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Abstract
Several species of the genus Datura have been cultivated for their hyoscyamine content. Hyoscyamine production in field-cultivated plants can often be limited by environmental conditions. The culture of hairy roots obtained by inoculation of Datura explantswith theA4 strain of Agrobacteriumrhizogenes offers promising prospects for the in vitro production of hyoscyamine. The objectives of this study were to select high-quality hairy root lines and then optimize hyoscyamine production by applying a salt stress. Potassium chloride (KCl) and calcium chloride (CaCl^sub 2^) were added at various elicitation times, and both had significant effects on hyoscyamine biosynthesis. The optimal concentration of KCl was 2 g L^sup -1^, combined with a contact time of 10 h for the selected Datura tatula line (L^sub DT^) and 24 h for the selected Datura stramonium (L^sub DS^) and Datura innoxia (L^sub DI^) lines. For CaCl^sub 2^, the optimum concentration was 2 g L^sup -1^ for L^sub DS^ and L^sub DT^, with respective elicitation times of 10 and 24 h. For L^sub DI^, the best result was obtained with a CaCl^sub 2^ concentration of 1 g L^sup -1^ and an elicitation time of 24 h. The highest hyoscyamine levels obtained for L^sub DS^, L^sub DT^, and L^sub DI^ were, respectively, 2.32-, 1.99-, and 1.85-fold the control levels with KCl elicitation and 2.08-, 2.07-, and 1.85-fold the control levels with CaCl^sub 2^ elicitation. The line resulting from D. tatula elicited with 2 g L^sup -1^ CaCl^sub 2^ for 24 h produced the most hyoscyamine content (16.978 mg g^sup -1^ DW), followed by L^sub DI^ and then L^sub DS^.