Aim

Three to five Italian rice cultivars with a contrasting (1-2 highly sensitive, 2-3 highly tolerant) capability to cope with salt stress conditions during the vegetative and reproductive stages will be selected for this investigation. The levels and the properties of selected enzymes playing a pivotal role in antioxidant defense [namely superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT; EC 1.11.1.6), ascorbate peroxidase (APX, EC 1.11.1.11) and glutathione reductase (GSHR, EC 1.6.4.2)] and in proline metabolism [namely P5C synthetase (P5CS, EC undefined), P5C reductase (P5CR, EC 1.5.1.2), proline dehydrogenase (ProDH, EC 1.4.3) and P5C dehydrogenase (P5CDH, EC 1.5.1.12)] will be studied in these genotypes, as well as the resulting levels of ROS, reduced ascorbate/GSH and free proline in tissues of osmotically-stressed seedlings. Either increased expression levels or higher substrate affinity are expected to contribute in providing the basis for higher salt tolerance through increased ROS scavenging and/or osmolyte accumulation.