Search Results (68)

This systematic review critically evaluates and synthesizes current evidence on the efficacy of biostimulants in enhancing soybean seed yield and quality. A comprehensive literature search was conducted following the PRISMA approach using the Web of Science (WoS) database, focusing on peer-reviewed studies from 2014 to 2025 reporting on the effects of biostimulants applied alone or in combination with other agro-inputs on soybean performance. Over 500 publications were retrieved from the database, of which 72 were included in this review. Extracted data were used to calculate changes in yield (kg ha⁻¹), percentage yield increase (%), oil content (%), and protein concentration (%). Our synthesis demonstrated that the sole application of biostimulants, including seaweed extracts, humic acids, amino acids, and beneficial microbes (Bradyrhizobium, PGPR, AMF), consistently enhanced soybean yield by 4% to 65%, while their interaction with other agro-inputs was shown to be capable of increasing yield by more than 150% under abiotic stress conditions, indicating strong synergistic effects. These improvements are mediated through various physiological mechanisms such as enhanced nutrient uptake, improved root growth, increased photosynthetic efficiency, and elevated stress tolerance. Furthermore, biostimulant application positively affects seed quality, increasing oil and protein content by 0.4–5.5% and 0.5–7.3%, respectively, by optimizing source–sink relationships and metabolic pathways. Overall, the greatest benefits are frequently observed through synergistic combinations of biostimulants with one another or with reduced rates of mineral fertilizers, highlighting a promising pathway toward sustainable crop intensification in soybean systems. Full article

Microbial volatile metabolites can enhance plant growth, yet the mechanisms by which plants perceive and transduce these signals are unknown. Growth of Arabidopsis thaliana Col-0 seedlings was found to be stimulated by volatiles from the soil bacterium Streptomyces coelicolor. To investigate volatile-responding candidate signaling molecules and genes, cultivation of seedlings in gas-phase contact with S. coelicolor genotypes was combined with GC-MS and plant transcriptomics. Components potentially involved were further studied using pure compounds and A. thaliana T-DNA mutants. Application of volatiles from S. coelicolor enhanced the growth of A. thaliana seedlings primarily by stimulating lateral root growth rate and inhibiting primary root extension. Concurrently, a family-wide induction of the Kelch-repeat F-box gene family KISS ME DEADLY (KMD) was observed. A. thaliana genotypes with a loss of function for the KMD family or other alterations of auxin/cytokinin signaling homeostasis suppressed the root response to both S. coelicolor total volatiles and the common microbial volatile 3-octanone. The results reveal a novel function of KMDs in mediating plant growth stimulation in response to volatile stimulation that alters auxin/cytokinin signaling and emphasize rhizospheric microbials as potential indicators of soil status to plants. Full article

Aims: The plant and soil microbiome serve as a reservoir of beneficial endophytic bacteria, including plant-growth-promoting (PGP) Bacillus subtilis, which enhances nutrient acquisition and protects plants against environmental stresses. We isolated novel bacteria from cultivated peanut plants selected from agricultural fields that survived a season of water scarcity and high temperatures. Experiments were conducted to determine whether plant survival was partially attributable to the presence of beneficial microbes that could be harnessed for future biotechnology applications. Methods and Results: Seven bacterial isolates of Bacillus spp. were identified through 16S rRNA sequencing, revealing close affiliations to B. subtilis, B. safensis, and B. velezensis. Growth curve analysis and colony morphology characterization revealed distinct growth patterns across different media types, while phytohormone production assays demonstrated variable indole-3-acetic acid (IAA) synthesis among isolates. When applied as seed biopriming agents to two hybrid peanut varieties, bacterial inoculation significantly enhanced root surface area and root tip development, with B. subtilis-TAM84A showing the most pronounced effects on ‘Schubert’ roots. In addition, vegetative growth assessments indicated increased branch numbers and plant height, particularly with treatments with B. velezensis strains TAM6B and TAM61A, and a consortium of all isolates. Under drought conditions, inoculated plants exhibited delayed wilting and improved recovery after rehydration, indicating enhanced drought resilience. Conclusions: Several local Bacillus strains recovered from drought-tolerant peanut plants showed improved growth and drought tolerance in greenhouse-grown peanut plants. Ongoing field studies aim to evaluate the potential of regionally adapted microbial populations as soil amendments during planting. Impact Statement: This study demonstrates that local strains of Bacillus isolated from drought-resistant peanut plants possess significant potential as bioinoculants to improve growth and drought tolerance in potted peanut plants. This work provides a foundation for utilizing regionally adapted microbial populations to address agricultural challenges related to water scarcity. Full article

Biostimulants boost plant growth, productivity, and nutrient retention, and can be produced from agri-food waste via microbial fermentation. In this study, undersized and unsold kiwifruits were fermented with Lactiplantibacillus plantarum to produce a fermented kiwifruit-based biostimulant (FKB). FKB was applied to soilless tomato plants (cv. Solarino) at two concentrations (50 and 100 mL L⁻¹) at the root level, every two weeks throughout the crop cycle. Fruits were analyzed for technological and chemical parameters, including color, texture, total soluble solids, titratable acidity, sugar/acid ratio, pH, electrical conductivity, total polyphenol content, antioxidant activity, and lycopene concentration. Additionally, metataxonomic analysis characterized the substrate microbial community at the beginning and the end of cultivation. Overall, the results indicate a dose-dependent effect of FKB on fruit quality parameters, with the highest concentration showing the most pronounced effects, specifically for the fruit firmness (8.02 N for FKB at 100 mL L⁻¹ vs. 7.25 N for the Control). Moreover, both tested concentrations were associated with increased antioxidant activity (on average +28%), and lycopene content (on average +57%) compared with the Control fruits. While overall microbial diversity remained largely unchanged, the relative abundance of bacterial taxa associated with nutrient cycling and plant–microbe interactions was modulated by the biostimulant, indicating subtle but potentially functionally relevant shifts in the rhizosphere microbiota. These findings suggest that fermented kiwifruit biomass can serve as an effective biostimulant, improving both fruit quality and the functional structure of the rhizosphere microbial community in soilless tomato cultivation. Full article

Recent advances in microbial bioremediation have significantly enhanced the effectiveness of wastewater management, offering innovative and sustainable alternatives to conventional treatment methods. Microorganisms, including bacteria, fungi, and algae, are increasingly recognized for their remarkable ability to degrade, transform, and remove a broad spectrum of pollutants such as organic compounds, heavy metals, and emerging contaminants from wastewater. Cutting-edge research has led to the development of novel approaches such as bioaugmentation, bio-stimulation, and the use of genetically engineered microbes, which have improved the efficiency, specificity, and resilience of bioremediation processes. The application of microbial consortia and advanced bioreactor designs further optimizes pollutant removal under diverse environmental conditions. Additionally, omics technologies and systems biology are providing deeper insights into microbial community dynamics and metabolic pathways, enabling the fine-tuning of bioremediation strategies for targeted outcomes. Despite ongoing challenges related to scalability, environmental variability, and regulatory considerations, these advances are paving the way for more robust, cost-effective, and eco-friendly wastewater management solutions. Overall, the integration of innovative microbial technologies holds great promise for addressing global water quality challenges and promoting environmental sustainability. Full article

Heavy metal (HM) contamination in agricultural soils poses a significant threat to soil health and plant productivity. This study investigates the impact of cadmium (Cd) and zinc (Zn) stress on tomato plants (Solanum lycopersicum) and explores the mitigation potential of microbial biostimulants (MBs), including arbuscular mycorrhizal fungi (AMF) and Pseudomonas fluorescens So_08 (PGPR), over a 52-day period using multi-omics approaches. Root exudate profiling revealed distinct metabolic changes under HM stress, which compromised soil–plant interactions. Cd stress reduced the secretion of phenylpropanoids (sum LogFC: −45.18), lipids (sum LogFC: −27.67), and isoprenoids (sum LogFC: −11–67), key metabolites in antioxidative defense, while also suppressing rhizosphere fungal populations. Conversely, Zn stress enhanced lipid exudation (such as sphingolipids and sterols, as sum LogFC of 8.72 and 9.99, respectively) to maintain membrane integrity and reshaped rhizobacterial communities. The MBs application mitigated HM-induced stress by enhancing specialized metabolite syntheses, including cinnamic acids, terpenoids, and flavonoids, which promoted crop resilience. MBs also reshaped microbial diversity, fostering beneficial species like Portibacter spp., Alkalitalea saponilacus under Cd stress, and stimulating rhizobacteria like Aggregatilinea spp. under Zn stress. Specifically, under Cd stress, bacterial diversity remained relatively stable, suggesting their resilience to Cd. However, fungal communities exhibited greater sensitivity, with a decline in diversity in Cd-treated soils and partial recovery when MBs were applied. Conversely, Zn stress caused decline in bacterial α-diversity, while fungal diversity was maintained, indicating that Zn acts as an ecological filter that suppresses sensitive bacterial taxa and favors Zn-tolerant fungal species. Multi-omics data integration combined with network analysis highlighted key features associated with improved nutrient availability and reduced HM toxicity under MB treatments, including metabolites and microbial taxa linked to sulfur cycling, nitrogen metabolism, and iron reduction pathways. These findings demonstrate that MBs can modulate plant metabolic responses and restore rhizosphere microbial communities under Cd and Zn stress, with PGPR showing broader metabolomic recovery effects and AMF influencing specific metabolite pathways. This study provides new insights into plant–microbe interactions in HM-contaminated environments, supporting the potential application of biostimulants for sustainable soil remediation and plant health improvement. Full article

The early stages of plant–microbe interaction are critical for establishing beneficial symbioses. We investigated how the endophytic fungus Fusarium solani strain FsK modulates tomato (Solanum lycopersicum) development and hormone pathways during in vitro co-cultivation. Seedlings were sampled at three early interaction stages (pre-contact, T1; initial contact, T2, 3 days post-contact, T3). Root traits and root and leaf transcripts for abscisic acid (ABA) and ethylene (ET) pathways were quantified, alongside fungal ET-biosynthesis genes. FsK altered root system architecture, increasing root area, lateral root number, root-hair length, and fresh biomass. These morphological changes coincided with tissue- and time-specific shifts. In leaves, FsK broadly affected ABA biosynthetic and homeostasis genes (ZEP1, NCED1, ABA2, AAO1, ABA-GT, BG1), indicating reduced de novo synthesis with enhanced deconjugation of stored ABA. ET biosynthesis was curtailed in leaves via down-regulation of ACC oxidase (ACO1–3), with isoform-specific changes in ACC synthase (ACS). The ET receptor ETR1 was transiently expressed early (T1–T2). FsK itself showed staged activation of fungal ET-biosynthesis genes. These results reveal coordinated fungal–plant hormone control at the transcriptional level that promotes root development during early interaction and support FsK’s potential as a biostimulant. Full article

Abiotic stressors such as drought, salinity, waterlogging, and high and low temperatures significantly reduce the growth and productivity of rice (Oryza sativa) and soybean (Glycine max), which are vital for global food and nutritional security. These stressors disrupt physiological, biochemical, and molecular processes, resulting in decreased yield and quality. Biostimulants represent promising sustainable solutions to alleviate stress-induced damage and improve crop performance under stressful conditions. This review provides a comprehensive analysis of the role of biostimulants in enhancing rice and soybean resilience under abiotic stress. Both microbial and non-microbial biostimulants including phytohormones such as salicylic acid; melatonin; humic and fulvic substances; seaweed extracts; nanoparticles; and beneficial microbes have been discussed. Biostimulants enhance antioxidant defenses, improve photosynthesis and nutrient uptake, regulate hormones, and activate stress-responsive genes, thereby supporting growth and yield. Moreover, biostimulants regulate molecular pathways such as ABA- and ROS-mediated signaling and activate key transcription factors (e.g., WRKY, DREB, NAC), linking molecular responses with physiological and phenotypic resilience. The effectiveness of biostimulants depends on crop species, growth stage, stress severity and application method. This review summarizes recent findings on the role of biostimulants in enhancing the mechanisms underlying growth, yield, and stress tolerance of rice and soybean under abiotic stress. Additionally, the incorporation of biostimulants into sustainable farming practices to increase productivity in the context of climate-related challenges has been discussed. Furthermore, the necessity for additional research to elucidate the underlying mechanisms, refine application methods, and verify their effectiveness in field conditions has been highlighted. Full article

Halotolerant endophytic fungi (HEFs) represent a critical biological resource in mitigating plant salt–alkali stress, demonstrating remarkable adaptability across diverse ecological environments. This comprehensive review analyzes 150 scientific publications, revealing HEFs’ multifaceted mechanisms of plant stress tolerance. Inhabiting over 30 host plant species without causing pathogenic effects, these fungi enhance plant resilience through sophisticated physiological strategies. Key findings highlight HEFs’ ability to modulate ionic homeostasis, elevate antioxidant capacities, and stimulate plant growth under saline conditions. The research unveils the potential of HEF metabolites as biostimulants and explores their co-evolutionary hypotheses with host plants. Despite promising laboratory and field validations, significant challenges remain in HEFs’ practical agricultural applications, including environmental factor interactions and biotechnological ethical considerations. Future research directions emphasize deeper investigations into HEFs’ ecological adaptability and microbiological interactions to unlock their full agricultural potential. Full article

Humic substances and beneficial microorganisms are key biostimulants for sustainable agriculture and global food security in the face of climate change. Marine bacteria are emerging as a promising source of plant-beneficial microbes, tapping into a microbial diversity as immense as the oceans themselves. However, their potential, limitations, and mechanisms of action––especially in combination with other biostimulants––remain largely unexplored. In this study, we isolated the Streptomyces sp. LAP3 strain from the giant limpet Scutellastra mexicana. We evaluated the efficacy of the marine bacterium, applied alone or in combination with the humic product Leonardite hydrolate (L), in enhancing tomato performance under field conditions. Treatments included: (1) marine Streptomyces (MS), (2) Leonardite hydrolate (L), (3) both biostimulants (MS + L), and (4) a control (CTRL). We assessed growth, photosynthetic performance, antioxidant responses, and fruit yield and quality. Both biostimulants individually improved plant performance, but their combination had a significant synergistic effect, markedly boosting tomato productivity, thermotolerance, and resilience during a heatwave. Enhanced photosynthetic efficiency and antioxidant enzyme activity were associated with improved agronomic traits. These results highlight the potential of combining Streptomyces sp. LAP3 and Leonardite hydrolate as an eco-friendly strategy to increase crop productivity, strengthen stress resilience, promote sustainable agriculture, and reduce reliance on agrochemicals. Full article

A diverse array of soil microorganisms exhibit plant growth-promoting (PGP) traits, many of which enhance root growth and development. These microorganisms include various taxa of bacteria, fungi, microalgae and yeasts—some of which are currently used in biofertilizers and biostimulant formulations. Recent studies have begun to unravel the complex communication between plant roots and beneficial microorganisms, revealing mechanisms that modulate root nitrogen (N) uptake beyond atmospheric N₂ fixation pathways. Root N uptake is tightly regulated by plants through multiple mechanisms. These include transcriptional and post-transcriptional control of plasma membrane-localized N transporters in the epidermis, endodermis, and xylem parenchyma. Additionally, N uptake efficiency is influenced by vacuolar N storage, assimilation of inorganic N into organic compounds, and the maintenance of electrochemical gradients across root cell membranes. Many of these processes are modulated by microbial signals. This review synthesizes current knowledge on how soil microorganisms influence root N uptake, with a focus on signaling molecules released by soil beneficial microbes. These signals include phytohormones, volatile organic compounds (VOCs), and various low-molecular-weight organic compounds that affect transporter expression, root architecture, and cellular homeostasis. Special attention is paid to the molecular and physiological pathways through which these microbial signals enhance plant N acquisition and overall nutrient use efficiency. Full article

The prolonged and intensive use of chemical inputs in agriculture, particularly synthetic fertilizers, has generated a variety of environmental and agronomic challenges. This has intensified the need for alternative, viable, and sustainable solutions. Plant-associated microbes have emerged as promising candidates in this regard. While research has largely focused on bacteria and fungi, comparatively less attention has been paid to other microbial groups such as microalgae and cyanobacteria. These photosynthetic microorganisms offer multiple agronomic benefits, including the ability to capture CO₂, assimilate essential micro- and macroelements, and synthesize a wide range of high-value metabolites. Their metabolic versatility enables the production of bioactive molecules with biostimulant and biocontrol properties, as well as biofertilizer potential through their intrinsic nutrient content. Additionally, several cyanobacterial species can fix atmospheric nitrogen, further enhancing their agricultural relevance. This review aims to summarize the potential of these microorganisms and their application in the agriculture sector, focusing primarily on their biofertilization, biostimulation, and biocontrol capabilities and presents a compilation of the products currently available on the market that are derived from these microorganisms. The present work also identifies the gaps in the use of these microorganisms and provides prospects for developing a suitable solution for today′s agriculture. Full article

The application of marine algae-derived biostimulants offers a sustainable approach to improving plant performance in aromatic and medicinal crops. This study investigated the effects of four macroalgal extracts and two commercial biostimulant products on the growth, physiology, and essential oil production of Lavandula angustifolia cultivated under greenhouse conditions at CREA, Pescia (Italy). Treatments included extracts from Ascophyllum nodosum (France and Greenland), Laminaria digitata (Iceland), Sargassum muticum (Italy), two commercial formulations (a seaweed-based and an amino acid-based biostimulant), and a control receiving only standard fertilization. Over a 10-week period, plants were evaluated for multiple parameters: plant height, leaf number and area, SPAD index (chlorophyll content), above- and below-ground biomass, flower production, microbial activity in the growth substrate, and essential oil yield. Algae extracts, particularly those from A. nodosum (Greenland) and S. muticum (Venice), significantly enhanced most parameters compared to the control and commercial products. These treatments yielded higher biomass, greater chlorophyll retention, increased flower number, and improved essential oil content. Rhizosphere microbial counts were also elevated, indicating a positive interaction between algae treatments and substrate biology. The study highlights the multifunctional nature of marine algae, whose complex composition of bioactive compounds appears to promote plant growth and secondary metabolism through multiple pathways. The superior performance of cold- and temperate-climate algae suggests a relationship between environmental origin and biostimulant efficacy. Compared to commercial inputs, the tested algae extracts showed broader and more consistent effects. These findings support the integration of macroalgae-based biostimulants into sustainable lavender cultivation strategies. Further research is recommended to optimize formulations, validate field performance, and explore synergistic effects with beneficial microbes or organic inputs. Full article

Constrained by site conditions and water resources, pear tree cultivation faces increasing drought stress. Paecilomyces variotii extract (PVE), a novel biostimulant extracted from wild sea buckthorn root-isolated strains and containing chitin, humic/fulvic acids, and beneficial microbes, has gained attention due to its high activity and efficacy in alleviating plant stresses (e.g., drought). In this study, Pyrus pyrifolia ‘Qiu Yue’ was used as the experimental material, and pot experiments were conducted to examine the drought-mitigating effects of different PVE concentrations. Drought stress was achieved by maintaining soil water content at 35–45% of water holding capacity for 45 days under natural evaporation conditions in rain shelters. The growth status of pear trees, soil enzyme activity, and metabolite levels were analyzed. The results showed that the application of 5 ng/mL PVE promoted pear tree growth, enhanced leaf antioxidant enzyme activity, and improved photosynthetic capacity and soil enzyme activity. Under normal water conditions, the shoot growth length, plant height, stem diameter, and root system activity of the 5 ng/mL PVE group were 31.91%, 12.05%, 3.54%, and 10.94% higher than those of the control group, respectively. Under drought stress, these values increased by 25.12%, 8.87%, 12.21%, and 16.98%, respectively. The addition of 5 ng/mL PVE facilitates trehalose release and upregulates starch-sucrose, glycerophospholipid, and galactose metabolic pathways, thereby potentiating drought stress tolerance in pear trees. However, at 20 ng/mL, reductions were observed in pear tree growth indicators, leaf antioxidant enzyme activity, soil enzyme activity, and trehalose content in root exudates compared to the 5 ng/mL PVE treatment. Overall, 5 ng/mL PVE effectively promotes pear tree growth and enhances drought resistance, making it suitable for broader use in pear cultivation practices. 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