Comparative Proteomic Insights into Leaf Senescence and Metabolic Regulation in Three High-Gluten Wheat Varieties

We conducted a comparative proteomic analysis of the wheat cultivar Xinmai 45 and its parental lines, Jimai 20 (paternal) and Xinmai 26 (maternal), to clarify the proteomic differences associated with delayed senescence in flag leaves. Data-independent acquisition (DIA) quantitative proteomics, coupled with bioinformatic analysis, was employed to identify differentially expressed proteins (DEPs) in mature leaf tissues and assess their enriched functions and pathways. A total of 599 and 670 DEPs were identified in Xinmai 45 relative to Jimai 20 (paternal) and Xinmai 26 (maternal), respectively, with most being down-regulated. Gene Ontology (GO) enrichment analysis revealed that DEPs were significantly associated with metabolic processes, responses to stimuli, and biological regulation, primarily driven by changes in catalytic activity and binding. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that the MAPK signaling and phenylpropanoid biosynthesis pathways were uniquely enriched in Xinmai 45 vs. Jimai 20 (paternal), suggesting enhanced stress signaling and defense priming; in contrast, pathways related to lipid metabolism (e.g., α-linolenic acid metabolism) were more prominent in Xinmai 45 vs. Xinmai 26 (maternal), pointing to differential membrane remodeling during senescence. Protein–protein interaction network analysis revealed that ribosomal proteins and RNA helicases occupied central positions, suggesting that protein synthesis and RNA metabolism may be important regulators of phenotypic differences. These proteomic differences may be associated with the superior stress resistance of Xinmai 45.