The response of tomato plants to long-term cadmium exposure was evaluated after a 90-days long culture in hydroponic conditions (0, 20, and 100 μM CdCl(2)). Cadmium preferentially accumulated in roots, and to a lower extent in upper parts of plants. Absolute quantification of 28 metabolites was obtained through (1)H NMR, HPLC-PDA, and colorimetric methods. The principal component analysis showed a clear separation between control and Cd treated samples. Proline and total ascorbate amounts were reduced in Cd-treated leaves, whereas α-tocopherol, asparagine, and tyrosine accumulation increased, principally in 100 μM Cd treated leaves. Carotenoid and chlorophyll contents decreased only in 100 μM Cd-mature-leaves, which correlate with a reduced expression of genes essential for isoprenoid and carotenoid accumulations. Our results show that tomato plants acclimatize during long-term exposure to 20 μM Cd. On the contrary, 100μM Cd treatment results in drastic physiological and metabolic perturbations leading to plant growth limitation and fruit set abortion.
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