Wheat grain protein accumulation and polymerization mechanisms driven by nitrogen fertilization

Abstract

In wheat (Triticum aestivum) grain yield and grain protein content are negatively correlated, making the simultaneous increase of the two traits challenging. Apart from genetic approaches, modification of nitrogen fertilization offers a feasible option to achieve this aim. In this study, a range of traits related to nitrogen-use efficiency in six Australian bread wheat varieties were investigated under different nitrogen treatments using 3-year multisite field trials. Changes in the individual storage protein composition were detected by high-performance liquid chromatography. Our results indicated that wheat grain yield and grain protein content reacted similarly to nitrogen availability, with grain yield being slightly more sensitive than grain protein content, and that genotype is a vital determinant of grain protein yield. Measurement of the glutamine synthetase activity of flag leaves and developing grains revealed that high nitrogen availability prompted the participation of glutamine in biological processes. In addition, a more significant accumulation of gluten macropolymer was observed under the high-nitrogen treatment from 21 days post-anthesis, and the underlying mechanism was elucidated by a comparative proteomics study. A yeast two-hybrid experiment confirmed this mechanism. The results of this study revealed that peptidyl-prolyl cis-trans isomerase (PPIase) was SUMOylated with the assistance of small ubiquitin-related modifier 1 and that high nitrogen availability facilitated this connection for the subsequent protein polymerization. Additionally, luminal-binding protein 2 in the endoplasmic reticulum played a similar role to PPIase in the aggregation of protein under high-nitrogen conditions.

Effects of different fertilization levels on the concentration of high molecular weight glutenin subunits of two spring, hard red bread wheat cultivars

“…Sabine, Oberfoster, Werteker, Grausgruber, and Lelly (1997) reported that the Glu-B1 alleles 7 + 9 and the Glu-D1 alleles 5 + 10 occurred more frequently in cultivars with better bread-making quality, and no cultivar with good quality contained subunits 6 + 8 and 2 + 12. Yu et al (2018) reported that grain protein content was more sensitive to N application than grain yield and that protein content was mainly determined by genotype. Moreover, SST806 is the commercial standard for spring wheat baking quality in South Africa.…”

“…Both can be improved through N fertilization strategies, such as the rates and timing of N fertilization Zhong et al, 2019). Yu et al (2018) reported that grain protein content was more sensitive to N application than grain yield and that protein content was mainly determined by genotype.…”

Wheat gluten protein and its impacts on wheat processing quality

“…Although the accumulation of polymeric proteins starts as early as 7 d post-anthesis and lasts during the entire period of grain development, the accumulation of UPP fraction only begins at the later stage of grain development (from 30 to 45 d post-anthesis). Yu et al [102] found that UPP formation involves peptidyl-prolyl cis-trans isomerase (PPIase) SUMOylation with the assistance of small ubiquitin-related modifier 1 and that high nitrogen availability facilitates this connection. Additionally, luminal binding protein 2 in the endoplasmic reticulum has a similar function to PPIase in the aggregation of protein.…”

Absence of Dx2 at Glu-D1 Locus Weakens Gluten Quality Potentially Regulated by Expression of Nitrogen Metabolism Enzymes and Glutenin-Related Genes in Wheat

“…Small ubiquitin-related modifier 1 (SUMO1) is involved in the transport of proteins from the nucleus to the cytoplasm, and it contributes to the stability of proteins [20]. PPIase and SUMO1 interact to facilitate the formation of protein polymers [21]. Protein disulfide isomerase (PDI) catalyzes the formation of disulfide bonds, which are regarded as the determinant bridges during protein polymerization [22].…”

“…Protein disulfide isomerase (PDI) catalyzes the formation of disulfide bonds, which are regarded as the determinant bridges during protein polymerization [22]. The high level expression of genes encoding PPIase, SUMO1, and PDI enhances the folding of storage proteins during grain-filling, thereby leading to the accumulation of more glutenin macropolymers (GMPs) [11,21,23]. HMW-GSs contribute to glutenin polymerization via intra-/intermolecular disulfide bonds and hydrogen bonds [4], and the effects of single HMW-GSs on glutenin polymerization have been reported [8].…”