Abstract
Wheat grain storage proteins (GSPs) make up most of the protein content of grain and determine flour end-use value. The synthesis and accumulation of GSPs depend highly on nitrogen (N) and sulfur (S) availability and it is important to understand the underlying control mechanisms. Here we studied how the einkorn (Triticum monococcum ssp. monococcum) grain proteome responds to different amounts of N and S supply during grain development. GSP composition at grain maturity was clearly impacted by nutrition treatments, due to early changes in the rate of GSP accumulation during grain filling. Large-scale analysis of the nuclear and albumin-globulin subproteomes during this key developmental phase revealed that the abundance of 203 proteins was significantly modified by the nutrition treatments. Our results showed that the grain proteome was highly affected by perturbation in the N:S balance. S supply strongly increased the rate of accumulation of S-rich α/β-gliadin and γ-gliadin, and the abundance of several other proteins involved in glutathione metabolism. Post-anthesis N supply resulted in the activation of amino acid metabolism at the expense of carbohydrate metabolism and the activation of transport processes including nucleocytoplasmic transit. Protein accumulation networks were analyzed. Several central actors in the response were identified whose variation in abundance was related to variation in the amounts of many other proteins and are thus potentially important for GSP accumulation. This detailed analysis of grain subproteomes provides information on how wheat GSP composition can possibly be controlled in low-level fertilization condition.
Highlights
Bread wheat (Triticum aestivum L.) is the main stable crop in many regions of the world and globally provides more than 20% of calories and proteins in the human diet
Gliadins are subdivided into ω1,2, ω5, α/β- and γ-gliadin classes and glutenins are classified as high-molecular-weight subunits (HMW-GS) or low-molecularweight subunits (LMW-GS; Wieser, 2007)
Grain storage protein composition is modified by N and S supply To study the response of nuclear, albumin-globulin and storage protein subproteomes of developing einkorn wheat grains to N and S supply, four treatments were applied to plants during the effective grain filling period
Summary
Bread wheat (Triticum aestivum L.) is the main stable crop in many regions of the world and globally provides more than 20% of calories and proteins in the human diet. The two main GSP fractions are glutenin and gliadin that when mixed together with water form gluten and are the main determinants of the rheological and bread-making properties of wheat dough. Gliadins are subdivided into ω1,2-, ω5-, α/β- and γ-gliadin classes and glutenins are classified as high-molecular-weight subunits (HMW-GS) or low-molecularweight subunits (LMW-GS; Wieser, 2007). These different GSP subclasses and subunits differ in the proportions of cysteine and methionine residues they contain, and are classified as being S-rich (α/β- and γ-gliadins, LMW-GS) or S-poor (ω1,2- and ω5-gliadins, HMW-GS; Shewry et al, 1997; Shewry et al, 2001)
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