Can silver nanoparticles boost strawberry growth?

A research team discovered that silver nanoparticles, eco‑produced by the bacterium Lysinibacillus fusiformis, can boost in‑vitro strawberry cultivation. Scientists added various AgNP doses (0, 100, 200 and 300 mg L⁻¹) to a standard growth medium and monitored plant development. At low concentrations (100‑200 mg L⁻¹) the plants produced more shoots, leaves and longer roots than the control. When the dose rose to 300 mg L⁻¹, the benefits faded, but chlorophyll content (the green photosynthetic pigment) kept increasing. After the in‑vitro phase, AgNP‑treated shoots were transferred to pots: 90 % survived, versus 70 % of untreated ones. This shows that nanoparticles not only promote growth but also help plants cope with transplant stress. The findings suggest that, with optimal dosing, AgNPs could make strawberry production more efficient and sustainable, cutting pesticide use and improving final product quality.

The AgNPs were synthesized via a biological reduction process: the Lysinibacillus fusiformis strain secretes enzymes and metabolites capable of converting Ag⁺ ions into silver particles ranging from 10 to 30 nm. Characterization by UV‑Vis spectroscopy, TEM and zeta‑potential confirmed good colloidal stability and a surface coated with functional groups (proteins, polysaccharides) that modulate interaction with plant cells. In vitro, AgNPs penetrate cell walls through endocytosis or diffusion via plasma membrane pores, generating a mild oxidative stress response. At moderate concentrations, this stress activates signaling pathways (e.g., MAPK, ROS‑mediated) that stimulate antioxidant synthesis and cell proliferation, promoting meristem formation and root elongation. The observed increase in chlorophyll at higher doses may stem from a greater availability of Ag⁺ ions that, in small amounts, act as cofactors for enzymes involved in pigment biosynthesis. However, excessive concentrations cause toxic Ag⁺ accumulation, inhibiting photosynthesis and disrupting the plasma membrane. The ex vitro acclimatization benefits from plant pre‑conditioning: roots previously exposed to AgNPs exhibit improved nutrient uptake and synthetic mycorrhizal formation, raising post‑transplant survival. These findings pave the way for more sustainable micropropagation protocols, yet further research is needed on long‑term bioavailability and environmental impact of released nanoparticles.