The long hydrophobic tails present in sorgoleone precursors mean that the molecules will be present in the membrane. Thus, it stands to reason that the synthesis enzymes carrying out the reactions put forward in Fig. should all be membrane associated, even if that association is at the membrane periphery. This is consistent with the cytosolic localization of many of the pathway enzymes, which could interact with intracellular precursors at the membrane interface. The order of reactions appears optimized to retain sorgoleone precursors on one side of the membrane, as the resorcinol derivatives cross the membrane slower than sorgoleone or dihydrosorgoleone. From an export perspective, the molecule with the closest transport rate to sorgoleone is dihydrosoroleone, which may simply be oxidized in the extracellular space if it is released before oxidation. In planta, maintaining biosynthetic precursors on one side of the membrane would be an attractive strategy to improve synthetic efficiency, as only half as many molecules would need to be made to reach a certain concentration on one side of the membrane, increasing enzymatic efficiency. However, as the concentration rises, it is clear that interleaflet exchange would occur over the hours and days in a plant lifetime, and so we would expect to find some concentration for all of the compounds of interest in the outer leaflet within sorghum root hairs.