Stevia rebaudiana (Bert.) is an emerging sugar alternative and anti-diabetic plant in Pakistan. That is why people did not know the exact time of propagation. The main objective of the present study was to establish feasible propagation methods for healthy biomass production. In the present study, seed germination, stem cuttings and micropropagation were investigated for higher productivity. Fresh seeds showed better germination (25.51-40%) but lost viability after a few days of storage. In order to improve the germination percentage, seeds were irradiated with 2.5, 5.0, 7.5 and 10 Gy gamma doses. But gamma irradiation did not show any significant change in seed germination. A great variation in survival of stem cutting was observed in each month of 2012. October and November were found the most suitable months for stem cutting survival (60%). In order to enhance survival, stem cuttings were also dipped in different plant growth regulators (PGRs) solution. Only indole butyric acid (IBA; 1000 ppm) treated cutting showed a higher survival (33%) than control (11.1%). Furthermore, simple and feasible indirect regeneration system was established from leaf explants. Best callus induction (84.6%) was observed on MS-medium augmented with 6-benzyladenine (BA) and 2,4-dichlorophenoxyacetic acid (2,4-D; 2.0 mg l(-1)). For the first time, we obtained the highest number of shoots (106) on a medium containing BA (1.5 mg l(-1)) and gibberellic acid (GA3; 0.5 mg l(-1)). Plantlets were successfully acclimatized in plastic pots. The current results preferred micropropagation (85%) over seed germination (25.51-40%) and stem cutting (60%).

An efficient method of regeneration for antidiabetic plant (Stevia rebaudiana) has been established for healthy biomass and main steviol glycosides (SGs) production, using different PGRs and agar concentrations. Higher callus induction (93.3%) was recorded when leaf explants were placed on an MS medium supplemented with 3.5 gL À1 agar and 2.0 mgL À1 2,4-D. The addition of 7.0 gL À1 agar and BA (1.0, 2.0 and 4.0 mgL À1 ) significantly (P < 0.01) influences shooting response (100%). A maximum mean shoot length (13.03 cm) and 28 shoots per explant were observed on a medium containing 1.0 mgL À1 BA. However, the maximum number of leaves (132.67) was encouraged by the addition of BA (1.0 mgL À1 ) and Kin (1.0 mgL À1 ). Lower agar (3.5 gL À1 ), IAA (2.0 mgL À1 ), and NAA (2.0 mgL À1 ) concentrations significantly influence the rooting percent (100%), the mean root length (2.9 cm), and the number of roots per plantlet (26.3). These plantlets were successfully acclimatized in the soil. The BA (3.0 mgL À1 ) in combination with Kin (3.0 mgL À1 ) and 3.5 gL À1 agar increases dulcoside-A content (Dul-A; 71.8 mg/g-DW) in shoots compared to control (50.81 mg/g-DW). Similar PGRs with 7.0 gL À1 significantly increases the production of steviosides (Stev. 82.48 mg/g-DW). A higher rebaudioside-A content (Reb-A; 12.35 mg/g-DW) was observed in shoots that underwent the addition of BA (1.0 mgL À1 ) and 7.0 gL À1 agar than in control (07.39 mg/g-DW).Hereby, we developed an efficient and cost-effective method for regeneration and major SGs production, which could be helpful for future studies on this species.

The callogenic and shoot organogenic potential of the medicinaly important plant, S. rebaudiana were investigated. Callus induction and shoot regeneration were induced from flower explants of greenhouse plants incubated on Murashige and Skoog (MS)-medium supplemented with different plant growth regulators (PGRs). The best callogenic response was observed on explants incubated on MSmedium supplemented with 2.0 mg/l 6-benzyladenine (BA) along with 2.0 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D) after 30-days of culture. Subsequent transfer of callogenic explants onto MS-medium supplemented with 2.0 mg/l BA gave 85.2% shoot organogenesis after 30-days following culture. Maximum number (21.6) of shoots/explant was recorded for 2.0 mg/l BA. Subsequent sub culturing of shoots after 3 weeks of culture, on medium with similar compositions of PGRs gave 5.1 cm longest shoot. The palynology of S. rebaudiana has also been investigated.

No abstract

No abstract