Fig. 4. Schematic showing the metabolic network used for elucidating the fluxes from 13C labeling data.
On the basis of earlier modeling work carried out in B. distachyon (33, 34), the biosynthesis of lignin was assumed to occur at two different locations: cytosol (c) and surface of endoplasmic reticulum (er). Reactions catalyzed by membrane-bound enzymes such as C3′H and C4H were confined to the ER compartment of the model. The remainder of the reactions was included in both the compartments. Exchange reactions were added for compounds present in both compartments to allow for their free exchange. Reactions highlighted with green arrows were included only in the 16 to 18 and 20 to 22 DAP models. caf, caffeic acid; cafSh, caffeoyl shikimate; cAlc, caffeyl alcohol; cAld, caffealdehyde; cCoA, caffeoyl CoA; cin, cinnamic acid; fAlc, coniferyl alcohol; fAld, coniferaldehyde; fCoA, feruloyl CoA; fer, ferulic acid; pco, p-coumaric acid; pcoA, p-coumaroyl CoA; pcoSh, p-coumaroyl shikimate; pAld, p-coumaraldehyde; pAlc, p-coumaryl alcohol.