Integrated metabolome and transcriptome analysis of the molecular mechanisms underlying fruit flavor formation during ripening of Pyrus pyrifolia

• Four KEGG pathways were significantly associated with pear fruit ripening, namely cysteine and methionine metabolism, the TCA cycle, amino acid biosynthesis, and starch and sucrose metabolism. • Ethylene synthesis was significantly enhanced during the ripening of non-climacteric pear fruits. • the increased synthesis of L-glutamate and L-alanine via the upregulated expression of aspartate aminotransferase enhanced the umami taste of the fruits. • The dynamic changes in TCA cycle, amino acid, and sugar metabolism provided a metabolic foundation for fruit flavor formation. In particular, increased synthesis of L-glutamate and L-alanine enhanced the umami taste of the pear fruits. Fruit ripening in pears is accompanied by changes in multiple metabolites and genes. The specific metabolites and genes underlying fruit flavor formation remain unclear. Here, two sister-line cultivars (‘Hujingli18’ and ‘Hujingli67’) were selected to compare metabolic and transcriptional profiles at two fruit developmental stages. Results showed that four KEGG pathways were significantly associated with fruit ripening, namely cysteine and methionine metabolism, the TCA cycle, amino acid biosynthesis, and starch and sucrose metabolism. Notably, ethylene synthesis was significantly enhanced during the ripening of pear fruits. The accumulation of sucrose is associated with the down-regulated expression of soluble acid invertase gene. The dynamic changes in TCA cycle and amino acid provided a metabolic foundation for fruit flavor formation. In particular, the increased synthesis of L-glutamate and L-alanine via the upregulated expression of aspartate aminotransferase enhanced the umami taste of the fruits. This study provides valuable insights into the pear fruit ripening process and offers significant implications for breeding programs and quality control strategies.