Mitochondrial glutathione peroxidase (OsGPX3) has a crucial role in rice protection against salt stress.

Highlights • GPX3 gene is induced by salt stress. • GPX3-silenced plants had germination rate and growth delay. • Salt induced leaf gas-exchange and photochemical parameters reduction in rice. • GPX3 silencing produced plants more susceptible to salinity. • Salt sensitivity of GPX3 silenced plants seems be independent of ROS accumulation. Abstract Rice is one of the world's most important crops and an excellent model system for understanding the interaction between genes and environmental changes. However, its productivity is often challenged by abiotic stresses, which results in the accumulation of reactive oxygen species. Glutathione peroxidases are part of the mechanism by which plants face oxidative stress. These enzymes can control redox homeostasis and also play a role in redox signaling. Here, we investigate the role of rice GPX3 in plant responses to salt stress using OsGPX3 -RNAi silenced rice plants (GPX3s). Our results indicate that GPX3s plants are more sensitive to salinity showing decreased biomass, CO 2 assimilation rate, stomatal conductance, and intercellular CO 2 partial pressure. Moreover, these plants present significant damage to photosystem II activity and decline in chlorophyll content. Salt stress induced ROS accumulation in both non-transformed (NT) and GPX3s plants, indicating that GPX3s sensibility to salt stress was not due to the significant impairment in redox equilibrium. Together, these results show GPX3 importance in rice to achieve salt stress tolerance via an independent ROS-scavenger mechanism. Moreover, it also provides new light into the cross-talk between chloroplasts and mitochondria, suggesting a novel role to this enzyme beyond its role as ROS-scavenger. [ABSTRACT FROM AUTHOR]