Varietal differences in protein body distribution and pearling fraction flour quality response to different nitrogen application rates in wheat

Nitrogen (N) enhances wheat protein content and flour nutritional quality. The protein content of wheat grain exhibits significant variations across different pearling fractions, which affect the processing quality of the resulting flour. We hypothesize that varietal differences in protein body distribution under different nitrogen application levels are directly regulated by the expression levels of genes involved in protein biosynthesis. This study aims to determine and characterize this relationship. Herein, the wheat varieties Ningmai 13 with relatively low protein content, Yangmai 16 with moderate protein content, and Xumai 32 with high protein content were subjected to two different levels of nitrogen application. The addition of N changed the spatial distribution of gliadin, glutenin, and protein across wheat varieties. The influence of N on the spatial expression of genes associated with amino acid biosynthesis, ribosome biosynthesis, and protein processing was genotype-dependent. Correlation analysis indicated that arginine succinate synthase (<i>argG</i>), translation initiation factor 6 (<i>EIF6</i>), and calnexin (<i>CNX</i>) may serve as potential targets for the modification of protein gradients via nitrogen coordination. The findings offer spatial insights into varietal differences in protein response to N levels, thereby establishing a mechanistic basis for molecular breeding strategies targeting the identified genes to develop optimized varieties. The goal of these strategies is the production of superior flour from specific pearling fractions for enhanced baking quality.