Induced production of tropane alkaloids, and expression of hyoscyamine 6β-hydroxylase (h6h) and putrescine N-methyl transferase (pmt2) genes in hairy roots and propagated plantlets of Atropa belladonna L. elicited by methyl jasmonate

Abstract

Atropa belladonna L. is an important medicinal plant due to the biosynthesis of hyoscyamine and scopolamine; two important tropane alkaloids, mostly well known for their anticholinergic properties acting on the parasympathetic nervous system. This study aimed to analyze the effect of methyl jasmonate (MJ), at different concentrations, on hyoscyamine and scopolamine production from in vitro hairy root culture and propagated plantlets of A. belladonna L. Gene expression analysis of two key enzymes PMT and H6H responsible for the biosynthesis of hyoscyamine and scopolamine, respectively, was also carried out under MJ application. MJ decreased the growth parameters in both plantlets and hairy root cultures. In shoots of the plantlets, MJ increased significantly the hyoscyamine and scopolamine contents to the highest value of 3.32 mg g−1 DW and 0.5 mg g−1 DW, respectively. Moreover, MJ up-regulated pmt2 and h6h gene expression in root of the plantlets, which is the site of biosynthesis of hyoscyamine and scopolamine, while the accumulation occurs in the aerial parts. In hairy root culture, the hyoscyamine content increased as the MJ concentration increased, and reached its highest level of 2.1 mg g−1 DW at 0.04 mM MJ, showing the same pattern as for pmt2 gene expression. Nevertheless, the scopolamine content decreased by increasing the MJ concentration as it also showed a reverse pattern compared to the h6h gene expression, presumably due to the negative effect of hyoscyamine accumulation on H6H enzyme activity.

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