Implication of peroxisomes and mitochondria in the halophyte Cakile maritima tolerance to salinity stress

The role of mitochondria and peroxisomes in the tolerance of the halophyte Cakile martima to salt stress was studied. The plants were subjected to 0, 100, and 200 mM NaCl for 5 weeks. The evaluation of oxidative stress according to the content of malondialdehyde (MDA), carbonyl (CO-) proteins, O-2(-), and H2O2, and the activities of several antioxidant enzymes, such as superoxide dismutase, peroxidase, and enzymes of the ascorbate-glutathione cycle were determined in two purified organelles, mitochondria and peroxisomes. The intact organelles were purified by centrifugation in Percoll density gradients. Results show that the content of MDA and CO- proteins was higher in mitochondria than in peroxisomes under the salt stress. The antioxidant enzymes showed higher activities in peroxisomes than in mitochondria under different NaCl concentrations. These activities were highest at 100 mM NaCl. Our results suggest that the ascorbate glutathione cycle in peroxisomes plays a key role in the tolerance of Cakile maritima to salinity.