Influence of feeding precursors on tropane alkaloid production during an abiotic stress in Datura innoxia transformed roots

The effects of feeding tropane alkaloid precursors in transformed root culture of Datura innoxia Mill. were studied during a stress treatment. The permeabilizing effect of Tween 20 on tropane alkaloid production by hairy root cultures was studied in flasks with different feeding of precursors (L-ornithine, L-arginine, L-phenylalanine, DL-beta-phenyllactic acid, and tropinone). It has been shown that the addition of various precursors alone (0.5 m mol l (-1)) was ineffective in stimulating hyoscyamine production. In contrast, a short treatment with Tween 20, combined with L-phenylalanine feeding, amplified the level of hyoscyamine released into the medium compared with the Tween treatment alone. Thus, the total hyoscyamine content per flask was increased (+ 40%) compared with the control. When DL-beta-phenyllactic acid (0.5 m mol l (-1)) was used, this last effect became more pronounced (+ 60%). These results show that permeabilization with Tween modulates tropane alkaloid accumulation by a release of alkaloids into the medium and a restoration of hyoscyamine root content. The simultaneous feeding of DL-beta-phenyllactic acid and tropinone during the Tween treatment gave a similar effect to that obtained with DL-beta-phenyllactic acid and Tween, suggesting that the synthesis of the tropate moiety determines the flux at the level of the esterification of tropine.