Enhanced vincamine production in selected tryptophan-overproducing shoots of Vinca minor

Vinca minor is the sole source of vincamine, an alkaloid known to be used in a variety of cerebral disorders. Three stable variant shoot lines (V10, V20 and V30) with tolerance thresholds of 10, 20 and 30 mg/l 5-methyltryptophan (5-MT; analogue of tryptophan), respectively, were selected. These lines showed twofold to threefold increase in tryptophan content and 1.5- to 2-fold increment in the total alkaloids in comparison to the wild line shoots. A maximum of 16-fold enhancement in vincamine production was recorded in V30 line followed by eightfold in V20 line. Inter simple sequence repeat (ISSR)-PCR amplification of all the three lines showed total of 65 bands; out of which 60 were monomorphic (92.3 %) and 5 were polymorphic (7.7 %). Tryptophan being a limiting factor in the indole alkaloid pathway plays a crucial role in modulating the flux towards vincamine production and its over-production positively resulted into enhanced vincamine production.