Grain color is a key agronomic trait that greatly determines food quality. The molecular and evolutionary mechanisms that underlie grain-color regulation are also important questions in evolutionary biology and crop breeding. Here, we confirm that both bHLH and MYB genes have played a critical role in the evolution of grain color in Triticeae. Blue grain is the ancestral trait in Triticeae, whereas white grain caused by bHLH or MYB dysfunctions is the derived trait. HvbHLH1 and HvMYB1 have been the targets of selection in barley, and dysfunctions caused by deletion(s), insertion(s), and/or point mutation(s) in the vast majority of Triticeae species are accompanied by a change from blue grain to white grain. Wheat with white grains exhibits high seed vigor under stress. Artificial co-expression of ThbHLH1 and ThMYB1 in the wheat endosperm or aleurone layer can generate purple grains with health benefits and blue grains for use in a new hybrid breeding technology, respectively. Our study thus reveals that white grain may be a favorable derived trait retained through natural or artificial selection in Triticeae and that the ancient blue-grain trait could be regained and reused in molecular breeding of modern wheat.

粮食作物是人类主要的能量来源,大部分作物品种的种子是白色或黄色,而小麦、玉米、水稻等物种中有些品种的种子因黄酮类物质花青素的积累表现出红、蓝、黑等颜色.不同于其他作物中天然存在有色种子的品种,蓝粒小麦则是普通小麦与其他物

Common wheat (Triticum aestivum L.) is one of the three major food crops in the world; thus, wheat breeding programs are important for world food security. Characterizing the genes that control important agronomic traits and finding new ways to alter them are necessary to improve wheat breeding. Functional genomics and breeding in polyploid wheat has been greatly accelerated by the advent of several powerful tools, especially CRISPR/Cas9 genome editing technology, which allows multiplex genome engineering. Here, we describe the development of CRISPR/Cas9, which has revolutionized the field of genome editing. In addition, we emphasize technological breakthroughs (e.g., base editing and prime editing) based on CRISPR/Cas9. We also summarize recent applications and advances in the functional annotation and breeding of wheat, and we introduce the production of CRISPR-edited DNA-free wheat. Combined with other achievements, CRISPR and CRISPR-based genome editing will speed progress in wheat biology and promote sustainable agriculture. © 2021, The Author(s).

The breeding of herbicide-resistant wheat varieties has helped control weeds in wheat fields economically and effectively. Imidazolinone (IMI) herbicides are popular as they have low toxicity in mammals, are effective at small doses, and exhibit broad-spectrum herbicidal action in the field. Therefore, the isolation and genetic and molecular characterization of IMI-resistant wheat mutants will enhance weed management in wheat fields. In the present study, 352 IMI-resistant plants were isolated by genetic screening from a mutant pool prepared by EMS-based random mutagenesis. Cloning of the mutated genes from the IMI-resistant plants indicated that ten taals alleles had been isolated, and mutation in one of three TaALS homolog genes conferred IMI resistance, and such a mutation is a dominant trait. Further analysis showed that taals-d exhibited the greatest IMI resistance, whereas taals-b exhibited the weakest resistance to IMI among three homologous taals mutants. In terms of IMI resistance, the taals triple mutant was stronger than the taals double mutants, and the taals double mutants were stronger than the single mutants, indicating a dose-dependent effect of the TaALS mutation on IMI resistance in wheat. Biochemical analysis indicated that the mutation in TaALS increased the tolerance of TaALS to inhibition by NI. Our work details the genetic and molecular characterization of als wheat mutants, provides a foundation for understanding IMI resistance and breeding wheat varieties with herbicide resistance, and indicates that genetic screening using a mutagenized pool is an effective and important means of breeding crops with additional desired agricultural traits. (C) 2020 Crop Science Society of China and Institute of Crop Science, CAAS. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd.

The ability to modify complex genomes precisely to create specific mutants is the holy grail of basic research and applied genetics in the postgenomic era. Programmable sequence-specific nucleases (e.g., zinc finger nucleases, transcription activator-like effector nucleases, and clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) systems (e.g., CRISPR/Cas9)), which induce targeted DNA breaks that are then repaired by endogenous repair machinery to generate mutants in a variety of organisms, are being developed at an unprecedented rate. Herein, this paper reviews the history, structure, and biological function of CRISPR/Cas systems, describing how it has been adapted for genome editing (especially CRISPR/Cas9, which has prompted a genome engineering revolution), and emphasizes recent applications and advances in the functional annotation of plant genomes and crop genetic improvement. In addition, the challenges of using the CRISPR/Cas9 system and strategies for improving its specificity are discussed. This review also introduces the creation of CRISPR-edited DNA-free plants, which may be more publicly acceptable than other genetically modified organisms. Finally, the future directions and applications of the CRISPR/Cas9 system are speculated on. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim