Growth and tropane alkaloid production inAgrobacterium transformed roots and derived callus ofDatura

Small callus pieces excised from theAgrobacterium transformed root line D₂ ofDatura stramonium, were cultured onto solidified MS medium supplemented with a 1.0 μM kinetin and three different concentrations (0.1, 0.5 and 1.0 μM) of 2,4-dichlorophenoxyacetic acid (2,4-D), and were examined for their alkaloid productivity in relation to organization level and growth rate. Growth of transformed roots (in a MS liquid medium without plant growth regulators) was greater than that of transformed calli excised from them and cultured separately. The addition of 1.0 μM 2,4-D to the culture medium had a positive effect on callus biomass production, while it inhibited root formation by this tissue (the lower the 2,4-D concentration in the medium the greater the number of roots which emerged from the calli). Hyoscyamine production was also higher in the transformed roots than in the transformed calli, and in these tissues the production of hyoscyamine was positively correlated with organogenesis index (i.e. its ability for rooting). At the same time, the epoxidation of hyoscyamine to scopolamine only took place in the transformed calli. This occurred to a greater extent at the lower concentrations of 2,4-D in the culture medium. The mode through which the 2,4-D could control the alkaloid production of transformed callus is discussed.