Q allele overexpression and alternative splicing can improve wheat yield by increasing thousand-kernel weight and grain number per spike

https://link.springer.com/article/10.1186/s12870-026-08188-4

BMC Plant Biology，Volume 26, article number 331, (2026)

Qingcheng Li,Yazhen Fan,Yang Li,Lu Lei,Shengling Zhang,Simin Xie,Lifen Lu,Xin Hu,Fengqi Lv,Zhenru Guo,Xin Chen,Linlin Zhou,Yan Wang,Jing Zhu,Li Kong,Xin Yuan,Jie Deng,Binjie Xu,Xinyou Cao,Yunfeng Jiang,Guoyue Chen,Qiang Xu,Qiantao Jiang,Yuming Wei,Youliang Zheng,Qing Chen&Pengfei Qi

Abstract

Background

Thousand-kernel weight and grain number per spike are key determinants of grain yield. Q is one of the most important domestication genes in wheat. A missense mutation (C3129T) at the microRNA172-binding site of Q (Q^c1 allele) significantly increases the thousand-kernel weight, but also results in extremely compact spikes, leading to decreases in grain number per spike and yield, which is unfavorable for breeding and wheat production.

Results

We characterized a new Q allele (Q^c1-Q1) obtained by treating the Q gene mutant line S-Cp1-1 (carrying Q^c1) with ethyl methanesulfonate. A comparison with the domesticated Q allele widely distributed in modern common wheat cultivars revealed that Q^c1-Q1 contains two missense mutations: C3129T (as in Q^c1) and G542A in the splice site of the second intron. G542A results in alternative splicing, leading to the production of two protein forms. Moreover, it reverses the extremely compact spike phenotype due to C3129T. Field experiments indicated that Q^c1-Q1 can increase wheat yield by simultaneously increasing the thousand-kernel weight and grain number per spike. Notably, the positive effect of Q^c1-Q1 on yield did not negatively affect grain quality. Furthermore, we developed a specific marker on the basis of G542A to accelerate the application of Q^c1-Q1 in wheat breeding programs.

Conclusion

In this study, we developed a new approach to generating favorable Q alleles, while also producing germplasm potentially useful for breeding new wheat varieties with optimal grain production.