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Based on the common step of alkaline extraction-acid precipitation, lignite treatment techniques have been developed to improve extraction efficiency and yield of humic acid (HA). This study explored the combination of bacterium Paenibacillus mucilaginosus (P.m) LT1906 and fungus Penicillium pimiteouiense (P.p) LL2205 strains for pre- and post-treatment of lignite collected from eastern Inner Mongol to enhance HA and fulvic acid (FA) yield and plant growth-promoting activity. The lignite was subjected to P.m followed by HNO3 treatment, HNO3 followed by P.p treatment, and a combination of P.m, HNO3 and P.p treatments, then performed by alkaline extraction-acid precipitation technique. The results indicated that P.m pretreatment increased HA yield by 12.47 %, while P.p posttreatment significantly enhanced FA yield by 13.37 %. Combined bacterial and fungal treatments notably improved the total yields of HA and FA by 19.12 %. Structural analysis showed that P.m pretreatment caused the deformation on the lignite surface and the complete lignite oxidation and leaching reactions, thereby increasing the production of HA, yet had no impact on the elemental composition or chemical structure of HA. P.p posttreatment introduced oxygencontaining functional groups and reduced aromatic components through oxidative depolymerization of lignite, leading to increased FA production and HA seed germination-promoting activity. [Display omitted] • Bacterial-fungal treatment improves humic and fulvic acid extraction from lignite. • Paenibacillus mucilaginosus deforms lignite to facilitate subsequent reactions. • Penicillium pimiteouiense introduces oxygen groups to enhance bioactivity. • Improved bioactivity of humic acids confirmed by wheat seed germination tests. [ABSTRACT FROM AUTHOR]

The rhizosphere is enriched with diverse microflora, allowing for delving prospective microorganisms to enhance crop growth and yield for varied soil conditions. Demand for millet growth-promoting microorganisms is a contemporary need for dryland agriculture. Therefore, a detailed survey was conducted in northern Karnataka, India, to identify the millet growing areas, particularly sorghum. The rhizobacteria from the sorghum (Sorghum bicolor L.) were assessed for promoting seed germination using the paper towel method and classified based on their efficiency. The elite isolates were positive for indole-3-acetic acid (IAA), gibberellic acid (GA), phosphate, zinc oxide solubilization, and hydrogen cyanide (HCN) production. The test isolates were antagonistic to Macrophomina phaseolina and Fusarium sp. and inhibited completely. Further evaluation of the cultures on sorghum growth-promoting attributes under pot culture conditions showed that the plants inoculated with PG-152 (Bacillus subtilis) recorded the highest plant height, chlorophyll content, root dry weight, shoot dry weight, and total dry weight under ideal conditions of fertilization. Two isolates, namely, PG-152 and PG-197, performing superior under pot culture conditions, were identified as Bacillus subtilis and PG-197 as Enterobacter sp., respectively, using 16S rDNA analysis. The sequences were allowed to screen open reading frames (ORF) and found several ORFs in Enterobacter cloacae and Bacillus subtilis, respectively. This study found that the rhizosphere is vital for identifying prospective isolates for biocontrol and plant growth-improving microorganisms. [ABSTRACT FROM AUTHOR]

The biomass production as well as the accumulation of secondary metabolites of plant is highly determined by the absorption of nutritional elements, in particular nitrogen (N) and phosphorus (P). Arbuscular mycorrhizal fungi (AMF) can absorb soluble P and transport it to plants, while phosphate solubilizing bacteria (PSB) can increase the content of solubilizing P in soil. Previous studies have identified the effects of either AMF or PSB inoculation on altering plant C:N:P stoichiometry, whether AMF interact with PSB in promoting plant growth and changing elemental concentration and composition of secondary metabolites by altering plant C:N:P stoichiometry remains ambiguous. In this study, we investigated the effects of inoculation of AMF, PSB, and their co-inoculation AMP (AMF and PSB) on the biomass growth, the C:N:P stoichiometry, the core microorganisms of rhizosphere soil, and the ginsenoside compositions of ginseng (Panax ginseng). The results showed that compared to control or single inoculation of AMF or PSB, co-inoculation of AMF and PSB significantly increased the AMF colonization rate on ginseng roots, increased the biomass of both above and under-ground parts of ginseng. Similarly, co-inoculation of AMF and PSB substantially increased the concentrations of N and P, reduced the ratios of C:P and N:P in the above-ground part of ginseng. The co-inoculation of AMF and PSB also increased concentrations of total ginsenosides and altered the compositions of ginsenosides in both the above and under-ground parts of ginseng. Analysis the rhizosphere microorganism showed that the co-inoculation of AMF and PSB recruited distinct core microorganisms that differ from the control and treatments with single inoculation of AMF or PSB. Our results suggested that PSB inoculation enhanced the positive effect of AMF in improving the absorption of nutrimental elements, altered the C:N:P stoichiometry and, ginsenosides concentration and composition of ginseng, influenced the plant rhizosphere microbial community. These findings offer valuable insights into enhancing plant biomass production and promoting secondary metabolites by improving the plant-fungi-bacterial relationships. [ABSTRACT FROM AUTHOR]

Background: Volatile organic compounds (VOCs) released by plants can act as signaling molecules mediating ecological interactions. Therefore, the study of VOCs mediated intra- and interspecific interactions with downstream plant physiological responses is critical to advance our understanding of mechanisms underlying information exchange in plants. Here, we investigated how plant-emitted VOCs affect the performance of an interspecific neighboring plant via induced shifts in root exudate chemistry with implications for root-associated microbiota recruitment. Results: First, we showed that VOCs emitted by potato-onion plants stimulate the growth of adjacent tomato plants. Then, we demonstrated that this positive effect on tomato biomass was attributed to shifts in the tomato rhizosphere microbiota. Specifically, we found potato-onion VOCs to indirectly affect the recruitment of specific bacteria (e.g., Pseudomonas and Bacillus spp.) in the tomato rhizosphere. Second, we identified and validated the compound dipropyl disulfide as the active molecule within the blend of potato-onion VOCs mediating this interspecific plant communication. Third, we showed that the effect on the tomato rhizosphere microbiota occurs via induced changes in root exudates of tomato plants caused by exposure to dipropyl disulfide. Last, Pseudomonas and Bacillus spp. bacteria enriched in the tomato rhizosphere were shown to have plant growth-promoting activities. Conclusions: Potato-onion VOCs—specifically dipropyl disulfide—can induce shifts in the root exudate of adjacent tomato plants, which results in the recruitment of plant-beneficial bacteria in the rhizosphere. Taken together, this study elucidated a new mechanism of interspecific plant interaction mediated by VOCs resulting in alterations in the rhizosphere microbiota with beneficial outcomes for plant performance. 4wKeniGUxY9GPejLMpvDe9 Video Abstract [ABSTRACT FROM AUTHOR]

To mitigate soil degradation and decrease dependency on chemical inputs in agriculture, this study examined the joint effects of coconut shell biochar and Bacillus strain Ya-1 on soil fertility, rhizosphere bacterial communities, and the growth of chili (Capsicum annuum L.). A controlled pot experiment with four treatments was conducted: control (CK), biochar only (C), Bacillus strain Ya-1 only (B), and a combination of both (BC). The BC treatment significantly enhanced the soil carbon and available phosphorus contents by approximately 20% and the soil nitrogen content and pH by 18% and 0.3 units, respectively, compared to the control. It also increased microbial biomass carbon and nitrogen by 25% and 30%, respectively, indicating improved soil microbial diversity as shown by the highest Pielou evenness index and Shannon index values. The combined application of biochar and the Ya-1 strain resulted in a 15% increase in chili plant height and a 40% improvement in root dehydrogenase activity, suggesting enhanced nutrient uptake and metabolism. Metabolic profiling showed shifts in stress response and nutrient assimilation under different treatments. Collectively, these results indicate the potential of biochar and microbial inoculants to significantly promote soil and plant health, providing a sustainable strategy to improve agricultural productivity and reduce reliance on chemical inputs. [ABSTRACT FROM AUTHOR]

Deschampsia antarctica and Colobantus quitensis are the only two vascular plants colonized on the Antarctic continent, which is usually exposed to extreme environments. Endophytic bacteria residing within plant tissues can exhibit diverse adaptations that contribute to their ecological success and potential benefits for their plant hosts. This study aimed to characterize 12 endophytic bacterial strains isolated from these plants, focusing on their ecological adaptations and functional roles like plant growth promotion, antifungal activities, tolerance to salt and low-carbon environments, wide temperature range, and biofilm formation. Using 16S rRNA sequencing, we identified several strains, including novel species like Hafnia and Agreia. Many strains exhibited nitrogen-fixing ability, phosphate solubilization, ammonia, and IAA production, potentially benefiting their hosts. Additionally, halotolerance and carbon oligotrophy were also shown by studied bacteria. While some Antarctic bacteria remain strictly psychrophilic, others demonstrate a remarkable ability to tolerate a wider range of temperatures, suggesting that they have acquired mechanisms to cope with fluctuations in environmental temperature and developed adaptations to survive in intermediate hosts like mammals and/or birds. Such adaptations and high plasticity of metabolism of Antarctic endophytic bacteria provide a foundation for research and development of new promising products or mechanisms for use in agriculture and technology. [ABSTRACT FROM AUTHOR]

Nilgirianthus ciliatus, extensively exploited for its pharmacological properties, is now classified as vulnerable. In vitro micropropagation offers a sustainable approach for ecological conservation and rational utilization of this biodiversity resource. This study aimed to reduce endophytes during in vitro propagation and isolating antimicrobial-resistant endophytes from N. ciliatus by employing various concentrations and exposure times of Plant Preservative Mixture (PPM). Optimal results were observed when nodal explants treated with 0.3% PPM for 8 h, followed by inoculation in Murashige and Skoog (MS) medium supplemented with 3 mg/L 6-benzylaminopurine (BAP) and 0.3% PPM. This protocol achieved 82% shoot regeneration with minimal endophytic contamination, suggesting that the duration of explant exposure to PPM significantly influences endophyte reduction. Two antimicrobial-resistant endophytes were isolated and identified as Bacillus cereus and Acinetobacter pittii through 16S rDNA sequencing. These endophytes exhibited plant growth-promoting characteristics, including amylolytic, proteolytic, lipolytic activities, indole-3-acetic acid production, phosphate solubilization, and stress tolerance. In vivo application of these endophytes as bioinoculants to N. ciliatus not only improved growth parameters but also significantly increased the levels of pharmacologically important compounds, squalene, and stigmasterol, as confirmed by High-performance thin-layer chromatography (HPTLC). This study demonstrates that PPM is a promising alternative for sustainable micropropagation of N. ciliatus. Furthermore, it highlights the potential of antimicrobial-resistant endophytes as bioinoculants to improve growth and medicinal value, offering a sustainable solution for conservation and large-scale cultivation of this species. [ABSTRACT FROM AUTHOR]

Introduction: Despite their adverse environmental effects, modern agriculture relies heavily on agrochemicals to manage diseases and pests and enhance plant growth and productivity. Some of these functions could instead be fulfilled by endophytes from the plant microbiota, which have diverse activities beneficial for plant growth and health. Methods: We therefore used a microbiome-guided top-down approach to select ten bacterial strains from different taxa in the core microbiome of tomato plants in the production chain for evaluation as potential bioinoculants. High-quality genomes for each strain were obtained using Oxford Nanopore long-read and Illumina short-read sequencing, enabling the dissection of their genetic makeup to identify phyto-beneficial traits. Results: Bacterial strains included both taxa commonly used as biofertilizers and biocontrol agents (i.e. Pseudomonas and Bacillus) as well as the less studied genera Leclercia, Chryseobacterium, Glutamicibacter, and Paenarthorbacter. When inoculated in the tomato rhizosphere, these strains promoted plant growth and reduced the severity of Fusarium Crown and Root Rot and Bacterial Spot infections. Genome analysis yielded a comprehensive inventory of genes from each strain related to processes including colonization, biofertilization, phytohormones, and plant signaling. Traits directly relevant to fertilization including phosphate solubilization and acquisition of nitrogen and iron were also identified. Moreover, the strains carried several functional genes putatively involved in abiotic stress alleviation and biotic stress management, traits that indirectly foster plant health and growth. Discussion: This study employs a top-down approach to identify new plant growth-promoting rhizobacteria (PGPRs), offering an alternative to the conventional bottom-up strategy. This method goes beyond the traditional screening of the strains and thus can expand the range of potential bioinoculants available for market application, paving the way to the use of new still underexplored genera. [ABSTRACT FROM AUTHOR]

Soil salinity is a worldwide problem threatening crop yields. Some plant growth‐promoting rhizobacteria (PGPR) could survive in high salt environment and assist plant adaptation to stress. Nevertheless, the genomic and metabolic features, as well as the regulatory mechanisms promoting salt tolerance in plants by these bacteria remain largely unknown. In the current work, a novel halotolerant PGPR strain, namely, Bacillus sp. strain RA can enhance tomato tolerance to salt stress. Comparative genomic analysis of strain RA with its closely related species indicated a high level of evolutionary plasticity exhibited by strain‐specific genes and evolutionary constraints driven by purifying selection, which facilitated its genomic adaptation to salt‐affected soils. The transcriptome further showed that strain RA could tolerate salt stress by balancing energy metabolism via the reprogramming of biosynthetic pathways. Plants exude a plethora of metabolites that can strongly influence plant fitness. The accumulation of myo‐inositol in leaves under salt stress was observed, leading to the promotion of plant growth triggered by Bacillus sp. strain RA. Importantly, myo‐inositol serves as a selective force in the assembly of the phyllosphere microbiome and the recruitment of plant‐beneficial species. It promotes destabilizing properties in phyllosphere bacterial co‐occurrence networks, but not in fungal networks. Furthermore, interdomain interactions between bacteria and fungi were strengthened by myo‐inositol in response to salt stress. This work highlights the genetic adaptation of RA to salt‐affected soils and its ability to impact phyllosphere microorganisms through the adjustment of myo‐inositol metabolites, thereby imparting enduring resistance against salt stress in tomato. [ABSTRACT FROM AUTHOR]

Global climate change poses a significant threat to plant growth and crop yield and is exacerbated by environmental factors, such as drought, salinity, greenhouse gasses, and extreme temperatures. Plant growth-promoting rhizobacteria (PGPR) help plants withstand drought. However, the mechanisms underlying PGPR-plant interactions remain unclear. Thus, this study aimed to isolate PGPR, Bacillus megaterium strains CACC109 and CACC119, from a ginseng field and investigate the mechanisms underlying PGPR-stimulated tolerance to drought stress by evaluating their plant growth-promoting activities and effects on rice growth and stress tolerance through in vitro assays, pot experiments, and physiological and molecular analyses. Compared with B. megaterium type strain ATCC14581, CACC109 and CACC119 exhibited higher survival rates under osmotic stress, indicating their potential to enhance drought tolerance. Additionally, CACC109 and CACC119 strains exhibited various plant growth-promoting activities, including phosphate solubilization, nitrogen fixation, indole-3-acetic acid production, siderophore secretion, 1-aminocyclopropane-1-carboxylate deaminase activity, and exopolysaccharide production. After inoculation, CACC109 and CACC119 significantly improved the seed germination of rice (Oryza sativa L.) under osmotic stress and promoted root growth under stressed and non-stressed conditions. They also facilitated plant growth in pot experiments, as evidenced by increased shoot and root lengths, weights, and leaf widths. Furthermore, CACC109 and CACC119 improved plant physiological characteristics, such as chlorophyll levels, and production of osmolytes, such as proline. In particular, CACC109- and CACC119-treated rice plants showed better drought tolerance, as evidenced by their higher survival rates, greater chlorophyll contents, and lower water loss rates, compared with mock-treated rice plants. Application of CACC109 and CACC119 upregulated the expression of antioxidant-related genes (e.g., OsCAT, OsPOD, OsAPX, and OsSOD) and drought-responsive genes (e.g., OsWRKY47, OsZIP23, OsDREB2, OsNAC066, OsAREB1, and OsAREB2). In conclusion, CACC109 and CACC119 are promising biostimulants for enhancing plant growth and conferring resistance to abiotic stresses in crop production. Future studies should conduct field trials to validate these findings under real agricultural conditions, optimize inoculation methods for practical use, and further investigate the biochemical and physiological responses underlying the observed benefits. [ABSTRACT FROM AUTHOR]

Codonopsis pilosula, commonly known as Dangshen, is a valuable medicinal plant, but its slow growth and susceptibility to environmental stress pose challenges for its cultivation. In pursuit of sustainable agricultural practices to enhance the yield and quality of Dangshen, the present study isolated a bacterial strain exhibiting plant growth-promoting potential from the rhizosphere of C. pilosula. This strain was subsequently identified as Bacillus licheniformisYB06. Assessment of its plant growth-promoting attributes revealed the potential of B. licheniformis YB06 as a biofertilizer. Whole-genome sequencing of B. licheniformis YB06 revealed a genome size of 4,226,888 bp with a GC content of 46.22%, harboring 4325 predicted protein-coding sequences. Genomic analysis of B. licheniformis YB06 revealed a diverse array of genes linked to induced systemic resistance (ISR) and plant growth-promoting (PGP) traits, encompassing phytohormone production, nitrogen assimilation and reduction, siderophore biosynthesis, phosphate solubilization, biofilm formation, synthesis of PGP-related amino acids, and flagellar motility. Seed germination assays demonstrated the positive effects of B. licheniformis YB06 on the germination and growth of C. pilosula seedlings. Furthermore, we explored various fertilization regimes, particularly the B. licheniformis YB06-based biofertilizer, were investigated for their impact on the structure and diversity of the C. pilosula rhizosphere soil bacterial community. Our findings revealed that fertilization significantly impacted soil bacterial composition and diversity, with the combined application of B. licheniformis YB06-based biofertilizer and organic fertilizer exhibiting a particularly pronounced enhancement of rhizosphere bacterial community structure and diversity. This study represents the first report on the beneficial effects of B. licheniformis YB06 on both the growth of C. pilosula and the composition of its rhizosphere soil microbial community. These findings provide a theoretical foundation and practical guidance for the development of novel bio-organic compound fertilizers, thereby contributing to the sustainable cultivation of C. pilosula. [ABSTRACT FROM AUTHOR]

SUMMARY: Due to the chelation of phosphorus in the soil, it becomes unavailable for plant growth and development. The mechanisms by which phosphorus‐solubilizing bacteria activate immobilized phosphorus to promote the growth and development of woody plants, as well as the intrinsic molecular mechanisms, are not clear. Through the analysis of microbial communities in the rhizosphere 16S V3–V4 and a homologous gene encoding microbial alkaline phosphomonoesterase (phoD) in phosphate‐efficient (PE) and phosphate‐inefficient apple rootstocks, it was found that PE significantly enriched beneficial rhizobacteria. The best phosphorus‐solubilizing bacteria, Bacillus sp. strain 7DB1 (B2), was isolated, purified, and identified from the rhizosphere soil of PE rootstocks. Incubating with Bacillus B2 into the rhizosphere of apple rootstocks significantly increased the soluble phosphorus and flavonoid content in the rhizosphere soil. Simultaneously, this process stimulates the root development of the rootstocks and enhances plant phosphorus uptake. After root transcriptome sequencing, candidate transcription factor MhMYB15, responsive to Bacillus B2, was identified through heatmap and co‐expression network analysis. Yeast one‐hybrid, electrophoretic mobility shift assay, and LUC assay confirmed that MhMYB15 can directly bind to the promoter regions of downstream functional genes, including chalcone synthase MhCHS2 and phosphate transporter MhPHT1;15. Transgenic experiments with MhMYB15 revealed that RNAi‐MhMYB15 silenced lines failed to induce an increase in flavonoid content and phosphorus levels in the roots under the treatment of Bacillus B2, and plant growth was slower than the control. In conclusion, MhMYB15 actively responds to Bacillus B2, regulating the accumulation of flavonoids and the uptake of phosphorus, thereby influencing plant growth and development. Significance Statement: In the rhizosphere soil of apple rootstocks on different phosphorus‐efficient/inefficient rootstocks, there exist distinct microbial communities. MhMYB15 can respond to the rhizobacterium Bacillus B2, and interact with flavonoids (MhCHS2) and phosphate transport proteins (MhPHT1;15) to promote plant root development and phosphate absorption. [ABSTRACT FROM AUTHOR]

In this study, bacteria with the best abilities in cellulose degradation, siderophore production, phosphate solubility, and Pythium parasitica inhibition were selected from termite nests and guts. The isolate BTNASP 5-2, BTPK 5-3 and BTNA 5-1 from termite guts exhibited highest in siderophore production index (SPI) (4.16 ± 0.21), phosphate solubilizing index (PSI) (2.10 ± 0.14) and percentage inhibition of radial growth (PIRG) (67.07 ± 4.02 %), respectively. The BGNACMC 4-3 isolated from termite nest gave the highest cellulolytic index (CI) of 5.17 ± 0.24. Bacterial classification was performed using 16s rRNA gene sequencing. The isolates BTPK 5-3, BGNACMC 4-3 and BTNA 5-1 were found closely related to Bacillus cereus, whereas the bacterial isolate BTNASP 5-2 was closely related to Bacillus subtilis. It is also suggested that the Bacillus cereus exhibited a variety of biological activities, denoting the highest cellulase, phosphate-solubilizing and antifungal activities, while Bacillus subtilis produced only a siderophore. The results obtained suggest that the bacteria selected will be used to develop bio-compost to promote plant growth, leading to sustainable farming. [ABSTRACT FROM AUTHOR]

Phytoremediation is a technique for reducing or stabilizing hazardous chemicals in polluted soil or ground water. There is a loss of agricultural products and a degradation in food quality as a result of abiotic stresses, such as those generated by heavy metals and pesticides that have an effect on plants. These toxic compounds are extensively employed in agriculture, and they have a significant influence on both human health and agricultural output. The accumulation of these toxic, persistent, and poorly biodegradable compounds causes soil and ecological disparities. PGRs, or plant growth regulators, are an appealing possibility for increasing the efficacy of phytoremediation. Plant growth-promoting rhizobacteria (PGPR), a ubiquitous root microbiome, is widely used as a biocontrol agent. They have the ability to improve plant growth by colonizing plant roots, which can benefit the plant. Several PGPRs, including P. aeruginosa, B.gladioli, and P.pseudoalcali, have been shown to be resistant to biotic and abiotic stressors. Because of their ability to digest xenobiotic chemicals, plant growth-promoting rhizobacteria (PGPR) are a promising candidate for use in the phytoremediation process. Microorganisms inhabiting the rhizosphere participate in plant resistance mechanisms by secreting and generating a variety of important compounds such as siderophores, phytohormones, and metal-binding proteins. Rhizobacteria play an important role in phytoremediation of pesticide- and heavy metal-polluted soil by decomposing toxicants and promoting plant development via mechanisms such as chelation, acidification, and phosphate solubilization. Plant growth regulators (PGRs) increase plant biomass while reducing the negative impacts of contaminants and boosting growth in harsh settings. The use of certain PGRs as exogenous treatments have also been investigated as a potential way to improving crop stress tolerance; however the efficiency varies depending on the specific stress and plant type. Several plant growth regulators, such as brassinosteroids, melatonin, strigolactones, and others, have been proven to be useful in overcoming abiotic stress. The current review focuses on the utilization of PGRs and PGPRs in phytoremediation of heavy metal and pesticide-polluted soils. [ABSTRACT FROM AUTHOR]

Plants and bacteria are co-evolving and interact with one another in a continuous process. This interaction enables the plant to assimilate the nutrients and acquire protection with the help of beneficial bacteria known as plant growth-promoting bacteria (PGPB). These beneficial bacteria naturally produce bioactive compounds that can assist plants' stress tolerance. Moreover, they employ various direct and indirect processes to induce plant growth and protect plants against pathogens. The direct mechanisms involve phytohormone production, phosphate solubilization, zinc solubilization, potassium solubilization, ammonia production, and nitrogen fixation while, the production of siderophores, lytic enzymes, hydrogen cyanide, and antibiotics are included under indirect mechanisms. This property can be exploited to prepare bioformulants for biofertilizers, biopesticides, and biofungicides, which are convenient alternatives for chemical-based products to achieve sustainable agricultural practices. However, the application and importance of PGPB in sustainable agriculture are still debatable despite its immense diversity and plant growth-supporting activities. Moreover, the performance of PGPB varies greatly and is dictated by the environmental factors affecting plant growth and development. This review emphasizes the role of PGPB in plant growth-promoting activities (stress tolerance, production of bioactive compounds and phytohormones) and summarises new formulations and opportunities. [ABSTRACT FROM AUTHOR]

The article investigates the mitigation of copper (Cu) toxicity with copper tolerant plant growth promoting rhizobacteria (PGPR) strains in marigold plant growth. The study discusses the in vitro testing of Cu-tolerant Providentia, Paenibacillus and Lysinibacillus PGPR strains and their effect on Cu accumulation by marigold. It measures plant growth promoting activities including production of siderophores, indole acetic acid, hydrogen cyanide and phosphate solubilization.

The article investigates the application of salt-adapted plant growth promoting rhizo-bacteria (SA-PGPR) as a biological natural approach to enhance crop productivity under saline stress. Topics discussed include impact of salinity on plant growth and associated micro-biome, role of SA-PGPR against salinity, genes involved in plant protection against salinity stress, salt tolerance mediated by plant growth promoting rhizobacteria, and extracellular molecules.

Indole-3-acetic acid (IAA), as an important regulator of potato growth, seriously affects the growth and yield of potato. Although many studies have reported that IAA-producing Bacillus can promote plant growth, little research has been conducted on its synthesis pathway and molecular mechanisms. In this study, an IAA-producing strain WL35 was identified as Fitibacillus barbaricus, and its yield was 48.79 mg·L−1. The results of the pot experiments showed that WL35 significantly increased plant height, stem thickness, chlorophyll content, and number of leaves of potato plants by 31.68%, 30.03%, 32.93%, and 36.59%, respectively. In addition, in the field experiments, WL35-treated plants increased commercial potato yield by 16.45%, vitamin C content by 16.35%, protein content by 75%, starch content by 6.60%, and the nitrogen, phosphorus, and potassium accumulation by 9.98%, 12.70%, and 26.76%, respectively. Meanwhile, the synthetic pathway of WL35 was found to be dominated by the tryptophan-dependent pathway, the IAM, TAM, and IPA pathways worked together, and the pathways that played a role at different times were different. Furthermore, RNA-seq analysis showed that there were a total of 2875 DEGs regulated in the samples treated with WL35 seed dressing compared with the CK, of which 1458 genes were up-regulated and 1417 genes were down-regulated. Potato roots express differential genes enriched in processes such as carbohydrate metabolism processes and cellular polysaccharide metabolism, which regulate potato plant growth and development. The above results provide a theoretical basis for the further exploration of the synthesis pathway of IAA and its growth-promoting mechanism in potato. [ABSTRACT FROM AUTHOR]

The isolation and identification of plant growth-promoting endophytic bacteria (PGPEB) from Achyranthes bidentata roots have profound theoretical and practical implications in ecological agriculture, particularly as bio-inoculants to address challenges associated with continuous monoculture. Our research revealed a significant increase in the abundance of these beneficial bacteria in A. bidentata rhizosphere soil under prolonged monoculture conditions, as shown by bioinformatics analysis. Subsequently, we isolated 563 strains of endophytic bacteria from A. bidentata roots. Functional characterization highlighted diverse plant growth-promoting traits among these bacteria, including the secretion of indole-3-acetic acid (IAA) ranging from 68.01 to 73.25 mg/L, phosphorus and potassium solubilization capacities, and antagonistic activity against pathogenic fungi (21.54%-50.81%). Through 16S rDNA sequencing, we identified nine strains exhibiting biocontrol and growth-promoting potential. Introduction of a synthetic microbial consortium (SMC) in pot experiments significantly increased root biomass by 48.19% in A. bidentata and 27.01% in replanted Rehmannia glutinosa. These findings provide innovative insights and strategies for addressing continuous cropping challenges, highlighting the practical promise of PGPEB from A. bidentata in ecological agriculture to overcome replanting obstacles for non-host plants like R. glutinosa, thereby promoting robust growth in medicinal plants. [ABSTRACT FROM AUTHOR]

The scarcity of freshwater resources resulting in a significant yield loss presents a pressing challenge in agriculture. To address this issue, utilizing abundantly available saline water could offer a smart solution. In this study, we demonstrate that the genome sequence rhizosphere bacterium Tritonibacter mobilis AK171, a halophilic marine bacterium recognized for its ability to thrive in saline and waterlogged environments, isolated from mangroves, has the remarkable ability to enable plant growth using saline irrigation. AK171 is characterized as rod-shaped cells, displays agile movement in free-living conditions, and adopts a rosette arrangement in static media. Moreover, The qualitative evaluation of PGP traits showed that AK171 could produce siderophores and IAA but could not solubilize phosphate nor produce hydrolytic enzymes it exhibits a remarkable tolerance to high temperatures and salinity. In this study, we conducted a comprehensive genome sequence analysis of T. mobilis AK171 to unravel the genetic mechanisms underlying its plant growth-promoting abilities in such challenging conditions. Our analysis revealed diverse genes and pathways involved in the bacterium's adaptation to salinity and waterlogging stress. Notably, T. mobilis AK171 exhibited a high level of tolerance to salinity and waterlogging through the activation of stress-responsive genes and the production of specific enzymes and metabolites. Additionally, we identified genes associated with biofilm formation, indicating its potential role in establishing symbiotic relationships with host plants. Furthermore, our analysis unveiled the presence of genes responsible for synthesizing antimicrobial compounds, including tropodithietic acid (TDA), which can effectively control phytopathogens. This genomic insight into T. mobilis AK171 provides valuable information for understanding the molecular basis of plant-microbial interactions in saline and waterlogged environments. It offers potential applications for sustainable agriculture in challenging conditions. [ABSTRACT FROM AUTHOR]

Objective: Pine needles are rich in many nutrients and exhibit antibacterial and antioxidant biological activities; however, the effects of different production methods of pine needle additives on the growth performance and intestinal flora of broiler chickens are not known. Methods: Normal diets were supplemented with pine needle fermentation juice (PNF), pine needle soaking juice (PNS), or pine needle powder (PNP), and the associated effects on growth performance, relative organ weights, intestinal development, intestinal histological morphology, intestinal flora, meat quality, and serum indicators in broiler chickens were observed. Results: The results showed that PNF, PNS, and PNP all significantly improved feed utilisation and promoted the growth and development of broilers. All three additives also significantly improved the structure of the intestinal flora, specifically increasing the diversity of bacteria; increasing the abundance of beneficial bacteria, such as Faecalibacterium, Rikenella, and Blautia; and decreasing the abundance of harmful bacteria, such as Staphylococcus. The antioxidant properties of pine needles were also found to intensify lipid metabolic reactions in the blood, thus leading to lower triglycerides and total cholesterol. Meanwhile, high doses of PNF reduced jejunum and ileum weights and also increased meat yellowness. Lastly, none of PNF, PNS, or PNP had an effect on relative organ weights or intestinal histological morphology. Conclusion: The addition of pine needles to the diet of broiler chickens can effectively promote their growth performance as well as improve their intestinal flora and serum status without side effects; in particular, the dose of 0.2% of either PNF and PNS is expected to have the capacity to replace growth-promoting antibiotics as diet additives. [ABSTRACT FROM AUTHOR]

Substrate supplementation and co-cultivation approaches were used to enhance activity of biofungicide Trichoderma viride. Biopesticides were produced using corn cobs (T), corn cobs + 1% keratin (K), corn cobs + 5% lignin (L), and corn cobs + 1% keratin + 5% lignin (K+L). Also, biopesticides were produced through co-culturing with Bacillus subtilis MTCC8142, by sequential inoculation (B+T) and simultaneous inoculation (T3+B2) (B2+T3). The highest spore count was produced by (T3+B2) of 6.25x108 spores/g of substrate, followed by (T) of 6.20x108 spores/g of substrate. GC-MS characterization of ethyl acetate extract of biopesticides revealed different metabolites produced under different conditions. The zone of inhibition of extract was greatest for (T) of 21 mm, followed by (K) of 20.7 mm and for (B2+T3) of 18 mm at 10 mg/mL concentration. (K) and (B2+T3) did not affect antifungal properties; however, other substrate-supplemented and co-cultivated biopesticides decreased them. Competition between two microbes prevented (T3+B2) from producing antimicrobial metabolites; hence, no zone of inhibition was observed. The biopesticides (K), (L) and (B2+T3) significantly enhanced growth of chili plants (Capsicum frutescens L.), outperforming other biopesticides. The production of phthalates, also known as phytotoxins, by B+T resulted in a decrease in plant growth. Adding 1% keratin to corn cobs (K) and (B2+T3) sequential inoculation are best ways to boost plant growth promoting activity of T. viride without affecting its biocontrol activity. [ABSTRACT FROM AUTHOR]

Bacterial endophytes from plants harbor diverse metabolites that play major roles in biocontrol and improve plant growth. In this study, a total of 12 endophytic bacteria were isolated from the ginger rhizome. The strain K3 was highly effective in preventing mycelia growth of Pythium myriotylum (78.5 ± 1.5% inhibition) in dual culture. The cell‐free extract (2.5%) of endophyte K3 inhibited 76.3 ± 4.8% mycelia growth, and 92.4 ± 4.2% inhibition was observed at a 5% sample concentration. The secondary metabolites produced by Bacillus licheniformis K3 showed maximum activity against Pseudomonas syringae (24 ± 1 mm zone of inhibition) and Xanthomonas campestris (28 ± 3 mm zone of inhibition). The strain K3 produced 28.3 ± 1.7 IU mL−1 protease, 28.3 ± 1.7 IU mL−1 cellulase, and 2.04 ± 0.13 IU mL−1 chitinase, respectively. The ginger rhizome treated with K3 in the greenhouse registered 53.8 ± 1.4% soft rot incidence, and the streptomycin‐treated pot registered 78.3 ± 1.7% disease incidence. The selected endophyte K3 improved ascorbate peroxidase (1.37 ± 0.009 µmole ASC min−1 mg−1 protein), catalase (8.7 ± 0.28 µmole min−1 mg−1 protein), and phenylalanine ammonia‐lyase (26.2 ± 0.99 Umg−1) in the greenhouse. In addition, K3 treatment in the field trial improved rhizome yield (730 ± 18.4 g) after 180 days (p < 0.01). The shoot length was 46 ± 8.3 cm in K3‐treated plants, and it was about 31% higher than the control treatment (p < 0.01). The lytic enzyme‐producing and growth‐promoting endophyte is useful in sustainable crop production through the management of biotic stress. [ABSTRACT FROM AUTHOR]

A polyphasic approach was applied to characterize taxonomically a novel endophytic bacterial strain, designated as EP178T, which was previously isolated from Passiflora incarnata leaves and characterized as plant-growth promoter. The strain EP178T forms Gram stain-negative and rod-shaped cells, and circular and yellow-pigmented colonies. Its growth occurs at 10–37 °C, at pH 6.0–8.0, and tolerates up to 7% (w/v) NaCl. The major cellular fatty acids found were summed feature 8 (C18:1 ω7c), summed feature 3 (C16:1 ω6c /C16:1 ω7c), and C16:0, and the predominant ubiquinone was Q-9. The phylogenetic and nucleotide-similarity analysis with 16S rRNA gene sequences showed that strain EP178T belongs to Pseudomonas genus. The genomic-based G + C content was 65.5%. The average nucleotide identity and digital DNA-DNA hybridization values between strains EP178T and the closest type strain, P. oryzihabitans DSM 6835T, were 92.6% and 52.2%, respectively. Various genes associated with plant-growth promoting mechanisms were annotated from genome sequences. Based on the phenotypic, genomic, phylogeny and chemotaxonomic data, strain EP178T represents a new species of the genus Pseudomonas, for which the name Pseudomonas flavocrustae sp. nov. was proposed. The type strain is EP178T (= CBMAI 2609T = ICMP 24844T = MUM 23.01T). [ABSTRACT FROM AUTHOR]

Microbes are thought to be distributed and circulated around the world, but the connection between marine and terrestrial microbiomes remains largely unknown. We use Plantibacter, a representative genus associated with plants, as our research model to investigate the global distribution and adaptation of plant‐related bacteria in plant‐free environments, particularly in the remote Southern Ocean and the deep Atlantic Ocean. The marine isolates and their plant‐associated relatives shared over 98% whole‐genome average nucleotide identity (ANI), indicating recent divergence and ongoing speciation from plant‐related niches to marine environments. Comparative genomics revealed that the marine strains acquired new genes via horizontal gene transfer from non‐Plantibacter species and refined existing genes through positive selection to improve adaptation to new habitats. Meanwhile, marine strains retained the ability to interact with plants, such as modifying root system architecture and promoting germination. Furthermore, Plantibacter species were found to be widely distributed in marine environments, revealing an unrecognized phenomenon that plant‐associated microbiomes have colonized the ocean, which could serve as a reservoir for plant growth‐promoting microbes. This study demonstrates the presence of an active reservoir of terrestrial plant growth‐promoting bacteria in remote marine systems and advances our understanding of the microbial connections between plant‐associated and plant‐free environments at the genome level. [ABSTRACT FROM AUTHOR]

I. cateinannulata has been shown to promote the growth of F. tataricum. However, whether its growth-promoting capacity is related to its ability to solubilize phosphorus has not been reported. Therefore, in this study, we sought to assess the phosphorus-solubilizing ability of 18 strains of I. cateinannulata by analyzing their growth in an inorganic phosphorus culture medium. The effects of F. tataricum on growth and effective phosphorus content were analyzed through field experiments. The results showed that all 18 strains of I. cateinannulata had a phosphorus release capacity, with phosphorus solubilization ranging from 5.14 ± 0.37 mg/L to 6.21 ± 0.01 mg/L, and strain 9 exhibited the best phosphorus solubilization effect. Additionally, the field results demonstrated that I. cateinannulata positively influenced the growth, root length, and yield of F. tataricum by increasing the chlorophyll and soluble phosphorus content. This study will provide a material basis and theoretical support for investigating the interaction mechanism between I. cateinannulata and F. tataricum. [ABSTRACT FROM AUTHOR]

Contamination of arsenic in drinking water and foods is a threat for human beings. To achieve the goal for the reduction of arsenic availability, besides conventional technologies, arsenic bioremediation by using some potent bacteria is one of the hot topics for researchers. In this context, bacterium, AKS4c was isolated from arsenic contaminated water of Purbasthali, West Bengal, India, and through draft genome sequence; it was identified as a strain of Micrococcus luteus that comprised of 2.4 Mb genome with 73.1% GC content and 2256 protein coding genes. As the accessory genome, about 22 genomic islands (GIs) associated with many metal-resistant genes were identified. This strain was capable to tolerate more than 46,800 mg/L arsenate and 390 mg/L arsenite salts as well as found to be tolerable to multi-metals such as Fe, Pb, Mo, Mn, and Zn up to a certain limit of concentrations. Strain AKS4c was able to oxidize arsenite to less toxic arsenate, and its arsenic adsorption property was qualitatively confirmed through X-ray fluorescence (XRF) and Fourier transform infrared spectroscopy (FTIR) analysis. Quantitative estimation of plant growth-promoting attributes like Indole acetic acid (IAA), Gibberellic acid (GA), and proline production and enhancement of rice seedling growth in laboratory condition leads to its future applicability in arsenic bioremediation as a plant growth-promoting rhizobacteria (PGPR). [ABSTRACT FROM AUTHOR]

Aims: Damping-off disease, caused by Fusarium oxysporum, affects the growth of Pinus massoniana seedlings. Plant growth-promoting fungi and rhizobacteria (PGPF and PGPR) are widely used in agriculture to control plant soil-borne disease, however, the joint mechanism by which they inhibit damping-off disease in forestry requires further exploration. Methods: The current study screened for the ability of antagonistic PGPF and PGPR strains to inhibit the pathogen, and used soil microbiome and plant transcriptome technologies to characterize the biocontrol mechanism. Results: PGPF strain 3Y, identified as Trichoderma longibrachiatum, and PGPR strain K29, identified as Burkholderia stabilis, were screened and found to strongly inhibit the growth of F. oxysporum through direct contact with the hyphae. The combined use of T. longibrachiatum and B. stabilis effectively reduced disease incidence and severity, and promoted the growth of P. massoniana seedlings, and enhanced soluble sugar, proline, SOD and POD activities. Compound strains treatment impacted the structure of rhizosphere bacterial microbial community, causing significant differences in the relative abundances of some key phyla and genera, promoting the enrichment of some beneficial microorganisms. Transcriptome profiles showed that combination treatment with the biocontrol strains induced the expressions of 8541 differentially expressed genes (DEGs). These genes participated in key biological pathways associated with starch and sucrose metabolism, plant hormone signal transduction, photosynthesis, antioxidant enzymes, and proline synthesis. Conclusion: The combined use of PGPF and PGPR strains controlled F. oxysporum infection of P. massoniana seedlings by regulating physiological responses and soil microbial community. [ABSTRACT FROM AUTHOR]

Microorganisms in the plant's rhizosphere are capable of solubilising insoluble soil phosphates and can promote plant growth. In this study, a total of 30 bacteria were isolated from soils in Changji city, and one highly efficient strain (B5) was identified as a member of Pseudomonadaceae. B5 exhibited phosphorus (P) solubilisation of 519.66 mg/L in a culture medium containing tricalcium phosphate (Ca3 (PO4)2). Results showed that strain B5 had a high P utilisation rate in a medium containing glucose (monosaccharide), ammonium sulphate and tricalcium phosphate. B5 treatment significantly promoted plant growth and increased the dry weight, the chlorophyll content as well as P content of tomato, marigold and cucumber. Moreover, B5 produced plant growth-promoting hormones, including indole-3-acetic acid (IAA) (4.18 g/L) and gibberellin (GA) (19.8 mg/L). In addition, organic acids including oxalic acid, succinic acid, gluconic acid, arabic-hexanoic acid and glutraic acid were produced by B5 under different phosphorus sources. Our results indicated that B5 is a potential candidate for development as a bioinoculant for horticultural application. [ABSTRACT FROM AUTHOR]

Aims: The application of silicon solubilizing rhizobacteria (SSB) with various plant growth-promoting properties to improve the uptake of nutrients by plants is becoming the global trend in sustaining rice production systems. However, the identification and profiling of SSB from the coastal halophyte are still limited. This study was aimed to identify and profile the SSB with plant growth-promoting properties isolated from the coastal halophyte rhizosphere soil. Methodology and results: The rhizosphere soil of halophyte (Poaceae) was sampled and screened for SSB. The SSB obtained was further in vitro screened for lignocellulolytic activities and phosphate solubilization properties. The most potential SSB were clustered and selected using principal component analysis (PCA) and further evaluated for in vitro siderophore and IAA production, followed by rice seed germination and seedling growth performance. A total of 46 SSB were isolated from the coastal halophyte with the silicon solubilizing index ranging 1.01-4.6. Eight SSB isolates (SSB34, SSB37, SSB41, SSB24, SSB45, SSB46, SSB25 and SSB29) were identified and selected from the clustering analysis. Further analysis revealed that rice seedlings inoculated with the isolates SSB24, SSB29 and SSB46 exhibited significant sprouting rates compared with control. All these three SSB isolates were identified using 16S rRNA sequencing as Pantoea stewartii subsp. Indologenes (SSB24), Burkholderia lata strain 383 (SSB29) and Ralstonia syzygii strain ATCC 49543. Conclusion, significance and impact of study: The selected SSB isolates can potentially be suggested as a sustainable approach to promote rice seedling growth. Moreover, exploring SSB under field conditions to improve rice seedling growth through increasing nutrient availability for plant uptake needed to be focused. [ABSTRACT FROM AUTHOR]

Aims: Phosphorus (P) and nitrogen (N) are essential nutrients required for the growth of crops, with scarce bioavailability in soil. The aim of this work was to study the inorganic P solubilization by three locally isolated bacteria of the genus Bacillus (San Luis, Argentina) and its influence in a co-culture with Tolypothrix tenuis, a diazotrophic and filamentous cyanobacterium used as a biofertilizer. Methodology and results: Morphological, biochemical and API50 CH tests clustered strains SL-3, SL-4 and SL-7 as members of the Bacillus subtilis group. The solubilization index (SI) on Pikovskaya’s (PVK) agar showed that isolate SL- 7 reached the highest solubilization value (SI=2.10), with better results than those obtained with Bacillus velezensis FZB42, a recognized plant growth-promoting bacterium (PGPB). In addition, T. tenuis was not able to solubilize tricalcium phosphate (TCP) on PVK agar. Individual cultures in Watanabe medium with TCP showed a reduction in the final biomass of 68.61% and their polyphosphate (poly-P) granules decreased considerably in size and quantity in relation to the cultures with soluble P, whose final biomass was 2.74 g/L. Co-cultures with strain SL-7 partially recovered the final biomass, reaching values of 1.37 to 1.42 g/L (p<0.01), while co-cultures with strain FZB42 showed no significant differences (p>0.05) in relation to the individual cyanobacterial culture with insoluble P. Conclusion, significance and impact of study: The results of this study indicate that the mixed inoculation of Bacillus sp. SL-7 and T. tenuis could be a promising biofertilizer for overcoming the limitation of P and N compounds and boosting sustainable agriculture. [ABSTRACT FROM AUTHOR]

Plant biostimulants have received attention as sustainable alternatives to chemical fertilizers. Extracellular polymeric substances (EPSs), among the compounds secreted by plant growth-promoting rhizobacteria (PGPRs), are assumed to alleviate abiotic stress. This study aims to investigate the effect of purified EPSs on rice under abiotic stress and analyze their mechanisms. A pot experiment was conducted to elucidate the effects of inoculating EPSs purified from PGPRs that increase biofilm production in the presence of sugar on rice growth in heat-stress conditions. Since all EPSs showed improvement in SPAD after the stress, Enterobacter ludwigii, which was not characterized as showing higher PGP bioactivities such as phytohormone production, nitrogen fixation, and phosphorus solubilization, was selected for further analysis. RNA extracted from the embryos of germinating seeds at 24 h post-treatment with EPSs or water was used for transcriptome analysis. The RNA-seq analysis revealed 215 differentially expressed genes (DEGs) identified in rice seeds, including 139 up-regulated and 76 down-regulated genes. A gene ontology (GO) enrichment analysis showed that the enriched GO terms are mainly associated with the ROS scavenging processes, detoxification pathways, and response to oxidative stress. For example, the expression of the gene encoding OsAAO5, which is known to function in detoxifying oxidative stress, was two times increased by EPS treatment. Moreover, EPS application improved SPAD and dry weights of shoot and root by 90%, 14%, and 27%, respectively, under drought stress and increased SPAD by 59% under salt stress. It indicates that bacterial EPSs improved plant growth under abiotic stresses. Based on our results, we consider that EPSs purified from Enterobacter ludwigii can be used to develop biostimulants for rice. [ABSTRACT FROM AUTHOR]

Industrialization and urbanization increased the use of chemicals in agriculture, vehicular emissions, etc., and spoiled all environmental sectors. It causes various problems among living beings at multiple levels and concentrations. Phytoremediation and microbial association are emerging as a potential method for removing heavy metals and other contaminants from soil. The treatment uses plant physiology and metabolism to remove or clean up various soil contaminants efficiently. In recent years, omics and artificial intelligence have been seen as powerful techniques for phytobial remediation. Recently, AI and modeling are used to analyze large data generated by omics technologies. Machine learning algorithms can be used to develop predictive models that can help guide the selection of the most appropriate plant and plant growth–promoting rhizobacteria combination that is most effective at remediation. In this review, emphasis is given to the phytoremediation techniques being explored worldwide in soil contamination. [ABSTRACT FROM AUTHOR]

Saline-sodic stress can limit the absorption of available zinc in rice, subsequently impacting the normal photosynthesis and carbohydrate metabolism of rice plants. To investigate the impact of exogenous zinc application on photosynthesis and carbohydrate metabolism in rice grown in saline-sodic soil, this study simulated saline-sodic stress conditions using two rice varieties, 'Changbai 9' and 'Tonghe 899', as experimental materials. Rice seedlings at 4 weeks of age underwent various treatments including control (CT), 2 μmol·L−1 zinc treatment alone (Z), 50 mmol·L−1 saline-sodic treatment (S), and 50 mmol·L−1 saline-sodic treatment with 2 μmol·L−1 zinc (Z + S). We utilized JIP-test to analyze the variations in excitation fluorescence and MR820 signal in rice leaves resulting from zinc supplementation under saline-sodic stress, and examined the impact of zinc supplementation on carbohydrate metabolism in both rice leaves and roots under saline-sodic stress. Research shows that zinc increased the chloroplast pigment content, specific energy flow, quantum yield, and performance of active PSII reaction centers (PIABS), as well as the oxidation (VOX) and reduction rate (Vred) of PSI in rice leaves under saline-sodic stress. Additionally, it decreased the relative variable fluorescence (WK and VJ) and quantum energy dissipation yield (φDO) of the rice. Meanwhile, zinc application can reduce the content of soluble sugars and starch in rice leaves and increasing the starch content in the roots. Therefore, the addition of zinc promotes electron and energy transfer in the rice photosystem under saline-sodic stress. It enhances rice carbohydrate metabolism, improving the rice plants' ability to withstand saline-sodic stress and ultimately promoting rice growth and development. [ABSTRACT FROM AUTHOR]

Plant biostimulants are widely applied in agriculture for their ability to improve plant fitness. In the present work, the impact of Graminaceae-derived protein hydrolysate (P) and its lighter molecular fraction F3 (< 1 kDa) on lettuce plants, subjected to either no salt or high salt conditions, was investigated through the combination of metabolomics and transcriptomics. The results showed that both treatments significantly modulated the transcriptome and metabolome of plants under salinity stress, highlighting an induction of the hormonal response. Nevertheless, P and F3 also displayed several peculiarities. F3 specifically modulated the response to ethylene and MAPK signaling pathway, whereas P treatment induced a down-accumulation of secondary metabolites, albeit genes controlling the biosynthesis of osmoprotectants and antioxidants were up-regulated. Moreover, according with the auxin response modulation, P promoted cell wall biogenesis and plasticity in salt-stressed plants. Notably, our data also outlined an epigenetic control of gene expression induced by P treatment. Contrarily, experimental data are just partially in agreement when not stressed plants, treated with P or F3, were considered. Indeed, the reduced accumulation of secondary metabolites and the analyses of hormone pathways modulation would suggest a preferential allocation of resources towards growth, that is not coherent with the down-regulation of the photosynthetic machinery, the CO2 assimilation rate and leaves biomass. In conclusion, our data demonstrate that, although they might activate different mechanisms, both the P and F3 can result in similar benefits, as far as the accumulation of protective osmolytes and the enhanced tolerance to oxidative stress are concerned. Notably, the F3 fraction exhibits slightly greater growth promotion effects under high salt conditions. Most importantly, this research further corroborates that biostimulants' mode of action is dependent on plants' physiological status and their composition, underscoring the importance of investigating the bioactivity of the different molecular components to design tailored applications for the agricultural practice. [ABSTRACT FROM AUTHOR]

Bacteria can be applied as biofertilizers to improve crop growth in phosphorus (P)‐limited conditions. However, their mode of action in a soil environment is still elusive. We used the strain ALC_02 as a case study to elucidate how Bacillus subtilis affects dwarf tomato cultivated in soil‐filled rhizoboxes over time. ALC_02 improved plant P acquisition by increasing the size and P content of P‐limited plants. We assessed three possible mechanisms, namely root growth stimulation, root hair elongation, and solubilization of soil P. ALC_02 produced auxin, and inoculation with ALC_02 promoted root growth. ALC_02 promoted root hair elongation as the earliest observed response and colonized root hairs specifically. Root and root hair growth stimulation was associated with a subsequent increase in plant P content, indicating that a better soil exploration by the root system improved plant P acquisition. Furthermore, ALC_02 affected the plant‐available P content in sterilized soil differently over time and released P from native P pools in the soil. Collectively, ALC_02 exhibited all three mechanisms in a soil environment. To our knowledge, bacterial P biofertilizers have not been reported to colonize and elongate root hairs in the soil so far, and we propose that these traits contribute to the overall effect of ALC_02. The knowledge gained in this research can be applied in the future quest for bacterial P biofertilizers, where we recommend assessing all three parameters, not only root growth and P solubilization, but also root hair elongation. This will ultimately support the development of sustainable agricultural practices. [ABSTRACT FROM AUTHOR]

Background: The current study was carried out to assess the alternative role of high temperature tolerant plant growth promoting rhizobacteria (PGPR) in alleviation of heat stress adverse effect in eggplant. Methods: PGPR was assessed for PGP potentialities and investigated for1-aminocyclopropane-1-carboxylate (ACC deaminase), and exopolysaccharide under normal and high temperature environment. The impact of PGPR application on plant physiology and biochemistry was investigated under normal and high temperature environments and plant growth regulators were evaluated using High Performance Liquid Chromatography (HPLC). Results: A significant impediment for morphological and physiological parameters of eggplant cultivars was observed during heat stress in absence of PGPR inoculation. The results showed that ACC-deaminase produced by PGPR boosted up significantly the extracellular polymeric substances (EPS) accumulation, conversion of ACC into a-ketobutyrate and ammonia, and reduce consequently the impact of high temperature on eggplant development. Conclusion: PGPR inoculation showed an alternative strategy to improve eggplant growth and development under high temperature condition in order to preserve agriculture sustainability and healthy crops. [ABSTRACT FROM AUTHOR]

Modern agriculture practices heavily depend on the application of chemical fertilizers and continuous application disturbs the soil quality and health. Fluorescent Pseudomonas are the well characterized group of bacteria proficient in plant growth promotion and have excellent phosphate solubilizing abilities and solubilize insoluble phosphate to plants available form via secretion of organic acids. This study focused on the phosphate solubilization ability of Pseudomonas, arouse of Aloin-A molecule, gluconic acid production, as well as biometric parameters of key medicinal plant, the Aloe vera (Aloe barbadensis). Two strains (P. putida and Pseudomonas sp.) were found very effective PSBs and solubilized 236.73 and 153.73 mg L−1 phosphate, respectively. High-performance liquid chromatography analysis (HPLC) showed the production of gluconic acid (GA). P. putida and P. sp. produced 23970 ± 231 and 21538 ± 129 mg L−1 GA, respectively. Inoculation of the plants with consortium of P. putida and Pseudomonas sp. enhanced the plant growth, soil available P and phosphate uptake in plants than individual inoculation. An increase in aloin-A content (18.15 and 28.71 fold) was recorded in A. barbadensis treated with a PSB consortium in a soil amended without and with TCP (tricalcium phosphate), respectively. P-uptake ultimately enhances the aloin-A synthesis and biomass of plant. Therefore, agronomic attributes of Aloe vera plants can be improved for used as a medicinal plant through application of potent Fluorescent Pseudomonas. [ABSTRACT FROM AUTHOR]

Thrombopoietin, the primary regulator of blood platelet production, was postulated to exist in 1958, but was only proven to exist when the cDNA for the hormone was cloned in 1994. Since its initial cloning and characterization, the hormone has revealed many surprises. For example, instead of acting as the postulated differentiation factor for platelet precursors, megakaryocytes, it is the most potent stimulator of megakaryocyte progenitor expansion known. Moreover, it also stimulates the survival, and in combination with stem cell factor leads to the expansion of hematopoietic stem cells. All of these growth-promoting activities have resulted in its clinical use in patients with thrombocytopenia and aplastic anemia, although the clinical development of the native molecule illustrated that "it's not wise to mess with mother nature", as a highly engineered version of the native hormone led to autoantibody formation and severe thrombocytopenia. Finally, another unexpected finding was the role of the thrombopoietin receptor in stem cell biology, including the development of myeloproliferative neoplasms, an important disorder of hematopoietic stem cells. Overall, the past 30 years of clinical and basic research has yielded many important insights, which are reviewed in this paper. [ABSTRACT FROM AUTHOR]

• Most PGR combinations induced callogenesis. • Only some few PGR combinations supported callus survivor after 2 years of subcultures. • Vincristine and vinblastine are produced in homogenous-looking calluses. • Vinblastine is only produced when culturing in 2,4-D (1.1 mg/L) plus BAP 0.4 (mg/L). In this work, we evaluated the effect of 29 PGR combinations and photoperiods on callogenesis while analyzing the fate of calluses during a two-year period. Variation of PGR combinations in the culture medium strongly affected callogenesis in terms of growth and callus morphology. Although most PGR combinations resulted in callogenesis, only few ones supported cell survivor in long-term basis for the generation of cell lines as homogenous-looking calluses. Analysis by tandem liquid chromatography quadrupole time of flight mass spectrometry (LC-QTOF-MS/MS) revealed production of vincristine (9.25 mg/kg), vinblastine (0.17 mg/kg), and vindoline (1.02 mg/kg) in cell lines when proper combinations of PGR are employed. These callus cell lines are a promising platform to establish suspension cultures seeking production of alkaloids, particularly vincristine and vinblastine. [ABSTRACT FROM AUTHOR]

Aims This study aimed to isolate plant growth and drought tolerance-promoting bacteria from the nutrient-poor rhizosphere soil of Thar desert plants and unravel their molecular mechanisms of plant growth promotion. Methods and results Among our rhizobacterial isolates, Enterobacter cloacae C1P-IITJ, Kalamiella piersonii J4-IITJ, and Peribacillus frigoritolerans T7-IITJ, significantly enhanced root and shoot growth (4˗5-fold) in Arabidopsis thaliana under PEG-induced drought stress. Whole genome sequencing and biochemical analyses of the non-pathogenic bacterium T7-IITJ revealed its plant growth-promoting traits, viz. solubilization of phosphate (40−73 µg/ml), iron (24 ± 0.58 mm halo on chrome azurol S media), and nitrate (1.58 ± 0.01 µg/ml nitrite), along with production of exopolysaccharides (125 ± 20 µg/ml) and auxin-like compounds (42.6 ± 0.05 µg/ml). Transcriptome analysis of A. thaliana inoculated with T7-IITJ and exposure to drought revealed the induction of 445 plant genes (log2fold-change > 1, FDR  < 0.05) for photosynthesis, auxin and jasmonate signalling, nutrient uptake, redox homeostasis, and secondary metabolite biosynthesis pathways related to beneficial bacteria-plant interaction, but repression of 503 genes (log2fold-change < −1) including many stress-responsive genes. T7-IITJ enhanced proline 2.5-fold, chlorophyll 2.5˗2.8-fold, iron 2-fold, phosphate 1.6-fold, and nitrogen 4-fold, and reduced reactive oxygen species 2˗4.7-fold in plant tissues under drought. T7-IITJ also improved the germination and seedling growth of Tephrosia purpurea, Triticum aestivum , and Setaria italica under drought and inhibited the growth of two plant pathogenic fungi, Fusarium oxysporum , and Rhizoctonia solani. Conclusions P. frigoritolerans T7-IITJ is a potent biofertilizer that regulates plant genes to promote growth and drought tolerance. [ABSTRACT FROM AUTHOR]

In the current investigation, the potential of using the bacterial species Pantoea agglomerans for phenol biodegradation was evaluated. The inhibitory effects of various doses of phenol (ranging from 200 to 1200 ppm) on the growth of P. agglomerans and the biodegradation rate were evaluated. The effects of temperature and pH were also investigated in order to determine the ideal parameters for maximum phenol biodegradation. Additionally, the ideal parameters for growth rate and beginning phenol content were determined using mathematical modeling employing modified Gompertz and Haldane models. The half-saturation coefficient (Ks) for Haldane and the maximum specific growth rate (max) for phenol-dependent growth kinetics (Ki) has been calculated to be 480.23 mg/L, 188.17 mg/L, and 0.887 mg/L, respectively. The Haldane equation can be applied to empirical data because of its tiny sum of squared error (SSR), which is 1.39 x 10-3. Additionally, the reformulated Gombertz model effectively predicts trends in the degradation of phenol. The starting amount of phenol impacted both the degradation rate and the period of lag time, and both of them raised further as the phenol level got higher. A 28°C incubation temperature and a pH of 7.0 were determined to be the ideal conditions for Pantoea agglomerans to grow and degrade phenol. The GC-MS data showed that many phenol derivatives were produced due to phenol degradation, such as catechol, 2-hydroxymucconic semialdehyde, and pyruvate. This may provide strong evidence that the degradation of phenol by P. agglomerans occurred via a meta-pathway. [ABSTRACT FROM AUTHOR]

In this study, 22 halophilic bacteria were isolated from plants collected together with rhizosphere soil from habitats with high salt content in and around Erzurum. Various plant growth-promoting (PGP) properties of these isolates (nitrogen fixing, phosphate solubilizing, ACC deaminase, and IAA and siderephore production) were determined. Bacteria positive for PGP properties and various combinations with these bacteria were subjected to pot experiments in saline medium (greenhouse conditions) and their effects on growth parameters (root and stem length, fresh and dry weight, protein, and chlorophyll and carotenoid content) of wheat plants were determined. As a result of the research, the isolates were evaluated as successful isolates 5%-41% yield increase in root length, 3.82%-54.97% in stem length, 7.14%-60.71% in wet weight, 5%-32.5% in dry weight, 13.78%-29.68% in dissolved protein content, 83.40%-120.22% in total chlorophyll content, and 45.79%-120.22% in total carotenoid content. 16S rRNA analysis showed that these 22 halophilic bacterial strains belonged to 11 different bacterial species (Bacillus pumilus, Bacillus endophyticus, Paenobacillus lautus, Planococcus citreus, Staphylococcus sciuri, Staphylococcus saprophyticus, Leucobacter iarius, Sphingomonas echinoides, Bacillus simplex, Bacillus cereus, Pantoea aggloremans). All isolates obtained in this study are new and original isolates. Inoculations with the isolates found in our study were much more effective and provided significant yield increases on wheat plants under saline irrigation compared to previous studies. These results conclude that the obtained isolates promote plant growth under saline conditions and have biofertilizer potential for wheat plants under saline conditions. [ABSTRACT FROM AUTHOR]

Conventional agriculture practice has heavily relied on chemical fertilizers to increase crop yield. However, long-term application of chemical fertilizers carries tremendous negative impact on the environment and is unsustainable. Hence, the search for an alternative source of fertilizers is required. Orchids are flowers and can be found in tropical countries. The growth and development of orchids are closely tied to the presence of plant growth promoting endophytic microorganisms (PGPM). PGPM harbours various beneficial traits such as potassium and phosphorus solubilization and indole acetic acid and siderophore production which enhance and support plant growth and development. This review article showed that PGPM isolated from orchids could be utilized in conventional agriculture to reduce dependency on chemical fertilizer. [ABSTRACT FROM AUTHOR]

The rhizosphere is the soil environment where the plant root is available and is a zone of maximum microbial activity, resulting in a confined nutrient pool in which essential macro-and micronutrients are extracted. The microbial population in the rhizosphere is relatively different from that of its surroundings due to root exudates that function as a source of nutrients for microbial growth. Those resulting in symbiotic and non-symbiotic nitrogen fixation are considerably important among all these interactions. In recent years, the use of bacteria (rhizobacteria) to promote plant growth has increased in several regions of the world and has acquired relevant importance in developing countries that are the producers of raw materials for food. In the present study Rhizobacteria was isolated from the soil and the production of IAA and phosphate solubilisation was studied. The effect of PGPR was shown on mat seeds (matki) and black-eyed pea seeds (chawali) on the growth of plants. [ABSTRACT FROM AUTHOR]

The unregulated dismantling and improper disposal of electronic waste lead to severe soil contamination by polychlorinated biphenyls (PCBs). Constructed wetlands (CWs) play an important role in PCBs removal as a result of the co-existence of anaerobic and aerobic conditions. However, the effects and mechanisms of different PCBs concentrations in soils on plant uptake and PCBs degradation within CWs are unclear. We evaluated the uptake and degradation of PCBs at different concentrations by Myriophyllum aquaticum (Vell.) Verdc. Planting significantly increased PCBs removal by 8.70% (p < 0.05) in soils with 1500 and 2500 μg/kg PCBs, whereas no significant effect was observed at 500 and 1000 μg/kg. PCBs levels did not significantly affect plant growth and PCBs accumulation. The contribution of plant uptake to PCBs removal was only 0.10–0.12%, indicating that microbial degradation was the dominant pathway for PCBs removal after planting with M. aquaticum. In the treatments with PCBs ≥ 1500 μg/kg, M. aquaticum increased the microbial population, altered the microbial community structure and enriched PCB-degrading bacteria. Functional prediction revealed that microbes in M. aquaticum rhizosphere secreted more peroxidase and glycosyltransferase than non-plant control, which were likely involved in PCBs metabolism. [ABSTRACT FROM AUTHOR]

The development of novel biotechnologies that promote a better use of N to optimize crop yield is a central goal for sustainable agriculture. Phytostimulation, biofertilization, and bioprotection through the use of bio-inputs are promising technologies for this purpose. In this study, the plant growth–promoting rhizobacteria Pseudomonas koreensis MME3 was genetically modified to express a nitric oxide synthase of Synechococcus SyNOS, an atypical enzyme with a globin domain that converts nitric oxide to nitrate. A cassette for constitutive expression of synos was introduced as a single insertion into the genome of P. koreensis MME3 using a miniTn7 system. The resulting recombinant strain MME3:SyNOS showed improved growth, motility, and biofilm formation. The impact of MME3:SyNOS inoculation on Brachypodium distachyon growth and N uptake and use efficiencies under different N availability situations was analyzed, in comparison to the control strain MME3:c. After 35 days of inoculation, plants treated with MME3:SyNOS had a higher root dry weight, both under semi-hydroponic and greenhouse conditions. At harvest, both MME3:SyNOS and MME3:c increased N uptake and use efficiency of plants grown under low N soil. Our results indicate that synos expression is a valid strategy to boost the phytostimulatory capacity of plant-associated bacteria and improve the adaptability of plants to N deficiency. Key points: • synos expression improves P. koreensis MME3 traits important for rhizospheric colonization • B. distachyon inoculated with MME3:SyNOS shows improved root growth • MME3 inoculation improves plant N uptake and use efficiencies in N-deficient soil [ABSTRACT FROM AUTHOR]