Population-specific responses of Lemna minor to silver nanoparticle exposure: Implications for standardizing toxicity...

The globally distributed and excellent growth properties of Lemna minor make it an ideal model species in ecotoxicology. However, the variability among different L. minor populations is often overlooked in laboratory toxicity assessments, which could lead to inaccurate toxicity evaluations, especially for newly emerging pollutants. In this study, we investigated the responses of L. minor populations from various regions (Wuhan (WH), South Korea (KR), Yunnan (YN), and Tibet (TB)) to silver nanoparticles (AgNPs), a newly emerging pollutant, at concentrations ranging from 0 to 10 mg L^-1 over a 72-hour exposure period. The results showed a significant increase in silver accumulation in L. minor tissues with increasing AgNPs concentration. Concurrently, photosynthetic pigments content (chlorophyll a, b, and carotenoids) and chlorophyll fluorescence parameters exhibited a dose-dependent decline, while malondialdehyde levels increased, indicating that AgNPs induced oxidative stress in different L. minor populations. Notably, the populations displayed significant differences in tolerance to AgNPs: the KR population showed the highest tolerance, followed by TB, while the YN and WH populations were more sensitive. Further analysis revealed that the differences in toxicity response among L. minor populations were mainly attributed to variations in Ag accumulation capacity. Therefore, it is recommended that, when using L. minor from different regions to assess AgNPs toxicity, parameters could be standardized based on the silver accumulated by the plants rather than the externally applied silver. This approach will improve the comparability of results across laboratories and provide a more accurate understanding of AgNPs toxicity in global aquatic ecosystems.