Effect of Silicon Ions on In Vitro Morphogenesis in Rauvolfia tetraphylla Using Shoot Tip Explants

Abstract

The study evaluates the effect of Silicon ions on in vitro morphogenesis in Rauvolfia tetraphylla using aseptic shoot tip explants. The explants were cultured on MS medium supplemented with varied concentrations of BA either singly or in combination with NAA. Of the tested concentrations, best response (80%) in explants for in vitro shoot production was recorded on MS medium fortified by BA (5.0 μM) and NAA (0.5 μM) with mean shoot number (9.66 ± 0.57) and shoot length (3.76 ± 0.16 cm) after 8 weeks of incubation. However, on evaluation of the morphogenic effect of different concentrations of silicon ions with optimized levels of BA and NAA, an increase in the percentage response and regeneration frequencies were observed. Of the tested combinations, MS culture medium supplemented with (5.0 μM BA + 0.5 μM NAA + 5.0 mM Na₂SiO₃) yielded 100% morphogenic response with mean shoot number (15.33 ± 0.66) and average length (5.73 ± 0.26) after 8 weeks of culture. In vitro rhizogenesis in 93% microshoots with maximum mean number (9.66 ± 0.66) of roots with mean root length (3.56 ± 0.23) per shootlet was recorded on ½ WPM medium supplemented with 0.5 μM IBA, after 4 weeks of incubation. The plantlets regenerated via this protocol were successfully acclimatized and hardened off under controlled conditions of growth chamber before their plantation to field conditions. The plantlets grew well under open sun and 90% survival rate was recorded after 12 weeks of transfer. The protocol developed can be used for propagation and conservation of rare and endangered plant assets.