Abstract
Morphometrical indexes, and spectrophotometrically measured protein and glutathione (GSH, GSSG) contents and activity of peroxidase (POD, EC 1.11.1.7), glutathione-reductase (GR, EC 1.6.4.2) and glutathione S-transferase (GST, EС 2.5.1.18) were examined in Hordeum vulgare L. seedlings after 0.01 and 0.1 mg/l AgNPs treatment during 24 h. We tested the hypothesis that the action of nanoparticles has a stressful effect on the physiological and biochemical processes of seedlings. Growth of roots was inhibited and fresh weight decreased by 29% and 21% under low and high concentrations respectively. Conversely, leaf growth was intensified, and leaf length (16% and 18%) and fresh weight (35% and 44%) increased at low and high concentrations respectively. POD activity in roots increased by 26% and 7%, and decreased in leaves to 57% and 81% of control at low and high concentrations respectively. GSH content changed insignificantly, but GSSG content increased in roots (2 and 2.5-fold) and in leaves (13% and 30%) at both AgNPs concentrations. GSH/GSSG-ratio decreased in roots (1.9 and 2.6-fold) and in leaves (1.1 and 1.3-fold) at low and high concentrations respectively. GR activity decreased at a concentration of 0.01 mg/l (7% in roots and 17% in leaves respectively) and increased at 0.1 mg/l (52% in roots and 6% in leaves). GST activity increased in leaves (52% and 78% at low and high concentrations) but decreased by 17% in roots under high concentration of nanosilver. Thus, the action of AgNPs on barley seedlings had a dose-dependent and organ-specific character. The various directions of changes in growth, metabolic processes and activity of antioxidant defense systems appear to be a stress response of barley seedlings to the impact of AgNPs, which underlines the necessity of detailed study of plant intracellular processes exposed to the action of nanomaterial.
Highlights
Modern nanotechnologies are used intensively in agronomy in order to provide rational selection of disease control molecules, as Rezvany et al (2012) reported, or control slow-release pesticides and develop diagnostic tools, according to Ashrafi et al (2013)
Disulfide (GSSG) content was calculated as the difference between total and reduced glutathione amounts (GSSG molecular mass was taken into account) and expressed in mcg/g FW
We have previously shown the glutathione S-transferase activation in roots of pea and maize seedlings exposed to the action of nickel ions at different concentrations (Khromykh et al, 2012), and enzyme activation in Acer platanoides leaves under pollutants action (Khromykh et al, 2014)
Summary
Modern nanotechnologies are used intensively in agronomy in order to provide rational selection of disease control molecules, as Rezvany et al (2012) reported, or control slow-release pesticides and develop diagnostic tools, according to Ashrafi et al (2013). Analysis of research reports reveals variations in the effect of the action of silver nanoparticles on the growth, development and metabolic processes of different plant species. In this context Lee et al (2012) emphasized that the phytotoxic effect of nano-silver on Phaseolus radiatus and Sorghum bicolor seedlings caused concentration-dependent delay of growth. Similar results were obtained by Ashrafi et al (2013) in an experiment on soybeans (Glycine max L.) where increase in mass of 100 seeds, crop quantity and crop capacity was observed after treatment by nano-silver
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