Schematic view of plastidic methylerythritol 4-phosphate (MEP) pathway providing the precursors for secologanin (monoterpene) synthesis.

<p>Enzymes analyzed in the present study are in bold face (DXS, 1-deoxy-D-xylulose 5-phosphate synthase; DXR, deoxyxylulose 5-phosphate reductoisomerase; HDS, hydroxymethylbutenyl diphosphate synthase). GAP, glyceraldehyde 3-phosphate; DXP, deoxyxylulose 5-phosphate; MEP, methylerythritol 4-phosphate; MEcPP, methylerythritol 2,4-cyclodiphosphate; HMBPP, hydroxymethylbutenyl diphosphate; IPP, isopentenyl diphosphate; DMAPP, dimethylallyl diphosphate; GPP, geranyl diphosphate; GGPP, geranylgeranyl diphosphate. ABA, abscisic acid. The step branching to thiamine from DXP is indicated. Furthermore, inhibition of DXS and DXR by 5-ketoclomazone (formed <i>in planta</i> from clomazone) and fosmidomycin, respectively, is highlighted. Dashed arrows indicate multiple steps.