Influence of Methyl Jasmonate and Salicylic Acid as Components of the Cultivation Medium for Rhizobium on Formation of Different-Efficiency Symbiotic Systems Glycine max — Bradyrhizobium japonicum

Abstract

Phytohormones are important in the main pathways of transduction of symbiotic signals between macro- and microsymbionts, and understanding of their participation in integration with other metabolic pathways, including prooxidant-antioxidant systems, is crucial in the formation of different-efficiency symbiotic systems. Aim. To investigate the effect of salicylic acid (SA, 50 μM) and methyl jasmonate (MJ, 0.75 μM) as components of the cultivation media of different in the activity and virulence rhizobia 604k and B1-20 on the peculiarities of the formation of symbiotic systems in terms of intensity and activity of catalase, as well as on the course of nodulation and nitrogen fixation. Methods. Microbiological (cultivation of nitrogen-fixing microorganisms, seed inoculation), physiological (vegetation experiment), biochemical (spectrophotometry, gas chromatography), and statistical. Results. It was found that the use of SA (50 μM) as an additional component of the culture medium of active rhizobia Tn5-mutant B1-20 for seed inoculation induces increased levels of peroxide production and catalase activity in soybean roots in the early stages of symbiosis, which contributes to the effectiveness of its symbiotic apparatus. Addition of MJ (0.75 μM) to the culture medium of rhizobia B1-20 does not affect changes in peroxide content and catalase activity in the roots, however, stimulates the processes of nodulation and reduces nitrogen fixation. It has been shown that modification of the cultivation medium of inactive rhizobia of the highly virulent strain 604k using SA (50 μM) or MJ (0.75 μM) does not change the peroxide content and leads to an increase in catalase activity in soybean roots during the formation of an ineffective symbiotic system with activation of nodulation processes. Conclusions. When using SA (50 μM) or MJ (0.75 μM) as components of the culture medium for rhizobia of different activity and virulence (604k and B1-20), differences were recorded in the levels of functioning of pro-antioxidant systems, in particular, in the production of peroxides and active catalase complexes, at the early stages of the formation of symbiotic systems of Glycine max — Bradyrhizobium japonicum, which affects the intensity of the processes of nodulation and nitrogen fixation.