Browsing by Author "Rishi, Valbha"

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    Biochemical Adaptations in Zea mays Roots to Short-Term Pb2+ Exposure: ROS Generation and Metabolism
    (Springer, 2015) Kaur, Gurpreet; Kaur, Shubhpreet; Singh,Harminder Pal; Batish, Daizy Rani; Kohli, R.K.; Rishi, Valbha
    The present study investigated the effect of lead (0, 16, 40 and 80 mg L?1 Pb2+) exposure for 3, 12 and 24 h on root biochemistry in hydroponically grown Zea mays (maize). Pb2+ exposure (80 mg L?1) enhanced malondialdehyde content (239 %�427 %), reactive carbonyl groups (425 %�512 %) and H2O2 (129 %�294 %) accumulation during 3�24 h of treatment, thereby indicating cellular peroxidation and oxidative damage. The quantitative estimations were in accordance with in situ detection of ROS generation (using 2?,7?-dichlorodihydrofluorescein diacetate dye) and H2O2 accumulation. Pb2+ treatment significantly reduced ascorbate and glutathione content during 3�24 h of exposure. On the contrary, levels of non-protein thiols were enhanced by 3�11.8 time over control in response to 16�80 mg L?1 Pb2+ treatment, after 24 h. A dose-dependent induction in ascorbate peroxidase and lipoxygenase enzyme activity was observed in Z. mays roots. The activities of ascorbate-recycling enzymes (dehydroascorbate reductase and monodehydroascorbate reductase) were significantly increased in relation to concentration and duration of Pb2+ treatment. The study concludes that Pb2+-exposure induces ROS-mediated oxidative damage during early period of exposure despite the upregulation of enzymes of ascorbate�glutathione cycle.
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    Exogenous nitric oxide (NO) interferes with lead (pb)-induced toxicity by detoxifying reactive oxygen species in hydroponically grown wheat (Triticum aestivum) roots,
    (PLOS ONE, 2015) Kaur, Gurpreet; Singh, Harminder Pal; Batish, Daizy R.; Kohli, R.K.; Rishi, Valbha
    Nitric Oxide (NO) is a bioactive signaling molecule that mediates a variety of biotic and abiotic stresses. The present study investigated the role of NO (as SNP [sodium nitroprusside]) in ameliorating lead (Pb)-toxicity in Triticum aestivum (wheat) roots. Pb (50 and 250 ?M) alone and in combination with SNP (100 ?M) was given to hydroponically grown wheat roots for a period of 0�8 h. NO supplementation reduced the accumulation of oxidative stress markers (malondialdehyde, conjugated dienes, hydroxyl ions and superoxide anion) and decreased the antioxidant enzyme activity in wheat roots particularly up to 6 h, thereby suggesting its role as an antioxidant. NO ameliorated Pb-induced membrane damage in wheat roots as evidenced by decreased ion-leakage and in situ histochemical localization. Pb-exposure significantly decreased in vivo NO level. The study concludes that exogenous NO partially ameliorates Pb-toxicity, but could not restore the plant growth on prolonged Pb-exposure.