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. 2021 Jan 8;230(1):73–89. doi: 10.1111/nph.17140

Fig. 1.

Fig. 1

Schematic diagram of cannabinoid biosynthesis including polyketide and isoprenoid precursor pathways. Precursor pathways are merged by a plastid‐localized aromatic prenyltransferase, with alkylresorcinolic acids and geranyl diphosphate intermediates forming cannabigeroids with a linear isoprenyl residue (Gülck & Møller, 2020). Cannabinoid synthesis concludes in the apoplastic storage cavity of glandular trichomes. Here, cannabigeroids are converted to tri‐ and di‐cyclic cannabinoids such as ∆9‐tetrahydrocannabinolic acid (THCA) and cannabidiolic acid (CBDA) via stereoselective oxidative cyclisation of the isoprenyl moiety. This occurs enzymatically by the cannabinoid synthases THCAS, CBDAS and CBCAS. The green arrow indicates location of the extracellular storage cavity of a Cannabis stalked glandular trichome; bar, 100 µm. Subcellular locations of cannabinoid and precursor pathway enzymes were predicted with the subcellular location software TargetP‐2.0 (http://www.cbs.dtu.dk/services/TargetP/). AAE, acyl‐activating enzyme; CBCA, cannabichromenic acid; CBCAS, cannabichromenic acid synthase; CBCOA, cannabiorcichromenic acid; CBCVA, cannabichromevarinic acid; CBDA, cannabidiolic acid; CBDAS, cannabidiolic acid synthase; CBDPA, cannabidiphorolic acid; CBDVA, cannabidivarinic acid; CMK, 4‐(cytidine 50‐diphospho)‐2‐C‐methyl‐d‐erythritol kinase; DXR, 1‐deoxy‐D‐xylulose‐5‐phosphate reductoisomerase; DXS, 1‐deoxy‐d‐xylulose 5 phosphate synthase; HDR, 1‐hydroxy‐2‐methyl‐2‐butenyl 4‐diphosphate reductase; HDS, 1‐hydroxy‐2‐methyl‐2‐butenyl 4‐diphosphate synthase; MCT, 2‐C‐methyl‐d‐erythritol 4‐phosphate cytidylyltransferase; MDS, 2‐C‐methyl‐d‐erythritol 2,4‐cyclodiphosphate synthase; MEP, 2‐C‐methyl‐d‐erythritol‐4‐phosphate; OAC, olivetolic acid cyclase; PT, prenyltransferase (e.g. geranylpyrophosphate:olivetolate geranyltransferase (GOT)); THCA, tetrahydrocannabinolic acid; THCAS, tetrahydrocannabinolic acid synthase; THCOA, tetrahydrocannabiorcolic acid; THCPA, tetrahydrocannabipgorolic acid; THCVA, tetrahydrocannabivarinic acid; TKS, tetraketide synthase.