Nanopartículas de prata no cultivo in vitro de Fisalis e Casaqueira

Abstract

With the increasing use of nanomaterials, mainly silver nanoparticles (AgNPs) due to their antimicrobial properties, understanding the effects of these nanoparticles on edible plants arises as a matter of extreme importance, since, silver nanoparticles are present in a series of products that are inevitably released into the environment without any restrictions. Understanding its effects on plant cells as well as elucidating questions regarding phytotoxicity may also cast doubt on its benefits in plant growth and development. In this context, the present study aimed to evaluate the effects of silver nanoparticles on in vitrocultivation of two fruit species: Physalis peruviana and Campomanesia rufa. For the P. peruviana experiment, seeds of this species were cultivated in MS medium (Murashige and Skoog) supplemented with different concentrations of AgNPs (0.0, 0.385, 0.77, 1.54 and 15.4 mg L-1). The AgNPs solution was synthesized and characterized in terms of the size of the nanoparticles, Zeta Potential and Polydispersivity. Growth and development of the seedlings were evaluated through growth, biochemical and anatomical analyzes. For the experiment with C. rufa, nodal segments of the seedlings established in vitro were cultured in MS medium, supplemented by BAP (5.62 μM), different concentrations of silver nanoparticles (0.0, 0.385, 0.77, 1.54 and 15.4 mg L-1) or silver nitrate (0.18 g L-1). The culture medium with the respective concentrations of AgNPs was characterized in relation to the size of the nanoparticles, Potential Zeta and Polydispersivity. Growth, biochemical, light microscopy and scanning microscopy of the plants were performed. The results of the experiment with P. peruviana demonstrated that at the end of 60 days of cultivation, the in vitro germination of this species was not affected by the presence of AgNPs and that at the concentration of 0,385 mg L-1the AgNPs promoted an increase in the biomass of seedlings. However, at higher concentrations (15.4 mg L-1) causes a reduction in the size of the seedlings and the root system. No alterations were observed in the antioxidant metabolism, however alterations in the vascular system were observed in the treatments with AgNPs in relation to the control. In the experiment with C. rufa, it was observed that AgNPs at concentrations of 0.385, 0.77 and 1.54 mg L-1did not affect the multiplication in vitro, in terms of number, height and fresh weight of the shoots, however, in the treatments with 15.4 mg L-1 of AgNPs and silver nitrate, there is a reduction in the number of shoots. No biochemical and anatomical changes were observed in the shoots. The characterization of the culture medium with AgNPs has demonstrated that the sterilization process of the culture medium promotes agglomeration of the AgNPs, which consequently leads to an increase in its size and, therefore, to a lower toxicity. From the above, it is concluded that the effects of AgNPs are concentration dependent and that factors such as temperature can promote an increase of the nanoparticles and therefore alter their intrinsic properties, resulting in less pronounced effects when compared with silver nanoparticles of sizes (1 to 100 nm)