Effect of polyamines on shoot multiplication and furanocoumarin production in Ruta graveolens cultures

Abstract

The influence of the polyamines putrescine (Put), spermine (Spr) and spermidine (Spd) on growth and furanocoumarin production was investigated by exogenous addition, at different concentrations, to shoot cultures of Ruta graveolens at different phases of growth. Preliminary studies indicated that addition of Put (20 μM) and Spr (80 μM) had a promotive effect on shoot multiplication rate and number of multiple shoots formed. Spd was toxic, even at lower concentrations. The growth-phase of the culture at the time of exogenous addition of polyamines was found to be an important factor. Put was most effective when added at the lag phase, while Spr was most effective when added in the log phase. Time course studies of growth and furanocoumarin content were carried out for each polyamine and phase of addition. It was seen that maximum production of furanocoumarins (256.8 mg/10 g DW) occurred in the second week when Put was added in the lag phase and 260.5 mg/10 g DW in the fourth week when Spr was added in the log phase. Put addition resulted in a 3.10 fold increase in psoralen, 6.12 in xanthotoxin and 1.46 fold in bergapten production. Spr addition resulted in a 1.31 fold increase in psoralen, 4.11 fold in xanthotoxin and 1.49 fold in bergapten production. Results indicate that alteration of growth and furanocoumarin production kinetics is a combined outcome of choice of polyamine and the phase of culture at the time of exogenous addition. Polyamine addition enabled significant enhancement in production of pharmaceutically important bergapten and xanthotoxin in shoot cultures of Ruta graveolens, which could be explored for commercial production.