title: Study on the correlation between copper oxide nanoparticles induced growth suppression and enhanced lignification in Indian mustard (Brassica juncea L.).
abstract: In this study, the morphological, physiological and molecular level effects of copper oxide nanoparticles (CuONPs) were studied in an economically important oil seed crop Brassica juncea L. The possible involvement of lignification on shoot-root growth retardation was also studied. The seedlings were exposed to 0, 20, 50, 100, 200, 400 and 500mg/L of CuONPs in semi-solid half strength Murashige and Skoog medium under controlled growth chamber conditions for 14 days. Exposure to CuONPs resulted in suppression of shoot-growth, reduction in total chlorophyll and carotenoids contents as well modification of root system architecture such as shortening of primary and lateral roots. Significant increases in hydrogen peroxide formation, peroxidase enzyme activity and lignification of shoots and roots were observed. The lipid peroxidation levels increased significantly in shoots and roots of B. juncea seedlings. Phloroglucinol-HCl staining revealed enhanced lignification of shoot and roots. Gene expression studies revealed significant activation of CuZn superoxide dismutase (CuZnSOD) in roots at all concentrations of CuONPs exposure. In shoots significant up-regulation of CuZnSOD gene was observed upon exposure to 100, 200 and 400 mg/L of CuONPs exposure. However no change in the expression levels of MnSOD gene was observed in both stem and roots. The expression of catalase (CAT) and ascorbate peroxidase (APX) genes were also not changed in shoots. However, significant inhibition of CAT and APX genes were observed in roots of B. juncea plants under exposure to 100, 200, 400 and 500 mg/L of CuONPs exposure. The SOD enzyme activity significantly increased in roots under exposure to 50-500 mg/L of CuONPs and in shoots as a result of exposure to 100-500 mg/L of CuONPs. The APX activity significantly decreased in roots upon exposure to 50-500 mg/L of CuONPs. In shoots, the APX activity significantly decreased upon exposure to 200-500 mg/L of CuONPs.
authors.affiliation: Department of Applied Biosciences, College of Life and Environmental Sciences, Konkuk University, Seoul, South Korea.
authors.forename: Prakash M Gopalakrishnan
authors.initials: PM
authors.lastname: Nair
authors.affiliation: Department of Applied Biosciences, College of Life and Environmental Sciences, Konkuk University, Seoul, South Korea. Electronic address: imcim@konkuk.ac.kr.
authors.forename: Ill Min
authors.initials: IM
authors.lastname: Chung
mesh_terms: D060387:Ascorbate Peroxidases / Q000378:metabolism; D018533:Biomass; D002374:Catalase / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D003300:Copper / Q000633:toxicity*; D006861:Hydrogen Peroxide / Q000378:metabolism; D008031:Lignin / Q000378:metabolism*; D015227:Lipid Peroxidation / Q000187:drug effects; D013058:Mass Spectrometry; D009149:Mustard Plant / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development; D053758:Nanoparticles / Q000633:toxicity*; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects*; D010087:Oxides; D009195:Peroxidase / Q000378:metabolism; D010544:Peroxidases / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects; D060888:Real-Time Polymerase Chain Reaction; D036226:Seedlings / Q000187:drug effects / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D015854:Up-Regulation; D000099156:Superoxide Dismutase 2
chemical_list: D060387:Ascorbate Peroxidases; D002374:Catalase; D002734:Chlorophyll; D003300:Copper; D006861:Hydrogen Peroxide; D008031:Lignin; D010087:Oxides; D009195:Peroxidase; D010544:Peroxidases; D013482:Superoxide Dismutase; D000099156:Superoxide Dismutase 2; C030973:cupric oxide
keywords: Brassica juncea; Copper oxide nanoparticles; Lignification; Peroxidase; Reactive oxygen species; Root morphology