Effect of polysaccharide coated CeO2 nanoparticles on total phenolic content of two crop species

Abstract

Cerium oxide nanoparticles (nCeO2) have been widely investigated because of their unique property - transition between Ce3+ and Ce4+ oxidation states which allows them multiple applications, such as a catalyst, an electrolyte material in fuel cells, for drug delivery, in agriculture (fertilizer, pesticides) etc. Despite these facts, the main restriction of nCeO2 application is their tendency for agglomeration, which led many researchers to coat them with different polymers. But literature data about the impact of coated nanoparticles on plant metabolism are scarce. Also, enhanced nCeO2 application has become the risk for the environment due to their accumulation in soil, air and water. Metal toxicity may lead to overproduction of reactive oxygen species (ROS) causing the abiotic stress and damage of important biological molecules in crop species. In current research, we performed a three week treatment of wheat and pea seedlings in hydroponics with 200 mgL-1 uncoated and glucose-, levan- and pullulan coated nCeO2 (G-CeO2, L-CeO2 and P-CeO2). Our goal was to study the impact of nanoparticles coating on Ce uptake, and on changes in total phenolic content (TPC), as indicator of oxidative stress, in monocotyledonous and dicotyledonous crop species. ICP-OES was used for determination of Ce concentration in shoots of treated crop species. The uptake of Ce was different among treated crop species. Ce uptake was increased after coating in pea, but decreased in wheat. High Ce content detected in wheat, caused the increase in shoot elongation without the effect on TPC. On the other hand, low Ce content measured in pea, had no influence on shoot elongation as well as TPC. Presented results suggest the difference in nCeO2 uptake and their effect on morphological parameters of plant without the impact on phenolic metabolism. Despite these results, further research is necessary.