DIA-based quantitative proteomics reveals the mechanism of foliar spraying glycine betaine and zinc in improving the quality of dry-cultivated rice

This study used DIA-based proteomics to elucidate how foliar application of glycine betaine (GB) and zinc (Zn) synergistically regulates quality formation in dry-cultivated rice. GB and Zn effectively improved both the appearance and eating quality of rice through multi-level coordinated actions. GB primarily enhanced drought tolerance and quality by regulating key protein expression: upregulated RRM domain proteins potentially directly regulated starch and protein synthesis; increased disease resistance proteins activated immune priming, establishing a dual "drought tolerance-immunity" protective system; SNF2 chromatin remodeling proteins participated in epigenetic reprogramming; and amino acid transporters optimized nitrogen allocation. Zn induced functional proteins that enhancedmetabolic homeostasis: Pyridoxal 5-phosphate synthase promoted antioxidant synthesis; dCTP pyrophosphatase and tRNA pseudouridine synthase ensured genomic stability and accurate protein synthesis; and 3-isopropylmalate dehydratase promoted the accumulation of flavor precursors. The combined application of GB and Zn produced significant synergistic effects: upregulated Hexosyltransferase served as a key node, likelystabilizing osmolytes and antioxidants via glycosylation modifications and participating in zinc ligand synthesis to facilitate zinc transport and grain enrichment. Persistent upregulation of Receptor-like serine/threonine-protein kinase (RLK) enhanced signal perception and transduction, thereby initiating drought-resistance defense pathways. Physiologically, combined foliar application significantly enhanced photosynthetic, promoted osmolyte accumulation, and increased antioxidant enzyme activities. Overall, GB stabilizes functional proteins, while Zn servesas a cofactor to activate enzymatic activity. Together, they create a"signal perception-defense activation-nutrition optimization" pathway that mitigates oxidative damage while enhancing stress resistance and quality in dry-cultivated rice, providing a theoretical foundationfor cultivating stress-resistant and high-quality crops.