). These changes increased the grain protein content and improved the bread-making quality of wheat. In conclusion, a missense mutation increases expression because of the resulting highly folded mRNA secondary structure around the miRNA172-binding site. Furthermore, this mutation improves the bread-making quality of wheat by repressing the expression of and influencing the physical interaction between Q and SPA. These findings provide new insights into the miRNA172-directed regulation of gene expression, with implications for wheat breeding.