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To identify future impacts on biomass production and yield quality of important C3 crops, spring wheat was grown in association with 13 weed species in a Mini-FACE (free-air carbon dioxide (CO2) enrichment) system under ambient (375 μl l-1) and elevated (526 μl l-1) CO2 concentrations. Wheat productivity was assessed at maturity and grain yield was subjected to various chemical analyses and baking quality tests. CO2 enrichment acted as carbon ‘fertiliser’ and increased the aboveground biomass production of wheat by 18.8% as there was a trend towards higher stem biomass. Although not statistically significant, wheat grain yield was increased by 13.4% due to a significant establishment of more grains per unit ground area. At the same time, thousand grain weight was non-significantly shifted towards smaller grain size classes, which may result in negative consequences for the crop market value. As a result of the CO2- induced physiological and biochemical modifications, concentration of total grain protein was significantly decreased by 3.5%, reducing the wheat grain quality with potentially far-reaching impacts on the nutritional value and use for processing industry. Although often not significant, the concentrations of amino acids per unit of flour were decreased by 0.2 to 8.3% due to elevated CO2 thereby affecting the composition of proteinogenic amino acids. Furthermore, gluten proteins tended to decline. Within the significant decreased gliadins, α- and ω5-gliadins were significantly reduced under CO2 enrichment; there was also a negative trend for ω1,2- and γ-gliadins. Changes in certain essential minerals were found as well, although not statistically significant. Concentrations of sodium, calcium, phosphorus and sulphur were slightly lowered and those of potassium and magnesium were slightly increased due to CO2 enrichment. The micro-element molybdenum was increased, while concentrations of iron, zinc, copper, manganese and aluminium were decreased. With regard to rheological and baking parameters defining the cereal quality for industrial processing, the resistance of the dough was significantly reduced by about 30%, while the extensibility was non-significantly increased by 17.1% under CO2 enrichment. Moreover, the bread volume was decreased non-significantly by about 9%. Elevated CO2 is obviously affecting grain characteristics important for consumer nutrition and health, industrial processing and marketing. Experimental evidence for these changes is still poor but deserves further attention.

An RNA interference approach was applied to silence α-gliadin genes in hexaploid wheat. A 313 bp fragment from the 5’ coding region of an α-gliadin sequence was cloned into the “hairpin” (hpRNAi) constructs pGliaRNAiSpacer and transformed into winter wheat cv. Florida by biolistic transformation. The resulting transgenic lines were then analysed for their α-gliadin content by an extraction/RPHPLC method. Distinct differences of the α-gliadin content ranging from unaltered to strongly reduced were found. Kernels of two lines with strongly reduced α-gliadin content were mixed, milled to white fl our, analysed for quantitative protein composition and used for functional testing in comparison with the wild type fl our. Protein analysis revealed that the lack of α-gliadins was compensated by an increase of albumins/globulins, ω-gliadins, γ-gliadins and HMW glutenin subunits. Dough resistance and extensibility of wild type and transgenic lines were similar, whereas gluten resistance of the transgenic increased drastically and extensibility decreased slightly. 2D gel electrophoresis showed that the transgenic wheat #6/6 lacked at least 20 storage proteins, but other distinct proteins were more abundant compared with the wild type. Major reductions in the α-gliadins do not make discernable differences in micro-scale measurements of flour functionality and have only a slightly detrimental effect in micro-baking tests.

Celiac disease is caused by sensitivity to wheat gluten in genetically susceptible individuals. The etiological role of the other wheat-related cereals, barley, rye, and oats, is still debated. In order to investigate this issue further, in this study we examined the immune response of celiac mucosal T cell lines to fractions from all four cereals. Cell stimulation was assessed by measuring proliferation (employing 3H-thymidine incorporation) or cytokine (IL-2, IFN-γ) production. All five T cell lines demonstrated immunoreactivity to protein fractions from the four related cereals. In some cell lines, reactivity to wheat, barley, and rye was only evident when these cereal fractions had been pretreated with tissue transglutaminase. This study confirms the similar T cell antigenic reactivity of these four related cereals and has implications for their exclusion in the gluten-free diet. However, despite oats stimulation of T cell lines, this cereal does not activate a mucosal lesion in most celiac patients. [ABSTRACT FROM AUTHOR]