Figure 3.

Time course of relative steady-state DXPS mRNA levels (•) and rate of monoterpene biosynthesis as measured by ¹⁴CO₂ incorporation (○) during leaf development in peppermint. Total RNA was isolated from oil gland secretory cells of leaves of different developmental stages in days (d) from emergence. A ³²P-labeled probe derived from DXPS clone pDS29 detected a transcript of about 3 kbp. Ethidium bromide-stained bands of 18S and 28S rRNA are shown as the internal controls. Leaves are fully expanded by 2 weeks, and 2.5-day leaves are the smallest from which oil gland secretory cells can be isolated (16).