Avaliação das alterações fisiológicas em plantas de vicia faba induzidas por nanopartículas de prata

Abstract

Nanotechnology is an emergent field in science and engineering, showing significant impacts on the economy, society and environment. The production, use and discard of nanomaterials (NMs) are leading to their inevitable release into the atmosphere, water and soil, it being innumerable the uncertainties about their fate, behavior and toxicity. As the plants are the basis of several food chains, and knowing that NMs have the ability to penetrate, translocate and accumulate in plants, a study about the effects of NMs on plants is necessary. In this context, the chlorophyll fluorescence imaging technique associated with others techniques such as gas exchange, thermal imaging and reactive oxygen species (ROS) analysis, may be a viable alternative to study the interactions between NMs and plants. The present study aimed to evaluate and characterize the alterations in physiological functioning of broad bean plants induced by the presence of silver nanoparticles (AgNPs), as well as silver at bulk scale (micrometric dimensions). The results demonstrated that the AgNPs induced a decrease in the operating capacity of photosystem II and an increase in the amount of energy dissipation by non-photochemical quenching process as a function of the AgNPs content into the leaves. The gas exchanges and thermal imaging analysis were altered when plants were submitted to AgNPs inoculation. In addition, the AgNPs induced an overproduction of ROS in the broad bean leaves. In general, the results suggest that the electrons of the chlorophyll in the excited state can be transferred to the metal surface of the AgNPs, inhibiting the electron transport chain, which implies the reduction of the photosynthetic yield associated with oxidative stress, through a marked increase in ROS production. In summary, the obtained results indicate that the production of chemical energy and, consequently, the plant productivity can be impacted by the AgNPs.