Biologically synthesized silver nanoparticles eclipse fungal and bacterial contamination in micropropagation of Capparis decidua (FORSK.) Edgew: A substitute to toxic substances

Abstract

Microbial contamination is a serious challenge in plant tissue culture, particularly in micropropagation of threatened and rare medicinally important plantsfor conservation purpose. Use of antibiotics exhibit harmful effects on plants, and continuous use makes bacteria more resistant. Also, chemicals used to control such contaminations are either toxic to the explant or have limited efficiency. Though nanobiotechnology offers an effective alternate to deal with the bacterial and fungal contamination, chemical synthesis of metal nanoparticles has limitations and found to be toxic, flammable and hard to get disposed. green synthesis of silver nanoparticles (AgNPs) employing plant extracts, being environment friendly, cost-effective, and single step, is gaining attention as better alternative method. In this study, the green synthesised silver nanoparticles were confirmed by UV-Vis spectroscopy (462.73 nm, 0.473 Abs) and Transmission Electron microscopy (TEM). The fruit extract of Capparis decidua served as an environmentally benign reducing agent and the phytochemicals of the extract as non-toxic agent to stabilize the AgNP (FTIR) upholding its significance as an eco-friendly approach compared to hazardous chemicals. The nano size (1.5-15 nm) makes the green synthesized AgNPs a better antimicrobial agent allowing easy diffusion into the cells. evaluation of decontamination as well as the survival rate of the explants was monitored using the explants (shoot tip and nodal segment) immersion in three different concentrations of AgNP solution (100, 300, and 500 mg/L) and controlled by 0.1% mercuric chloride treatment demonstrating promising decrease in decontamination. However, the survival was expedient excluding immersion in 100 mg/L for 20 or 30 min. The MS media supplementation by AgNP solution (50, 100, 300 and 500 mg/L), controlled by 70% ethanol treatment divulged the superior decontamination rate at 150 mg/L of AgNPs (90.2% for bacteria and 94.4% for fungal contamination) with 80.5% survival. The increased concentration gave 100% bacterial and 98.6% fungal decontamination but a reduced survival percent (68.5%). This work potentially showed that nanosizedAgNPs could serve as an appropriate antimicrobial substitute to chemicals being innocuous to the explant regeneration.