Copper-induced changes in growth, photosynthesis, antioxidative system activities and lipid metabolism of cilantro (Coriandrum sativum L.)

The present study aims to investigate the effect of copper (as CuSO4, 5H(2)O) supply (0, 25 and 50 mu M) on performance of cilantro (Coriandrum sativum L.) plants grown under hydroponic conditions. All applied Cu concentrations drastically reduced the biomass production, length of the shoots and the roots and disturbed the ions (Cu, Ca, Fe, Zn and Mg) homeostasis. Either Cu-starvation (0 mu M) or Cu-toxicity (25 and 50 mu M) significantly reduced the net photosynthetic rate, stomatal conductance and transpiration rate resulting in reduced water use efficiency. Under Cu-toxicity, the variations in gas exchange parameters were associated with a remarkable decline in the photosynthetic pigments including Chlorophyll a, Chlorophyllb, Chlorophyll (a + b) and carotenoids. Additionally, an enhanced lipid peroxidation (evaluated as Malondialdehyde (MDA) contents) with a concomitant increase in proline, total soluble sugars and melanoidins contents were observed under these conditions. The increased MDA levels resulted in decrease in total lipid content and alteration of the fatty acid profiles in both shoots and roots with a general tendency toward the accumulation of saturated fatty acids that mirrors a decline in the desaturases activity. Although the increased activity of enzymatic antioxidants including catalase (CAT), gaiacol peroxidase (GPX) and ascorbate peroxidase (APX), the oxidative-induced injuries caused by 25 and 50 mu M Cu were found to be irreversible and the optimal growth parameters were not achieved.