Uptake and Translocation of Tri- and Hexa-Valent Chromium and Their Effects on Black Gram (Vigna mungo L. Hepper cv. Co4) Roots |
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Authors: | Thirupathi Karuppanapandian Kumariah Manoharan |
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Institution: | (1) Department of Plant Sciences, Centre of Potential in Genomic Sciences, School of Biological Sciences, Madurai Kamaraj University, 625 021 Madurai, India |
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Abstract: | An equal concentration (100 μM) of Cr(III)- and Cr(VI)-induced changes in activities of antioxidative enzymes and metabolites
of ascorbate-glutathione cycle was studied in 7-d-old black gram (Vigna mungo L Hepper cv. Co4) seedlings for 5-d after infliction
of Cr stress. Seeds were germinated and grown in the presence or absence of Cr under controlled environmental conditions.
Uptake and translocation of Cr rate was relatively higher during first 12 h of treatment with both speciation of Cr, Cr(III)-
and Cr(VI)-treated black gram roots retained 15 times more Cr than the shoots. Significantly increased lipid peroxidation
was observed in the form of accumulation of malondialdehyde (MDA) and production of hydrogen peroxide (H2O2) molecule and superoxide (O2 ) radical after 6 h of infliction with Cr(VI) and after 12 h in Cr(III)-treated black gram roots. Superoxide dismutase (SOD)
and ascorbate peroxidase (APX) activities were significantly increased under Cr(VI)-treatment after 12 and 6 h, respectively.
However, catalase (CAT) and monodehydroascorbate reductase (MDHAR) activities were not significantly increased under Cr(Ill)-treatment.
There was a steep increase of 2.71 μmol g-1 FW in ascorbic acid (AA) content was observed between 6 and 24 h of Cr(VI)-treatment. Oxidized glutathione (GSSG) content
was steadily increased through the course of Cr(III)- and Cr(VI)-treatments, where as reduced glutathione (GSH) level was
decreased after 24 h of treatment. GSH/GSSG ratio was rapidly decreased in treatment with Cr(III) than the Cr(VI). There was
significant increase of 99 nmol g-1 FW in non-protein thiol (NPT) content was recorded between 6 and 24 h of Cr(VI)-treatment. The present results showed differential
response to AA and H2O2 signaling by Cr(III) and Cr(VI), AA in combination with APX was more effective in mitigating oxidative stress as against
the role of GSH as an antioxidant. |
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Keywords: | antioxidative enzymes black gram Cr phytotoxtcity lipid peroxidation metabolites reactive oxygen species |
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