CRISPR-based editing of the ω- and γ-gliadin gene clusters reduces wheat immunoreactivity without affecting grain protein quality

Deletion of wheat alpha-gliadins from chromosome 6D improves gluten strength and reduces immunodominant celiac disease epitopes

Wheat gliadins and glutenins confer valuable end-use characteristics but include amino acid sequences (epitopes) that can elicit celiac disease (CeD) in genetically predisposed individuals. The onset of CeD in these individuals is affected by the amount and duration of the exposure to immunogenic epitopes. Therefore, a reduction of epitopes that result in high immune responses in the majority of CeD patients (immunodominant epitopes) may reduce the incidence of CeD at a population level. We generated gamma radiation-induced deletions encompassing the α-gliadins in each of the three wheat genomes and characterized them using exome capture. These deletions, designated as Δgli-A2, Δgli-B2, and Δgli-D2, were deposited in GRIN-Global. The Δgli-A2 and Δgli-B2 deletions showed limited effects on breadmaking quality, but the Δgli-D2 deletion significantly increased gluten strength and improved breadmaking quality without compromising dough elasticity, protein content, or grain yield. The stronger effect of Δgli-D2 on gluten strength was associated with an increased proportion of glutenins and the deletion of α-gliadins with seven cysteines, which are absent in the GLI-A2 and GLI-B2 loci. We show that α-gliadins with seven cysteines are incorporated into the gluten polymer, where they likely function as chain terminators limiting the expansion of the gluten polymer and reducing its strength. In addition to its beneficial effects on breadmaking quality, the Δgli-D2 deletion eliminates major wheat immunodominant CeD epitopes. The deployment of this publicly available Δgli-D2 deletion can simultaneously improve wheat gluten strength and reduce the population-wide burden of CeD.

CRISPR/Cas9-mediated multiplex gene editing of gamma and omega gliadins: paving the way for gliadin-free wheat

Wheat is a staple cereal in the human diet. Despite its significance, an increasing percentage of the population suffers adverse reactions to wheat, which are triggered by wheat gluten, particularly the gliadin fractions. In this study, we employed CRISPR/Cas [clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR-associated protein] multiplexing to introduce targeted mutations into γ- and ω-gliadin genes of wheat, to produce lines deficient in one or both immunogenic gliadin fractions simultaneously. For this study, eight single guide RNAs (sgRNAs) were designed and combined into four plasmids to produce 59 modified wheat lines, of which 20 exhibited mutations in the target genes. Characterization of these lines through Sanger sequencing or next-generation sequencing revealed a complex pattern of InDels, including deletions spanning multiple sgRNAs. The mutations were transmitted to the offspring, and the analysis of homozygous derived lines by reverse-phase HPLC and monoclonal antibodies showed a 97.7% reduction in gluten content. Crossing these lines with other CRISPR/Cas lines deficient in the α-gliadins allowed multiple mutations to be combined. This work represents an important step forward in the use of CRISPR/Cas to develop gluten-free wheat.

Wheat genomics: genomes, pangenomes, and beyond

There is an urgent need to improve wheat for upcoming challenges, including biotic and abiotic stresses. Sustainable wheat improvement requires the introduction of new genes and alleles in high-yielding wheat cultivars. Using new approaches, tools, and technologies to identify and introduce new genes in wheat cultivars is critical. High-quality genomes, transcriptomes, and pangenomes provide essential resources and tools to examine wheat closely to identify and manipulate new and targeted genes and alleles. Wheat genomics has improved excellently in the past 5 years, generating multiple genomes, pangenomes, and transcriptomes. Leveraging these resources allows us to accelerate our crop improvement pipelines. This review summarizes the progress made in wheat genomics and trait discovery in the past 5 years.

The emerging role of biotechnological advances and artificial intelligence in tackling gluten sensitivity

Gluten comprises an intricate network of hundreds of related but distinct proteins, mainly "gliadins" and "glutenins," which play a vital role in determining the rheological properties of wheat dough. However, ingesting gluten can trigger severe conditions in susceptible individuals, including celiac disease, wheat allergy, or non-celiac gluten sensitivity, collectively known as gluten-related disorders. This review provides a panoramic view, delving into the various aspects of gluten-triggered disorders, including symptoms, diagnosis, mechanism, and management. Though a gluten-free diet remains the primary option to manage gluten-related disorders, the emerging microbial and plant biotechnology tools are playing a transformative role in reducing the immunotoxicity of gluten. The enzymatic hydrolysis of gluten and the development of gluten-reduced/free wheat lines using RNAi and CRISPR/Cas technology are laying the foundation for creating safer wheat products. In addition to biotechnological interventions, the emerging artificial intelligence technologies are also bringing about a paradigm shift in the diagnosis and management of gluten-related disorders. Here, we provide a comprehensive overview of the latest developments and the potential these technologies hold for tackling gluten sensitivity.

Advances in Gluten Hypersensitivity: Novel Dietary-Based Therapeutics in Research and Development

Gluten hypersensitivity is characterized by the production of IgE antibodies against specific wheat proteins (allergens) and a myriad of clinical allergic symptoms including life-threatening anaphylaxis. Currently, the only recommended treatment for gluten hypersensitivity is the complete avoidance of gluten. There have been extensive efforts to develop dietary-based novel therapeutics for combating this disorder. There were four objectives for this study: (i) to compile the current understanding of the mechanism of gluten hypersensitivity; (ii) to critically evaluate the outcome from preclinical testing of novel therapeutics in animal models; (iii) to determine the potential of novel dietary-based therapeutic approaches under development in humans; and (iv) to synthesize the outcomes from these studies and identify the gaps in research to inform future translational research. We used Google Scholar and PubMed databases with appropriate keywords to retrieve published papers. All material was thoroughly checked to obtain the relevant data to address the objectives. Our findings collectively demonstrate that there are at least five promising dietary-based therapeutic approaches for mitigating gluten hypersensitivity in development. Of these, two have advanced to a limited human clinical trial, and the others are at the preclinical testing level. Further translational research is expected to offer novel dietary-based therapeutic options for patients with gluten hypersensitivity in the future.