Effects of nitrogen nutrition on the synthesis and deposition of the ω-gliadins of wheat

† Background and Aims The v-gliadin storage proteins of wheat are of interest in relation to their impact on grain processing properties and their role in food allergy, particularly the v-5 sub-group and wheat-dependent exerciseinduced anaphylaxis. The v-gliadins are also known to be responsive to nitrogen application. This study therefore compares the effects of cultivar and nitrogen availability on the synthesis and deposition of v-gliadins in wheat grown under field conditions in the UK, including temporal and spatial analyses at the protein and transcript levels. † MethodsSDS‐PAGE,westernblottingandN-terminalaminoacidsequencingwereusedtocomparethepatternsof v-gliadin components in mature grain of six British wheat (Triticum aestivum) cultivars and their accumulation during the development of grain grown in field plots with varying nitrogen supply. Changes in gene expression during development were determined using real-time reverse transcription‐PCR (RT‐PCR). Spatial patterns of geneexpressionandproteinaccumulationweredeterminedby in situhybridizationandimmunofluorescencemicroscopy, respectively. † Key ResultsTwopatternsofv-gliadinswereidentifiedinthesixcultivars,includingbothmonomeric‘gliadin’proteins and subunits present in polymeric ‘glutenin’ fractions. Increasing the level of nitrogen fertilizer in field plots resulted in increased expression of v-gliadin transcripts and increased proportions of v-5 gliadins. Nitrogen supply also affected the spatial patterns of v-gliadin synthesis and deposition, which were differentially increased in the outer layers of the starchy endosperm with high levels of nitrogen. † ConclusionsWheatv-gliadinsvaryinamountandcompositionbetweencultivars,andintheirresponsetonitrogen supply.Theirspatialdistributionisalsoaffectedbynitrogensupply,beingmosthighlyconcentratedinthesub-aleurone cells of the starchy endosperm under higher nitrogen availability.