Administration - Research Publications
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Item Eugenol-inhibited root growth in Avena fatuainvolves ROS-mediated oxidative damage(Elsevier, 2015) Ahuja, Nitin; Singh, Harminder Pal; Batish, Daizy. R.; Kohli, R.K.,Plant essential oils and their constituent monoterpenes are widely known plant growth retardants but their mechanism of action is not well understood. We explored the mechanism of phytotoxicity of eugenol, a monoterpenoid alcohol, proposed as a natural herbicide. Eugenol (100–1000 µM) retarded the germination of Avena fatua and strongly inhibited its root growth compared to the coleoptile growth. We further investigated the underlying physiological and biochemical alterations leading to the root growth inhibition. Eugenol induced the generation of reactive oxygen species (ROS) leading to oxidative stress and membrane damage in the root tissue. ROS generation measured in terms of hydrogen peroxide, superoxide anion and hydroxyl radical content increased significantly in the range of 24 to 144, 21 to 91, 46 to 173% over the control at 100 to 1000 µM eugenol, respectively. The disruption in membrane integrity was indicated by 25 to 125% increase in malondialdehyde (lipid peroxidation byproduct), and decreased conjugated diene content (~10 to 41%). The electrolyte leakage suggesting membrane damage increased both under light as well as dark conditions measured over a period from 0 to 30 h. In defense to the oxidative damage due to eugenol, a significant upregulation in the ROS-scavenging antioxidant enzyme machinery was observed. The activities of superoxide dismutases, catalases, ascorbate peroxidases, guaiacol peroxidases and glutathione reductases were elevated by ~1.5 to 2.8, 2 to 4.3, 1.9 to 5.0, 1.4 to 3.9, 2.5 to 5.5 times, respectively, in response to 100 to 1000 µM eugenol. The study concludes that eugenol inhibits early root growth through ROS-mediated oxidative damage, despite an activation of the antioxidant enzyme machinery.Item Phytotoxicity and cytotoxicity of Citrus aurantiifolia essential oil and its major constituents: Limonene and citral(Elsevier B.V., 2017) Fagodia, S.K.; Singh, H.P.; Batish, Daizy R.; Kohli, R.K.The essential oils are fast emerging as the source of natural herbicides owing to their environmentally benign properties. The focus of the present study, thus, was to investigate the phytotoxicity and cytotoxicity of Citrus aurantiifolia oil, and its major constituents-citral and limonene. C. aurantiifolia oil was selected due to its extreme commercialisation and safe nature. GC?MS analysis revealed that C. aurantiifolia oil is rich in monoterpenes (83.93%), with limonene (40.92%) and citral (27.46%) as the major compounds. Phytotoxicity was assessed against three agricultural weeds, Avena fatua, Echinochloa crus-galli and Phalaris minor, at concentration ranging from 0.10?1.50?mg/ml. Percent germination, IC50 value and seedling growth (root and coleoptile length) were significantly reduced in a dose-response manner. C. aurantiifolia oil, citral and limonene caused alteration in the cell cycle of Allium cepa root meristematic cells as evidenced by decrease in mitotic index (MI) and increase in chromosomal aberrations at progressive concentrations (0.01?0.10?mg/ml) and time periods (3?h and 24?h). Cytotoxic evaluation confirmed mitodepressive effect of the tested volatiles though the intensity was variable. Overall, citral was the most toxic followed by C. aurantiifolia oil and limonene. The significant phytotoxic activity of C. aurantiifolia oil and citral suggests the possibility of being developed into eco-friendly and acceptable products for weed management in agriculture system. ? 2017 Elsevier B.V.