Effects of different experimental strategies on the concentrations of a scopolamine, b hyoscyamine, c anisodamine and d cuscohygrine in HB-grown H. niger hairy root cultures. Values represent the mean of 2 samples, error bars refer to total culture content of the respective alkaloids. Symbols indicate significant difference (t test, p < 0.05) in alkaloid content in roots (asterisk), growth medium (dagger) and total culture (double dagger) in comparison to control. MeJ hairy roots elicited with 1.0 mM methyl jasmonate on the 26th day, collected after 24 h; DMSO hairy roots permeabilized with 20 % (v/v) dimethyl sulfoxide on the 30th day, collected after 24 h; XAD-2 culture subjected to in situ extraction with Amberlite XAD-2 resin from 30 to 50 days, collected on 50th day; C control group—cultures grown for the same period of time without the presence of MeJ, DMSO or XAD-2