The intensity of drought-induced oxidative processes in soybeans depends on symbiosis with Bradyrhizobium strains

The intensity of drought-induced oxidative processes by the degree of superoxide anion radical generation and the activity of NADPH oxidase in soybean associated with different activity and virulence of Bradyrhizobium strains were studied. The importance of active Bradyrhizobium japonicum for the formation of effective symbiosis with soybean to improve the realization of the adaptive potential of plants during drought and post-stress period has been established. Increased NADPH oxidase activity in nodules (by 3.5 – 4.7 times), as well as excessive production of superoxide radical in nodules (by 1.5 – 2 times) and roots (from 113 to 323%) of soybean in symbiosis with efficient Bradyrhizobium strains were observed during drought. However, the development of oxidative processes in effective soybean-rhizobial symbioses slowed down after exposure to stress. This indicates the adaptation of soybean plants associated with active Bradyrhizobium strains to growing conditions. In symbiotic systems with ineffective Bradyrhizobium strains, a significant increase in NADPH oxidase activity in nodules (by 3.3 – 6.0 times) and intensification of superoxide radical formation in nodules (by 2 – 3 times) and roots (from 260 to 330%) recorded both under drought and post-stress period. This indicates a significant development of oxidative processes and the inability to realize the adaptive potential of soybean plants in symbiosis with ineffective Bradyrhizobium strains. Thus, excessive formation of the superoxide radical and an increase in the activity of NADPH oxidase indicate the appearance of oxidative processes, which are a typical reaction in response to drought in soybean-rhizobial symbioses of varying efficiency. At the same time, the development of oxidative processes depends on the ability of soybean plants in symbiosis with Bradyrhizobium japonicum to realize their adaptive potential in during drought and post-stress period