Para-nodulation of rape upon inoculation with nitrogen-fixing rhizosphere bacteria

This work is the first demonstration of the possibility of para-nodule formation on the roots of rape (Brassica napus var. napus) under the effect of 2,4-dichlorophenoxyacetic acid (2,4-D) with parallel inoculation with pure or mixed cultures of diazotrophic bacteria. The para-nodules (p-nodules) formed on the rape seedling roots after their treatment with 2,4-D and concomitant infection with nitrogen-fixing bacteria were found to be structurally and morphologically different from the formations appearing under the impact of 2,4-D alone. A stable endosymbiosis was shown to be established between the cells of rape p-nodules and the introduced nitrogen-fixing bacteria. The diazotrophic bacteria localized inside the rape p-nodules were found to increase their nitrogenase activity six times as compared to the activity of the same cultures recorded on plant roots after conventional inoculation.