CONICET | Buscador de Institutos y Recursos Humanos

Plants exposed to hostile environmental conditions such as drought or extreme temperaturesusually undergo oxidative stress, which has long been assumed to significantly contribute to thedamage suffered by the organism. Reactive oxygen species (ROS) overproduced under stressconditions were proposed to destroy membrane lipids and to inactivate proteins and photosystems,ultimately leading to cell death. Accordingly, considerable effort has been devoted, overthe years, to improve stress tolerance by strengthening antioxidant and dissipative mechanisms.Although the notion that ROS cause indiscriminate damage in vivo has been progressivelyreplaced by the alternate concept that they act as signaling molecules directing critical plantdevelopmental and environmental responses including cell death, the induction of genes encodingantioxidant activities is commonplace under many environmental stresses, suggesting thattheir manipulation still offers promise. The features and consequences of ROS effects depend onthe balance between various interacting pathways including ROS synthesis and scavenging,energy dissipation, conjugative reactions, and eventually reductive repair. They represent manypossibilities for genetic manipulation. We report, herein, a comprehensive survey of transgenicplants in which components of the ROS-associated pathways were overexpressed, and of thestress phenotypes displayed by the corresponding transformants. Genetic engineering of differentstages of ROS metabolism such as synthesis, scavenging, and reductive repair revealed astrong correlation between down-regulation of ROS levels and increased stress tolerance inplants grown under controlled conditions. Field assays are scarce, and are eagerly required toassess the possible application of this strategy to agriculture.