Figure 6.

Spatial Model of Iridoid Biosynthesis and Translocation in Periwinkle Leaves.

The MEP pathway and iridoid biosynthesis to 7-deoxyloganic acid occurs in IPAP cells, while the terminal LAMT and SLS reactions occur in the leaf epidermis. The model shows 7-deoxyloganic acid hydroxylase in leaf epidermis, but this reaction and its location still remain to be elucidated. The model shows that MIA assembly from secologanin and tryptamine also takes place in leaf epidermal cells. Solid lines represent a single enzymatic step, whereas double arrows indicate the involvement of multiple enzyme steps. The question mark indicates the putative transport system of 7-deoxyloganic acid from IPAP cells to leaf epidermal cells.

[See online article for color version of this figure.]