Influence of the low temperatures (18°C) in the generation of intracellular oxidative stress in the phytopathogen bacterium Pseudomonas savastanoi pv. phaseolicola NPS3121

Low temperatures are a key condition for various phytopathogenic bacteria, by favouring their pathogenic potential and the development of plant diseases. So far, the signal transduction pathways related to low temperatures in phytopathogenic bacteria are little understood. The occurrence of intracellular oxidative stress under this condition has been suggested as a molecular event belonging to this signalling pathway. In this study, using the Pseudomonas savastanoi pv. phaseolicola model bacteria, we evaluated intracellular redox state under low-temperature (18°C) conditions. Generation of an oxidative-stress biosensor (pKL1) and fluorometry analyses with the P. savastanoi pv. phaseolicola-roGFP2 bioreporter strain were performed. At low temperatures (18°C) the response capacity or roGFP2 oxidation diminished in relation to 28°C. Likewise, changes in the intracellular redox potential of P. savastanoi pv. phaseolicola during its growth at 28°C and 18°C were observed, with greater oxidation degree in cells grown at 18°C. These results demonstrated that low temperatures induce intracellular oxidative stress in P. savastanoi pv. phaseolicola. From this study, the oxidative stress is established as part of the cellular response to low-temperature conditions in this bacteria. This is the first report of the relation of oxidative stress with low-temperature conditions in phytopathogens bacteria.