Effect of growth regulator on shoot-bud Induction and plant Regeneration
The in vitro raised seedlings used as a source of explants for micro-propagation studies by decapitated cotyledonary–stage seedlings in various concentrations of BAP and TDZ (0.0, 0.25, 0.5 and 1 mg l-1) (Fig. 1A). Decapitated seedlings cultured on MSB medium without any PGRs were differentiated into a single shoot primordial per an explant within… weeks. Of the different concentrations of TDZ and BAP tested, supplementation of 0.25 mg l-1 TDZ to MS medium gave better response, than the other concentration of these two PGRs. Based on the results of this experiment, shoot-bud development and shoot regeneration were significantly affected by various levels of TDZ and BAP, and analysis of variation revealed significant (P < …) differences between the media in both TDZ and BAP (fig. 4).
The effect of different concentrations of TDZ and BAP was tested and compared on in vitro regeneration from cotyledon explants (Fig. 2) of L. austriacum (Fig. 5). Some explants were placed on MSB medium without any PGRs used as control, in this explants no buds induced and after a while, became chlorosis. Subsequently, depending upon the type and concentration of cytokinin, the explants developed regenerants within … weeks of culture. BAP and TDZ tested at different concentration (0.0, 0.25, 0.5 and 1 mg l-1) induced shoot organogenesis (Fig. 2B). The maximum frequency of shoot formation was … shoot/explant on regeneration medium with 1 mg l-1 BAP (Fig. 6B) and … shoot/explant on that with 0.5 mg l-1 TDZ (Fig. 6A). Thus, the shoots were induced more efficiently at lower concentrations of TDZ than that of BAP. Lower concentration of TDZ was, therefore, concluded to be an effective cytokinin for L. austriacum shoot organogenesis from cotyledon explants.
Cotyledon segments from 3-week old seedling of L. austriacum cultured in MSB medium fortified with …… Callus was initiated after… days from cut ends of explants and covered the whole surface of explants within… weeks in MSB medium containing different concentration of TDZ and BAP (0.0, 0.1, 0.25, 0.5 and 1 mg l-1). Cotyledon derived callus then induced shoots visibly after …. day of culture in MS medium supplemented with BAP and TDZ. Multiple shoots observed in all concentration of BAP and TDZ used, but better regeneration response with maximum number of shoots (… shoots/explants) were produced at 0.5 mg l-1 BAP (Fig. 6B).
Figure 5. Effects of different concentrations of TDZ and BAP on direct regeneration from cotyledon explants of L. austriacum. The bars represent means ± SE. Bars followed by the same letter are not significantly different (P < ….) according to…
Shoot elongation from induced shoot buds
Shoots induced from all types of explants were individually separated and further tested for their elongation on MSB medium supplemented with different concentrations of BAP and TDZ. The length of elongated shoots was recorded after … weeks...