Response of Trigonella foenum-graecum L. on CuO Nanoparticles Exposure

Abstract

Nanoparticles have gained much importance in last two decades, especially metal nanoparticles due to their unique physical, optical, electrical, magnetic and chemical properties. Nanoparticles interact with the plants and effect seed germination and growth of plant. Trigonella foenum- graecum L. (fenugreek) is one of the important medicinal plants containing important phytochemicals. The aim of this study was to evaluate the response of T. foenum-graecum L. to copper oxide nanoparticles using plant tissue culture technique at different concentrations along with polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP) capped nanoparticles. The results showed that seed germination was not affected by CuONPs. However, growth of shoot and root was maximum in T. foenum- graecum L. seedlings at 50 mg/L of CuONPs, uncapped and capped and reduced with increase in concentration of NPs indicating toxicity. In a parallel experiment, Cu-acetate salt solution showed 100% seed germination but it restricted root and shoot elongation due to high salinity at 1%. Phytochemical screening of shoot and root extracts was also carried out showing maximum flavonoid and phenolic contents accumulation in Cu-acetate treated plantlets as compared to CuONP and control with maximum radical scavenging DPPH and antioxidant activity. PEG and PVP treated plantlets accumulated more flavonoid and phenolic contents as compared to CuONP-PEG and CuONP-PVP, indicating increased secondary metabolites production due to abiotic stress. But DPPH radical scavenging activity was higher in CuONPPEG, 50mg/L and CuONP-PVP, 100 mg/L as compared to PEG and PVP. Callus was induced from stem and leaf explants of T. foenum-graecum L. treated with CuONP, CuONP-PEG and CuONP-PVP. Maximum fresh and dry weight was found in control i.e. stem explant; 1.65g and 0.10g and leaf explant; 1.33g and 0.09g after 30 days as compared to explants treated with nanoparticles. Although growth was decreased in explants treated with CuONPs but results revealed maximum flavonoid and phenolic contents accumulation in explants treated with CuONP-PVP with maximum antioxidant activity. Overall results indicate that CuONPs treatment affect the seedling growth of T. foenumgraecum L. depending on concentration without inhibiting seed germination. These experiments also showed that in vitro culture of T. foenum-graecum L. can be exploited for enhanced production of secondary metabolites.