The spatiotemporal changes of metabolites in Pinellia ternata at different development stages by MALDI-MSI

Pinellia ternata is an herb species in the Pinellia genus with significant economic value due to its medicinal properties. Understanding the accumulation and spatial distribution characteristics of metabolites during the development of the medicinal part, the rhizome of P. ternata (PR), provides a basis for targeted metabolic regulation and quality evaluation. In this study, we used matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI) and MS/MS to analyse metabolites at 5 representative stages (S1 to S5) of rhizome development in cross and longitudinal sections of the rhizome. A total of 168 metabolites were detected, with 13 being metabolites previously reported in PR. Additionally, Venn analysis revealed 12 bioactive differential metabolites during the growth process. Their spatial distribution and composition were analyzed, showing that alkaloids and amino acids were significantly distributed throughout the entire region and had higher relative contents compared to other metabolites. Flavonoids were more distributed in the outer regions of PR, potentially playing a greater role in combating biotic or abiotic stresses. Specifically, in cross-sections, arginine, nicotinamide, and 2-pentylpyridine showed a clear trend of accumulation from the outer to the inner from S1 to S5, while trigonelline, adenosine, cytidine, 3,4-dihydroxycinnamyl alcohol, raffinose, choline alfoscerate, liquiritin, and apii exhibited the opposite trend. For longitudinal sections, trigonelline, 2-pentylpyridine, choline alfoscerate and baicalein showed a trend of accumulation from the area of bud end to the far region during S1 to S5, while arginine showed opposite distribution trends. These findings deepen our understanding of the metabolic processes involved in the development of PR and have potential implications for variety improvement and quality control.