Bacterial endophyte-mediated enhancement of in planta content of key terpenoid indole alkaloids and growth parameters of Catharanthus roseus

Abstract

Catharanthus roseus is particularly known for its therapeutically useful terpenoid indole alkaloids, including the anticancer bisindole alkaloids (vinblastine and vincristine), as well as other alkaloids like ajmalicine and serpentine. The high cost, scarcity and commercially non-viable chemical syntheses of the bisindole alkaloids have sustained the research effort on the plant till date. The present study was undertaken to determine the effect of endophytes isolated from C. roseus on the growth parameters/biomass and in planta content of key terpenoid indole alkaloids like vindoline, vincristine, serpentine and ajmalicine. Out of the four endophytes isolated three were bacterial (V1, V2, V3) and one was fungal (V4). In the initial glasshouse experiments, V1 and V3 treatments were found to outperform the remaining two in terms of improvement in plant growth parameters. The bacterial endophytes, V1 and V3 were identified as Staphylococcus sciuri and Micrococcus sp., respectively through 16S rRNA gene sequence analysis. Treatment with both these endophytes was used on field grown plants to determine their effect on plant growth parameters and in planta contents of selected terpenoid indole alkaloids. It was found that both of them significantly increased the plant height but V3 was found to be superior to V1 when enhancement in weight of shoot, root and leaf or in planta content of vindoline, ajmalicine and serpentine was considered. The results of this study clearly indicate the possibility of using bacterial endophytes like V3 as bio-inoculants for enhancing plant growth/biomass and in planta content of key terpenoid indole alkaloids like vindoline (that may be used for bisindole alkaloid semi-synthesis), serpentine and ajmalicine.