ORIGINAL PAPER The effect of calcium on the antioxidant systems in the halophyte Cakile maritima under salt stress Nader Ben Amor • Wided Megdiche • Ana Jime ´nez • Francisca Sevilla • Chedly Abdelly Received: 17 May 2009 / Revised: 8 September 2009 / Accepted: 6 November 2009 / Published online: 10 December 2009 Ó Franciszek Go ´rski Institute of Plant Physiology, Polish Academy of Sciences, Krako ´w 2009 Abstract The purpose of the current investigation was to study the effect of Ca 2? (0, 3.5 and 20 mM concentrations) on the antioxidant systems in the halophyte Cakile mari- tima under NaCl stress (0, 100, 200 and 400 mM NaCl). Plants treated with both moderate calcium (3.5 mM) and salt levels (100 mM) showed the maximum growth, and the addition of 20 mM calcium to the nutrient media did not significantly reduce the growth under the moderate salt treatment. The absence of calcium associated with high salt concentration induced a strong reduction of biomass pro- duction. The tolerance of C. maritima at moderate salinity and calcium was related with the lowest values of the parameters indicative of oxidative stress (malondialdehyde, electrolyte leakage and hydrogen peroxide concentration). This was accompanied with a higher peroxidase, superox- ide dismutase, ascorbate peroxidase, monodehydroascor- bate reductase, dehydroascorbate reductase and glutathione reductase activities. In contrast, in the absence of calcium, those enzymes showed the lowest activities under all salt treatments. As a whole, it can be noticed that salt tolerance was improved by moderate calcium concentration; how- ever, the absence of calcium has a drastic effect on C. maritima. Keywords Antioxidant enzymes Á Calcium Á Halophyte Á Salt stress Abbreviations ASC Ascorbate CAT Catalase DHAR Dehydroascorbate reductase EL Electrolyte leakage GR Glutathione reductase GSH Reduced glutathione MDA Malondialdehyde MDHAR Monodehydroascorbate reductase POX Peroxidase ROS Reactive oxygen species SOD Superoxide dismutase TAC Total antioxidant capacity Introduction Salinity is one of the most common environmental stresses that affect plant growth and development. In the arid and semi-arid zones, the combination of inappro- priate irrigation practices and high evapo-transpiration rates is largely responsible for extending soil/water salinization (Owens 2001). This is also true for Tunisia: an arid and semi-arid Mediterranean country (100– 700 mm of mean annual rainfall). Hence, around 10% of the whole territory area and 20% of the cultivated areas of Tunisia are salinized (Hachicha et al. 1994; Debez et al. 2006). Salt damage to plants is produced by a combination of several causes, including mainly osmotic injury and specific ion toxicity (Nandwal et al. 2000), Communicated by M. Horbowicz. N. Ben Amor Á W. Megdiche Á C. Abdelly (&) Laboratoire d’Adaptation des Plantes aux Stress Abiotiques, CBBC, BP 901, 2050 Hammam-Lif, Tunisia e-mail: chedly.abdelly@cbbc.rnrt.tn A. Jime ´nez Á F. Sevilla Department of Plant Stress Biology and Pathology, Centro de Edafologı ´a y Biologı ´a Aplicada del Segura, Consejo Superior de Investigaciones Cientificas (CSIC), Apdo. 164, 30100 Murcia, Spain 123 Acta Physiol Plant (2010) 32:453–461 DOI 10.1007/s11738-009-0420-2