Résumé
Reactive oxygen species (ROS) scavenging systems are involved in various biotic and abiotic stresses. Oxidative stress in latex cells is related to an in situ coagulation of rubber particles that hampers latex flow, and consequent rubber production. Many antioxidant enzymes catalyse redox reactions, such as the ascorbate-glutathione cycle. Genetic modification was undertaken to improve the ROS-scavenging system. Hevea transgenic lines over-expressing the HbCuZnSOD gene, converting O2 - into H2O2, and the E. coli GSHJ, involved in glutathione biosynthesis, were successfully established and regenerated. These modifications dramatically affected the somatic embryogenesis process and plant development. The TS5T8An and TS l 2T3A82 lines overexpressing HbCuZnSOD and EcGSHJ, respectively, were selected for further experiment under a water deficit treatment. TS5T8An plants showed a higher SOD activity and pro li ne content than control plants. TS 12T3A82 plants had a higher thiol and proline contents as well as a higher glutathione reductase activity in leaves. These results suggest that increasing ROS-scavenging capacity improved physiological status for a better tolerance to abiotic stress. (Résumé d'auteur)