Silicon Promotes Adventitious Shoot Regeneration and Enhances Salinity Tolerance ofAjuga multifloraBunge by Altering Activity of Antioxidant Enzyme

Abstract

We investigated the effect of Si concentration on shoot regeneration and salinity tolerance of Ajuga multiflora. Addition of Si to the shoot induction medium significantly increased the frequency of shoot induction. The average number of shoots regenerated per explant decreased on the medium containing NaCl alone, while there was less decrease when the shoot induction medium was supplemented with both NaCl and Si. The shoot induction percentage increased linearly with increasing concentration of Si in the NaCl containing medium. Addition of Si to the shoot induction medium significantly increased SOD, POD, APX, and CAT activity in regenerated shoot buds as compared with the control. The inclusion of Si to the NaCl containing medium significantly increased the SOD activity in leaves and roots, while it decreased POD, APX, and CAT activity in both organs. Scanning electron microscopic analysis showed that there are no distinct differences in the structure of stomata between the control and Si-treated plants. However, NaCl treatment significantly affected the structure and number of stomata as compared to the control. Wavelength dispersive X-ray analysis confirmed the high Si deposition in trichomes of plants grown in the Si containing medium but not in plants grown in the medium without Si.

Application of silicon sources in yam (Dioscorea spp.) micropropagation

“…Reports of satisfactory in vitro results for Si supplementation include studies of ornithogalum (Ziv et al, 2010), begonia (Lim et al, 2012), water reed (Mathé et al, 2012), rice (He et al, 2013), pear (Reed et al, 2013), orchids Soares et al, 2012;Colombo et al, 2016), banana plants (Asmar et al, 2013a, b), ajuga (Sivanesan and Jeong, 2014), and anthurium (Dias et al, 2014). However, no study has reported the effects of Si addition to yam micropropagation culture media.…”

Application of silicon in plant tissue culture

“…These results highlight the cryoprotective role of Si, which can be incorporated into cryoprotective mixtures. The ameliorating effect of Si on salt stress has been reported in in vitro culture of Ajuga multiflora (Sivanesan and Jeong 2014), Salvia splendens (Soundararajan et al 2013), and S. tuberosum (Qing et al 2005). There are reports that show Si-induced salinity tolerance as a result of reducing NaCl uptake by plants and the consequent preservation of stomatal ultrastructure, photosynthetic activity, antioxidant enzyme production, and modulation of free proline content (Qing et al 2005;Soundararajan et al 2013;Sivanesan and Jeong 2014).…”

“…The ameliorating effect of Si on salt stress has been reported in in vitro culture of Ajuga multiflora (Sivanesan and Jeong 2014), Salvia splendens (Soundararajan et al 2013), and S. tuberosum (Qing et al 2005). There are reports that show Si-induced salinity tolerance as a result of reducing NaCl uptake by plants and the consequent preservation of stomatal ultrastructure, photosynthetic activity, antioxidant enzyme production, and modulation of free proline content (Qing et al 2005;Soundararajan et al 2013;Sivanesan and Jeong 2014). The results of another study investigating the effects of Si on aluminum (Al) tolerance of Picea abies cells indicated that Si is able to reduce the free Al concentration in the cell wall and Si is able to reduce Al toxicity (Prabagar et al 2011).…”

“…The molecular and biochemical bases of Si action on organogenesis and somatic embryogenesis remain unknown. It has been reported that Si accumulation in plant leaves cultured on MS medium supplemented with Si would be more increased compared to the leaves of plants cultured on MS medium without Si inclusion (Sivanesan and Jeong 2014).…”

“…Silicon supplementation to the culture medium increases the shoot induction frequency and average number of shoots per explant (Sivanesan and Jeong 2014). It has been shown that Si can be effective for shoot regeneration in rice (Islam et al 2005) and reed (Máthé et al 2012).…”