A production strain of soybean nodule bacteria RZ300 Bradyrhizobium japonicum resistant to drying on the seed surface: cultural properties and genomic features
Year: 2026
Type: article
Abstract: Pre-sowing treatment of cultivated legume seeds with nodule bacteria preparations is a standard agronomic practice. This is particularly important in soybean cultivation, as effective microsymbionts of soybeans are often absent from the soil. However, as many studies have shown, the efficacy of biopreparations depends largely on the survival of rhizobial cells on seeds during drying. In this study, we analyzed the viability of three production strains of Bradyrhizobium japonicum Kirchner (634b, 640 and RZ300) on soybean (Glycine max L.) seeds of various origins (varieties: EN Argenta, Bara and Prudence). The experiments evaluated several parameters: inoculant concentrations (10 and 100 %), drying temperatures (5, 15, and 25 °C), and protective polymer-carbohydrate formulations. The experiments revealed that the soybean variety had no noticeable effect on the viability of the studied rhizobial strains, while the strains themselves differed significantly in this regard. The RZ300 strain demonstrated the highest resistance to drying on soybean seeds. A comparative genomic analysis of this strain and the less resistant B. japonicum strain 634b revealed the presence of the opgC gene in the RZ300 strain (encodes the ОpgC protein involved in the biosynthesis of osmoregulated periplasmic glucans (OPGs)). This gene is absent in strain 634b and may potentially determine the increased resistance of nodule bacteria to drying on seeds. An evaluation of various protective formulations demonstrated that formulations based on 50 % sucrose provide the best protection, with rhizobia showing the highest resistance to drying at +5 °C. The results obtained in this study can be used both in the selection of effective inoculant strains and for providing technological support in the development of biological products. The genomic data support the development of genetic screening systems to identify promising strains and the potential introduction of the opgC gene into promising rhizobial strains to improve their manufacturability, i. e. to enable effective early seed inoculation.
DOI: 10.18699/vjgb-26-47
Language: English
Subfield: Plant Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: diamond
Funder: Russian Science Foundation
OpenAlex ID: W7162490689