Effects of long-term cadmium exposure on growth and metabolomic profile of tomato plants

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 mu M CdCl2). Cadmium preferentially accumulated in roots, and to a lower extent in upper parts of plants. Absolute quantification of 28 metabolites was obtained through H-1 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 alpha-tocopherol, asparagine, and tyrosine accumulation increased, principally in 100 mu M Cd treated leaves. Carotenoid and chlorophyll contents decreased only in 100 mu M 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 mu M Cd. On the contrary, 100 mu M Cd treatment results in drastic physiological and metabolic perturbations leading to plant growth limitation and fruit set abortion. (c) 2010 Elsevier Inc. All rights reserved.