Multi-omics analysis reveals distinct phosphate-starvation responses and pathway-level metabolic adaptation associated with low-phosphorus tolerance in oat

Abstract Phosphorus (Pi) deficiency is a major nutritional constraint limiting crop productivity. To investigate genotype-dependent LP adaptation in oat, we compared the LP-tolerant cultivar TY2 and LP-sensitive cultivar QH444 using physiological and multi-omics analyses. LP treatment induced distinct responses between the two cultivars. TY2 maintained greater growth stability, increased root investment, stronger soluble-sugar accumulation, and improved redox homeostasis under LP stress. Transcriptomic analysis revealed a broader LP-responsive gene set in TY2 involving phosphate-starvation signaling, phosphorus transport and reutilization, lipid-associated metabolism, and carbon-energy metabolism. Proteomic analyses revealed candidate changes associated with ribosome-related and redox functions despite the absence of individually significant proteins after multiple-testing correction. Metabolomic profiling further identified cultivar-dependent responses involving carbohydrate, cofactor/redox, and amino-acid-associated pathways. Multi-omics integration highlighted central carbon, energy, and amino acid metabolism as convergent processes in TY2, whereas lipid-associated responses were mainly supported at the transcriptomic and metabolomic levels, suggesting lipid adjustment under LP stress. Overall, LP tolerance in TY2 was associated with greater physiological stability, a broader detected phosphate-starvation transcriptional response, and coordinated metabolic regulation across multiple omics layers. These findings provide insights into genotype-dependent LP adaptation and identify candidate processes for improving phosphorus-use efficiency in oat.