Single‐cell sequencing and mass spectrometry imaging reveal the multicellular compartmentalization map of plant triterpenes: A ginsenoside in Panax ginseng example

Revealing the multicellular compartmentalization map is crucial for plant breeding and metabolism regulation. Despite the importance of triterpenes as active compounds, there has been no report on their biosynthetic multicellular mapping. In this study, ginsenosides are used as an example to reveal the multicellular compartmentalization map of plant triterpenes. The study used mass spectrometry imaging to reveal the primary distribution of ginsenosides in the cork layer of roots, the epidermis of stems, and the upper epidermis of leaves of Panax ginseng. Single-cell sequencing was employed to annotate ten cell types; pseudotime analysis demonstrated that leaves gradually developed from mesophyll cells to the bundle sheath and epidermis. We constructed a multicellular compartmentalization map, which revealed that most genes related to ginsenoside biosynthesis were highly expressed in guard cells and palisade mesophyll cells, with the epidermis serving as the primary distribution area for most ginsenosides. Finally, metabolic engineering studies of the epidermis demonstrated that plant tissue regulation is an effective approach to enhance the yield of active compounds.