Biochemical Response of Oakleaf Lettuce Seedlings to Different Concentrations of Some Metal(oid) Oxide Nanoparticles

Rita Jurkow,Agnieszka Sękara,Robert Pokluda,Andrzej Kalisz,Sylwester Smoleń

doi:10.3390/agronomy10070997

Rita Jurkow, Agnieszka Sękara + Show 3 more

Open Access

https://doi.org/10.3390/agronomy10070997

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Abstract

Nanoparticles (NPs) significantly modify the physiological functions and metabolome of plants. The purpose of the study was to investigate the effect of CeO2, Fe2O3, SnO2, TiO2, and SiO2 nanoparticles, applied in foliar spraying of oakleaf lettuce at concentrations 0.75% to 6%, on the antioxidant enzyme activity and content of non-enzymatic antioxidants, chlorophyll pigments, fresh weight (FW) and dry weight (DW). It was found that 3% Fe2O3-NPs caused a 27% decrease in fresh weight compared to control plants. Fe2O3-NPs caused an increase in dry weight (g 100 g−1 FW) when compared to the control for all concentrations, but total DW (g per plant) was similar for all NPs treatments. Significant increases in chlorophyll a + b content after treatment with 1.5% and 6% SiO2-NPs, 3% Fe2O3-NPs, and 3% TiO2-NPs were noted. Fe2O3-NPs caused a significant increase in the activity of ascorbate peroxidase, guaiacol peroxidase, and catalase (only for 3% Fe2O3-NPs). SnO2-NPs decreased ascorbate peroxidase (APX) and guaiacol peroxidase (GPOX) activity (for all tested concentrations) but increased catalase (CAT) activity when a 3% suspension of these NPs was applied. The level of glutathione (GSH) increased due to application of all metal/metalloid oxides, with the exception of SnO2-NPs. When all concentrations of TiO2-NPs were applied, L-ascorbic acid increased significantly, as well as increasing at higher concentrations of SiO2-NPs (3% and 6%) and at 0.75% and 3% Fe2O3-NPs. SiO2-NPs and TiO2-NPs significantly elevated the carotenoid and total phenolic content in treated plants compared to the control. The total antioxidant capacity of plants treated with 3% CeO2-NPs was almost twice as high as that of the control.

Highlights

Nanoparticles (NPs) are atomic or molecular aggregates with at least one dimension in the range from 1 to 100 nm [1]
Treatment of oakleaf lettuce seedlings with metalloid oxide nanoparticles (MO-NPs) at different concentrations usually did not have a significant effect on the fresh weight (FW) of the plants in comparison to the control (Table 1)
The results presented proved that a higher concentration of CeO2 -NPs applied to oakleaf lettuce caused an increase in total phenolic (TP) content, which is in agreement with the results of Ma et al [47]

Summary

Introduction

Nanoparticles (NPs) are atomic or molecular aggregates with at least one dimension in the range from 1 to 100 nm [1]. The reactiveness of metal-based NPs in plants is determined by their metal compound, size, high surface-to-volume ratio, shape, and, most importantly, the dose at which they are Agronomy 2020, 10, 997; doi:10.3390/agronomy10070997 www.mdpi.com/journal/agronomy. NPs might directly provoke either alterations of membranes and other cell structures and molecules, or activity of protective mechanisms [5]. The indirect effects of NPs are caused inter alia by the release of toxic ions (e.g., metal ions), enhancement of the bioavailability of some toxic compounds, or by causing overproduction of reactive oxygen species (ROS) [1,2,6]

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