Effects of sucrose and pH levels on in vitro shoot regeneration from leaf explants of Bacopa monnieri and accumulation of bacoside A in regenerated shoots

Abstract

Brahmi (Bacopa monnieri) is an important medicinal plant mainly used for the treatment of neurological disorders and depression. Recent investigations revealed that bacoside A is major chemical component shown to be responsible for memory facilitating action of brahmi. The current investigation was carried out to assess the potential for increasing biomass and the concentration of bacoside A in the in vitro regenerated shoots by varying sucrose and pH levels of shoot regeneration medium. The leaf explants were cultured on the Murashige and Skoog (MS) medium supplemented with 2 mg l -1 kinetin (KN) and with varying concentrations of sucrose (0, 1, 2, 3, 4, 5 and 6% at pH 5.8) and pH (4.5, 5.0, 5.5, 6.0 and 6.5 with 2% sucrose) with the objective of verifying the effects of sucrose and pH level on shoot regeneration and to verify the accumulation of bacoside A in the regenerated shoots. The shoot biomass increased (150.50 ± 2.84 shoots per explant, fresh wt 6.31 ± 0.12 g and dry wt 250 ± 5.00 mg) on the medium supplemented with 2% sucrose and pH which was set at 4.5. The results of HPLC analysis indicate that increase in sucrose concentration (0, 1, 2, 3, 4, 5 and 6% at pH 5.8) lead to decrease in the bacoside A content (39.51, 22.43, 13.05, 12.17, 10.73, 9.56 and 8.93 mg g -1 dry wt, respectively) in regenerated shoots. These findings provide evidence that stressful condition of inadequate supply of carbon elevated synthesis of bacoside A in brahmi shoots. However, 2% sucrose is found suitable for biomass accumulation. Therefore, medium supplemented with 2% sucrose and pH set at 4.5 was found suitable for both biomass (6.31 ± 0.12 g fresh wt and 250 ± 5.00 mg dry wt) and bacoside A accumulation (13.09 mg g -1 dry wt).

Review of Literature

“…Similar findings were reported by Siddique and Anis (2007a) in Cassia angustifolia and B. monnieri (Naik et al 2010) and Perveen et al (2011) in Albizia lebbeck. These studies indicated that the effect of pH value on plant regeneration depends on plant species.…”

Influence of pH and plant growth regulators on secondary metabolite production and antioxidant activity of Stevia rebaudiana (Bert)

“…The effects of different PGR, medium strength and pH value on secondary metabolite accumulation have previously been studied in various plants [11,12,13] though limited data exist on the topic regarding S. rebaudiana [7,14]. In the present study, half-rather than fullstrength Murashige and Skoog (MS) media was used for the experiments as our preliminary data showed far better germination, growth and development of plantlets in lower salt media.…”

Effect of Media pH on Shoot Proliferation of Papaya (Carica papaya L.)

“…The pH also influences the status of the solidifying agent in medium, a pH higher than 6 produces a very hard medium and a pH lower than 5 does not sufficiently hard medium (Bhatia and Ashwath, 2005). The reduced pH might favor the assimilation of ions by the cultured cells from the medium and in turn regulation of metabolic pathway of cultured cells (Naik et al, 2010). From above studies, it can be concluded that MS basal media at pH was found most optimum for shoot proliferation in papaya.…”