Creation of the first ultra‐low gluten barley (Hordeum vulgare L.) for coeliac and gluten‐intolerant populations

Abstract

SummaryCoeliac disease is a well‐defined condition that is estimated to affect approximately 1% of the population worldwide. Noncoeliac gluten sensitivity is a condition that is less well defined, but is estimated to affect up to 10% of the population, and is often self‐diagnosed. At present, the only remedy for both conditions is a lifelong gluten‐free diet. A gluten‐free diet is often expensive, high in fat and low in fibre, which in themselves can lead to adverse health outcomes. Thus, there is an opportunity to use novel plant breeding strategies to develop alternative gluten‐free grains. In this work, we describe the breeding and characterization of a novel ultra‐low gluten (ULG) barley variety in which the hordein (gluten) content was reduced to below 5 ppm. This was achieved using traditional breeding strategies to combine three recessive alleles, which act independently of each other to lower the hordein content in the parental varieties. The grain of the initial variety was shrunken compared to wild‐type barleys. We implemented a breeding strategy to improve the grain size to near wild‐type levels and demonstrated that the grains can be malted and brewed successfully. The ULG barley has the potential to provide novel healthy foods and beverages for those who require a gluten‐free diet.

Recent Progress and Recommendations on Celiac Disease From the Working Group on Prolamin Analysis and Toxicity

“…In barley, an ultra-low gluten variety has been developed that is safe for CD patients, as it contains <20 mg/kg of gluten. It was developed by combining existing induced recessive mutations through breeding (140). This strategy is very difficult to implement in bread wheat as it has three genomes and one does not want to remove all gluten genes (141), but other approaches may be successful (142,143).…”

Wheat Seed Proteins: Factors Influencing Their Content, Composition, and Technological Properties, and Strategies to Reduce Adverse Reactions

“…Assays of these genotypes with intestinal T-cell clones derived from the biopsy samples of coeliac patients showed almost complete suppression of disease-related T-cell epitopes (Gil-Humanes et al, 2010). More recently, the same group used the clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) gene editing technology to target conserved regions adjacent to the coding sequence of the 33-mer peptide in the α2-gliadin genes α/β-gliadins (Gli-A2) and/or γ -and No negative effects on enterocyte height (Frisoni et al, 1995;Lafiandra, Colaprico, Kasarda, & Porceddu, 1987) α/β-gliadins (Gli-A2) and (Autran, 1975;Branlard, Dardevet, Amiour, & Igrejas, 2003; β-, γ -, and ω-gliadins Activated CD T-cell response (Gianfrani et al, 2012) Urinary lactulose/ rhamnose ratio (L/R ratio measured by high-pressure liquid chromatography Well tolerated by all patients (Zanini et al, 2013) α/β-, γ -, or (Ingversen, Koie, & Doll, 1973;Sestak et al, 2015Sestak et al, , 2016 lys3b ( ELISA and mass spectrometry Grain has application in the preparation of food and beverages for coeliacs (Tanner, Blundell, Colgrave, & Howitt, 2016) lys1 (5HL) and lys3a (5HS) DH lines (Risø 1508 x Hiproly)…”

Celiac Antigenicity of Ancient Wheat Species

“…Downregulating genes that give rise to gliadin proteins can also be used to develop celiac safe wheat. Recently, ultra-low gluten barley was produced using traditional breeding techniques where three recessive alleles were combined to develop parental barley varieties with low hordein levels [13].…”