Physicochemical characteristics and metabolomic profiling of representative rice cultivars distinct in eating quality

This study aimed to identify shared physicochemical disparities between high eating quality rice and conventional high-yield cultivars across indica and japonica subspecies, and screen core taste-related trait indicators, while characterizing intrasubtype metabolic variation in indica rice. Four representative rice cultivars (two premium fragrant rice: Yuzhenxiang, Daohuaxiang No. 2; two high-yield rice: Huanghuazhan, Kendao 2066) were comprehensively evaluated via sensory, texture, RVA and multi-component quantitative detection; Untargeted metabolomics was further performed on the two indica cultivars Yuzhenxiang and Huanghuazhan. Rice with superior eating quality featured low protein, amino acids and citric acid, moderate soluble sugars, abundant 2-AP, elevated amylopectin long/short chain ratio and low gelatinization temperature. A total of 1,318 differential metabolites were identified, with arginine biosynthesis and linoleic acid metabolism as the most significantly enriched pathways. A three-indicator multiple linear regression model with R ² = 0.972 was constructed for preliminary quantitative prediction only within tested materials. Findings from this multi-indicator integrated analysis revealed that starch structure, aroma compound 2-AP and small-molecule flavor substances jointly regulate rice taste across subspecies; among them, 2-AP, amylopectin long/short chain ratio and RVA consistency viscosity act as core regulators of rice eating quality for both indica and japonica rice, while differential metabolites mainly account for taste variation within indica varieties. This study provides multi-dimensional theoretical references and candidate markers for high-quality rice breeding and quality evaluation.