Integrated transcriptome and metabolome analysis of the differential regulation of physiological metabolism in...

This study utilized 'Qinmi No.9' passion fruit to explore pre-harvest methyl jasmonate (MeJA) treatment effects on fruit quality and regulatory mechanisms via physiological assays, transcriptomics, and metabolomics. MeJA delayed peel yellowing, elevated total soluble solids, total flavonoid, soluble protein contents, and polygalacturonase, polyphenol oxidase, and lipoxygenase activities, but decreased titratable acidity, pectin content, and electrical conductivity, with MeJA_10 (1.0 mM MeJA) presenting optimal comprehensive performance. Transcriptomic analysis revealed that MeJA_5 (0.5 mM MeJA) mainly enriched plant hormone signal transduction and glycolysis/gluconeogenesis pathways, while MeJA_10 activated tryptophan metabolism and phenylpropanoid biosynthesis significantly; five hub genes (At2g46620, OGT, ENDOV, SAMHD1, and γ-TMT) were identified by WGCNA. Metabolomic data showed MeJA_10 induced more differentially accumulated metabolites (226) than MeJA_5 (146): MeJA_5 vs CK mainly altered organoheterocyclic compounds and phenylpropanoids/polyketides, while MeJA_10 vs CK predominantly regulated lipids/lipid-like molecules and organic acids/derivatives. Integrated analysis demonstrated that MeJA_5 enriched glycolysis/gluconeogenesis and α-linolenic acid metabolism, and MeJA_10 highly enriched starch/sucrose metabolism, tryptophan metabolism, and phenylpropanoid biosynthesis. MeJA_10 triggered more differentially expressed genes and metabolites than MeJA_5, confirming its stronger activation of metabolic and genetic expression for better fruit quality promotion.