Epipactis atrorubens (Hoffm.) Besser. is a regionally rare orchid species with highly ornamental properties due to its very beautiful bright flowers, therefore it is of considerable interest as a horticultural plant for use in botanical gardens and greenhouses. The objective of the research was to assess metal accumulation and some pro- and antioxidant reactions in E. atrorubens, colonizing serpentine dumps post asbestos mining. Additionally, some physicochemical properties of substrates, microbiotic characteristics and water status were investigated in orchids growing on two serpentine dumps and in a natural forest habitat of the Middle Urals, Russia. The dump substrates were characterized by the strong stoniness and the high content of Mg, Ni, Cr and Co (by 1.8 times on average) compared to the natural habitat. In these sites, E. atrorubens was characterized by increased mycorrhization. In the rhizome and roots of E. atrorubens the concentrations of most metals studied were considerably higher (more than 4 times on average) than in the leaves. It was found that orchids colonizing serpentine dumps produced more lipid peroxidation products (by 1.4 times on average) in the leaves which was accompanied by the more active synthesis of such non-enzymatic antioxidants as ascorbate, free proline, soluble phenolic compounds (including flavonoids) and non-protein thiols. The study suggests that non-enzymatic antioxidants increased the adaptive potential of E. atrorubens and contributed to its naturalization on serpentine dumps post asbestos mining.

In a changing climate, sustainable agriculture urgently requires environmentally friendly solutions. Increasing soil salinity severely limits crop productivity, as excess salts induce osmotic and ion-specific toxicity in plants. A promising strategy for mitigating these effects and enhancing plant salt tolerance involves the use of biofertilizers based on plant growth-promoting (PGP) rhizobacteria. In this study, novel salt-tolerant PGP strains were isolated and characterized from the rhizosphere of the halophyte Atriplex prostrata grown in soils with varying salinity levels. Twelve isolates were screened for key PGP traits, including indole-3-acetic acid (IAA) production, phosphate solubilization, siderophore synthesis, and NaCl tolerance. Two strains, AP9 and AP12, demonstrated the most comprehensive PGP potential. Based on 16S rRNA gene sequencing, they were identified as members of the genus Serratia. In an experiment under salt stress (75, 150, and 225 mM NaCl), inoculation of wheat (Triticum aestivum L.) seeds with these strains significantly improved germination rates and stimulated root and shoot development. The treated plants also exhibited reduced levels of key oxidative stress markers—malondialdehyde (MDA) and proline. Thus, the Serratia sp. AP9 and AP12 strains exhibit pronounced PGP activity and efficacy in enhancing the salt tolerance of wheat. These results indicate that these isolates are promising candidates for the development of novel biofertilizers for sustainable agriculture on saline soils.

The increasing biogeochemical imbalance of nitrogen (N) heightens the importance of studying rhizosphere bacteria, which aid crop nutrient uptake, and their responses to N deficiency. The aim of the study was to assess variety-specific responses of the tomatoes and their associated rhizobacteriome to low N availability. Three determinant varieties of Solanum lycopersicum L. were cultivated in pot-scale experiment during 10 weeks on low-fertility substrate (sod-podzolic soil:peat:clay:sand, 1:1:1:2, v/v), half of which were supplemented with ammonium nitrate (60 mg N kg⁻¹ in total). A comprehensive methodology was employed, including 16S rRNA metagenomic Nanopore sequencing, quantitative assessment of N-cycling bacteria, and analysis of plant growth, photosynthetic pigments, total N in biomass, and fine root architecture. Results demonstrated that N deficiency significantly reduced plant biomass and photosynthetic pigments. The rhizosphere contained a diverse community of N-transforming bacteria (38 identified genera), whose composition and relative abundance were strongly influenced by both tomato variety and N fertilization. Nitrogen application increased the abundance of N-fixers and altered alpha-diversity in a variety-dependent manner. Significant correlations were found between the abundance of key bacterial genera (e.g., Stenotrophomonas, Rhizobium) and N parameters in plants and substrates. The study concludes that the response of the tomato rhizobacteriome to N availability is variety-specific, which is important for the development of microbiome management strategies for enhancing N use efficiency.

Salinization of agricultural soils is a global problem causing crop yield declines. This impact is caused by osmotic and oxidative stress, which plants often rely on endophytic bacteria to overcome. A bacterial isolate from the roots of the halophyte Plantago salsa was studied between 2024 and 2026, and its ability to increase barley tolerance to moderate salt stress was determined. Based on 16S rRNA gene sequencing (1410 bp), the isolate PS-50.1 was identified as Providencia sp. It demonstrated key plant growth-promoting properties, including indole-3-acetic acid production (21.4 mg L⁻¹) and phosphate solubilization (69.0 mg L⁻¹). The strain supported barley growth at 7% NaCl. Inoculation of barley seeds with this strain (10⁸ CFU L⁻¹) significantly reduced moderate salt stress in plants both in vitro and in a pot experiment. Inoculated plants under salinity conditions had greater shoot length (+11.6%) compared to non-inoculated; higher pre-flag leaf fresh weight; demonstrated decreased levels of prooxidants (H₂O₂ by 44.8% and malondialdehyde by 31.8%), higher proline accumulation (up to 2.0-fold), and increased antioxidant enzyme activity (catalase by 26.6% and ascorbate peroxidase by 191%). Furthermore, inoculated plants showed 9.4% higher water use efficiency and photosynthetic rate (+5.5%) under salt stress compared to uninoculated plants. These results indicate that the halophytic strain Providencia sp. PS-50.1 is a promising candidate for the development of microbial preparations aimed at increasing crop productivity under saline conditions.