); [EMAIL_ADDRESS] (A.A.); [EMAIL_ADDRESS] (M.V. ); [EMAIL_ADDRESS] (N.D.T.) [PERSON]  
1 Department of Pharmacy, University of Salerno, 84084 Fisciano, Italy; [EMAIL_ADDRESS] (M.A. ); [EMAIL_ADDRESS] (A.A.); [EMAIL_ADDRESS] (M.V. ); [EMAIL_ADDRESS] (N.D.T.) [PERSON]  
1 Department of Pharmacy, University of Salerno, 84084 Fisciano, Italy; [EMAIL_ADDRESS] (M.A. ); [EMAIL_ADDRESS] (A.A.); [EMAIL_ADDRESS] (M.V. ); [EMAIL_ADDRESS] (N.D.T.) [PERSON]  
1 Department of Pharmacy, University of Salerno, 84084 Fisciano, Italy; [EMAIL_ADDRESS] (M.A. ); [EMAIL_ADDRESS] (A.A.); [EMAIL_ADDRESS] (M.V. ); [EMAIL_ADDRESS] (N.D.T.) [PERSON]  
1 Department of Pharmacy, University of Salerno, 84084 Fisciano, Italy; [EMAIL_ADDRESS] (M.A. ); [EMAIL_ADDRESS] (A.A.); [EMAIL_ADDRESS] (M.V. ); [EMAIL_ADDRESS] (N.D.T.) [PERSON]  
1 Department of Pharmacy, University of Salerno, 84084 Fisciano, Italy; [EMAIL_ADDRESS] (M.A. ); [EMAIL_ADDRESS] (A.A.); [EMAIL_ADDRESS] (M.V. ); [EMAIL_ADDRESS] (N.D.T.) [PERSON]  
1 Department of Pharmacy, University of Salerno, 84084 Fisciano, Italy; [EMAIL_ADDRESS] (M.A. ); [EMAIL_ADDRESS] (A.A.); [EMAIL_ADDRESS] (M.V. ); [EMAIL_ADDRESS] (N.D.T.) [PERSON]  
1 Department of Pharmacy, University of Salerno, 84084 Fisciano, Italy; [EMAIL_ADDRESS] (M.A. ); [EMAIL_ADDRESS] (A.A.); [EMAIL_ADDRESS] (M.V. ); [EMAIL_ADDRESS] (N.D.T.) [PERSON]
different compounds, with diverse biological functions in the plant kingdom and for human health [3]. Many studies have been focused on elucidating the isoprenoid pathways, identifying the enzymatic steps, their genetic control, and uncovering potential enzymatic bottlenecks, with the final aim being metabolic bioengineering or refactoring a plant's natural product biosynthetic pathways in microorganisms [4]. Most plant isoprenoids, including also diterpenes, derive from two common C\({}_{5}\) precursors, IPP and its isomer DMAPP, through two distinct pathways: the well-studied prevalent (MVA) pathway, which predominates in cytosol, and the more recently unveiled deoxyxylulose 5-phosphate/2-C-methyl-D-erythriitol 4-phosphate (DXP/MEP) mevalonate-independent pathway, localized in the plastids (Figure 1). Briefly, the condensation of pyruvate and glyceraldehyde 3-phosphate (G3P) produces the 1-deoxy-D-xylulose 5-phosphate (DXP), catalyzed by the 1-deoxy-D-xylulose 5-phosphate synthase (DXS), the first committed step in the plastidial MEP-pathway. DXP is then reorganized and reduced to 2-C-methyl-D-erythriitol 4-phosphate (MEP), by 1-deoxy-D-xylulose 5- phosphate reductoisomerase (DXR). MEP is then cyclized to the intermediate methylerythriitol 2,4-cyclodiphosphate (ME-cPP), through the action of three consecutive enzymatic steps, involving a cytidylation step (by 4-Diphosphocytidyl-2-C-methyl-D-erythriitol synthase, CMS), an ATP-dependent phosphorylation (by the CMK 4-(cytidine 5\({}^{\prime}\)-diphospho)-2-C-methyl-D-erythriitol kinase), and a cyclization step (by the 2-C-methyl-D-erythriitol 2,4-cyclodiphosphate synthase, MDS). The final two enzymatic steps of the MEP-pathway consist in the synthesis of the hydroxymethylbutenyl 4-diphosphate (HMBPP) from ME-cPP, catalyzed by the hydroxymethylbutenyl 4-diphosphate synthase (HDS) and the conversion of HMBPP into a 5:1 mixture of IPP and its isomer DMAPP, by the IPP and DMAPP synthase (IDS). According to the number of C\({}_{5}\) units of IPP and DMAPP, different isoprenoids are formed: in particular, diterpenes contain four C\({}_{5}\) units, characterized by a large diversity in their chemical structure, with more than 18,000 structures thus far described [5].