Effects of salicylic acid on paraquat tolerance in<Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> plants |
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Authors: | Hye-Sook?Kim Chang-Jin?Lim Joon-Chul?Kim Email author" target="_blank">Chang-Duck?JinEmail author Tae-Jin?Han |
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Institution: | (1) Division of Biological Sciences, Kangwon National University, 200-701 Chunchon, Korea;(2) Division of Biology, Hallym University, 200-702 Chunchon, Korea |
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Abstract: | Foliar spraying ofArabidopsis thaliana (Columbia ecotype) plants with a 1.0-mM salicylic acid (SA) solution significantly improved their tolerance to subsequent
paraquat (PQ)-induced oxidative damage. Leaf injuries, including losses of chlorophyll, protein, and fresh weight, were reduced.
Our analysis of antioxidant enzymes in the leaves showed that SA pre-treatment effectively retarded rapid decreases in the
activities of Superoxide dismutase (SOD), catalase, and ascorbate peroxidase that are normally associated with PQ exposure.
In addition, guaiacol peroxidase activity was remarkably increased. In a native gel assay of peroxidase (POD) isozymes, staining
activity of the POD1 isozyme, which disappeared in plants exposed only to 10 μM PQ, was significantly recovered by the 1.0-mM
SA pre-treatment POD2 isozyme activity was also pronounced in all SA-treated plants compared with the control. A 12-h SA pre-treatment,
without subsequent PQ stress, also caused a small increase in the endogenous H2O2 content that accompanies the symptoms of mild leaf injuries. This enhanced level occurred in parallel with a slight SOD increase
and a catalase decrease. From our results, it can be assumed that, due to the small increase in SOD as well as catalase inactivation
via SA pre-treatment, a moderate increase in H2O2 levels may occur. In turn, a large induction of guaiacol peroxidase leads to enhanced PQ tolerance inA. thaliana plants. |
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Keywords: | antioxidant enzymes Arabidopsis thaliana H2O2 paraquat salicylic acid (SA) |
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