ABSCISIC ACID AND ETHYLENE PRODUCTION BY BIOTECHNOLOGICAL STRAINS OF Bradyrhizobium japonicum

The aim of the work was to research the production of phytohormones that inhibits the plants growth and development ? abscisic acid and ethylene by various nitrogen?fixing symbiotic efficiency biotechnological strains of Bradyrhizobium japonicum under the conditions in vitro. The amounts of abscisic acid were determined by TLC-spectrodensitometry and that of ethylene ? by gas chromatography. It was shown that symbiotic nitrogen?fixing bacteria of soybean were able to synthesize abscisic acid (56.5?72.0 ?g / g of absolutely dry biomass) and ethylene (0.046?3.461 nmol/h?g of absolutely dry biomass). It was revealed that the differences in amounts of abscisic acid and ethylene in B. japonicum were strains properties and they were not related directly to conditions of cultivation, nitrogenase activity of the bacteria and their effectiveness in symbiosis with soybean plants. The ability of biotechnological strains of B. japonicum to synthesize the phytohormones inhibiting the plant growth and development under the conditions in vitro may be an additional factor that increases virulence of the bacteria and determines their potential activity in infection of plants. The data obtained are important for development of the technology of microbiological preparations?legume inoculants with combined properties.