An Overexpressed Q Allele Leads to Increased Spike Density and Improved Processing Quality in Common Wheat (Triticum aestivum)

• Published in: G3 : genes - genomes - genetics Vol. 8; no. 3; pp. 771 - 778
• Main Authors: Xu, Bin-Jie, Chen, Qing, Zheng, Ting, Jiang, Yun-Feng, Qiao, Yuan-Yuan, Guo, Zhen-Ru, Cao, Yong-Li, Wang, Yan, Zhang, Ya-Zhou, Zong, Lu-Juan, Zhu, Jing, Liu, Cai-Hong, Jiang, Qian-Tao, Lan, Xiu-Jin, Ma, Jian, Wang, Ji-Rui, Zheng, You-Liang, Wei, Yu-Ming, Qi, Peng-Fei
• Format: Journal Article
• Language: English
• Published: United States Oxford University Press 01.03.2018; Genetics Society of America
• Subjects: Alleles; Artificial chromosomes; bread-making quality; Chromosome Mapping; Cloning, Molecular; compact spike; Gene Expression; Gene Expression Regulation, Plant; Gene loci; Genetic Association Studies; Genotype & phenotype; Gluten; MicroRNAs; MicroRNAs - genetics; Molecular weight; mutant screen report; Mutant Screen Reports; Mutation; Phenotype; Plant Breeding; Plant Proteins - genetics; point mutation; Potassium; protein content; Proteins; Quantitative Trait Loci; Quantitative Trait, Heritable; RNA Interference; Transcription factors; Triticum - genetics; wheat breeding; wheat breeding; protein content; compact spike; bread-making quality; mutant screen report; point mutation
• DOI: 10.1534/g3.117.300562
• ISSN: 2160-1836

Abstract Spike density and processing quality are important traits in modern wheat production and are controlled by multiple gene loci. The associated genes have been intensively studied and new discoveries have been constantly reported during the past few decades. However, no gene playing a significant role in the development of these two traits has been identified. In the current study, a common wheat mutant with extremely compact spikes and good processing quality was isolated and characterized. A new allele (Qc1) of the Q gene (an important domestication gene) responsible for the mutant phenotype was cloned, and the molecular mechanism for the mutant phenotype was studied. Results revealed that Qc1 originated from a point mutation that interferes with the miRNA172-directed cleavage of Q transcripts, leading to its overexpression. It also reduces the longitudinal cell size of rachises, resulting in an increased spike density. Furthermore, Qc1 increases the number of vascular bundles, which suggests a higher efficiency in the transportation of assimilates in the spikes of the mutant than that of wild type. This accounts for the improved processing quality. The effects of Qc1 on spike density and wheat processing quality were confirmed by analyzing nine common wheat mutants possessing four different Qc alleles. These results deepen our understanding of the key roles of Q gene, and provide new insights for the potential application of Qc alleles in wheat quality breeding.