Ghan Singh Malothu, Rajinikanth Marka and Rama Swamy Nanna*
In the present investigation the role of different plant growth regulators (PGRs) on direct regeneration from various explants, cotyledon, hypocotyl and leaf was studied to find out the regeneration potentiality of the explant and also role of PGRs in Turkey berry/pea egg plant, S. torvum. The explants such as hypocotyl (0.4-0.8 cm long), cotyledon (0.6-0.8 cm2) from 3 week old and leaves (1.0 cm2) from 6 week old in vitro grown seedlings were excised and cultured on MS medium with various concentrations of BAP/KIN alone and also in combination with 0.5-1.0 mg/L IAA showed the direct shoots regeneration. All the explants have shown the maximum percentage of response (>90%) and highest number of direct induction of multiple shoots per explant (55±0.15 cotyledon, 52±0.13 leaf and 31±0.17 hypocotyl explants) was found at 0.5 mg/L IAA+2.5 mg/L BAP in comparison to different concentrations of cytokinins alone used and as well as in combination with IAA. Thus, it is clear that cotyledon explants were found to be more potential in producing high frequency number of shoots per explant among all other explants tested in the present investigations. Cytokinnes BAP/KIN alone or in combination with IAA was found more effective in inducing shoot regeneration in all the explants of S. torvum. However, 2.5 mg/L BAP/KIN with 0.5 mg/L IAA combination induced highest number of shoots. At 3.5 and 4.0 mg/L BAP in combination with 1.0 mg/L IAA, shoots were formed along with the callus. For in vitro rooting the elongated microshoots were transferred on to root induction medium (RIM) fortified with 0.25-2.0 mg/L NAA/IAA. Maximum percentage of response (92%), average number of roots (20.3±0.03) per micro shoot with highest length of roots (9.6±0.09) was observed at 1.0 mg/L IAA. In vitro rooted plantlets were transferred in to sterile vermiculate and soil (1:1) mix and subsequently these were acclimatized in the green house. The in vitro rooted plantlets were transferred into field. The survival percentage was found to be 90% and the plantlets were normal in morphology, flowering and fruiting. Thus, the regeneration protocol developed in the present investigation can be used for conservation and genetic transformation experiments in S. torvum, not only a medicinal plant but also a model plant.
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