Green Sterilization of Rosmarinus officinalis L. Stem Surfaces with Silver Nanoparticles Synthesized Using Rubia tinctorum L. Cell Culture Extracts

Rosmarinus officinalis L. is a phenolic-rich plant. Because of its phenolic content, browning is an obstacle while obtaining callus from its stem explants. In this study, silver nanoparticles were synthesized through a biological procedure and used in surface sterilization of R. officinalis stem explants. Extracts of Rubia tinctorum cell culture biomass were used in bioreduction of Ag+ to Ag degrees. 10 ml extract was added to 90 ml 1 mM AgNO(3 )solution. The color of the mixture started to turn pink 1 h after mixing, which reflected the formation of silver nanoparticles. After 24 h, the mixture was used for surface sterilization. Sterile explant percentages varied between 40 and 97 %. No browning was observed during surface sterilization and the culture period. Moreover, all of the sterile explants formed yellow callus tissues that turned green in the second week of their formation. Due to their non-toxic nature, silver nanoparticles showed no adverse effects on stem explants. The results showed that this method can be used in surface sterilization of plant explants, especially those which have a browning problem caused by their phenolic contents. Furthermore, because of the non-toxicity of silver nanoparticles, they may serve as an alternative method for surface sterilization for explants which are easily damaged by commonly used surface sterilizing agents