Nanoparticle Impacts microRNA Expression in Plant

Titanium Dioxide (TiO₂) is one of the most widely used pigments in the world. Due to its heavy use in industry and daily life, such as food additives, cosmetics, pharmaceuticals, and paints, many residues are released into the environment and currently TiO₂ nanoparticles are considered an emerging environmental contaminant. Although several studies have shown the effect of TiO₂ nanoparticles on a wide range of organisms including bacteria, algae, plankton, fish, mice, and rats, little research has been performed on land plants. In this study, we investigated the effect of TiO₂ nanoparticles on the growth, development, and gene expression of tobacco, an important economic and agricultural crop. We found that TiO₂ nanoparticles significantly inhibited the germination rates, root lengths, and biomasses of tobacco seedlings after 3 weeks of exposure to 0.1%, 1%, 2.5%, and 5% TiO₂ nanoparticles and that overall growth and development of the tobacco seedlings significantly decreased as TiO₂ nanoparticle concentrations increased. Roots were more sensitive to nanoparticle exposure. Nano-TiO₂ also significantly influenced the expression profiles of microRNAs (miRNAs). Low concentrations (0.1% and 1%) of TiO₂ nanoparticles dramatically induced miRNA expression in tobacco seedlings with miR395 and miR399 exhibiting the greatest fold changes of 285 fold and 143 fold, respectively. The results of this study show that TiO₂ nanoparticles have a negative impact on tobacco growth and development and that miRNAs may play an important role in tobacco resistance to heavy metals/nanoparticles by regulating gene expression.