Effects of methyl jasmonate on root growth, biochemical characteristics and h6h gene expression in Hyoscyamus reticulatus L. hairy roots

Henabne(Hyoscyamus reticulatus L.) is a rich source of tropane alkaloids including hyoscyamine (Hyos) and scopolamine (SCP), widely used in pharmaceutical field. The aim of the present study was to assess the effect of different concentrations (0, 50, 100 and 200 µM) of methyl jasmonate (MeJA) at two different times of exposure (24 and 48 h) on growth, antioxidant enzymes activity, tropane alkaloids content, and the expression level of hyoscyamine-6-beta-hydroxylase (h6h) gene in H. reticulatus hairy root cultures. The results showed that MeJA at high concentration (200 µM) led to the decline of fresh and dry weight of hairy roots. Catalase (CAT), guaiacol peroxidase (GPX) and ascorbate peroxidase (APX) activities were significantly increased by MeJA, especially at 200 µM in elicited hairy roots. As well, CAT and GPX activities, but not of APX, were also affected by exposure time of MeJA. According to the GC/MS analysis, the highest percentage of SCP (13.96%) and Hyos (21.9%) were respectively obtained when hairy roots were exposed to MeJA at concentrations of 100 and 200 µM for 48 and 24 h, which were, respectively, 1.6- and 1.25-fold higher than those in the control roots. According to the results of semi-quantitative RT-PCR analysis, the highest expression of h6h gene (6-fold higher than in the control) was obtained after 24 h exposure to 100 µM MeJA. These results indicate that MeJA, due to stimulation of the expression of key genes involved in the biosynthetic pathway of tropane alkaloids, could be used as an effective elicitor for increased production of Hyos and SCP.