Biomodified mineral fertilizers (BMFs) were produced by enriching the ammophos fertilizer with PGPR Bacillus velezensis BS89 with the use of two technologies: BMF 1, the ammophos fertilizer with the ...addition of spores of Bacillus velezensis BS89 on a dry carrier (diatomite); and BMF2, ammophos granules treated with spores of Bacillus velezensis BS89 in a cell suspension. The effects of BMFs on maize growth and productivity and the rhizosphere bacterial community were assessed. BMFs significantly increased maize growth, dry matter, minerals, starch and protein contents in maize grain. The application of biomodified mineral fertilizers resulted in the significant increase in the yield and some parameters of maize plants such as ear length and number of kernels in the row. The yield was increased by 7.5–7.6%, ear length by 9%, and number of kernels in the row by 6.7–7%, as compared with ammophos. However, we found no considerable differences in the composition of the bacterial community of the maize rhizosphere after the use of BMFs as compared with the use of ammophos at the level of the phyla, which was confirmed by the ecological indices of biodiversity: the Shannon index and the Simpson index. Comparison of the experimental variants with bulk soil showed differences in the microbiome composition of the dominant bacterial phyla. A greater abundance of Proteobacteria and Bacteroidetes and a lower abundance of Chloroflexi was registered in bulk soil as compared with the other experimental variants where maize plants were present. The highest percentage (5.3%) of unidentified taxonomic phyla was also found in bulk soil. Our studies showed that maize is the main structuring factor during formation of the microbiome composition in the rhizosphere. The application of biomodified fertilizers BMF1 and BMF2 considerably increased the abundance of bacteria representing the minority of the community, namely, those from the phyla Verrucomicrobia, Chloroflexi, Planctomycetes, Proteobacteria, Firmicutes and Chlamydiae, as compared with the use of ammophos. Thus, the application of biomodified mineral fertilizers is a promising agronomic and ecological strategy for boosting maize yield and the quality of grain under field conditions.
Efficient plant-growth-promoting rhizobacteria (PGPR) used as biofertilizers and biological control agents are promising substitutes for minimizing the application of synthetic agrochemicals in crop ...production. We studied the effect of PGPR strain Bacillus velezensis BS89 alone and in combination with three forms of nitrogen fertilizers (ammonium nitrate, carbamide, and ammonium sulfate) on the productivity of two strawberry varieties in three-year field experiments. We first showed that the application of PGPR Bacillus velezensis BS89 on strawberries demonstrated the same effect as the application of nitrogen fertilizers. Use of the strain BS89 increased the chlorophyll content in plant leaves by 2.7–6.8%, and also increased the yield of berries by 6.7–36.4% for cv. Rusich and 7.5–19.3% for cv. Troitskaya depending on the form of nitrogen fertilizer. The best results in the yield of strawberry plants of the cv. Rusich were achieved in the variant BS89 + ammonium nitrate (41.9–57.4%), and the cv. Troitskaya—in the BS89 + carbamide variant (8.1–38.8%). Three-year use of strain BS89 for cv. Rusich resulted in an increase of runner’s weight by 212.1%, and also the weight of the roots by 120%, thereby significantly improving the mineral nutrition of plants. This is mainly associated with the plant growth-promoting activity of Bacillus velezensis BS89, which was able to produce a high amount of IAA—494.1 µg/mL. We believe that the PGPR strain BS89 can be successfully used for growing strawberries. However, each variety requires careful selection of the composition of nitrogen fertilizers and analysis of the compatibility of fertilizers and the PGPR strain.
Due to long-term domestication, breeding and divergent selection, a vast genetic diversity in poultry currently exists, with various breeds being characterized by unique phenotypic and genetic ...features. Assuming that differences between chicken breeds divergently selected for economically and culturally important traits manifest as early as possible in development and growth stages, we aimed to explore breed-specific patterns and interrelations of embryo myogenesis, nitric oxide (NO) metabolism and post-hatch growth rate (GR).
These characteristics were explored in eight breeds of different utility types (meat-type, dual purpose, egg-type, game, and fancy) by incubating 70 fertile eggs per breed. To screen the differential expression of seven key myogenesis associated genes (
,
,
,
,
,
, and
), quantitative real-time PCR was used.
We found that myogenesis associated genes expressed in the breast and thigh muscles in a coordinated manner showing breed specificity as a genetic diversity signature among the breeds studied. Notably, coordinated ("accord") expression patterns of
,
, and
were observed both in the breast and thigh muscles. Also, associated expression vectors were identified for
and
in the breast muscles and for
and
genes in the thigh muscles. Indices of NO oxidation and post-hatch growth were generally concordant with utility types of breeds, with meat-types breeds demonstrating higher NO oxidation levels and greater GR values as compared to egg-type, dual purpose, game and fancy breeds.
The results of this study suggest that differences in early myogenesis, NO metabolism and post-hatch growth are breed-specific; they appropriately reflect genetic diversity and accurately capture the evolutionary history of divergently selected chicken breeds.
Elements of fractal analysis are widely used in scientific research, including several biological disciplines. In this study, we hypothesized that chicken breed biodiversity manifests not only at the ...phenotypic level, but also at the genetic-system level in terms of different profiles of fractal conformity and bioconsolidation in the early myogenesis gene expression. To demonstrate this effect, we developed two mathematical models that describe the fractal nature of the expression of seven key genes in the embryonic breast and thigh muscles in eight breeds of meat, dual purpose, egg and game types. In the first model, we produced breed-specific coefficients of gene expression conformity in each muscle type using the slopes of regression dependencies, as well as an integral myogenesis gene expression index (MGEI). Additionally, breed fractal dimensions and integral myogenesis gene expression fractal dimension index (MGEFDI) were determined. The second gene expression model was based on plotting fractal portraits and calculating indices of fractal bioconsolidation. The bioconsolidation index of myogenesis gene expression correlated with the chick growth rate and nitric oxide (NO) oxidation rate. The proposed fractal models were instrumental in interpreting the genetic diversity of chickens at the level of gene expression for early myogenesis, NO metabolism and the postnatal growth of chicks.
Backgrounds and aims Soils are known to influence the survival and the biocontrol activity of Pseudomonas bacteria. However, few studies have focused on the development of the phytopathogenic fungus ...Fusarium culmorum under various soil conditions and its interactions with the antagonistic microflora. The aims of our research were to study the development of Fusarium culmorum and Pseudomonas fluorescens in two soils with different textures and on barley roots and to assess the influence of these soils in the growth, colonization capacity and interactions between the phytopathogen and the antagonist. Methods Development of F. culmorum and P. fluorescens was studied in dynamics on membranes in two nonsterile soils with different textures, as well as on barley roots. F. culmorum was identified by indirect immunofluorescent method, and P. fluorescens was visualised with the use of a gus-marked strain. Results P. fluorescens 2137gus suppressed considerably the mycelium growth and the macroconidia formation of F. culmorum in both soils. However, bacterium did not decrease considerably the density of the fungal mycelium on the surface of barley roots. On the contrary, the amount of the 2137gus was decreased considerably on roots in the light loamy soil in the presence of F. culmorum. Nevertheless, biocontrol effect of P. fluorescens 2137gus was expressed in the light loamy soil. There was no direct correlation between the mycelia density on membranes in soils and the amount of the fungus on roots at the beginning of colonization. The amount of the fungus on root surface did not correlate directly with the intensity of barley root rot. Conclusion The behaviour and interactions of F. culmorum and P. fluorescens depend on soil type and the habitat (soil or roots).
Evolution of beneficial plant-microbe symbioses is presented as a result of selective processes induced by hosts in the associated microbial populations. These processes ensure a success of “genuine ...mutualists” (which benefit the host, often at the expense of their own fitness) in competition with “symbiotic cheaters” (which consume the resources provided by host without expressing the beneficial traits). Using a mathematical model describing the cyclic microevolution of rhizobia-legume symbiosis, we suggest that the selective pressures in favor of N₂-fixing (Fix⁺) strains operate within the in planta bacterial population due to preferential allocation of C resources into Fix⁺ nodules (positive partners' feedbacks). Under the clonal infection of nodules, Fix⁺ strains (“genuine mutualists”) are supported by the group (inter-deme, kin) selection while under the mixed infections, this selection is ineffective since the Fix⁺ strains are over-competed by Fix⁻ ones (“symbiotic cheaters”) in the nodular habitats. Nevertheless, under mixed infections, Fix⁺ strains may be supported due to the coevolutionary responses form plant population which induce the mutualism-specific types of natural (group, individual) selection including the frequency dependent selection implemented in rhizobia population during the competition for host infection. Using the model of multi-strain bacterial competition for inoculation of symbiotic (rhizospheric, nodular) habitats, we demonstrate that the individual selection in favor of host-specific mutualist genotypes is more intensive than in favor of non-host-specific genotypes correlating the experimental data on the coordinated increases of symbiotic efficiency and specificity in the rhizobia-legume coevolution. However, an overall efficiency of symbiotic system is maximal when the non-host-specific mutualists are present in rhizobia population, and selection in favor of these mutualists operating at the whole population level is of key importance for improving the symbiosis. Construction of the agronomically valuable plant-microbe systems should provide the optimization of host-specific versus non-host-specific mutualists' composition in legume inoculants combined with the clonal penetration of these mutualists into the nodules.
We created the mathematical model for the evolution of the Efficiency of Mutualistic Symbioses (EMS) which was estimated as the microsymbiont impacts on the host’s reproductive potential. Using the ...example of rhizobia–legume interaction, the relationships were studied between EMS and Functional Integrity of Symbiosis (FIS) which is represented as a measure for concordance of changes in the partners’ genotypic frequencies under the environmental fluctuations represented by the minor deviations of the systemic model parameters. The FIS indices correlate positively with EMS values suggesting an enhancement of FIS
via the natural selection operating in the partners’ populations in favor of high EMS. Due to this selection, nodular habitats may be closed for colonization by the non-beneficial bacterial strains and the Genotypic Specificity of Mutualism (GSM) in partners’ interactions is enhanced: the selective advantage of host-specific
vs non-host-specific mutualists is increasing. The novelty of our model is to suggest a selective background for macroevolutionary events reorganizing the structure and functions of symbiotic systems and to present its evolution as a result of shifting the equilibrium between different types of mutualists under the impacts of the symbiosis-stipulated modes of natural selection.
In order to analyze the microevolutionary processes in host-associated microorganisms, we simulated the dynamics of rhizobia populations composed of a parental strain and its mutants possessing the ...altered fitness within “plant-soil” system. The population dynamics was presented as a series of cycles (each one involves “soil→rhizosphere→nodules→soil” succession) described using recurrent equations. For representing the selection and mutation pressures, we used a universal approach based on calculating the shifts in the genetic ratios of competing bacterial genotypes within the particular habitats and across several habitats. Analysis of the model demonstrated that a balanced polymorphism may be established in rhizobia population: mutants with an improved fitness do not supplant completely the parental strain while mutants with a decreased fitness may be maintained stably. This polymorphism is caused by a rescue of low-fitted genotypes via negative frequency-dependent selection (FDS) that is implemented during inoculation of nodules and balances the Darwinian selection that occurs during multiplication or extinction of bacteria at different habitats. The most diverse populations are formed if the rhizobia are equally successful in soil and nodules, while a marked preference for any of these habitats results in the decrease of diversity. Our simulation suggests that FDS can maintain the mutualistic rhizobia–legume interactions under the stress conditions deleterious for surviving the bacterial strains capable for intensive N
2 fixation. Genetic consequences of releasing the modified rhizobia strains may be addressed using the presented model.
The mathematical model for evolution of the plant–microbe facultative mutualistic interactions based on the partners’ symbiotic feedbacks is constructed. Using the example of rhizobia–legume ...symbiosis, we addressed these feedbacks in terms of the metabolic
(
C
↔
N
)
exchange resulting in the parallel improvements of the partners’ fitness (positive feedbacks). These improvements are correlated to the symbiotic efficiency dependent on the ratio of N
2-fixing bacterial strains (“genuine mutualists”) to the non- N
2-fixing strains (“symbiotic cheaters”) in the root nodules. The computer experiments demonstrated that an interplay between the frequency-dependent selection (FDS) and the Darwinian (frequency-independent) selection pressures implemented in the partners’ populations ensures an anchoring or even domination for the newly generated host-specific mutualists (which form N
2-fixing nodules only with one of two available plant genotypes) more successfully than for the non-host-specific mutualists (which form N
2-fixing nodules with both plant genotypes). The created model allows us to consider the mutualistic symbiosis as a finely balanced polymorphic system wherein the equilibrium in bacterial population may be shifted in favor of “genuine mutualists” due to the partner-stipulated selection for an improved symbiotic efficiency implemented in the plant population.
