The Qc5 Allele Increases Wheat Bread-Making Quality by Regulating SPA and SPR

Abstract

Common wheat (Triticum aestivum L.) is an important food crop with a unique processing quality. The Q gene positively regulates the processing quality of wheat, but the underlying mechanism remains unclear. Here, a new Q allele (Qc5) responsible for compact spikes and good bread performance was identified. Compared with the Q allele widely distributed in modern common wheat cultivars, Qc5 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 Qc5 expression during the spike development stage and a consequent increase in spike density. Furthermore, this missense mutation weakened the physical interaction between Qc5 and storage protein activator (SPA) in seeds and suppressed the expression of storage protein repressor (SPR). These changes increased the grain protein content and improved the bread-making quality of wheat. In conclusion, a missense mutation increases Q 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 SPR 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.

Molecular Genetics Enhances Plant Breeding

“…For example, while also considering the ABA pathway, Yu et al [ 23 ] used qRT-PCR to demonstrate the up-regulation of PHO-encoding genes by ABA in maize and rice. On the other hand, Xiao et al [ 29 ] validated SbDOF21 as a key regulator for starch biosynthesis in sorghum, and Guo et al [ 30 ] characterized a new SPR -repressor Q allele ( Q c5 ) for compact spikes and bread quality in wheat. The other studies which stand out are those by Mažeikienė et al [ 27 ] and Liu et al [ 28 ], who brought RNA-seq technology to the new promissory crops Ribes nigrum and Sacha Inchi ( Plukenetia volubilis ).…”

“…Finally, Chen et al [ 35 ] went one step further and explored mutagenesis as a reliable source of de novo allelic variation. The authors characterized mutant Q alleles ( Q s1 and Q c1 -N8 ) for grain yield and grain protein in the wheat cultivar ‘Shumai482’ and its S-Cp 1-1 mutant [ 35 ], complementing the results achieved by Guo et al [ 30 ] in terms of compact spikes and bread quality. In spite of these exciting results achieved for the development of trans-genesis, classical intercrossing has not lost validity as a breeding strategy, but rather it has been permeable to the latest genomic advances, such as marker-assisted backcrossing (MABC) [ 37 ], introgression breeding, and genomic-assisted recurrent selection [ 41 ].…”

“…For original datasets, please refer to the published articles [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ] within the second Special Issue of IJMS on “Molecular Genetics and Plant Breeding 2.0” ( , as accessed on 6 June 2023).…”

Fine-mapping and validation of Gpc-5B as the locus responsible for increases in the grain protein content, grain size, and spike density in common wheat (Triticum aestivum L.)

“…The Q allele arose following a spontaneous mutation to the microRNA172-binding region of the q allele during wheat evolution (Simons et al 2006). Q in uences many domestication-related traits, including threshability, spike morphology, plant height, rachis fragility, and owering time (Förster et Guo et al 2022). Q has homoeoalleles on wheat chromosomes 5BL (5Bq) and 5DL (5Dq).…”

MicroRNA164e suppresses NAC100 transcription factor‐mediated synthesis of seed storage proteins in chickpea

“…This large‐scale detection of miRNAs had facilitated the delineation of a novel role of miR167 in suppressing fatty acid metabolism and seed oil accumulation in Camelina (Na et al ., 2019). In wheat, miR172 had been indicated to negatively affect the bread processing quality by altering the expression of gliadins and glutenins (Guo et al ., 2022). Several attempts have also been made to detect miRNAs regulating SSPs in important legumes, including soybean (Yu et al ., 2019), chickpea (Pradhan et al ., 2021), and Phaseolus (Parreira et al ., 2021).…”