Infuence of chemically synthesized copper nanoparticles and cupric ions on oxalate oxidation system in germinating Sorghum grain

Abstract

We have earlier reported the effects of chemically synthesized copper nanoparticles (CuNPs) on oxalate oxidase (OxOx) activity, extracted from the shoot tissue of germinating grain sorghum i.e. <em>in vitro. </em>Here, we tried to study this effect <em>in vivo </em>and compare it with those of Cu²⁺<em>.</em> We describe herein, characterization of CuNPs and their effects on oxalate oxidation system i.e. OxOx activity, total oxalate and H₂O₂ content <em>in vivo</em> i.e. in shoot tissues/leaves of germinating grain Sorghum (<em>Sorghum </em><em>vulgare</em> L). To achieve it, grain sorghum seeds were grown up to 10 days in laboratory, irrigated with Hoagland’s solution containing either CuNPs (1.0 ppm) or Cu²⁺ (1.0 ppm) after 4 days of germination. Control were irrigated with Hoagland solution only. The shoot/leaves of the seedling plants were harvested at 4, 6, 8 and 10 day of germination and analysed quantitatively for OxOx activity, soluble protein, H₂O₂ and total oxalate. The growth of the Sorghum seedling plants supplemented with CuNPs and Cu²⁺was decreased significantly (<em>P</em> <0.1) at all growth stages compared to control. This inhibitory effect of CuNPs was higher than Cu²⁺. CuNPs decreased the activity of OxOx but Cu²⁺ had no effect at day 10. Both CuNPs and Cu²⁺ decreased the specific activity of OxOx and H₂O₂ content but increased total oxalate content at day 10. The decrease in H₂O₂ content in both CuNPs and Cu²⁺ supplemented shoot tissues with concomitant increase in oxalate content confirmed the decreased activity of OxOx in CuNPs and Cu²⁺ supplemented seedling plants.