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Centaurea cyanus L. is a common field weed in Eastern Europe but only in Poland biotypes of this species with resistance to acetolactate synthase (ALS) inhibitors have been confirmed. This phenomenon is constantly developing and spreading to consecutive regions of Poland. This study aimed to assess the response of selected Polish C. cyanus populations to tribenuron-methyl and to analyse the genetic variability of the ALS gene of C. cyanus populations resistant to ALS inhibitors. Between 2017 and 2021, 13 seed samples were collected from eastern Poland and a dose-response study with tribenuron-methyl was performed. Eleven populations resistant to tribenuron-methyl were identified. All populations from this study as well as 6 additional resistant populations characterised in the previous dose-response studies were subjected to molecular analysis of the ALS gene. Target-site resistance due to mutations P197S, P197Q, P197T and P197A were identified in 8 populations from Warmia-Masuria and Podlaskie provinces. This is the first case of target-site resistance (TSR) in C. cyanus confirmed by sequencing of the ALS gene. Moreover in some resistant plants, ten changes in the amino acid ALS sequence were identified in comparison to those in the susceptible ones. In none of the populations were all mutations detected in the same individual. The highest frequency of mutations was detected in Warmia-Masuria province. Some C. cyanus populations resistant to ALS inhibitors showed hormesis effect concerning shoot fresh weight after tribenuron-methyl treatment. Stimulation due to half the recommended dose of tribenuron-methyl was the highest and the difference between untreated and treated plants was statistically significant in two populations from Warmia-Masuria and in one from Podlaskie province. [ABSTRACT FROM AUTHOR]

The review is devoted to the analysis of modern literature data on rhizosphere bacteria and their role in the vital activity of plants. The structure of the rhizosphere is characterized, the role of plants as centers of formation of microbial communities is shown, data on the taxonomic affiliation of the main groups of microorganisms inhabiting the rhizosphere are presented. The associative relationships of rhizobacteria with a partner plant and the modern concept of a holobiont as a combination of a plant organism and associated microorganisms are considered. The role of rhizobacteria in the processes of azo fixation is discussed in detail. The mechanisms of direct stimulation of plant growth through the synthesis of phytohormones, improvement of phosphorus and nitrogen nutrition and increase in stress resistance, as well as indirect stimulation through antagonism with respect to phytopathogenic microorganisms are presented. The criteria for the selection of rhizobacteria for practical purposes are discussed. [ABSTRACT FROM AUTHOR]

Abstract Centaurea cyanus L. is a common field weed in Eastern Europe but only in Poland biotypes of this species with resistance to acetolactate synthase (ALS) inhibitors have been confirmed. This phenomenon is constantly developing and spreading to consecutive regions of Poland. This study aimed to assess the response of selected Polish C. cyanus populations to tribenuron-methyl and to analyse the genetic variability of the ALS gene of C. cyanus populations resistant to ALS inhibitors. Between 2017 and 2021, 13 seed samples were collected from eastern Poland and a dose-response study with tribenuron-methyl was performed. Eleven populations resistant to tribenuron-methyl were identified. All populations from this study as well as 6 additional resistant populations characterised in the previous dose-response studies were subjected to molecular analysis of the ALS gene. Target-site resistance due to mutations P197S, P197Q, P197T and P197A were identified in 8 populations from Warmia-Masuria and Podlaskie provinces. This is the first case of target-site resistance (TSR) in C. cyanus confirmed by sequencing of the ALS gene. Moreover in some resistant plants, ten changes in the amino acid ALS sequence were identified in comparison to those in the susceptible ones. In none of the populations were all mutations detected in the same individual. The highest frequency of mutations was detected in Warmia-Masuria province. Some C. cyanus populations resistant to ALS inhibitors showed hormesis effect concerning shoot fresh weight after tribenuron-methyl treatment. Stimulation due to half the recommended dose of tribenuron-methyl was the highest and the difference between untreated and treated plants was statistically significant in two populations from Warmia-Masuria and in one from Podlaskie province.

Three strains of Lactiplantibacillus plantarum and three bifidobacteria (Bifidobacterium animalis subsp. lactis, Bifidobacterium breve, and Bifidobacterium subtile) were used as target strains; in addition, for each microorganism, the cell-free supernatant (CFS) was produced and used as an ingredient of the growth medium. Namely CFSs from lactobacilli were used on bifidobacteria and CFSs from bifidobacteria were used on lactobacilli. The viable count was assessed, and the data were modelled through a reparametrized Gompertz equation cast both in the positive and negative form to evaluate the parameters t-7log, which is the time after which the viable count was 7 log CFU/mL, and the t-7log*, which is the time after which the viable count was below 7 log CFU/mL; the difference between the t-7log* and t-7log defines the stability time. Statistics through a multiparametric ANOVA (analysis of variance) provided evidence for the presence of a bifidogenic and/or bioactive factor produced by bifidobacteria and active on lactobacilli, and vice versa (bioactive factor of lactobacilli with a functional effect on bifidobacteria), although further studies are required to better explain the mechanisms beyond the positive effects. In addition, the influence on the target strains can be found during the growth phase (stimulation), as well as during senescence and death phase (protective effect), with a strong strain/species dependence on both CFS production and target strain. [ABSTRACT FROM AUTHOR]

Ethanol has been reported as a supplementary substrate for microalgae cultivation, however, information about its effect on the morphology, growth and desired metabolites accumulation of Chlorella sorokiniana is limited. To bridge this gap, the effects of exogenous ethanol on C. sorokiniana was screened by providing 0.00, 0.0025, 0.025, 0.1 and 1% (v/v) ethanol. Results showed ethanol caused multifaceted effects. 0.0025% and 0.025% ethanol caused a small increase in cell volume, growth and photosystem II (PSII) function. In contrast, cell volume conspicuously increased and was up to 2.5-fold (63.5 µm3) and 3.6-fold (91.3 µm3) higher in the 0.1% and 1% ethanol treatment groups, respectively, compared with the control (25.1 µm3). 1% ethanol conspicuously reduced chlorophyll concentration, inhibited growth, damaged the photosynthetic apparatus and decreased PSII electron transport. Carbohydrate and lipid accumulation increased in the 0.1% (112.6±7.8 µg mL-1) and 1% (217.87±31.6 µg mL-1) ethanol by 1.6 and 50-fold, compared to the control (70.5±2.2 µg mL-1and 7.2±2.6 µg mL-1). The cell permeability also increased coinciding with the pronounced increse of reactive oxygen species, particularly in the 0.1 and 1% ethanol treatment groups. There were giant palmloid-like cells containing unequal and numerous daughter cells in the higher ethanol treatments, indicating the cell cycle has been altered through suppression of mother cell cytokinesis, which could serve as a protective function to overcome ethanol stress. The results suggest that ethanol has the potential to be used as an impotent substrate to induce lipid and carbohydrate accumulation in C. sorokiniana cultivation. [ABSTRACT FROM AUTHOR]

Three cyanobacterial strains, Anabaena laxa C11, Nostoc carneum BF2, Anabaena doliolum BF4, producing plant growth promoting metabolites such as sugars, indole acetic acid and proteins were selected for priming seeds of three varieties of tomato and two of spinach, followed by nursery raising of seedlings in soil-less potting mixes. The performance of two tomato varieties NS2533 and NS4266, was superior, as compared to Jewel, with enhancement of 12% to 29% in terms of length and weight of root/shoots, as well as 76% more pigments. In tomato, Nostoc carneum BF2 was superior, closely followed by Anabaena laxa C11. Among the two Spinach varieties evaluated, Pusa All green responded with 15–20% significantly higher values of seedling traits, as compared to Mulayam. Vigor indices were significantly higher with the cyanobacterial priming treatments, with Anabaena laxa C11, showing 27% higher values, over control. Principal Component and Multivariate Analyses highlighted the significant correlation between chlorophyll and available N content of mix with biometrical and pigment-related attributes. Transplantation of best performing varieties of tomato -NS4266 and spinach -Pusa All green in climate-controlled polyhouse recorded significantly higher yields in the cyanobacterium-primed plants, over control. Such promising crop-cyanobacterium interactions can be explored for enhancing the productivity of nursery-raised vegetable crops. [ABSTRACT FROM AUTHOR]

Researchers have recently sought a comprehensive strategy to reduce the harmful effects of synthetic chemicals in agricultural production to improve productivity and quality. Biostimulants benefit plants by protecting soil and water resources and eliminating adverse environmental effects from pesticides and chemical fertilizers. Plant biostimulants, also called bioactivators, are becoming increasingly well­liked in the agricultural sector due to their capacity to boost a plant’s growth rate and increase its resistance to stress. Biostimulants are frequently used because they can increase crop quality, nutrient assimilation, growth rate, and stress tolerance. This article thoroughly examines biostimulants’ effects on ornamental plants, concentrating on their ability to withstand environmental stressors. Prior studies have demonstrated that a combination of non­pathogenic microbes, protein hydrolysates, humic and fulvic acids, and algal extracts benefits ornamental plants. This review’s main aims are biostimulants’ effects on raising agricultural yield, enhancing nutrient uptake, enhancing photosynthesis, and shielding plants from biotic and abiotic stress. The role of biostimulants in more resilient and sustainable farming practices is also covered. [ABSTRACT FROM AUTHOR]

The possibility of using radiation from a two-frequency pulsed copper vapor laser with wavelengths of 510.6 and 578.2 nm with an exposure of 30 to 120 s to stimulate the development of coniferous trees (spruce, pine, larch) with single seed irradiation is shown. The stimulation effect manifests itself at various early stages of development, such as the awakening of seeds in the aquatic environment in the first hours of the experiment (according to the electron absorption spectroscopy data), seed germination, and seedling growth under stressful cultivation conditions. Possible causes of light exposure to plant seeds are discussed. [ABSTRACT FROM AUTHOR]

Researchers have recently sought a comprehensive strategy to reduce the harmful effects of synthetic chemicals in agricultural production to improve productivity and quality. Biostimulants benefit plants by protecting soil and water resources and eliminating adverse environmental effects from pesticides and chemical fertilizers. Plant biostimulants, also called bioactivators, are becoming increasingly well-liked in the agricultural sector due to their capacity to boost a plant’s growth rate and increase its resistance to stress. Biostimulants are frequently used because they can increase crop quality, nutrient assimilation, growth rate, and stress tolerance. This article thoroughly examines biostimulants’ effects on ornamental plants, concentrating on their ability to withstand environmental stressors. Prior studies have demonstrated that a combination of non-pathogenic microbes, protein hydrolysates, humic and fulvic acids, and algal extracts benefits ornamental plants. This review’s main aims are biostimulants’ effects on raising agricultural yield, enhancing nutrient uptake, enhancing photosynthesis, and shielding plants from biotic and abiotic stress. The role of biostimulants in more resilient and sustainable farming practices is also covered

Lipopolysaccharide is the main structural component of the outer membrane of Gram-negative bacteria, which can also be a part of extracellular polymeric substances. Lipopolysaccharides of bacteria that stimulate the growth and development of plants belong to the group of molecules that form a microbe-associated molecular pattern (MAMP). These glycoconjugates of both symbiotic and phytopathogenic bacteria induce the activation of immune responses in plants. However, the level of plant response under the infl uence of symbiont lipopolysaccharides diff ers signifi cantly, also due to their structural features, which make it possible to bypass or weaken the reactions of innate autoimmunity. In this paper, we present the results of the analysis of the reactions of wheat seedlings Triticum aestivum L. after incubation with lipopolysaccharide of associative bacteria Azospirillum palustre B2(T). Incubation of wheat seedlings in the presence of A. palustre B2 lipopolysaccharide for three days led to the activation of plant growth processes, namely an increase in the length of shoots, roots, the area of the fi rst leaf, and a change in the content of pigments in the leaves.

Abstract Background The production of Pleurotus ostreatus mycelium as a promising object for use in food and other industries is hampered by a lack of information about the strain-specificity of this fungus mycelium growth and its acquisition of various biological activities. Therefore, this research aimed to investigate mycelial growth of different P. ostreatus strains on varies solid and liquid media as well as to evaluate strains antagonistic, antibacterial, antiradical scavenging activities, and total phenolic content. Results Potato Dextrose Agar medium was suitable for all strains except P. ostreatus strain 2460. The best growth rate of P. ostreatus 2462 strain on solid culture media was 15.0 ± 0.8 mm/day, and mycelia best growth on liquid culture media—36.5 ± 0.2 g/l. P. ostreatus strains 551 and 1685 were more susceptible to positive effect of plant growth regulators Ivin, Methyur and Kamethur. Using of nutrient media based on combination of natural waste (amaranth flour cake and wheat germ, wheat bran, broken vermicelli and crumbs) has been increased the yield of P. ostreatus strains mycelium by 2.2–2.9 times compared to the control. All used P. ostreatus strains displayed strong antagonistic activity in co-cultivation with Aspergillus niger, Candida albicans, Issatchenkia orientalis, Fusarium poae, Microdochium nivale in dual-culture assay. P. ostreatus 2462 EtOAc mycelial extract good inhibited growth of Escherichia coli (17.0 ± 0.9 mm) while P. ostreatus 2460 suppressed Staphylococcus aureus growth (21.5 ± 0.5 mm) by agar well diffusion method. The highest radical scavenging effect displayed both mycelial extracts (EtOH and EtOAc) of P. ostreatus 1685 (61 and 56%) by DPPH assay as well as high phenolic content (7.17 and 6.73 mg GAE/g) by the Folin-Ciocalteu’s method. The maximal total phenol content (7.52 mg GAE/g) demonstrated of P. ostreatus 2461 EtOH extract. Conclusions It is found that the growth, antibacterial, antiradical scavenging activity as well as total phenolic content were dependent on studied P. ostreatus strains in contrast to antagonistic activity. The proposed culture mediums of natural waste could be an alternative to commercial mediums for the production mycelial biomass of P. ostreatus strains.

The stimulation of growth and development of crops using ionising radiation (radiation hormesis) has been reported by many research groups. However, specific genes contributing to the radiation stimulation of plant growth are largely unknown. In this work, we studied the impact of the low-dose γ-irradiation of barley seeds on the growth dynamics and gene expression of eight barley cultivars in a greenhouse experiment. Our findings confirmed that candidate genes of the radiation growth stimulation, previously established in barley seedlings (PM19L-like, CML31-like, and AOS2-like), are significant in radiation hormesis throughout ontogeny. In γ-stimulated cultivars, the expression of these genes was aligned with the growth dynamics, yield parameters, and physiological conditions of plants. We identified contrasting cultivars for future gene editing and found that the γ-stimulated cultivar possessed some specific abiotic stress-responsive elements in the promotors of candidate genes, possibly revealing a new level of radiation hormesis effect execution. These results can be used in creating new productive barley cultivars, ecological toxicology of radionuclides, and eustress biology studies. [ABSTRACT FROM AUTHOR]

This article presents data on isolation and characterization of native plant growth-promoting rhizobacteria (PGPR) from the rhizosphere and root-endosphere of X Triticosecale Wittmack growing in Almaty region. A total of 22 distinct (eighteen gram-negative and four gram-positive) bacterial isolates were identified, classified according to their spore-forming activity: eighteen non-spore-forming and four spore-forming bacteria. Bacterial isolates were screened in vitro for PGPR characteristics and evaluated for their beneficial effects on the early growth of triticale variety X Triticosecale Wittmack. The findings of our research indicated isolation of four growth-promoting bacteria (AS4, AS6, AR1, TS6), three antifungal bacteria (AR2 and AS7), and one strain of combined action, i.e. high growth-promoting and fungistatic activity (AR6). Research has demonstrated that PGPR can be utilized as biofertilizers for crop production. Study marks the beginning of a larger investigation into the bacterial diversity of the triticale variety X Triticosecale Wittmack in the Almaty region. [ABSTRACT FROM AUTHOR]

Green synthesized nanoparticles are believed to alleviate the detrimental effects of chemical fertilizers and the multidrug resistance of various microbial strains. This study evaluates the use of bush tea-mediated zinc oxide nanoparticles (ZnO NPs) for chickpea fertilization and assesses their cytotoxicity, antioxidant and antibacterial activity. The study demonstrated that the application of ZnO NPs improved the number of leaves, nodules, biomass and yield of chickpea cultivars under glasshouse conditions. The authors suggest that biosynthesized ZnO NPs are a good plant growth stimulant. The control with no nanoparticles application, had higher values of photosynthetic rate and water use efficiency in the Desi genotype whereas for the Kabuli genotype, 25 mg/L showed higher values of stomatal conductance and transpiration efficiency, while 15 mg/L gave the highest water use efficiency and photosynthetic rate. Furthermore, the inhibitory activities of bacteria were reported in which E. coli and S. aureus were the most sensitive bacterial strains. The ZnO NPs also quenched free radicals that demonstrate antioxidant activity. Thus, they can be beneficial to both plants and humans as they reduce oxidative stress that can cause diseases. Furthermore, toxicity to cells was evaluated and ZnO NPs were less toxic to the studied cells with IC50 values of 16.17 µg/mL and 21.30 µg/mL against lung cancer and embryonic cell lines. Thus, the use of ZnO nanoparticles with antimicrobial activity could help fight against several diseases attacking humans and plants.

Three strains of Lactiplantibacillus plantarum and three bifidobacteria (Bifidobacterium animalis subsp. lactis, Bifidobacterium breve, and Bifidobacterium subtile) were used as target strains; in addition, for each microorganism, the cell-free supernatant (CFS) was produced and used as an ingredient of the growth medium. Namely CFSs from lactobacilli were used on bifidobacteria and CFSs from bifidobacteria were used on lactobacilli. The viable count was assessed, and the data were modelled through a reparametrized Gompertz equation cast both in the positive and negative form to evaluate the parameters t-7log, which is the time after which the viable count was 7 log CFU/mL, and the t-7log*, which is the time after which the viable count was below 7 log CFU/mL; the difference between the t-7log* and t-7log defines the stability time. Statistics through a multiparametric ANOVA (analysis of variance) provided evidence for the presence of a bifidogenic and/or bioactive factor produced by bifidobacteria and active on lactobacilli, and vice versa (bioactive factor of lactobacilli with a functional effect on bifidobacteria), although further studies are required to better explain the mechanisms beyond the positive effects. In addition, the influence on the target strains can be found during the growth phase (stimulation), as well as during senescence and death phase (protective effect), with a strong strain/species dependence on both CFS production and target strain.

The influence of the culture medium without bacterial cells, obtained after the cultivation of endophytic bacteria Priestia endophytica UCM B-5715, on the growth and synthesis of some metabolites in lettuce and chicory seedlings under in vitro conditions was studied. Bacteria were cultivated in liquid LB medium at 37 ºC for 24 h with periodic stirring. The culture fluid was separated from the cell biomass. For preparing the test solution, the supernatant was sterilized by filtration through a filter with a pore diameter of 0.2 µm (Sartorius, Minisart) and diluted with sterile distilled water. The 20% culture fluid (30 µl/plant) was applied to 3-day-old seedlings. In 28 days root and shoot weights of treated chicory plants were 54.3 ± 6.9 and 260.0 ± 20.2 mg, respectively (8.0 ± 0.7 and 91.4 ± 7.0 mg for the control plants). Total flavonoid content and antioxidant activity increased only in chicory plants after the addition of the test solution. Significant changes in the metabolism of treated plants were detected. In the treated lettuce plants asparagine content increased compared to the control (90 vs 22 µg/g, p < 0.1). The median content of fructose was also higher in treated lettuce and chicory plants (1469 vs 73 µg/g and 2278 vs 1051 µg/g). Therefore, the use of culture fluid obtained after the cultivation of P. endophytica UСM B-5715 stimulated the growth of lettuce and chicory plants, affecting the synthesis of some compounds in single-treated plants. These results indicate the potential of compounds excreted during bacterial growth to create natural growth stimulators. [ABSTRACT FROM AUTHOR]

The abrupt release of heavy metals (HM) within environment by anthropogenic sources affect the living populations. Plants face many intricacies to survive under such conditions, therefore remediation of HM-contaminated soils is need of the hour. However, chemical processes are very costly and non-sustainable, henceforth HM-microbe associations play an integral role in reducing HM-stress from plants. Plants and microbes within rhizosphere are well adapted to metalliferous environment, thereby prove to be a best assistant for phytoremediation. Root exudates act as nutrients for microbes for establishment of inter-communication systems. Plant–microbe associations is a conducive dimension for phytoremediation, a low input, highly productive, and sustainable technology for maintaining HM-toxicity in soils. It is an emerging technology and is recommended for cleaning up the polluted sites, since plant growth promoting microbes (PGPM) have shown their effectively toward metal toxicity through their detoxification and resistance mechanisms along with growth promoting traits. Microbe-assisted phytoremediation is mainly facilitated either through direct or indirect manner. They synthesize various nutritional and phytohormonal substances namely, growth regulators, siderophores, enzymes, transformation of mineral nutrients (phosphate, potassium, nitrogen etc.). Further, they also modulate the metal detoxification, accumulation, and sequestration abilities of plants through secreting extracellular components, organic acids, biosurfactants, chelators etc. Besides, the metal bioavailability within soil is also modulated via different mechanisms like acidification, precipitation, complexation, or redox reactions. Apart from this, genetic engineering is a progressive approach that is combined with microbe-assisted phytoremediation to attain excellent results. The cumulative knowledge of transgenics, engineering designs, ecological knowledge is an essential element for phytoremediation using genetically engineered microbes. In this review, we have presented the advancement made hitherto for effective understanding of molecular, biochemical, and physiological mechanisms associated with plant–microbe interactions during phytoremediation. Along with this, we have shed light on the mechanisms involved in phytoremediation, therefore, this sustainable technology is widely accepted in reclaiming HM-toxicity to induce the yield and quality of soils and crops. [ABSTRACT FROM AUTHOR]

2-Ketones are signal molecules reported as plant growth stimulators, but their applications in vegetables have yet to be achieved. Solid lipid nanoparticles (SLNs) emerge as a relevant nanocarrier to develop formulations for the controlled release of 2-ketones. In this sense, seedlings of Lactuca sativa exposed to 125, 375, and 500 µL L−1 of encapsulated 2-nonanone and 2-tridecanone into SLNs were evaluated under controlled conditions. SLNs evidenced a spherical shape with a size of 230 nm. A controlled release of encapsulated doses of 2-nonanone and 2-tridecanone was observed, where a greater release was observed as the encapsulated dose of the compound increased. Root development was strongly stimulated mainly by 2-tridecanone and leaf area (25–32%) by 2-nonanone. Chlorophyll content increased by 15.8% with exposure to 500 µL L−1 of 2-nonanone, and carotenoid concentration was maintained with 2-nonanone. Antioxidant capacity decreased (13–62.7%) in L. sativa treated with 2-ketones, but the total phenol concentration strongly increased in seedlings exposed to some doses of 2-ketones. 2-Tridecanone strongly modulates the enzymatic activities associated with the scavenging of H2O2 at intra- and extracellular levels. In conclusion, 2-ketones released from SLNs modulated the growth and the antioxidant system of L. sativa, depending on the dose released. [ABSTRACT FROM AUTHOR]

Summary: The elevation of CO2 in the atmosphere increases plant biomass but decreases their mineral content. The genetic and molecular bases of these effects remain mostly unknown, in particular in the root system, which is responsible for plant nutrient uptake.To gain knowledge about the effect of elevated CO2 on plant growth and physiology, and to identify its regulatory in the roots, we analyzed genome expression in Arabidopsis roots through a combinatorial design with contrasted levels of CO2, nitrate, and iron.We demonstrated that elevated CO2 has a modest effect on root genome expression under nutrient sufficiency, but by contrast leads to massive expression changes under nitrate or iron deficiencies. We demonstrated that elevated CO2 negatively targets nitrate and iron starvation modules at the transcriptional level, associated with a reduction in high‐affinity nitrate uptake. Finally, we inferred a gene regulatory network governing the root response to elevated CO2. This network allowed us to identify candidate transcription factors including MYB15, WOX11, and EDF3 which we experimentally validated for their role in the stimulation of growth by elevated CO2.Our approach identified key features and regulators of the plant response to elevated CO2, with the objective of developing crops resilient to climate change. See also the Commentary on this article by Kaiser, 239: 818–820. [ABSTRACT FROM AUTHOR]

Summary: The elevation of CO2 in the atmosphere increases plant biomass but decreases their mineral content. The genetic and molecular bases of these effects remain mostly unknown, in particular in the root system, which is responsible for plant nutrient uptake.To gain knowledge about the effect of elevated CO2 on plant growth and physiology, and to identify its regulatory in the roots, we analyzed genome expression in Arabidopsis roots through a combinatorial design with contrasted levels of CO2, nitrate, and iron.We demonstrated that elevated CO2 has a modest effect on root genome expression under nutrient sufficiency, but by contrast leads to massive expression changes under nitrate or iron deficiencies. We demonstrated that elevated CO2 negatively targets nitrate and iron starvation modules at the transcriptional level, associated with a reduction in high‐affinity nitrate uptake. Finally, we inferred a gene regulatory network governing the root response to elevated CO2. This network allowed us to identify candidate transcription factors including MYB15, WOX11, and EDF3 which we experimentally validated for their role in the stimulation of growth by elevated CO2.Our approach identified key features and regulators of the plant response to elevated CO2, with the objective of developing crops resilient to climate change. See also the Commentary on this article by Kaiser, 239: 818–820. [ABSTRACT FROM AUTHOR]

The article focuses on evaluating the potential of co-applying arbuscular mycorrhizal fungi and bacterial strains from different taxonomic groups to enhance the growth of common bean plants and suppress Rhizoctonia solani-induced root rot. It study investigates the impact of 14 bacterial strains on R. solani mycelial growth in laboratory tests and explores their combined application with two arbuscular mycorrhizal fungi in a greenhouse experiment.

Forty pure microbial cultures have been isolated from sewage sludge to develop biopreparations using the microbiological screening method. Among all studied microorganisms sixteen strains of different taxonomic groups (2 strains of each Bacillus and Streptomyces, 7 strains of Pseudomonas, and 1 strain of each of the following Acinetobacter, Rhizobium, Pseudarthrobacter, Sphingomonas, and Rothia) were selected providing the best cellulose-degrading ability, as well as having good growth and quick biomass accumulation on various substrates. The isolates were additionally tested for the ability to consume organic and mineral nitrogen species, and to encourage seedlings' growth. Moreover, we have evaluated the nitrogenase activity for some strains. As a result, the following strains of Bacillus megaterium № 10, Rhizobium pusense № 25, Sphingomonas paucimobilis № 49, Pseudomonas fluorescens № 83, Streptomyces albidoflavus № 81, Streptomyces graminearus № 61 demonstrated the potential to be used as bio-activator for sewage sludge composting and as multifunctional biologics in crop production. [ABSTRACT FROM AUTHOR]

Glyphosate is a nonselective herbicide of systemic action that inhibits the enzyme 5-enolpyruvylshikimate-3-phosphate synthase, thus compromising amino acid production and consequently the growth and development of susceptible plants. The objective of this study was to evaluate the hormetic effect of glyphosate on the morphology, physiology, and biochemistry of coffee plants. Coffee seedlings (Coffea arabica cv Catuaí Vermelho IAC-144) were transplanted into pots filled with a mixture of soil and substrate and subjected to ten doses of glyphosate: 0, 11.25, 22.5, 45, 90, 180, 360, 720, 1440, and 2880 g acid equivalent (ae) ha−1. Evaluations were performed using the morphological, physiological, and biochemical variables. Data analysis for the confirmation of hormesis occurred with the application of mathematical models. The hormetic effect of glyphosate on coffee plant morphology was determined by the variables plant height, number of leaves, leaf area, and leaf, stem, and total dry mass. Doses from 14.5 to 30 g ae ha−1 caused the highest stimulation. In the physiological analyses, the highest stimulation was observed upon CO2 assimilation, transpiration, stomatal conductance, carboxylation efficiency, intrinsic water use efficiency, electron transport rate, and photochemical efficiency of photosystem II at doses ranging from 4.4 to 55 g ae ha−1. The biochemical analyses revealed significant increases in the concentrations of quinic acid, salicylic acid, caffeic acid, and coumaric acid, with maximum stimulation at doses between 3 and 140 g ae ha−1. Thus, the application of low doses of glyphosate has positive effects on the morphology, physiology, and biochemistry of coffee plants. [ABSTRACT FROM AUTHOR]

Cadmium stress is a barrier to crop production, yield, quality, and sustainable agriculture. In the current study, we investigated the characteristics of bacterial strain Pseudomonas sp. OBA 2.4.1 under cadmium (CdCl2) stress and its influence on Cd stresses in pea (Pisum sativum L.) seedlings. It was revealed that strain OBA 2.4.1 is tolerant of up to 2 mM CdCl2, and seed treatment with the bacterium enhanced pea plant growth (length of seedlings) under 0.5 mM cadmium stress. This bacterial strain showed plant growth-promoting properties, including biofilm formation and siderophore activity. An important advantage of the studied strain OBA 2.4.1 is its ability to colonize the plant roots. Moreover, the inoculation with strain OBA 2.4.1 significantly reduced oxidative stress markers in pea seedlings under cadmium stress. These findings suggest that cadmium stress-tolerant strain OBA 2.4.1 could enhance pea plant growth by mitigating stress-caused damage, possibly providing a baseline and eco-friendly approach to address heavy metal stress for sustainable agriculture. [ABSTRACT FROM AUTHOR]

Chlamydomonas reinhardtii is a eukaryotic, unicellular photosynthetic organism and a potential algal platform for producing biomass and recombinant proteins for industrial use. Ionizing radiation is a potent genotoxic and mutagenic agent used for algal mutation breeding that induces various DNA damage and repair responses. In this study, however, we explored the counterintuitive bioeffects of ionizing radiation, such as X- and γ-rays, and its potential as an elicitor to facilitate batch or fed-batch cultivation of Chlamydomonas cells. A certain dose range of X- and γ-rays was shown to stimulate the growth and metabolite production of Chlamydomonas cells. X- or γ-irradiation with relatively low doses below 10 Gy substantially increased chlorophyll, protein, starch, and lipid content as well as growth and photosynthetic activity in Chlamydomonas cells without inducing apoptotic cell death. Transcriptome analysis demonstrated the radiation-induced changes in DNA damage response (DDR) and various metabolic pathways with the dose-dependent expression of some DDR genes, such as CrRPA30, CrFEN1, CrKU, CrRAD51, CrOASTL2, CrGST2, and CrRPA70A. However, the overall transcriptomic changes were not causally associated with growth stimulation and/or enhanced metabolic activities. Nevertheless, the radiation-induced growth stimulation was strongly enhanced by repetitive X-irradiation and/or subsequent cultivation with an inorganic carbon source, i.e., NaHCO3, but was significantly inhibited by treatment of ascorbic acid, a scavenger of reactive oxygen species (ROS). The optimal dose range of X-irradiation for growth stimulation differed by genotype and radiation sensitivity. Here, we suggest that ionizing radiation within a certain dose range determined by genotype-dependent radiation sensitivity could induce growth stimulation and enhance metabolic activities, including photosynthesis, chlorophyll, protein, starch, and lipid synthesis in Chlamydomonas cells via ROS signaling. The counterintuitive benefits of a genotoxic and abiotic stress factor, i.e., ionizing radiation, in a unicellular algal organism, i.e., Chlamydomonas, may be explained by epigenetic stress memory or priming effects associated with ROS-mediated metabolic remodeling. [ABSTRACT FROM AUTHOR]

The aim of the present study was to develop an experimental system for an exploration of ethylene-dependent responses using intact growing Ranunculus sceleratus plants and to approbate the system for assessing the role of ethylene in salinity tolerance and ion accumulation. Plants were cultivated in sealed plastic containers in a modified gaseous atmosphere by introducing ethylene or 1-methylcyclopropene (1-MCP), a competitive inhibitor of ethylene action. High humidity inside the containers induced a fast elongation of the leaf petioles of R. sceleratus. The effect was ethylene-dependent, as 1-MCP completely blocked it, but exogenous ethylene further promoted petiole elongation. Exogenous ethylene decreased (by 48%) but 1-MCP increased (by 48%) the Na+ accumulation in leaf blades of NaCl-treated plants. The experimental system was further calibrated with ethylene and silica xerogel, and the optimum concentrations were found for inducing leaf petiole elongation (10 μL L–1 ethylene) and preventing leaf petiole elongation (200 g silica xerogel per 24 L), respectively. The second experiment involved a treatment with NaCl in the presence of 1-MCP, ethylene, or 1-MCP + ethylene, both in normal and high air humidity conditions. In high humidity conditions, NaCl inhibited petiole elongation by 25% and ethylene treatment fully reversed this inhibition and stimulated elongation by 12% in comparison to the response of the control plants. Treatment with 1-MCP fully prevented this ethylene effect. In normal humidity conditions, NaCl inhibited petiole elongation by 20%, which was reversed by ethylene without additional elongation stimulation. However, 1-MCP only partially inhibited the ethylene effect on petiole elongation. In high humidity conditions, ethylene inhibited Na+ accumulation in NaCl-treated plants by 14%, but 1-MCP reversed this effect. In conclusion, the stimulation of endogenous ethylene production in R. sceleratus plants at a high air humidity or in flooded conditions reverses the inhibitory effect of salinity on plant growth and concomitantly inhibits the accumulation of Na+ in tissues. R. sceleratus is a highly promising model species for use in studies regarding ethylene-dependent salinity responses and ion accumulation potential involving the manipulation of a gaseous environment. [ABSTRACT FROM AUTHOR]

The response of phytoplankton and its satellite bacteria to various concentrations (0.01%–10% v/v) of ethanol is studied. To elucidate the effect of ethanol, single-strains of phytoplankton (SSP) culture, pure strains of satellite bacteria isolated from nonaxenic SSP cultures, and Escherichia coli were screened. Results indicate that ethanol could promote the growth and photosynthetic efficiency (Fv/Fm) of SSP at 0.01% and the growth of satellite bacteria at 0.01%–1%. Nevertheless, ethanol inhibited the growth and Fv/Fm of SSP at 0.1%–1%, and killed bacteria and SSP at 10% concentration. Further investigation on a satellite bacterium (Mameliella alba) revealed that ethanol promotes growth by serving as a growth stimulant rather than a metabolic carbon source. The 16S rRNA gene amplicon indicated that all nonaxenic SSP cultures harbor distinct satellite bacteria communities where the SSP culture of Skeletonema costatum, Phaeodactylum tricornutum, and Dunaliella bardawil were dominated by bacteria genera of Marivita (∼80%), Dinoroseobacter (∼47%), and Halomonas (∼87%), respectively, indicating that every SSP cultures have their own distinct satellite bacterial community. The bacteria family Rhodobacteraceae was dominant in the two marine diatoms, whereas Halomonadaceae was dominant in the saline green microalga. Compared to their respective controls, the supply of 0.5% ethanol to SSP cultures promoted the growth of the satellite bacteria but did not cause a significant difference in species composition of satellite bacteria. Therefore, a low concentration of ethanol can promote the growth of bacteria in a non-selective way. This study enriched our knowledge about the effect of ethanol on aquatic microbes and provided a baseline for basic and applied biotechnological research in the aquatic environment in the future. [ABSTRACT FROM AUTHOR]

Recent studies have shown that nanomaterials, including carbon nanotubes, are associated with a wide range of effects on living organisms, from stimulation to toxic effects. Plants are an important object of such research, which is associated with the potential use of carbon nanomaterials in agriculture and environmental protection. At the same time, the specific mechanisms of formation of plant resistance to the effects of carbon nanotubes remain not fully understood, especially in woody plants. Therefore, we studied the effect of aqueous colloids of multi-walled carbon nanotubes (MWCNTs) with an outer diameter of 10–30 nm and a length of about 2 μm at a concentration of 1, 10, 50, and 100 mg/L on morphometric parameters and the level of expression of stress resistance genes in Betula pubescens Ehrh. and B. pendula Roth. plants in greenhouse conditions. The results showed an increase in the length and diameter of the shoot in the studied plants. The dry biomass of the leaf increased by 30%, the stem by 42%, and the root by 49% when using MWCNTs at a concentration of 10 mg/L. The expression of the stress resistance genes DREB2 and PR-10 significantly increased under the influence of 1 mg/L MWCNTs on plants of both species. At the same time, the use of 100 mg/L nanoparticles led to a decrease in the studied parameters in Betula pendula, which may be associated with the negative effect of MWCNTs in high concentrations. The revealed positive effects of low concentrations of MWCNTs on morphometric parameters and stimulation of stress resistance genes by nanotubes open up prospects for their use in woody plant biotechnology. [ABSTRACT FROM AUTHOR]

The modern approach to the creation of biological products to stimulate plant growth is based on the study of specific inter-bacterial interactions. This study describes the impact that the introduction of strains of the genus Pseudomonas has on annual and perennial leguminous plants and the ecosystem of the leguminous plant—the indigenous microbial community. The objects of research under the conditions of vegetation experiments were plants of field peas (Pisum sativum L.), white lupine (Lupinus albus L.), chickpea (Cicer arietinum L.), alfalfa (Medicago sativa subsp. varia (Martyn) Arcang.), and white sweet clover (Melilotus albus Medik.). For the treatment of plant seeds, a liquid culture of strains of growth-stimulating bacteria Pseudomonas koreensis IB-4, and P. laurentiana ANT 17 was used. The positive effect of the studied strains on the germination, growth and development of plants was established. There was no inhibitory effect of inoculants on rhizobia; on the contrary, an increase in nodule formation was observed. The possibility of recultivation of oil-contaminated soil using chickpea and alfalfa as phytomeliorants and growth-stimulating strains P. koreensis IB-4, P. laurentiana ANT 17 as inoculants was evaluated. It is proved that seed treatment improved the morphological parameters of plants, as well as the efficiency of oil destruction. [ABSTRACT FROM AUTHOR]

High temperatures inhibit plant growth. A proposed strategy for improving plant productivity under elevated temperatures is the use of plant growth-promoting rhizobacteria (PGPR). While the effects of PGPR on plant shoots have been extensively explored, roots—particularly their spatial and temporal dynamics—have been hard to study, due to their below-ground nature. Here, we characterized the time- and tissue-specific morphological changes in bacterized plants using a novel non-invasive high-resolution plant phenotyping and imaging platform—GrowScreen-Agar II. The platform uses custom-made agar plates, which allow air exchange to occur with the agar medium and enable the shoot to grow outside the compartment. The platform provides light protection to the roots, the exposure of it to the shoots, and the non-invasive phenotyping of both organs. Arabidopsis thaliana, co-cultivated with Paraburkholderia phytofirmans PsJN at elevated and ambient temperatures, showed increased lengths, growth rates, and numbers of roots. However, the magnitude and direction of the growth promotion varied depending on root type, timing, and temperature. The root length and distribution per depth and according to time was also influenced by bacterization and the temperature. The shoot biomass increased at the later stages under ambient temperature in the bacterized plants. The study offers insights into the timing of the tissue-specific, PsJN-induced morphological changes and should facilitate future molecular and biochemical studies on plant–microbe–environment interactions. [ABSTRACT FROM AUTHOR]

2-Ketones are signal molecules reported as plant growth stimulators, but their applications in vegetables have yet to be achieved. Solid lipid nanoparticles (SLNs) emerge as a relevant nanocarrier to develop formulations for the controlled release of 2-ketones. In this sense, seedlings of Lactuca sativa exposed to 125, 375, and 500 µL L−1 of encapsulated 2-nonanone and 2-tridecanone into SLNs were evaluated under controlled conditions. SLNs evidenced a spherical shape with a size of 230 nm. A controlled release of encapsulated doses of 2-nonanone and 2-tridecanone was observed, where a greater release was observed as the encapsulated dose of the compound increased. Root development was strongly stimulated mainly by 2-tridecanone and leaf area (25–32%) by 2-nonanone. Chlorophyll content increased by 15.8% with exposure to 500 µL L−1 of 2-nonanone, and carotenoid concentration was maintained with 2-nonanone. Antioxidant capacity decreased (13–62.7%) in L. sativa treated with 2-ketones, but the total phenol concentration strongly increased in seedlings exposed to some doses of 2-ketones. 2-Tridecanone strongly modulates the enzymatic activities associated with the scavenging of H2O2 at intra- and extracellular levels. In conclusion, 2-ketones released from SLNs modulated the growth and the antioxidant system of L. sativa, depending on the dose released.

Autotrophic acidophilic bacteria Acidithiobacillus ferrooxidans is a model species for studying metal bioleaching from low-grade sulfide ores and concentrates. Arsenopyrite gold-bearing concentrates are refractory and often processed using biohydrometallurgical approaches; therefore, it is important to develop methods to improve arsenopyrite bioleaching. In the present work, we have studied the possibility of improving arsenopyrite concentrate bioleaching by the strain of A. ferrooxidans. For this purpose, we have analyzed the genome of the strain A. ferrooxidans TFBk to reveal the genes potentially important in the bioleaching process. Genes determining resistance to arsenic, as well genes involved in the utilization of C1-compounds and resistance to oxidative stress, were revealed. Therefore, the possibility of increasing the rate of arsenopyrite concentrate bioleaching using C1-compounds (methanol and formate) was studied. Formate was able to increase both the biomass yield of the strain A. ferrooxidans TFBk as well as the bioleaching rate. In addition, the effect of redox potential increase by means of the addition of sodium persulfate in the medium on arsenopyrite concentrate bioleaching was studied. It was shown that the addition of 0.1% sodium persulfate stimulated strain growth, while a higher concentration inhibited it. Despite this, the rate of concentrate bioleaching increased in the presence of 0.5–1.0% of persulfate, which may be explained by the interactions of added oxidizer with concentrate components. [ABSTRACT FROM AUTHOR]

A water extract derived from the isolated cell walls of Chlorella sorokiniana (C. sorokiniana, Chlorella water extract, CWE) was analyzed for the presence of lipopolysaccharide (LPS)-related material via the Limulus amebocyte lysate (LAL) assay and evaluated for its growth stimulation effect on the bone marrow cells and splenocytes in vitro cell cultures. The extract contained low levels of LPS-related material, and a mass spectrum suggested that the extract contained many components, including a low level of a lipid A precursor, a compound known as lipid X, which is known to elicit a positive response in the LAL assay. Treatment with the CWE dose- and time-dependently stimulated the growth of mouse bone marrow cells (BMCs) and splenocytes (SPLs). Treatment with the CWE also increased specific BMC subpopulations, including antigen-presenting cells (CD19+ B cells, 33D1+ dendritic cells and CD68+ macrophages), and CD4+ and CD8+ T cells, but decreased the number of LY6G+ granulocytes. Treatment with the CWE also increased cytokine mRNA associated with T cell activation, including TNFα, IFNγ, and granzyme B in human lymphoblasts. The present study indicates that the cell wall fraction of C.sorokiniana contains an LPS-like material and suggests a candidate source for the bioactivity that stimulates growth of both innate and adaptive immune cells. [ABSTRACT FROM AUTHOR]

The dynamic interactions of plants and arbuscular mycorrhizal fungi (AMF) that facilitate the efficient uptake of minerals from soil and provide protection from various environmental stresses (biotic and abiotic) are now also attributed to a third component of the symbiosis. These are the less investigated mycorrhizae helper bacteria (MHB), which constitute a dense, active bacterial community, tightly associated with AMF, and involved in the development and functioning of AMF. Although AMF spores are known to host several bacteria in their spore walls and cytoplasm, their role in promoting the ecological fitness and establishment of AMF symbiosis by influencing spore germination, mycelial growth, root colonization, metabolic diversity, and biocontrol of soil borne diseases is now being deciphered. MHB also promote the functioning of arbuscular mycorrhizal symbiosis by triggering various plant growth factors, leading to better availability of nutrients in the soil and uptake by plants. In order to develop strategies to promote mycorrhization by AMF, and particularly to stimulate the ability to utilize phosphorus from the soil, there is a need to decipher crucial metabolic signalling pathways of MHB and elucidate their functional significance as mycorrhiza helper bacteria. MHB, also referred to as AMF bioenhancers, also improve agronomic efficiency and formulations using AMF along with enriched population of MHB are a promising option. This review covers the aspects related to the specificity and mechanisms of action of MHB, which positively impact the formation and functioning of AMF in mycorrhizal symbiosis, and the need to advocate MHB as AMF bioenhancers towards their inclusion in integrated nutrient management practices in sustainable agriculture. [ABSTRACT FROM AUTHOR]

Phosphate-based drinking water softeners are commonly used to prevent scale formation in drinking water distribution infrastructure. The main reason for drinking water softening is primarily economic (protection of pipes and extension of equipment life), while the health aspect of such treatment is usually neglected. The aim of this work is to investigate the effects of phosphate-based drinking water softeners on growth stimulation of Legionella pneumophila. Bacterial growth was observed at two different phosphate concentrations. On average, an increase in growth of 1.19-1.28 log CFU/mL was observed in selected samples with added phosphates compared with the control. The results of the in vitro experiment confirmed that the added phosphates stimulate the growth of L. pneumophila; growth stimulation could therefore be expected in drinking water distribution systems (DWDS) when phosphates are used as well. The availability of phosphorus in DWDS may be a crucial limiting factor for biofouling control. Consequently, phosphate-based chemicals for drinking water should be avoided or used with prudence, especially in drinking water with high concentrations of other nutrients. [ABSTRACT FROM AUTHOR]

Endophytic properties of entomopathogenic fungi currently receive considerable attention from the scientific community. In the present work, it was shown that the fungus Beauveria bassiana (strain BBK-1) is able to successfully colonize broad bean and sweet pepper plants under laboratory conditions. The green peach aphid actively bred on both plant species. The density of aphids developing on plants colonized by B. bassiana was significantly lower as compared to the control, both on peppers and beans. The growth-stimulating effect of endophytic colonization by B. bassiana was less pronounced on beans, while on sweet pepper plants, a significant increase in plant height and an earlier onset of the budding were found. The observed effects indicate that B. bassiana has a potential to be used as a polyfunctional biocontrol agent in agricultural practice.

Glyphosate is a nonselective herbicide of systemic action that inhibits the enzyme 5-enolpyruvylshikimate-3-phosphate synthase, thus compromising amino acid production and consequently the growth and development of susceptible plants. The objective of this study was to evaluate the hormetic effect of glyphosate on the morphology, physiology, and biochemistry of coffee plants. Coffee seedlings (Coffea arabica cv Catuaí Vermelho IAC-144) were transplanted into pots filled with a mixture of soil and substrate and subjected to ten doses of glyphosate: 0, 11.25, 22.5, 45, 90, 180, 360, 720, 1440, and 2880 g acid equivalent (ae) ha−1. Evaluations were performed using the morphological, physiological, and biochemical variables. Data analysis for the confirmation of hormesis occurred with the application of mathematical models. The hormetic effect of glyphosate on coffee plant morphology was determined by the variables plant height, number of leaves, leaf area, and leaf, stem, and total dry mass. Doses from 14.5 to 30 g ae ha−1 caused the highest stimulation. In the physiological analyses, the highest stimulation was observed upon CO2 assimilation, transpiration, stomatal conductance, carboxylation efficiency, intrinsic water use efficiency, electron transport rate, and photochemical efficiency of photosystem II at doses ranging from 4.4 to 55 g ae ha−1. The biochemical analyses revealed significant increases in the concentrations of quinic acid, salicylic acid, caffeic acid, and coumaric acid, with maximum stimulation at doses between 3 and 140 g ae ha−1. Thus, the application of low doses of glyphosate has positive effects on the morphology, physiology, and biochemistry of coffee plants.

Ionizing radiation, in addition to its genotoxic effects, induces reactive oxygen species (ROS) that can cause cellular damage or act as signaling molecules in cells. Typically, plants or algae that are exposed to mild primary stress exhibit resistance to subsequent severe stress through metabolic remodeling, which is referred to as stress priming. In contrast, this study explored a different stress priming effect in which ionizing radiation and ROS induced growth stimulation and metabolic activation in Chlamydomonas reinhardtii under normal growth conditions. To further examine this counterintuitive role of stress priming, the genotoxicity and cytotoxicity of stress were minimized by employing indirect or transient treatment. The C. reinhardtii cells were treated for 1 h with X-irradiated or H 2 O 2 -containing tris-acetate-phosphate (TAP) medium for indirect X-irradiation or transient H 2 O 2 treatment, and then cultured to compare growth and metabolic activity. Indirect X-irradiation at 6 or 50 Gy or transient H 2 O 2 treatment at 30 or 110 μM did not induce changes in DNA damage or cell death but did significantly increase the growth and chlorophyll, protein, starch, and lipid contents in a dose- or concentration-dependent manner. Such growth stimulation was inhibited by treatment with the ROS scavenger ascorbic acid and enhanced by treatment with sodium bicarbonate, an additional carbon source. Furthermore, the expression of the cell cycle regulatory CrCDKA1 gene was strongly induced by chromatin modification after transient H 2 O 2 treatment. These results suggest that indirect irradiation with X-rays or transient treatment with H 2 O 2 within a specific dose or concentration range can induce growth stimulation by enhancing the metabolic activity in C. reinhardtii. These effects may be partially explained by chromatin modification and metabolic remodeling through ROS-mediated signaling associated with stress priming and concomitant stress memory. • ROS production via X-irradiation correlates with growth stimulation in Chlamydomonas. • Treatment of H 2 O 2 at low concentrations boosts algal growth and metabolic activities. • Indirect or transient stress priming enables growth stimulation without genotoxicity. • Transient H 2 O 2 treatment induces chromatin modifications associated with cell cycle. [ABSTRACT FROM AUTHOR]

Phosphorus is one of the main nutrients that ensure the formation of high and stable crop yields with a favorable quality of marketable products. One of the promising directions for improving the phosphorus nutrition of agricultural crops is biological phosphate mobilization with the help of soil microorganisms, which contributes to the transfer of sparingly soluble phosphorus compounds from the soil and fertilizers into a form accessible to higher plants. Aboriginal soil phosphate mobilizing bacteria were isolated from the rhizosphere soil of the northern region of the Republic of Kazakhstan. Of the five phosphate mobilizing bacteria: Acinetobacter calcoaceticus 2/5 pr, Stenotrophomonas rhizophila 1/7 c, Pseudomonas koreensis 4/5 kr, Acinetobacter calcoaceticus 1/5 pr, Pseudomonas koreensis 3/4 pr, three strains were selected: Acinetobacter calcoaceticus 2/5 pr, Pseudomonas koreensis 4/5 kr, Acinetobacter calcoaceticus 1/5 pr, with high soil phosphate mobilization activity. The properties of phosphate-mobilizing bacteria have been studied, their ability to stimulate plant growth and convert insoluble tricalcium phosphate Ca3(PO4) 2 into a form accessible to plants has been established. The ability to phosphate mobilization and stimulation of plant growth determines the positive effect of the introduction of phosphate mobilizing bacteria on crop yields. The selected strains of phosphate-mobilizing bacteria are promising as a basis for creating a complex biological fertilizer for a wide range of agricultural crops. [ABSTRACT FROM AUTHOR]

Experiments were carried out to study the consequences of inoculating Rhododendron 'Nova Zembla' and 'Alfred' microcuttings and young plants with Serendipita indica (formerly Piriformospora indica), an endophytic fungus. The inoculation at the in vitro rooting stage decreased the in vitro root and shoot quality, but after planting microplants in a greenhouse in a non-fertilised peat substrate, the plants grew 33% taller, with 10% more leaves and with more abundant roots in comparison with the non-inoculated microplants. The young plants rooted in vitro, acclimated in a greenhouse in a peat substrate and inoculated with S. indica at the time of the transplantation to the pots displayed, after 15 months, an increase in the shoot lengths by 35% and 13%, depending on the cultivar, in the leaf number by 47% and in the chlorophyll content by 31% when compared with the non-inoculated plants. The beneficial effect of S. indica on the young Rhododendron plants indicates the possibility of its practical use in the nursery production of this plant.

Modern forestry in the European Union and in Poland is in constant search of environment-friendly technological solutions. These also relate to nursery production, in which attempts are made to apply non-chemical plant-protection products. The objective of this study was to assess the effects of salicylic acid, oxalic acid and chitosan (applied in the form of Beta-chikol®) in controlling damping-off and promoting the growth of Scots pine seedlings under nursery conditions. All the substances were used in seed treatment and in the form of foliar spray, 4 times during the growing season, in the following concentrations: salicylic acid 1% and 2%, oxalic acid 0.5% and 1%, and chitosan 2%. Seedlings were inventoried three times: 3 and 6 weeks after seed sowing, and at the end of the growing season. All seedlings were counted in 1-metre segments of individual rows of the seedbed. At the end of the growing season, parameters of seedling growth like shoot length, root-collar diameter, root length and the dry mass of above-ground parts were determined. The growth of pine seedlings was found to be stimulated by both chitosan and oxalic acid, while salicylic acid proved inhibitory to growth when present at 2% concentration, and showed no detectable influence on biometric parameters at 1% concentration. Numbers of seedlings germinating per 1-metre segment were significantly greater than in the (unprotected) control, where chitosan was applied. Likewise, oxalic acid applied at both concentrations was associated with greater numbers of germinating pine seedlings than in the control, albeit the statistical significance of this difference was achieved only 6 weeks after seed sowing, and only with the 0.5% concentration. Numbers of seedlings per metre-long segment were significantly lower in response to both concentrations of salicylic acid applied. Both chitosan (applied as Beta-chikol®) and 0.5% oxalic acid resulted in seedling protection against damping-off and enhanced growth, whereas the applied concentrations of salicylic acid were presumably excessive, hence the negative impact on both germination and growth.

Barley is the main forage crop in the Russian Federation. Barley grain is also used for food and brewery (Filippov, 2013). It is common knowledge that low doses of gamma irradiation can have a stimulating effect on the growth and development of plants, in particular barley. However, there is a lack of knowledge about the molecular pathways responsible for the formation of the stimulation effect after low-dose seed irradiation. The use of varieties with different radio sensitivity to low-dose gamma irradiation will allow studying specific molecular mechanisms to form a stimulating irradiation effect. Such knowledge could further help in the development of varieties with a large stable productivity over the years and with high resistance to biotic and abiotic stressors. In 2019 there was conducted a gamma irradiation of the original seeds of nine winter and spring barley varieties developed in the FSBSI “Agricultural Research Center “Donskoy” in order to assess intensity of the response on low-dose ionizing irradiation based on changes in the morphological parameters of irradiated and unirradiated plants. The original seeds of each barley variety were irradiated at the FSBSI “All-Russian Research Institute of Radiology and Agroecology” by the gamma device “GUR-120” with 60Со radiation sources at a dose of 20 Gy (dose rate of 60 Gy/hour). The statistical data processing was performed by the Microsoft Office Excel 2019. The morphological analysis of the length and weight of roots and sprouts made it possible to establish the presence or absence of the stimulating irradiation effect on the studied indicators of the varieties and to conduct their subsequent ranking according to the value of the radiobiological effect. There have been identified the winter and spring barley varieties with different sensitivity to a dose of 20 Gy. The stimulating irradiation effect was established in such varieties as “Foks 1”, “Ratnik”, “Yerema” and “Master”. The variety “Leon” had an inhibitory irradiation effect.

The aim of the present study was to develop an experimental system for an exploration of ethylene-dependent responses using intact growing Ranunculus sceleratus plants and to approbate the system for assessing the role of ethylene in salinity tolerance and ion accumulation. Plants were cultivated in sealed plastic containers in a modified gaseous atmosphere by introducing ethylene or 1-methylcyclopropene (1-MCP), a competitive inhibitor of ethylene action. High humidity inside the containers induced a fast elongation of the leaf petioles of R. sceleratus. The effect was ethylene-dependent, as 1-MCP completely blocked it, but exogenous ethylene further promoted petiole elongation. Exogenous ethylene decreased (by 48%) but 1-MCP increased (by 48%) the Na+ accumulation in leaf blades of NaCl-treated plants. The experimental system was further calibrated with ethylene and silica xerogel, and the optimum concentrations were found for inducing leaf petiole elongation (10 μL L–1 ethylene) and preventing leaf petiole elongation (200 g silica xerogel per 24 L), respectively. The second experiment involved a treatment with NaCl in the presence of 1-MCP, ethylene, or 1-MCP + ethylene, both in normal and high air humidity conditions. In high humidity conditions, NaCl inhibited petiole elongation by 25% and ethylene treatment fully reversed this inhibition and stimulated elongation by 12% in comparison to the response of the control plants. Treatment with 1-MCP fully prevented this ethylene effect. In normal humidity conditions, NaCl inhibited petiole elongation by 20%, which was reversed by ethylene without additional elongation stimulation. However, 1-MCP only partially inhibited the ethylene effect on petiole elongation. In high humidity conditions, ethylene inhibited Na+ accumulation in NaCl-treated plants by 14%, but 1-MCP reversed this effect. In conclusion, the stimulation of endogenous ethylene production in R. sceleratus plants at a high air humidity or in flooded conditions reverses the inhibitory effect of salinity on plant growth and concomitantly inhibits the accumulation of Na+ in tissues. R. sceleratus is a highly promising model species for use in studies regarding ethylene-dependent salinity responses and ion accumulation potential involving the manipulation of a gaseous environment.

The modern approach to the creation of biological products to stimulate plant growth is based on the study of specific inter-bacterial interactions. This study describes the impact that the introduction of strains of the genus Pseudomonas has on annual and perennial leguminous plants and the ecosystem of the leguminous plant—the indigenous microbial community. The objects of research under the conditions of vegetation experiments were plants of field peas (Pisum sativum L.), white lupine (Lupinus albus L.), chickpea (Cicer arietinum L.), alfalfa (Medicago sativa subsp. varia (Martyn) Arcang.), and white sweet clover (Melilotus albus Medik.). For the treatment of plant seeds, a liquid culture of strains of growth-stimulating bacteria Pseudomonas koreensis IB-4, and P. laurentiana ANT 17 was used. The positive effect of the studied strains on the germination, growth and development of plants was established. There was no inhibitory effect of inoculants on rhizobia; on the contrary, an increase in nodule formation was observed. The possibility of recultivation of oil-contaminated soil using chickpea and alfalfa as phytomeliorants and growth-stimulating strains P. koreensis IB-4, P. laurentiana ANT 17 as inoculants was evaluated. It is proved that seed treatment improved the morphological parameters of plants, as well as the efficiency of oil destruction.

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Currently, there is an active development of environmentally friendly methods of farming. However, the range of products for this type of farming system is limited. Growth stimulation is one of the mechanisms ensuring plant resistance to diseases that reduce crop yields. The aim of the work is to study the effect of laboratory samples of new biological products based on B. subtilis BZR 336 g, B. subtilis BZR 517, P. chlororaphis 245 F strains and organo-mineral fertilizers PRK White Pearl Brown (WPB) and PRK White Pearl Universal” (WPU) on plant growth and development of plants, as well as study of the possibility of their joint use for subsequent inclusion in organic farming systems or integrated plant protection. Growthpromoting ability was assessed in winter wheat and sunflower plants grown in sand in a climatic chamber. As comparison variants there were seed treatment with water (control), chemical (Dividend Star, KS) and biological (Fitosporin-M, F, B. subtilis 26 D) standards. In two plant cultures there was an expected retardant effect of the chemical standard and the growth-promoting effect of the biological standard. Statistically significant data were obtained for such a parameter as the shoot length. On winter wheat, laboratory samples provided the shoot length of 24.1-25.2 mm (an addition to the control of 3.4-8.2%), organic and mineral fertilizers - 23.9-24.5 mm (2.6-5.2%), mixtures with WPU - 23.2-24.4 mm (-0.4-4.7%), mixtures with WPB - 24.1-25.9 mm (3.4-11.2%), a significant increase in root length was not observed in this culture. On winter wheat, it is advisable to use the studied products separately. Sunflower is more responsive to the action of laboratory samples. They provided a shoot length of 13.6-14.6 mm (20.9-27.0%) and a root of 9.2-10.2 mm (4.5-15.9%). Organo-mineral fertilizers provided a shoot length of 14.2-14.5 mm (23.5-26.1%) and the root length of 10.8 mm (22.7%). Mixtures with WPU provided shoot length of 14.7-15.4 mm (27.8-33.9%), mixtures with WPB provided shoot length of 11.9-14.5 mm (3.5-26.1%), and no significant increase in root length was noted. The data obtained indicate the presence in the laboratory samples of fungicidal biological products growth-promoting properties, which vary depending on the culture and additionally used organic and mineral fertilizers. To confirm the results, additional experiments are necessary. Research in this direction will allow the rational use of the studied means of protection and increase plant yields in systems of organic, ecologized and integrated farming, and can help reduce the pesticidal pressure on agrocenoses.Conflict of interest: the authors stated that there was no conflict of interest.

Abstract Background Soil salinity is a real challenge in nowadays crop production in many regions. Various strategies have been applied to increase plant salinity tolerance. Salicylic acid (SA) frequently has been reported to increase plant salinity tolerance; however, the comparative efficiency of soil (root) or foliar application of SA has not been well tested yet. In this study, the effects of root or leaf pretreatment, and leaf treatment with 100 mg L−1 salicylic acid were evaluated on growth characteristics of tomato seedlings (Solanum lycopersicum Mill) under salinity stress. The plants were grown 3 weeks in sand that were fed with Hoagland nutrient solution with or without 100 mM NaCl. Results The results showed that salinity significantly reduced tomato seedling growth and traits of plant height, leaf area, shoot fresh weight, and nutrient concentration of potassium, calcium, iron and zinc compared to control plants. However, leaf SPAD value, root fresh and dry weights, leaf concentration of sodium, proline and soluble sugars were significantly increased under 100 mM NaCl salinity compared to control plants. Application of salicylic acid particularly by foliar pretreatment increased the tomato plant growth and those traits that were reduced by NaCl salinity. Application of SA, particularly foliar pretreatment, also increased the root fresh and dry weights, leaf proline and soluble sugars concentrations as compared with salinity alone. Foliar SA pretreatment significantly increased leaf K and Fe concentrations, whereas leaf Ca was significantly increased by either root or leaf pretreatment with SA under salinity. Conclusion The results indicate that the most to least effective method of SA application was leaf pretreatment, root pretreatment and leaf treatment, respectively, to recover the reduced growth parameters of tomato plant under salinity stress.