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Effect of nitrogen and carbon sources on multiple shoot regeneration and withanolides contents of Withania somnifera were evaluated. Inclusion of L-glutamine (20 mg/l) in medium fortified with the optimal levels of 1.5 mg/l 6-benzyladenine (BA) and 0.3 mg/l indole-3-acetic acid (IAA) resulted in the production of 58 shoots/explant. Sucrose at 4 % and 20 mg/l L-glutamine with ide ´al concentrations of BA and IAA improved shoot multiplication (62 shoots/explant) while 6 % sucrose enhanced withanolides contents in regenerated multiple shoots. All the shoots were rooted (26 roots/shoot) when cultured in MS medium amended with 15 mg/l ammonium nitrate, 2 mg/l IBA, and 2 % sucrose. The present study resulted in the production of 4.42-fold higher multiple shoots and 2.6- fold higher roots as well as enhancing the contents of all major withanolides (withaferin A, withanone, withanolide A and B) in regenerated plants when compared to previous reports on W. somnifera regeneration.
An efficient mass multiplication protocol was developed for Withania somnifera (L.) Dunal from nodal explants of field-grown plants on Murashige and Skoog medium (MS) supplemented with 6-benzyladenine (BA) [1.5 mg L⁻¹], indole-3-acetic acid (IAA) [0.3 mg L⁻¹] and with the addition of polyamine, spermidine (20 mg L⁻¹) (shoot multiplication medium). A total of 46.4 shoots were obtained from nodal explants and they were elongated in the same medium in a culture duration of 6 weeks. The elongated shoots produced roots in MS medium fortified with putrescine (20 mg L⁻¹) after 4 weeks, and all the rooted plants were successfully hardened and acclimatized with a survival rate of 100%. An average of 276 shoots (46 × 6) was produced when at least six nodal explants obtained from each of the 46 in vitro grown shoots were cultured by microcutting method in the same shoot multiplication medium. On an average, 12,696 plants could be produced from all the shoots (276 × 46) by microcuttings in a period of 7 months. HPLC revealed a significant increase in the quantities of withanolide A, withanolide B, withaferin A and withanone in the leaves, stems, and roots of in vitro regenerated plants compared to the field-grown parent plants. Ploidy analysis using flow cytometry revealed genetic stability of in vitro regenerated plants. This protocol will be useful for scale-up production of withanolides on commercial scale.
To determine the possibility of generating the Podophyllotoxin accumulation using Podophyllum hexandrum adventitious roots derived from root segments, several nutrient constituents (carbon sources, media strength, initial medium pH, ammonium and nitrate proportion and phosphate ratio) were evaluated in culture. The maximum biomass accumulation was recorded in 0.50 MS medium containing 3 mg/l indole-3-butyric acid and 2 % sucrose, and the maximum accumulation of Podophyllotoxin was documented in the same strength of MS medium with 6 % of sucrose. When the initial medium pH was on 6 in the optimized MS medium, the biomass and Podophyllotoxin accumulations were highest. The lower concentration of ammonium (10 mM) in combination with a moderate concentration of nitrate (20 mM) was found ideal for maximum accumulations of biomass and Podophyllotoxin. Maximum Podophyllotoxin accumulation (6.4 mg/g dry weight) was recorded at the higher concentration of phosphate (2.25 mM), and lower concentration of phosphate (1.25 mM) showed highest growth accumulation. The outcome of the present work will be helpful for the large-scale cultivation of adventitious root for the production of Podophyllotoxin.
The influence of cytokinins and culture conditions including medium volume, harvest time and elicitation with abiotic elicitors (SA/MeJ) have been studied for the optimal production of biomass and withanolides in the multiple shoot culture of Withania somnifera. Elicitation of shoot inoculum mass (2 g 1-1 FW) with SA at 100 μM in the presence of 0.6 mg 1-1 BA and 20 mg 1-1 spermidine for 4 h exposure time at the 4th week in 20 m1 liquid medium recorded higher withanolides production (withanolides A [8.48 mg g-1 DW], withanolides B [15.47 mg g-1 DW], withaferin A [29.55 mg g-1 DW] and withanone [23.44 mg g-1 DW]), which were 1.14 to 1.18- fold higher than elicitation with MeJ at 100 μM after 5 weeks of culture. SA-elicited cultures did not exhibit much variation in biomass accumulation when compared to control. This cytokinin induces and SA-elicited multiple shoot culture protocol provides a potential alternative for the optimal production of biomass and withanolides utilizing liquid culture.
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