Genetic analysis of mitochondrial functions and stress responses

Unfavorable environmental conditions limit plant growth and require extensive adaptation for survival. During abiotic stress, production of reactive oxygen species (ROS) can increase and create additional oxidative stress for the plants. Mitochondria regulate cellular energy homeostasis and redox balance by integrating metabolic pathways that are important in adaptive responses to stress conditions. In mitochondria, over-reduction of the electron transport chain is the primary reason for ROS accumulation, which can be reduced by protecting and stabilizing the electron flow. To reveal the function of genes encoding members of the mitochondrial electron transport in stress responses, we are characterizing 13 Arabidopsis thaliana mutants carrying mutations in genes encoding such proteins. When compared to wild type several mutants showed morphological and physiological changes under abiotic stress conditions. Phenotypic differences in tolerance to drought and salinity were revealed through in vitro germination and growth tests, as well as by complex phenotyping of soil-grown plants. Several mutants showed altered tolerance to osmotic, oxidative and salt stress. In some cases, we found a strong correlation between the mutations and the photosynthetic activity and energy production.