Unveiling the spatial distribution and molecular mechanisms of terpenoid biosynthesis in and using multi-omics and DESI-MSI.

and are rich in diterpenoids and have therapeutic effects on cardiovascular diseases. In this study, the spatial distribution of diterpenoids in both species was analyzed by a combination of metabolomics and mass spectrometry imaging techniques. The results indicated that diterpenoids in were mainly abietane-type norditerpenoid quinones with a furan or dihydrofuran D-ring and were mainly distributed in the periderm of the roots, e.g. cryptotanshinone and tanshinone IIA. The compounds in were mainly phenolic abietane-type tricyclic diterpenoids with six- or seven-membered C-rings, and were widely distributed in the periderm, phloem, and xylem of the roots, e.g. 11-hydroxy-sugiol, 11,20-dihydroxy-sugiol, and 11,20-dihydroxy-ferruginol. In addition, the leaves of were rich in tanshinone biosynthesis precursors, such as 11-hydroxy-sugiol, while those of were rich in phenolic acids. Genes in the upstream pathway of tanshinone biosynthesis were highly expressed in the root of , and genes in the downstream pathway were highly expressed in the root of . Here, we describe the specific tissue distributions and mechanisms of diterpenoids in two species, which will facilitate further investigations of the biosynthesis of diterpenoids in plant synthetic biology.