Search Results (161)

Insect pests cause severe damage and yield losses to many agricultural crops globally. The use of chemical pesticides on agricultural crops is not recommended because of their toxic effects on the environment and consumers. In addition, pesticide toxicity reduces soil fertility, poisons ground waters, and is hazardous to soil biota. Therefore, applications of entomopathogenic nematodes (EPNs) and plant growth-promoting rhizobacteria (PGPR) are an alternative, eco-friendly solution to chemical pesticides and mineral-based fertilizers to enhance plant health and promote sustainable food security. This review focuses on the biological and ecological aspects of these organisms while also highlighting the practical application of molecular communication approaches in developing a novel plant health product. This insight will support this innovative approach that combines PGPR and EPNs for sustainable crop production. Several studies have reported positive interactions between nematodes and bacteria. Although the combined presence of both organisms has been shown to promote plant growth, the molecular interactions between them are still under investigation. Integrating molecular communication studies in the development of a new product could help in understanding their relationships and, in turn, support the combination of these organisms into a single plant health product. Full article

Salinization hinders the restoration of vegetation in salt-affected soils by negatively impacting plant growth and development. Halophytes play a key role in the restoration of saline and degraded lands due to unique features explaining their growth aptitude in such extreme ecosystems. Suaeda fruticosa is an euhalophyte well known for its medicinal properties and its potential for saline soil phytoremediation. However, excessive salt accumulation in soil limits the development of this species. Research findings increasingly advocate the use of extremophile rhizosphere bacteria as an effective approach to reclaim salinized soils, in conjunction with their salt-alleviating effect on plants. Here, a pot experiment was conducted to assess the role of a halotolerant plant growth-promoting actinobacterium, Glutamicibacter sp., on the growth, nutritional status, and shoot content of proline, total soluble carbohydrates, and phenolic compounds in the halophyte S. fruticosa grown for 60 d under high salinity (600 mM NaCl). Results showed that inoculation with Glutamicibacter sp. significantly promoted the growth of inoculated plants under stress conditions. More specifically, bacterial inoculation increased the shoot concentration of proline, total polyphenols, potassium (K⁺), nitrogen (N), and K⁺/Na⁺ ratio in shoots, while significantly decreasing Na⁺ concentrations. These mechanisms partly explain S. fruticosa tolerance to high saline concentrations. Our findings provide some mechanistic elements at the ecophysiological level, enabling a better understanding of the crucial role of plant growth-promoting rhizobacteria (PGPRs) in enhancing halophyte growth and highlight their potential for utilization in restoring vegetation in salt-affected soils. Full article

Soil salinization severely restricts crop growth and presents a major challenge to global agriculture. In this study, a plant-growth-promoting rhizobacterium (PGPR) was isolated and identified as Proteus sp. through 16S rDNA analysis and was subsequently named Proteus sp. JHY1. Under salt stress, exogenous dopamine (DA) significantly enhanced the production of indole-3-acetic acid and ammonia by strain JHY1. Pot experiments revealed that both DA and JHY1 treatments effectively alleviated the adverse effects of 225 mM NaCl on rice, promoting biomass, plant height, and root length. More importantly, the combined application of DA-JHY1 showed a significant synergistic effect in mitigating salt stress. The treatment increased the chlorophyll content, net photosynthetic rate, osmotic regulators (proline, soluble sugars, and protein), and reduced lipid peroxidation. The treatment also increased soil nutrients (ammoniacal nitrogen and available phosphorus), enhanced soil enzyme activities (sucrase and alkaline phosphatase), stabilized the ion balance (K⁺/Na⁺), and modulated the soil rhizosphere microbial community by increasing beneficial bacteria, such as Actinobacteria and Firmicutes. This study provides the first evidence that the synergistic effect of DA and PGPR contributes to enhanced salt tolerance in rice, offering a novel strategy for alleviating the adverse effects of salt stress on plant growth. Full article

Cadmium (Cd) is a highly toxic heavy metal that can greatly affect crops and pose a threat to food security. Plant growth-promoting rhizobacteria (PGPR) are capable of alleviating the harm of Cd to crops. In this research, a Cd-tolerant PGPR strain was isolated and screened from the root nodules of semi-wild soybeans. The strain was identified as Pseudomonas sp. strain KM25 by 16S rRNA. Strain KM25 has strong Cd tolerance and can produce indole-3-acetic acid (IAA) and siderophores, dissolve organic and inorganic phosphorus, and has 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity. Under Cd stress, all growth indicators of soybean seedlings were significantly inhibited. After inoculation with strain KM25, the heavy metal stress of soybeans was effectively alleviated. Compared with the non-inoculated group, its shoot height, shoot and root dry weight, fresh weight, and chlorophyll content were significantly increased. Strain KM25 increased the superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities of soybean seedlings, reduced the malondialdehyde (MDA) content, increased the Cd content in the roots of soybeans, and decreased the Cd content in the shoot parts. In addition, inoculation treatment can affect the community structure of endophytic bacteria in the roots of soybeans under Cd stress, increasing the relative abundance of Proteobacteria, Bacteroidetes, Sphingomonas, Rhizobium, and Pseudomonas. This study demonstrates that strain KM25 is capable of significantly reducing the adverse effects of Cd on soybean plants while enhancing their growth. Full article

Plant growth-promoting rhizobacteria (PGPR) have significant potential for enhancing soil quality and plant growth; however, their agricultural application is limited by challenges such as immobilization and desiccation vulnerability. Background: This study addressed PGPR solid formulation by applying JetCutter-assisted immobilization technology to PGPR strains isolated from the rhizosphere of hazelnut (Corylus avellana). Methods: Four immobilized PGPR strains were evaluated under controlled greenhouse conditions: Serratia proteamaculans, Pseudomonas mohnii, Pseudomonas baetica, and Bacillus safensis. Their effects on root development, gas exchange parameters, dissolved organic carbon (DOC), and soil enzymatic activities (phosphatase, urease, protease, and β-glucosidase) were assessed. Principal component analysis (PCA) was used to identify the top-performing strain. Results: Treatment with encapsulated bacteria resulted in a 27% increase in DOC compared to controls (p < 0.05), while phosphatase and urease activities increased by 35% and 28%, respectively. Root length and volume improved by 18% and 22%, respectively, with PCA identifying P. baetica as the most effective strain. Conclusions: Immobilized Gram-negative PGPR strains enhanced root development and soil biochemical activity in hazelnuts, whereas B. safensis enhanced photosynthesis but had minimal impact on soil properties. These results highlight functional differences and support the use of PGPR immobilization to promote early plant establishment. Full article

Plant growth-promoting rhizobacteria (PGPR) are beneficial soil microorganisms that enhance plant growth and stress tolerance through various mechanisms, including phytohormone production, EPS production, phosphate solubilization, and extracellular enzyme production. These bacteria establish endosymbiotic relationships with plants, improving nutrient availability and overall crop productivity. Despite extensive research on PGPR isolation, their practical application in agricultural fields has faced challenges due to environmental stresses and limited survival during storage. To address these limitations, the present study aimed to isolate salt-tolerant bacterial strains and formulate them with organic carriers to enhance their stability and effectiveness under saline conditions. The isolated bacterial strains exhibited high salt tolerance, surviving NaCl concentrations of up to 850 millimolar. These strains demonstrated basic key plant growth-promoting traits, including phosphate solubilization, auxin production, and nitrogen fixation. The application of carrier-based formulations with both strains, Bacillus wiedmannii (RR2) and Bacillus paramobilis (RR3), improved physiological and biochemical parameters in wheat plants subjected to salinity stress. The treated plants, when subjected to salinity stress, showed notable increases in chlorophyll a (73.3% by Peat + RR3), chlorophyll b (41.1% by Compost + RR3), carotenoids (51.1% by Peat + RR3), relative water content (77.7% by Compost + RR2), proline (75.8% by compost + RR3), and total sugar content (12.4% by peat + RR2), as compared to the stressed control. Plant yield parameters such as stem length (35.1% by Peat + RR3), spike length (22.5% by Peat + RR2), number of spikes (67.6% by Peat + RR3), and grain weight (39.8% by Peat + RR3) were also enhanced and compared to the stressed control. These results demonstrate the potential of the selected salt-tolerant PGPR strains (ST-strains) to mitigate salinity stress and improve wheat yield under natural field conditions. The study highlights the significance of carrier-based PGPR applications as an effective and sustainable approach for enhancing crop productivity in saline-affected soils. Full article

The Qinghai–Tibet Plateau, a critical ecological barrier and major livestock region, faces deteriorating grasslands and rising forage demand under its harsh alpine climate. Oat (Avena sativa L.), valued for its cold tolerance, rapid biomass accumulation, and ability to thrive in nutrient-poor soils, can expand winter feed reserves and partly alleviate grazing pressure on native rangelands. However, genetic improvement alone has not been sufficient to address the environmental challenges. This issue is particularly severe in the Qaidam Basin, where soil salinization, characterized by high pH, poor soil structure, and low nutrient availability, significantly limits crop performance. Rhizosphere growth-promoting bacteria (PGPR) are environmentally friendly biofertilizers known to enhance crop growth, yield, and soil quality, but their application in the saline soil of the Qaidam Basin remains limited. We evaluated two PGPR application rates (B1 = 75 kg hm⁻² and B2 = 150 kg hm⁻²) on ‘Qingtian No. 1’ oat, assessing plant growth, soil physicochemical properties, and rhizosphere microbial communities. The results indicated that both treatments significantly increased oat productivity, raised the comprehensive growth index, augmented soil organic matter, and lowered soil pH; B1 chiefly enhanced above-ground biomass and fungal community stability, whereas B2 more strongly promoted root development and bacterial community stability. Structural equation modeling showed that PGPR exerted direct effects on the comprehensive growth index and indirect effects through soil and microbial pathways, with soil properties contributing slightly more than microbial factors. Notably, rhizosphere organic matter, fungal β-diversity, and overall microbial community stability emerged as positive key drivers of the comprehensive growth index. These findings provide a theoretical basis for optimizing PGPR dosage in alpine forage systems and support the sustainable deployment of microbial fertilizers under saline soil conditions in the Qaidam Basin. Full article

Rice sustains a large global population, making its sustainable production vital for food security. Alternate wetting-and-drying (AWD) irrigation offers a promising approach to reducing water use in rice paddies but can impact grain yields. Plant growth-promoting rhizobacteria (PGPR) can enhance rice productivity under AWD cultivation conditions. This review explores integrating PGPR into AWD systems, focusing on their mechanisms for promoting growth and water stress resilience. It examines diverse microbial communities, particularly bacteria, and their contributions to nutrient acquisition, root development, and other beneficial processes in rice under fluctuating moisture, as well as the influence of AWD on rice’s structural and physiological development. The challenges and opportunities of AWD are also addressed, along with the importance of bacterial selection and interactions with the native soil microbiome. This synthesizes current research to provide an overview of PGPR’s potential to improve sustainable and productive rice cultivation under AWD. Future studies can leverage powerful tools such as e-DNA and NGS for a deeper understanding of these complex interactions. Full article

Maize (Zea mays L.) relies heavily on nitrogen and phosphorus inputs, typically supplied through organic and inorganic fertilizers. However, excessive agrochemical use threatens soil fertility and environmental health. Sustainable alternatives, such as poultry manure (PM) and plant growth-promoting rhizobacteria (PGPR), offer promising solutions. This study examines the effects of a phytobiotic bacterial formulation (PHY), composed of Bacillus subtilis and Microbacterium sp., applied alone and in combination with PM, on maize’s rhizosphere bacteriobiome across key growth stages. Field trials included four treatments: a control, PHY-coated seeds, PM, and combined PHY_PM. The results show that early in development, the PM-treated rhizospheres increased the abundance of beneficial genera such as Sphingomonas, Microvirga, and Streptomyces, though levels declined in later stages. The PHY_PM-treated roots in the seedling phase showed a reduced abundance of taxa like Chryseobacterium, Pedobacter, Phyllobacterium, Sphingobacterium, and Stenotrophomonas, but this effect did not persist. In the PM-treated roots, Flavisolibacter was significantly enriched at harvesting. Overall, beneficial bacteria improved microbial evenness, and the PHY_PM treatment promoted bacterial diversity and maize growth. A genome analysis of the PHY strains revealed plant-beneficial traits, including nutrient mobilization, stress resilience, and biocontrol potential. This study highlights the complementarity of PM and PGPR, showing how their integration reshapes bacteriobiome and correlates with plant parameters in sustainable agriculture. Full article

SABATH methyltransferase can methylate small-molecule metabolites of plants to generate different products, and it plays a crucial role in plant growth and development as well as stress response. In this study, 13 SABATH genes distributed on five chromosomes of cucumbers were identified, and the synergistic effects among their domains, gene structures, conserved motifs, phylogenetic relationships, collinearity analysis, cis-acting elements, expression patterns, and plant growth-promoting rhizosphere bacteria (PGPR) were analyzed. The gene structure and conserved motifs of the same group of CsSABATH have similar intron numbers and conserved motifs. We detected 10 cis-elements in the promoter of the CsSABATH gene, indicating that they may be involved in different signaling pathways. qRT-PCR revealed the tissue-specific, drought and salt stress-responsive expression of the SABATH gene in cucumbers. Furthermore, we also verified that the expression level of CsaV3_6G046510 after inoculation with PGPR-GD17 bacteria under drought and salt stress was significantly lower than normal drought and salt dress, indicating that this gene may respond to PGPR and in abiotic stress play an important role. This study provides valuable insights into the molecular characteristics and evolutionary history of the SABATH gene family in cucumbers, laying a foundation for further analysis of the function of the CsSABATH gene in cucumbers. Full article

Overgrazing (OG) is an important driver of grassland ecosystem degradation and productivity decline. Plants may effectively cope with OG stress by regulating their synergistic interactions with plant growth-promoting rhizobacteria (PGPR) through root exudates. However, the synergistic regulatory mechanisms remain unclear. Under OG stress, Leymus chinensis recruited the specific PGPR strain Paraburkholderia graminis (B24) by regulating specific root exudate compounds, including amino acids, alkaloids, and organic acids, which enhance B24 chemotaxis and biofilm formation. The B24 inoculation systematically regulated the transcription of key plant growth and development genes, including those involved in nutrient transport and cell wall expansion, which enhanced nutrient uptake and promoted the overall growth of L. chinensis. Furthermore, B24 regulated the homeostasis of endogenous L. chinensis through the synergistic effects of hormones and the trade-off between growth and defense. Integrated transcriptomic and metabolomic analyses revealed that B24 regulation enhanced carbon and nitrogen metabolism, and energy supply after mowing, forming a holistic adaptive mechanism that enabled L. chinensis to effectively recover from mowing-induced stress, thereby improving its adaptability and regenerative capacity. This study provides a scientific basis and support for elucidating the response mechanisms of how grassland plants cope with OG stress, optimizing grassland management, and rapidly restoring and enhancing grassland productivity. Full article

The co-application of biochar, plant growth-promoting rhizobacteria (PGPR), and phosphorus- and potassium-bearing minerals has emerged as a promising strategy for improving soil nutrient availability. However, the synergistic effects and impact factors that facilitate this optimization are yet to be fully elucidated. To address this knowledge gap, we conducted a pot experiment to evaluate the effects of these amendments on tea yield and phosphorus (P)/potassium (K) availability, while employing Random Forest (RF) and Partial Least Squares Structural Equation Modeling (PLS-SEM) to reveal the underlying mechanisms driving these improvements. The results demonstrated that the tripartite combination significantly enhanced tea yield, leaf P/K concentrations, and soil available P (AP)/available K (AK) levels compared to individual applications or pairwise combinations. Analytical modeling identified Chloroflexi bacteria containing pqqc functional genes as key drivers of AP enhancement. The AP was further modulated by β-glucosidase activity, NaHCO₃-P, and AK levels. Critical determinants of AK dynamics included phosphorus-solubilizing bacterial populations, catalase activity, and fundamental soil chemical properties. In summary, our research conclusively shows that the co-application of phosphorus- and potassium-bearing minerals, PGPR, and biochar represents an effective approach to enhancing P and K accessibility in soil, thereby offering a viable alternative to conventional P and K fertilizers in tea cultivation. Full article

The application of microbial fertilizers derived from plant growth-promoting rhizobacteria (PGPR) is an important approach to increase crop yield while reducing the use of chemical fertilizers. Here, UPLC-MS/MS analyses were used to identify a bacterium, Bacillus sp. SYM-4, with a strong ability to secrete IAA. The strain was identified from 36 bacteria obtained from the rhizospheric soil of maize. Further inoculation experiments showed that Bacillus sp. SYM-4 was able to colonize the maize rhizosphere, resulting in a significant increase in IAA concentrations in seedlings. In addition, the antioxidant enzyme activity and chlorophyll content of maize seedlings were also significantly increased after inoculation with Bacillus sp. SYM-4. Therefore, Bacillus sp. SYM-4 was determined to be a PGPR for maize seedling growth. After further making it into microbial fertilizer, we found that, when 20% of the normal amount of chemical fertilizer was replaced with microbial fertilizer (Bacillus sp. SYM-4) and applied to field-cultivated maize seedlings, the growth of the maize plants at different stages was significantly promoted. Compared with the maize grown following application of a commercial microbial fertilizer (Pathfinder pioneer), seedlings grown using 20% Bacillus sp. SYM-4 microbial fertilizer and 80% chemical fertilizer showed significantly increased height. Substitution of chemical fertilizer (20%) with microbial fertilizer (Bacillus sp. SYM-4) treatment resulted in increases in maize yield over several measures (numbers of kernel rows on each ear, bald tip length, 100-grain weight and yield, and kernel nutrient content) compared to plants treated with pure chemical fertilizer. In this study, the replacement of a proportion of conventional fertilizer with a microbial substitute demonstrates a new technique with great potential for the green and efficient cultivation of maize. Full article

Salinity stress severely limits maize (Zea mays L.) productivity, necessitating sustainable mitigation strategies to ensure food security in affected regions. This study investigates the efficacy of compost (5 and 10 t/ha) and plant growth-promoting rhizobacteria (PGPR; Azospirillum brasilense) in enhancing maize productivity and soil health under salinity stress (EC_e 3.5 and 6.3 dS/m) across three varieties (Single Cross 131, 132, and 178) in field experiments conducted in 2023 and 2024. Combined compost-10 + PGPR treatment significantly increased grain yield by up to 197% and straw yield by nearly 300% in Single Cross 178 under high salinity, surpassing single treatments. Nitrogen content in grains and straw rose by 157%, while proline, peroxidase activity, and chlorophyll content improved, indicating robust stress tolerance. Soil properties, including pH, EC_e, sodium adsorption ratio, and exchangeable sodium percentage, were significantly ameliorated, with bulk density reduced and porosity increased. Soil organic matter and microbial populations (bacteria and fungi) were also enhanced. Single Cross 178 exhibited superior stress tolerance, highlighting varietal differences. These findings, supported by comparisons with the existing literature, underscore the synergistic role of compost and PGPR in improving nutrient uptake, antioxidant defenses, and soil structure. This study offers a sustainable strategy for maize cultivation in saline environments, with implications for global food security. Full article

Intensive research has been conducted for many years to develop environmentally friendly techniques for plant cultivation that optimize the fertilization process. One of the most promising areas within the fertilizer industry is using microbiologically enriched fertilizers, which incorporate beneficial bacteria or fungi. Biofertilizers are the focus of studies on both their production technologies and their effects on crop growth and yield, presenting a potential alternative to conventional mineral fertilizers. The prolonged and improper use of mineral fertilizers, along with inadequate plant protection, a lack of organic fertilization, and poor crop rotation practices, negatively impact soil health, disrupting microbial populations and ultimately diminishing yield quality and quantity. Microorganisms, particularly specific groups known as plant growth -promoting rhizobacteria (PGPR) and beneficial fungi, are estimated to make up 85% of the total soil biomass and play a crucial role in soil fertility by mineralizing organic matter, suppressing pests and pathogens, forming humus, and maintaining proper soil structure. They also provide optimal conditions for plant growth. Soil microorganisms can be categorized as either autochthonous, naturally present in the soil, or zymogenic, which develop when easily assimilable organic matter is added. Key microorganisms such as Micrococcus, Bacillus, Azotobacter, and nitrogen-fixing bacteria like Rhizobium and Bradyrhizobium significantly contribute to soil health and plant growth. Microbially enhanced fertilizers not only supply essential macro- and micronutrients but also improve soil quality, enhance nutrient use efficiency, protect plants against pathogens, and restore natural soil fertility, fostering a balanced biological environment for sustainable agriculture. Full article