Potential application of biogenically synthesized silver nanoparticles as an anticontaminant agent in citrus micropropagation systems

Abstract Background Silver nanoparticles (AgNPs) have gained attention as antimicrobial agents in plant tissue culture to reduce microbial contamination. The present study aimed to investigate the plant-protective potential of green-synthesized AgNPs at optimized concentrations in citrus micropropagation media. AgNPs were synthesized using juice of Citrus sinensis through an environmentally friendly and cost-effective approach. Results The optimized synthesis ratio for AgNPs was 1:4 (orange juice: 1% AgNO₃). UV–Vis spectroscopy showed a characteristic peak at 450 nm. Zetasizer analysis revealed a particle size of 100.2 ± 0.12 nm with a zeta potential of − 23.8 mV, indicating stability. Energy-dispersive X-ray (EDX) analysis confirmed the presence of silver (33.06%), while scanning electron microscopy (SEM) showed predominantly spherical nanoparticles with an average size of 37.41 nm. The antimicrobial efficacy of AgNPs was evaluated in the micropropagation media of three citrus species ( Citrus sinensis , Citrus reticulata , and Citrus micrantha ) at concentrations of 2, 3, and 5 ppm. Among the treatments, 3 ppm AgNPs effectively reduced microbial contamination and significantly enhanced plant growth parameters, including shoot length, root length, number of leaves, and chlorophyll content ( P < 0.05). Gene expression analysis of the PP2A housekeeping gene showed no significant variation between treated and control plants under the tested conditions. Conclusion The findings suggest that green-synthesized AgNPs, particularly at an optimized concentration of 3 ppm, have potential as antimicrobial agents in citrus micropropagation systems under controlled in vitro conditions. However, these results are based on short-term experiments involving limited plant species, and further studies are required to evaluate long-term effects and broader applicability before generalizing their use.