Figure 7.

Effects of C. roseus Alkaloids on Elicitation of C. roseus Cells.

(A) Top: Elicitor-triggered alkaloid formation, influenced by selected MIAs. The “effector” alkaloids, added 10 min prior to the elicitor (10 µM each), are named at the bottom. Data are total alkaloid contents produced in 24 h after elicitor contact and consist of the color-coded individual compounds. The figure represents a typical, single experiment that was repeated with two different batches and yielded similar relations between the total alkaloids of each sample. Standard deviation of the HPLC-based determination of the extracted individual alkaloids ranges from 8 to 13%, as shown in test experiments with added vincristine and catharanthine.

(B) Bottom: Effects of the same MIAs at the elicitor-stimulated PLA2 in the plasma membrane. If indicated, an alkaloid was added 10 min prior to the substrate, together with elicitor plus GTP, to give a final concentration of 10 µM. Data are means ± se; n = 5. Asterisks indicate significant (P < 0.05) inhibition by alkaloids.