Chaffei Chiraz, Suzuki Akira, Masclaux-Daubresse Céline, Ghorbel Mohamed Habib, Gouia Houda
Unité de recherche Nutrition et métabolisme azotés et protéines de stress (99UR/09-20), département de biologie, faculté des sciences de Tunis, campus universitaire El Manar I, 1060 Tunis, Tunisie.
C R Biol. 2006 Oct;329(10):790-803. doi: 10.1016/j.crvi.2006.06.008. Epub 2006 Jul 31.
Tomato seedlings grown on nitric medium and treated with various cadmium concentrations (0 to 50 microM) were used. Results obtained show that cadmium remains predominantly located in the roots, which then seem to play the role of trap-organs. Increasing cadmium concentration in the medium leads particularly to a decrease in NO3- accumulation, together with a decrease in the activity of glutamine synthetase and in the quantity of plastidic isoform ARNm (GS2), and, on the contrary, to an increase of the cytosolic isoform ARNm (GS1). On the other hand, stimulations were observed for NADH-dependent glutamate synthase, NADH-dependent glutamate dehydrogenase, ARNm quantity of this enzyme, ammonium accumulation, and protease activity. In parallel, stimulations were observed for NAD+ and NADP+-dependent malate dehydrogenase and NADP+-dependent isocitrate dehydrogenase. These results were discussed in relation to the hypothesis attributing to the dehydrogenase enzymes (GDH, MDH, ICDH) an important role in the plant defence processes against cadmium-induced stresses.
使用在硝酸盐培养基上生长并经不同镉浓度（0至50微摩尔）处理的番茄幼苗。所得结果表明，镉主要集中在根部，根部似乎起到了捕获器官的作用。培养基中镉浓度的增加尤其导致硝酸盐积累减少，同时谷氨酰胺合成酶活性以及质体同工型ARNm（GS2）数量减少，相反，胞质同工型ARNm（GS1）增加。另一方面，观察到依赖NADH的谷氨酸合酶、依赖NADH的谷氨酸脱氢酶、该酶的ARNm数量、铵积累和蛋白酶活性受到刺激。同时，观察到依赖NAD +和NADP +的苹果酸脱氢酶以及依赖NADP +的异柠檬酸脱氢酶受到刺激。针对脱氢酶（GDH、MDH、ICDH）在植物抵御镉诱导胁迫过程中起重要作用这一假设对这些结果进行了讨论。
