Unveiling characteristic metabolic accumulation over enzymatic-catalyzed process of Tieguanyin oolong tea manufacturing by DESI-MSI and multiple-omics

To achieve an integrative understanding of the spatial distribution and chronological flavoring compounds accumulation, desorption-electrospray-ionization coupled mass-spectrometry-imaging (DESI-MSI) and multi-omics techniques were performed on the leaf samples collected from the enzymatic-catalyzed-process (ECP) stage of Tieguanyin oolong tea manufacturing. The result of DESI-MSI visualization indicated transform or re-distribution of catechins, flavonols and amino acids were on-going attributing to the multi-stress over ECP stage. Out of identified 2621 non-volatiles and 45,771 transcripts, 43 non-volatiles and 12 co-expressed pathways were screened out as biomarkers and key cascades in response to adverse conditions. The targeted metabolic analysis on the characteristic flavoring compounds showed that the accumulations of free amino acids were enhanced, while catechins, flavonol glycosides, and alkaloids exhibited dynamic changes. This result suggests withering and turning-over process are compatible and collectively regulate the metabolic accumulation and development of flavoring metabolites, facilitating to the development of characteristic quality of Tieguanyin tea.