High concentration of cadmium induces AtPCS2 gene expression in Arabidopsis thaliana (L.) Heynh ecotype Wassilewskija seedlings |
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Authors: | Chris Fabien Moussavou Moudouma Vincent Gloaguen Catherine Riou Lionel Forestier and Ga?lle Saladin |
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Institution: | (1) Laboratoire de Chimie des Substances Naturelles (EA 1069), Universit? de Limoges, Facult? des Sciences et Techniques, 123 avenue Albert Thomas, 87060 Limoges Cedex, France;(2) Unit? de G?n?tique Mol?culaire et Animale (UMR INRA 1061), Universit? de Limoges, Facult? des Sciences et Techniques, 123 avenue Albert Thomas, 87060 Limoges Cedex, France; |
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Abstract: | In Arabidopsis thaliana, two genes encoding phytochelatin synthase (PCS; EC 2.3.2.15), AtPCS1 and AtPCS2, have been identified. Until now, only AtPCS1 was shown to play a role in response to Cd. To gain insight into the putative role of AtPCS2, three Cd concentrations (50, 100 and 200 μM) and long-term exposure (7 days) were tested on 1-week-old A. thaliana ecotype Wassilewskija (Ws) seedlings. Since 100 μM Cd did not alter seedling metabolism, as shown by unchanged total soluble
protein and free proline contents, we investigated plantlet response to this concentration in addition to Cd accumulation.
Seedlings accumulated Cd in roots and shoots. As phytochelatins and glutathione (GSH) contents increased in treated seedlings,
we suggested that Cd might be translocated via the phytochelatin pathway. Specific enzymatic activities of γ-glutamylcysteine
synthetase (GCS; EC 6.3.2.2), glutathione synthetase (GS; EC 6.3.2.3) and PCS were twice much more stimulated in shoots and
roots after Cd exposure except GS that remained constant in shoots. As expression of genes encoding GCS and GS was unchanged
in response to Cd, we suggested a regulation at translational or post-translational level. Surprisingly, AtPCS1 and AtPCS2 were differentially up-regulated after Cd treatment: AtPCS1 in shoots and AtPCS2 in whole plantlets. This last result suggests that PCS2 could be involved in plant response to high concentration of Cd in
Ws ecotype and supports a putative role of PCS2, not redundant with PCS1, in a long-term response to Cd. |
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