Cobalt oxide nanoparticles aggravate DNA damage and cell death in eggplant via mitochondrial swelling and NO signaling pathway

BACKGROUND: Despite manifold benefits of nanoparticles (NPs), less information on the risks of NPs to human health and environment has been studied. Cobalt oxide nanoparticles (Co3O4-NPs) have been reported to cause toxicity in several organisms. In this study, we have investigated the role of Co3O4-NPs in inducing phytotoxicity, cellular DNA damage and apoptosis in eggplant (Solanum melongena L. cv. Violetta lunga 2). To the best of our knowledge, this is the first report on Co3O4-NPs showing phytotoxicity in eggplant. RESULTS: The data revealed that eggplant seeds treated with Co3O4-NPs for 2 h at a concentration of 1.0 mg/ml retarded root length by 81.5 % upon 7 days incubation in a moist chamber. Ultrastructural analysis by transmission electron microscopy (TEM) demonstrated the uptake and translocation of Co3O4-NPs into the cytoplasm. Intracellular presence of Co3O4-NPs triggered subcellular changes such as degeneration of mitochondrial cristae, abundance of peroxisomes and excessive vacuolization. Flow cytometric analysis of Co3O4-NPs (1.0 mg/ml) treated root protoplasts revealed 157, 282 and 178 % increase in reactive oxygen species (ROS), membrane potential (APm) and nitric oxide (NO), respectively. Besides, the esterase activity in treated protoplasts was also found compromised. About 2.4-fold greater level of DNA damage, as compared to untreated control was observed in Comet assay, and 73.2 % of Co3O4-NPs treated cells appeared apoptotic in flow cytometry based cell cycle analysis. CONCLUSION: This study demonstrate the phytotoxic potential of Co3O4-NPs in terms of reduction in seed germination, root growth, greater level of DNA and mitochondrial damage, oxidative stress and cell death in eggplant. The data generated from this study will provide a strong background to draw attention on Co3O4-NPs environmental hazards to vegetable crops.

Toxicity of cadmium on the growth and yield of Solanum melongena L.

Heavy metal cadmium is biomagnified through food chain and causes Itai-Itai disease in human. The present investigation reports the results of the effect of cadmium on seed germination, germination relative index (G.R.I.), seedling growth, chlorophyll stability index (CSI) and yield of Solanum melongena L. cv Pusa uttam. Effect of different concentrations of heavy metal cadmium (CdCl2) in Hoagland's nutrient solution (10(-2) M, 10(-4) M, 10(-5) M and 10(-8) M) were employed for all seedling and physiological parameters of brinjal. Cadmium showed toxic effects at high concentrations 10(-2) M but promotory at lower concentration (10(-8) M) with regard to growth and yield.

Differential effect of cadmium and mercury on growth and metabolism of Solanum melongena L. seedlings.

The present investigation reports the results of the effect of cadmium and mercury individually on seed germination, seedling growth, number of lateral roots, fresh and dry weights and seedling metabolism in Solanum melongena. Effect of different concentrations of these two heavy metals (Cadmium--50, 100, 300, 500, 700, 1000, 3000, 5000, 7000 and 9000 ppm and Mercury--5, 10, 15, 20, 25, 30, 35, 40, 45 and 50 ppm) and durations for 6, 12 and 24 h were employed for all seedling parameters of brinjal. Both Cd and Hg showed drastic effects at high concentrations and longer duration with regard to seedling growth and metabolism.