Search Results (74)

The saline–alkali soil environment profoundly influences the diversity and composition of soil microbial communities, reshaping their ecological network structures. As a vital staple crop, rice (Oryza sativa L.) plays a crucial role in global food security, highlighting the urgent need to improve its cultivation efficiency in saline–alkali soils. However, the mechanisms by which rice roots recruit beneficial microorganisms from native soils under prolonged saline–alkali stress remain largely unclear, and limited research has been conducted on the effectiveness of microbial inoculants in enhancing rice salt tolerance. This study investigated microbial communities in a saline field subjected to over a decade of continuous rice cultivation. Plant growth-promoting microorganisms were isolated and screened from the rhizosphere. The findings revealed long-term salt stress significantly altered microbial diversity and community composition, although the overall microbial network structure remained resilient. A total of 21 plant growth-promoting strains were identified, indicating that rice roots under sustained salt stress selectively recruit beneficial microbes that contribute to plant growth and stress adaptation. Further experimental validation demonstrated that synthetic microbial communities outperformed individual strains in promoting rice seedling growth under high-salinity conditions, likely due to synergistic microbe and microbe–plant interactions. In conclusion, while saline–alkali conditions disrupt native microbial communities, rice exhibits adaptive capacity by selectively enriching growth-promoting microorganisms. The application of synthetic microbial consortia presents a promising strategy to enhance rice resilience and productivity in saline–alkali environments. Full article

Climate change causes major agricultural losses, driven both by the rise of plant diseases and by extreme weather events such as droughts and floods. Increased precipitation can lead to waterlogging of important crops. The roots of plants submerged in water have limited access to oxygen, which leads to hypoxia, which, in turn, reduces plant resistance to other factors, e.g., plant pathogens. On the other hand, beneficial microorganisms can help plants oppose abiotic stress, e.g., by producing plant hormones or osmoprotectants such as trehalose, to increase plant tolerance to drought. It turns out that plant-beneficial microorganisms can also increase plant resistance to waterlogging. This can be achieved by various mechanisms that involve the production of 1-aminocyclopropane-1-carboxylate (ACC) deaminase, which reduces the amount of ethylene accumulated in the submerged roots. This can stimulate the production of reactive oxygen species scavengers that protect plants from the oxidative stress caused by less efficient anaerobic metabolism, produce plant hormones that help plants to better adapt to low-oxygen conditions, and shape the plant microbiome, supporting plant growth in waterlogging conditions. This review outlines plant responses to waterlogging and discusses examples of microorganisms that improve plant tolerance, focusing on their underlying mechanisms. Full article

Soil salinity stress, intensified by extreme weather patterns, significantly threatens global watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai] production. Watermelon, a moderately salt-sensitive crop, exhibits reduced germination, stunted growth, and impaired fruit yield and quality under saline conditions. As freshwater resources decline and agriculture’s dependency on irrigation leads to soil salinization, we need sustainable mitigation strategies for food security. Recent advances highlight the potential of using salt-tolerant rootstocks and breeding salt-resistant watermelon varieties as long-term genetic solutions for salinity. Conversely, agronomic interventions such as drip irrigation and soil amendments provide practical, short-term strategies to mitigate the impact of salt stress. Biostimulants represent another tool that imparts salinity tolerance in watermelon. Plant growth-promoting microbes (PGPMs) have emerged as promising biological tools to enhance watermelon tolerance to salt stress. PGPMs are an emerging tool for mitigating salinity stress; however, their potential in watermelon has not been fully explored. Nanobiochar and nanoparticles are another unexplored tool for addressing salinity stress. This review highlights the intricate relationship between soil salinity and watermelon production in a unique manner. It explores the various mitigation strategies, emphasizing the potential of PGPM as eco-friendly bio-inoculants for sustainable watermelon management in salt-affected soils. Full article

Strain 53B2 was isolated from a commercial maize (Zea mays L.) field located in the Yaqui Valley, Mexico. Its draft genome comprises 5,844,085 bp, with a G + C content of 37.5%, an N50 of 602,122 bp, an L50 of 4, and a total of 129 contigs. Genome-based taxonomic affiliation showed this strain belonged to Priestia megaterium. Genome annotation revealed 6394 coding DNA sequences (CDSs), organized into 332 subsystems. Among these, several CDSs were associated with traits relevant to plant growth promotion, including categories such as iron acquisition and metabolism (40 CDSs) and secondary metabolism (6 CDSs), among others. In vitro metabolic assays supported genomic predictions, confirming the strain’s ability to produce IAA, solubilize phosphate, and tolerate abiotic stress. Additionally, greenhouse trials demonstrated that inoculation with Priestia megaterium 53B2 significantly enhanced plant growth parameters (p ≤ 0.05) versus uninoculated control: stem height increased by 22.8%, root length by 35.7%, stem and root fresh weights by 39.6% and 66.1%, and stem and root dry weights by 33.7% and 44.7%, respectively. This first report on the beneficial potential of Priestia megaterium 53B2 highlights its potential as a sustainable bioinoculant for maize cultivation. Full article

Microbial interactions within the rhizosphere are fundamental to plant health, influencing nutrient availability, stress tolerance, and pathogen resistance. Beneficial microbes, such as plant growth-promoting microbes (PGPMs), including bacteria and mycorrhizal fungi, enhance plant resilience through mechanisms like nutrient solubilization, phytohormone production, and pathogen suppression via antimicrobial compounds and siderophores. Root exudates, composed of sugars, organic acids, and secondary metabolites, act as chemoattractants that shape the rhizosphere microbiome by recruiting beneficial microbes. Microbial metabolites can, in turn, modulate plant physiology and exudate profiles, thereby reinforcing mutualistic interactions. Stress conditions alter exudate composition, enabling plants to attract specific microbes that aid in stress mitigation. Given the growing interest in microbiome-based agricultural solutions, this review aims to synthesize recent literature on plant–microbe interactions, with a focus on bidirectional signaling between plants and microbes. A structured literature search was conducted using databases such as PubMed, Scopus, and ScienceDirect to identify key studies on root exudation, microbial functions, and synthetic microbial communities (SynComs). We highlight major findings on how engineered microbiomes can enhance plant growth, resilience, and productivity, particularly under stress conditions. This review also explores how advances in SynCom design can promote sustainable agriculture by reducing reliance on chemical inputs. Full article

Titanium dioxide nanoparticles (TiO₂-NPs) were synthesized using the molten salt method and systematically characterized. TiO₂-NPs were evaluated for their capacity to promote the growth of Capsicum annuum cultivars together with the plant growth-promoting microorganisms (PGPMs) Bacillus thuringiensis (Bt) and Trichoderma harzianum (Th). The variables analyzed included physiological parameters and antioxidant responses. The capacity of TiO₂-NPs to scavenge free radicals was also investigated, along with their biocompatibility, using Artemia salina as an in vivo model. The results demonstrated that TiO₂-NPs exhibited a nanocuboid-type morphology, negative surface charge, and small surface area. It was noted that TiO₂-NPs enhanced the CFU and spore production of Bt (1.56–2.92 × 10⁸ CFU/mL) and Th (2.50–3.90 × 10⁸ spores/mL), respectively. It was observed that TiO₂-NPs could scavenge DPPH, ABTS, and H₂O₂ radicals (IC₅₀ 48.66–109.94 μg/mL), while not compromising the viability of A. salina at 50–300 μg/mL. TiO₂-NPs were determined to enhance the root length and fresh and dry weights of chili peppers. Similarly, TiO₂-NPs in synergy with Bt and Th increased the activity of β-1,3-Glucanase (2.45 nkat/g FW) and peroxidase (69.90 UA/g FW) enzyme activity, and increased the TPC (29.50 GA/g FW). The synergy of TiO₂-NPs with the PGPMs consortium also upregulated the total chlorophyll content: 210.8 ± 11.4 mg/mg FW. The evidence from this study unveils the beneficial application of TiO₂-NPs with Bt and Th as an efficient approach to promote the physiology and antioxidant responses of chili peppers. Full article

Reducing the use of chemical inputs (fertilizers, pesticides) in agriculture while maintaining crop productivity is the main challenge facing sub-Saharan African family farming systems. The use of effective microorganisms (EM) is among the various innovative approaches for minimizing chemical inputs and the environmental impact of agricultural production and protecting soil health while enhancing crop yields and improving food security. This study sought to characterize the microbial biodiversity of local beneficial microorganisms (BMs) products from locally fermented forest litter and investigate their ability to enhance tomato plant growth and development. Beneficial microorganisms (BMs) were obtained by anaerobic fermentation of forest litter collected in four agroecological regions of Senegal mixed with sugarcane molasses and various types of carbon sources (groundnut shells, millet stovers, and rice bran in different proportions). The microbial community composition was analyzed using next-generation rDNA sequencing, and their effects on tomato growth traits were tested in greenhouse experiments. Results show that regardless of the litter geographical collection site, the dominant bacterial taxa in the BMs belonged to the phyla Firmicutes (27.75–97.06%) and Proteobacteria (2.93–72.24%). Within these groups, the most prevalent classes were Bacilli (14.41–89.82%), α-proteobacteria (2.83–72.09%), and Clostridia (0.024–13.34%). Key genera included Lactobacillus (13–65.83%), Acetobacter (8.91–72.09%), Sporolactobacillus (1.40–43.35%), and Clostridium (0.08–13.34%). Fungal taxa were dominated by the classes Leotiomycetes and Sordariomycetes, with a prevalence of the acidophilic genus Acidea. Although microbial diversity is relatively uniform across samples, the relative abundance of microbial taxa is influenced by the litter’s origin. This is illustrated by the PCoA analysis, which clusters microbial communities based on their litter source. Greenhouse experiments revealed that five BMs (DK-M, DK-G, DK-GM, NB-R, and NB-M) significantly (p < 0.05) enhanced tomato growth traits, including plant height (+10.75% for DK-G and +9.44% for NB-R), root length (+56.84–62.20%), root volume (+84.32–97.35%), root surface area (+53.16–56.72%), and both fresh and dry shoot biomass when compared to untreated controls. This study revealed that forest-fermented litter products (BMs), produced using litter collected from various regions in Senegal, contain beneficial microorganisms known as plant growth-promoting microorganisms (PGPMs), which enhanced tomato growth. These findings highlight the potential of locally produced BMs as an agroecological alternative to inorganic inputs, particularly within Senegal’s family farming systems. Full article

The increasing global population and intensifying resource limitations present a formidable challenge for sustainable crop production, especially in developing regions. This review explores the pivotal role of microbial ecosystem services in alleviating environmental stresses that impede agricultural productivity. Soil microbiota, particularly plant growth-promoting microbes (PGPMs), are integral to soil health and fertility and plant resilience against both abiotic (drought, salinity, temperature extremes, heavy metals) and biotic (pathogen) stresses. These microorganisms employ a variety of direct and indirect mechanisms, including the modulation of phytohormones, nutrient solubilization, the production of stress-alleviating enzymes, and the synthesis of antimicrobial compounds, to enhance plant growth and mitigate adverse environmental impacts. Advances in microbial biotechnology have expanded the toolkit for harnessing beneficial microbes, enabling the development of microbial inoculants and consortia tailored for specific stress conditions. This review highlights the multifaceted contributions of soil microbes, such as improving nutrient uptake, promoting root development, facilitating pollutant degradation, and supporting carbon sequestration, all of which underpin ecosystem resilience and sustainable agricultural practices. Furthermore, the synergistic interactions between plant roots and rhizospheric microbes are emphasized as key drivers of soil structure enhancement and long-term productivity. By synthesizing current research on the mechanisms of microbe-mediated stress tolerance, this review underscores the potential of microbial interventions to bridge the gap between food security and environmental conservation. The integration of microbial solutions into agroecosystems offers a promising, eco-friendly strategy to revitalize soils, boost crop yields, and ensure agricultural sustainability in the face of mounting environmental challenges. Full article

The escalating threats posed by plant pathogens and the environmental repercussions of conventional agrochemicals necessitate sustainable agricultural solutions. This review focuses on plant growth-promoting microorganisms (PGPMs) such as bacteria, filamentous fungi, and yeasts, which play a pivotal role as biocontrol agents. These organisms enhance plant growth and resilience through nutrient solubilization, phytohormone production, and antagonistic activities against pathogens, offering a dual benefit of disease suppression and growth enhancement. However, the effective application of PGPMs faces challenges, including variability in field performance, survival and colonization under field conditions, and regulatory hurdles. This paper discusses these challenges and explores recent advances in utilizing these bioagents in sustainable agriculture, underscoring the importance of integrated pest management systems that reduce chemical inputs, thus promoting ecological balance and sustainable farming practices. Full article

Soil microorganisms provide multifaceted benefits, including maintaining soil nutrient dynamics, improving soil structure, and instituting decomposition, all of which are important to soil health. Unpredictable weather events, including flooding from heavy rainfall, flash floods, and seawater intrusion, profoundly impact soil ecology, which is primarily challenged by flooding stress, and imbalances these microbial communities and their functions. This disturbance impairs the symbiotic exchanges between microbes and plants by limiting root exudates and habitats for microbes, as well as nutrient acquisition efficiency for plants. Therefore, this review comprehensively examines the changes in soil microbial communities that occur under flooding conditions. Flooding reduces soil oxygen (O₂) levels, limiting aerobic microbes but promoting anaerobic ones, including potential pathogens. In flooded soil, O₂ deficiency indirectly depends on the size of the soil particles and water turbidity during flooding. O₂ depletion is critical in shaping microbial community adaptation, which is linked to variations in soil pH, nutrient concentrations, and redox status, and fresh and saline water vary differently in terms of the adaptation of microorganisms. Wet soil alters soil enzyme activity, which influences microbial community composition. Notably, three-month post-flooding conditions allow microbial communities to adapt and stabilize more effectively than once-weekly flooding frequency. Based on the presence of aboveground species, fungi are found to reduce under flooding conditions, while nematode numbers, surprisingly, increase. Direct and indirect impacts between soil microbes and physio-chemical properties indicate positive or negative feedback loops that influence the soil ecosystem. Over the years, beneficial microorganisms such as plant-growth-promoting microbes (PGPMs) have been identified as important in regulating soil nutrients and microbial communities in wetland environments, thereby enhancing soil health and promoting better plant growth and development. Overall, understanding the mechanisms of belowground ecosystems under flooding conditions is essential for optimizing agricultural practices and ensuring sustainable crop production in flood-prone areas. Full article

Improving wheat drought stress tolerance is a critical and challenging task, and more research is necessary since many parts of the world depend on this crop for food and feed. Our current work is focused on the influence of probiotic microorganisms in combination with calcium salts on the physiological and biochemical metabolic pathways that wheat uses when exposed to drought stress and on the analysis of gene expression levels that contribute to wheat drought tolerance. The research was conducted in the laboratory under controlled conditions, simulating a prolonged drought. Seedlings were treated with different microorganisms (Bacillus subtilis, Lactobacillus paracasei, and some yeast) in 10⁵ CFU/mL concentrations for seed priming and later in the same concentration for seedling spraying. A total of 70 g/m² CaCO₃ or 100 g/m² CaCl₂ was added to the soil before sowing the seeds. Almost all tested treatments improved plant growth and positively affected prolonged drought resistance in winter wheat. Bacillus subtilis, in combination with calcium salts, had the greatest effect on maintaining the relative leaf water content (RWC). The proline, malondialdehyde (MDA), and H₂O₂ tests proved the significant positive impact of the treatments on the plant’s response at the biochemical level, with growth parameters close to those of irrigated plants, for example, the ones treated with B. subtilis alone or with Ca salts had the lowest H₂O₂ content, 0.86–0.96 μmol g⁻¹ FW, compared to 3.85 μmol g⁻¹ FW for the Control, along with lower levels of drought-induced gene expression. All the presented results show statistically significant differences (p < 0.05). This study showed that tested microorganisms in combination with calcium salts can activate plants’ defense reactions in response to drought. The practical significance of this study is that these ecological measures can be useful under field conditions. Full article

A field trial was conducted on eight-year-old ‘Anna’ apple (Malus domestica) trees from 2021 to 2023 in northern Egypt. The objective of this study was to determine the effects of replacing mineral fertilizer with compost and microorganism applications. Treatments were prepared using combinations of three mineral fertilizer NPK (nitrogen (N), phosphorus (P) and potassium (K)) levels (75% recommended NPK rate, 50% and 25% recommended rate), with two compost levels (with/without) and two bacteria/fungi biological blend (PGPM) levels (with/without). This design resulted in 12 treatments in addition to a control treatment consisting of the full NPK recommended rate (100% NPK). Leaf nutrient concentrations, vegetative growth, fruit set percentage, fruit drop percentage, yield and fruit quality were measured in 2022 and 2023. Our results indicated that vegetative growth parameters were significantly influenced by the fertilizer treatments in both seasons. The application of 75% NPK + compost + PGPM or 50% NPK + compost + PGPM significantly increased shoot length, shoot diameter, leaf area and leaf-specific weight compared with the control (100% NPK). The greatest values of leaf nutrients and production and quality parameters were obtained with treatments 75% NPK + compost + PGPM or 50% NPK + compost + PGPM. Applying 75% NPK + compost + PGPM or 50%NPK + compost + PGPM increased total soluble solids and anthocyanin concentrations but reduced fruit nitrate and nitrite levels compared with the control (100% NPK). This study shows that it is possible to reduce mineral fertilizer application by 25–50% while improving the yield if compost and microbial inoculants are applied. Full article

This review delves into the role of plant growth-promoting microbes (PGPMs) in sustainable agriculture by enhancing soil health, improving plant stress tolerance, and controlling diseases. PGPMs, which include bacteria, fungi, and other microorganisms, are increasingly recognized as important contributors to promoting eco-friendly agricultural practices. Their ability to improve nutrient availability, stimulate plant growth, and protect crops from environmental stressors makes them a cornerstone for resilient and efficient farming systems. By reducing dependency on synthetic fertilizers and pesticides, PGPMs play a vital role in preserving environmental resources, minimizing greenhouse gas (GHG) emissions, and combating climate change’s negative impacts. This article thoroughly explores the complex interactions between PGPMs, soil nutrients, plant pathogens, and abiotic stressors. It also examines how these interactions influence phytohormone production and signaling pathways, ultimately impacting crop growth and development. Furthermore, this review discusses how PGPMs enhance nutrient uptake, modulate plant immune responses, and improve stress resilience, offering a holistic understanding of their multifaceted contributions to farming. By synthesizing current research and highlighting future directions, this review underscores the potential of PGPMs to revolutionize agricultural activities, ensuring food security and environmental sustainability in the face of global challenges. Full article

Soil salinity, affecting 20–50% of irrigated farmland globally, poses a significant threat to agriculture and food security, worsened by climate change and increasing droughts. Traditional methods for managing saline soils—such as leaching, gypsum addition, and soil excavation—are costly and often unsustainable. An alternative approach using plant growth-promoting microorganisms (PGPMs) offers promise for improving crop productivity in saline conditions. This study tested twenty-three bacterial strains, one yeast, and one fungal strain, isolated from diverse sources including salicornia plants, sandy soils, tomato stems or seeds, tree leaves, stems, and flowers. They were initially submitted to in vitro selection tests to assess their ability to promote plant growth under salt stress. In vitro tests included auxin production, phosphate solubilization, and co-culture of microorganisms and tomato seedlings in salt-supplemented media. The Bacillus sp. strain 44 showed the highest auxin production, while Bacillus megaterium MJ had the strongest phosphate solubilization ability. Cryptococcus sp. STSD 4 and Gliomastix murorum (4)10-1(iso1) promoted germination and the growth of tomato seedlings in an in vitro co-culture test performed on a salt-enriched medium. This innovative test proved particularly effective in selecting relevant strains for in planta trials. The microorganisms that performed best in the various in vitro tests were then evaluated in vivo on tomato plants grown in greenhouses. The results showed significant improvements in growth, including increases in fresh and dry biomass and stem size. Among the strains tested, Gliomastix murorum (4)10-1(iso1) stood out, delivering an increase in fresh biomass of 94% in comparison to the negative control of the salt modality. These findings highlight the potential of specific PGPM strains to enhance crop resilience and productivity in saline soils, supporting sustainable agricultural practices. Full article

The rapid growth of the human population has significantly increased the demand for food, leading to the intensification of agricultural practices that negatively impact the environment. Climate change poses a significant threat to global food production, as it can disrupt crop yields and modify the lifecycle stages of phytopathogens and pests. To address these challenges, the use of microbial inoculants, which are bioproducts containing beneficial microorganisms known as plant growth promotion microorganisms (PGPMs), has emerged as an innovative approach in sustainable agriculture. This review covers the isolation and identification of beneficial strains, the screening and selection process, the optimization of production techniques, and the importance of quality control and field testing. It also discusses the key points for the development and formulation of high-quality microbial inoculants, as well as highlights their advancements, current challenges, and future directions for research and application. Full article