The study was focused on changes in protein content and peroxidase activity in pea roots subjected to infection with Rhizobium leguminosarum and to low temperature. The amount of protein and peroxidase activity were shown to change in the course of interaction with nodular bacteria and to depend on the temperature and root zones susceptibility to rhizobia. It was concluded that changes in the content of soluble protein and peroxidase activity witness adaptation changes in pea seedlings, hich facilitate normal course of metabolic processes and ensure regulation of plant interaction with Rhizobium in hypothermal conditions.