Comprehensive analysis of Q gene near‐isogenic lines reveals key molecular pathways for wheat domestication and improvement

• Published in: The Plant journal : for cell and molecular biology Vol. 102; no. 2; pp. 299 - 310
• Main Authors: Zhang, Zengcui, Li, Aili, Song, Gaoyuan, Geng, Shuaifeng, Gill, Bikram S., Faris, Justin D., Mao, Long
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.04.2020
• Subjects: Alleles; cell wall; Cell walls; Chemical composition; Chemical synthesis; Domestication; Edible Grain; Fertility; Fertility - genetics; Gene expression; Gene Expression Profiling; Genes; Glumes; Molecular modelling; Mutation; Organ Specificity; Phenotype; Plant Proteins - genetics; Pollen; Pollen - genetics; Q gene; Spikes; Sporogenesis; threshability; Tissue analysis; Transcription Factors - genetics; Transcriptome; Triticum - genetics; Triticum aestivum; Wall thickness; Wheat; domestication; fertility; wheat; threshability; cell wall; Triticum aestivum; Q gene
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/tpj.14624

Summary The wheat AP2‐like transcription factor gene Q has played a major role in domestication by conferring the free‐threshing character and pleiotropically affecting numerous other traits. However, little information is known regarding the molecular mechanisms associated with the regulation of these traits by Q, especially for the structural determination of threshability. Here, transcriptome analysis of immature spike tissues in three lines nearly isogenic for Q revealed over 3000 differentially expressed genes (DEGs) involved in a number of pathways. Using phenotypic, microscopic, transcriptomic, and tissue‐specific gene expression analyses, we demonstrated that Q governs threshability through extensive modification of wheat glumes including their structure, cell wall thickness, and chemical composition. Critical DEGs and pathways involved in secondary cell wall synthesis and regulation of the chemical composition of glumes were identified. We also showed that the mutation giving rise to the Q allele synchronized the expression of genes for micro‐sporogenesis that affected pollen fertility, and may determine the final grain number for wheat spikes. Transcriptome dissection of genes and genetic pathways regulated by Q should further our understanding of wheat domestication and improvement. Significance Statement The Q gene has played a major role in the domestication of wheat, and contributed to the rise of modern human civilization. The knowledge gained in this study regarding the genes, pathways, and physiological mechanisms underpinning seed threshability and pollen fertility, two important traits pleiotropically regulated by Q, provides a better understanding of wheat domestication and improvement.