Comparative Metabolomics Analysis Reveals the Taste Variations among Three Selected Wampee Cultivars.

Sugars and acids of wampee predominantly influence consumer taste preference and its commercial value. The molecular basis of taste variations is currently unknown due to the lack of a large-scale investigation of metabolites in wampee. Here, three tastes cultivars, including YF1 (sweet), YF2 (sweet-sour) and YF3 (sour) wampees with sugar-acid ratios ranging from 1.74 to 26.32, were selected. Then, UPLC-MS/MS based widely targeted metabolome analysis was performed to uncover the molecular mechanism underlying these taste variations, followed by the analysis of KEGG pathways. Results showed that 449, 470, 147 metabolites differed between YF1 vs YF2, YF1 vs YF3, and YF2 vs YF3. Fifty of them were screened as common differential metabolites (DMs) by Venn diagram, including 9 phenolic acids. Among them, the abundance level of methyl 3-O-methyl gallate (M3MG) showed a positive correlation with the titratable acids (R = 0.9009) and negative correlation with sugar-acid ratio (R = 0.9802) in three cultivars. Therefore, M3MG could be a taste biomarker for wampees. KEGG pathway enrichment analysis also verified that M3MG played a crucial role in the "biosynthesis of amino acids" pathway. These results above provide important insights into the taste-forming mechanism of wampee and will be beneficial for superior eating quality wampee breeding.