Novel insights into the effect of nitrogen on storage protein biosynthesis and protein body development in wheat caryopsis.

Molecular and cytological mechanisms concerning the effects of nitrogen on wheat (Triticum aestivum L.) storage protein biosynthesis and protein body development remain largely elusive. We used transcriptome sequencing, proteomics techniques, and light microscopy to investigate these issues. In total, 2585 differentially expressed genes (DEGs) and 57 differentially expressed proteins (DEPs) were found 7 days after anthesis (DAA), and 2456 DEGs and 64 DEPs were detected 18 DAA after nitrogen treatment. Gene ontology terms related to protein biosynthesis processes enriched these numbers by 678 and 582 DEGs at 7 and 18 DAA, respectively. Further, 25 Kyoto Encyclopedia of Genes and Genomes pathways were involved in protein biosynthesis at both 7 and 18 DAA. DEPs related to storage protein biosynthesis contained gliadin and glutenin subunits, most of which were up-regulated after nitrogen treatment. Quantitative real-time PCR analysis indicated that some gliadin and glutenin subunit encoding genes were differentially expressed at 18 DAA. Structural observation revealed that wheat endosperm accumulated more and larger protein bodies after nitrogen treatment. Collectively, our findings suggest that nitrogen treatment enhances storage protein content, endosperm protein body quantity, and partial processing quality by altering the expression levels of certain genes involved in protein biosynthesis pathways and storage protein expression at the proteomics level.