Phosphorus Alters the Metabolism of Sugars and Amino Acids in Elite Wheat Grains

Phosphorus supply significantly influences starch and amino acid accumulation in wheat grains, yet the mechanisms coordinating sugar-amino acid metabolic crosstalk under differential phosphorus availability remain elusive. To address this knowledge gap, we conducted a controlled trial on phosphorus supplementation using wheat (Triticum aestivum L. cv. Xindong 20) with three treatments: P0 (0 kg·ha^-1, phosphorus deficiency), LP (105 kg·ha^-1, normal phosphorus), and HP (210 kg·ha^-1, phosphorus excess). Seed samples were collected at 7, 14, and 21 days post-anthesis (DPA). This design enabled a systematic analysis of how phosphorus availability modulates the metabolic relationship between amino acids and sugars during grain development. Proteomic profiling of starch granule-associated proteins (SGAPs) demonstrated that wheat reprograms carbohydrate allocation in response to phosphorus availability. Notably, differentially expressed proteins (DEPs) exhibited tissue-specific regulation patterns: pericarp-localized DEPs were predominantly up-regulated, whereas endosperm-associated DEPs showed down-regulation under phosphorus modulation. Mechanistically, phosphorus application triggered accelerated starch catabolism in the pericarp (Pe) concomitant with enhanced starch anabolism in the endosperm (En), thereby altering the temporal dynamics of starch granule development. These findings elucidate key regulatory patterns of phosphorus nutrition in wheat grain metabolism, establishing a biochemical framework for the optimization of starch quality parameters. The identified phosphorus-responsive metabolic networks reveal pivotal mechanisms that support the development of precision breeding strategies and phosphorus-efficient cultivation practices. This research offers novel pathways to simultaneously improve both grain yield and nutritional quality in wheat production systems.