Protective role of exogenous spermidine against paraquat toxicity in radish chloroplasts |
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Authors: | Sun-mi?Ahn Email author" target="_blank">Chang-Duck?JinEmail author |
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Institution: | (1) Division of Life Sciences, Kangwon National University, 200-701 Chunchon, Korea |
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Abstract: | When radish chloroplasts were pretreated with 1 mM spermidine (Spd) and then exposed to 30 M paraquat (PQ), they improved
their tolerance to subsequent PQ-induced oxidative damages. That included the decreases in the contents of chlorophyll, protein,
and ascorbate, as well as the increases in malondialdehyde (MDA) and H2O2 levels. Analysis of antioxidant enzymes showed that Spd pretreatment effectively prevented the PQ-induced decreases in the
total activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX). In contrast, the normally enhanced activities
of dehydroascorbate reductase (DHAR) and glutathione reductase (GR) in PQ-treated chloroplasts were reversed by Spd pretreatment
In a native gel assay, the Cu/ZnSOD isozyme, which disappeared under the PQ alone treatment, was significantly recovered when
tissues were pretreated with Spd. The dominant APX4 isozyme activity, which was preferentially decreased in response to PQ
alone treatment, was also strongly reactivated by earlier Spd exposure. Therefore, we suggest that Spd could play a substantial
role in protecting the radish chloroplasts from PQ stress. Furthermore, the enhancement of the Cu/ZnSOD and APX4 isozymes
by Spd pretreatment seems to be responsible for prevention of the PQ-induced decreases in the total activities of SOD and
APX, thereby providing a tolerance to PQ toxicity. |
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Keywords: | antioxidant enzyme chloroplast paraquat toxicity radish spermidine |
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