Localization of enzymes of artemisinin biosynthesis to the apical cells of glandular secretory trichomes of Artemisia annua L.

The initial enzymes of artemisinin biosynthesis, i.e. amorpha-4,11-diene synthase, amorpha-4,11-diene hydroxylase and artemisinic aldehyde Δ11(13) reductase are expressed in apical cells of glandular trichomes of Artemisia annua. No expression of these ezymes is observed in the photosynthetic sub-apical cells. Artemisinin appears to be biosynthesized exclusively in apical cells.