In vitro mass propagation and greenhouse establishment of Withania somnifera (L.) Dunal (Solanaceae) and comparison of growth and chemical compounds of tissue cultured and seed raised plants

Abstract

Withania somnifera (L.) Dunal (Solanaceae) is normally propagated by seeds. The percentage germination is low, due to the presence of certain inhibitory compounds in the fruit. Among the local and Indian cultivars, the Indian cultivar is preferred by the pharmaceutical industry due to the starchy nature of roots. The local cultivar is listed as a threatened plant. In the present study, W. somnifera was successfully mass propagated in vitro, acclimatized and compared with seed raised plants. The best callus production was observed in Murashige and Skoog (MS) medium supplemented with 1.0 μM kinetin (Kin), 4.5 μM benzyl amino purine (BAP), and 1.5 μM naphthelene acetic acid (NAA) within a 14 day dark period. Shoot initiation was observed in calli produced from shoot tips and nodal segments cultured in the above medium but not from the calli produced from leaf pieces. The highest shoot multiplication was observed in calli from nodal segments cultured in the presence of 9.0 μM BAP and 1.0 μM indole-3-actic acid (IAA) (11.30±1.60). Growth regulator free MS medium was the best medium for rooting. In vitro produced plants were acclimatized successfully (80%) in a potting mixture of river sand: top soil: compost (2:1:1). The rate of photosynthesis was higher in tissue cultured plants at three months (4.86±0.40 and 5.67±0.31 for morning and noon respectively) and six months (6.20±0.52 and 6.67±0.33 for morning and noon respectively), while stomatal resistance showed the opposite of that. TLC fingerprints indicated that there was no significant difference in chemical identities (steroids) present in tissue cultured and seed raised plants.