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The use of a complex biological product (CBP) based on native microbiological consortiums of coniferous forest litter accelerated the composting process of coniferous wood waste. The contribution of micromycetes and bacteria to the activation of coniferous wood waste composting processes using the different fertilizers rates was studied. A fractal analysis has confirmed the formation of a micromycetes-bacterial system in the treatment with optimal rates of NPK and CBP. In this case the better decomposition of wood waste was observed. It was noted that micromycetes of the genus Penicillium dominated in the composts obtained with CBP addition. This compost was not phytotoxic. Thus, for coniferous sawdust decomposition and its further humification, it is necessary to use both micromycetes and bacteria. The use of organic material resulting from wood waste decomposition with CBP and optimal rates of NPK is an effective way to increase the content of organic substances in soils and their potential fertility. [ABSTRACT FROM AUTHOR]

Results indicate an evolutionary pressure on the symbiotic genome of Rhizobium galegae biovars as seen in the formation of distinct clusters by the R. galegae biovar officinalis and R. galegae biovar orientalis. Further, the Caucasian R. galegae biovar orientalis strains exhibit more diversity than R. galegae biovar officinalis strains.

In silico analysis of open reading frames of genomic islands of Sinorhizobium meliloti Rm1021 was performed. This strain is a typical representative of soil bacteria forming nitrogen-fixing symbiosis with legume host plants from the alfalfa cross-inoculation group. It was demonstrated that genomic islands had mosaic structure, in which blocks of functional genes, IS-elements and noncoding RNA alternated. Genomic islands contained as well the components of T4SS and T4CP systems, and lacked systems of conjugative mobilization of islands. It was concluded that two of the three islands could be the variants of reduced integrative conjugative elements, and the third island represented a reduced integrated conjugative transposon. Site-specific integration of islands occurred into a 15-31 bp sequence (depending on the island) localized at the 3′-end of the tRNA gene, which is then shifted rightward, while the remaining part of the tRNA gene is completed by a similar sequence that exists in the island. A suggestion on the existence of “speciesspecific insertion hotspots” for genomic islands of root nodule bacteria was put forward. [ABSTRACT FROM AUTHOR]

Comparative sequence analysis of symbiotic genes (nodA, nodC, nodD, nifH), which are elements of accessory component of the rhizobial genome, demonstrated that the strains of Rhizobium leguminosarum bv. viciae, isolated from the nodules of a relic legume, Vavilovia formosa, the closest relative of hypothetical common ancestor of the tribe Fabeae, represented a group separated from the strains of R. leguminosarum bv. viciae, isolated from other representatives of this tribe (Vicia, Lathyrus, Pisum, Lens). No isolation was observed relative to the genes representing the core component of the rhizobial genome (16S rDNA, ITS, glnII) or relative to host specificity of the rhizobia. The data obtained suggest that sequence divergence of symbiotic genes marks the initial stage of sympatric speciation, which can be classified as the isolation of the relic “vaviloviae” symbiotype, a possible evolutionary precursor of the “viciae” biotype. [ABSTRACT FROM AUTHOR]

Sandwich-like docking configurations of the heterodimeric complex of NFR5 and K1 Vicia sativa receptor-like kinases together with the putative ligand, Nod factor (NF) of Rhizobium leguminosarum bv. viciae, were modeled and two of the most probable configurations were assessed through the analysis of the mutual polymorphisms and conservatism. We carried out this analysis based on the hypothesis that in a contact zone of two docked components (proteins or ligands) the population polymorphism or conservatism is mutual, i.e., the variation in one component has a reflected variation in the other component. The population material of 30 wild-growing V. sativa (leaf pieces) was collected from a large field (uncultivated for the past 25-years) and pooled; form this pool, 100 randomly selected cloned fragments of NFR5 gene and 100 of K1 gene were sequenced by the Sanger method. Congruence between population trees of NFR5 and K1 haplotypes allowed us to select two respective haplotypes, build their 3D structures, and perform protein-protein docking. In a separate simulation, the protein-ligand docking between NFR5 and NF was carried out. We merged the results of the two docking experiments and extracted NFR5-NF-K1 complexes, in which NF was located within the cavity between two receptors. Molecular dynamics simulations indicated two out of six complexes as stable. Regions of mutual polymorphism in the contact zone of one complex overlapped with known NF structural variations produced by R. leguminosarum bv. viciae. A total of 74% of the contact zone of another complex contained mutually polymorphic and conservative areas. Common traits of the obtained two stable structures allowed us to hypothesize the functional role of three-domain structure of plant LysM-RLKs in their heteromers. [ABSTRACT FROM AUTHOR]

Legume plants can obtain combined nitrogen for their growth in an efficient way through symbiosis with specific bacteria. The symbiosis between Rhizobium galegae and its host plant Galega is an interesting case where the plant species G. orientalis and G. officinalis form effective, nitrogen-fixing, symbioses only with the appropriate rhizobial counterpart, R. galegae bv. orientalis and R. galegae bv. officinalis, respectively. The symbiotic properties of nitrogen-fixing rhizobia are well studied, but more information is needed on the properties of the host plants. The Caucasus region in Eurasia has been identified as the gene centre (centre of origin) of G. orientalis, although both G. orientalis and G. officinalis can be found in this region. In this study, the diversity of these two Galega species in Caucasus was investigated to test the hypothesis that in this region G. orientalis is more diverse than G. officinalis. The amplified fragment length polymorphism fingerprinting performed here showed that the populations of G. orientalis and R. galegae bv. orientalis are more diverse than those of G. officinalis and R. galegae bv. officinalis, respectively. These results support the centre of origin status of Caucasus for G. orientalis at a genetic level. Analysis of the symbiosis-related plant genes NORK and Nfr5 reveals remarkable diversity within the Nfr5 sequence, although no evidence of adaptive evolution could be found. [ABSTRACT FROM AUTHOR]