Aspergillus flavus fungus elicitation improves vincristine and vinblastine yield by augmenting callus biomass growth in Catharanthus roseus

The influence of fungus elicitor Aspergillus flavus on alkaloid yield was investigated in Catharanthus roseus. The study reveals increased yield of vinblastine and vincristine in cultivated tissues. Different concentrations of extract applied to solid MS medium were: 0.05 % (T-1), 0.15 % (T-2), 0.25 % (T-3), and 0.35 % (T-4) along with control (T-0). The callus biomass, embryo formation and plant regeneration were studied in response to elicitor treatments. The embryogenic callus was induced from hypocotyls of in vitro germinated seeds and various tissues were exposed to fungal elicitation. The use of A. flavus fungal elicitation improved callus biomass growth, which later differentiated into embryos, maximum somatic embryo induction being in T-2 (106.53/callus mass). Biochemical analysis revealed more accumulation of sugar, protein and proline in growing tissues especially amended with elicitor. The somatic embryos germinated into plantlets on 2.24 A mu M BA added MS medium. The percent germination, shoot-, root length of germinated somatic embryos were high in low doses of elicitation (T-1/T-2). The quantitative analysis of vinblastine and vincristine yield was conducted in different elicitor treated tissues by the use of HPTLC. Vinblastine yield was maximum in germinating embryos (0.837 A mu g gm(-1) dry weight), A. flavus elicitation at T-2 improved vinblastine yield further (0.903 A mu g gm(-1) dry weight). Compared to vinblastine, the yield of vincristine was low and on A. flavus addition, maximum vincristine yield was noted (0.216 A mu g gm(-1) dry weight). The highest 7.88 and 15.50 % increased yield of vinblastine and vincristine respectively was noted on A. flavus elicitated tissues. In order to understand the role of elicitor on plant defense responses various antioxidant enzymes activity were investigated as the addition of elicitor induced cellular stress on tissues. Maturated and germinating somatic embryos had high SOD activity and on elicitation the activity of enzymes was further increased, indicating extra cellular stress on tissues, which yielded enriched level of vinblastine and vincristine at T-2/T-1.