Root Exudates Research Articles

Allelopathic potential and chemical profile of wheat, rice and barley against the herbicide-resistant weeds Portulaca oleracea L. and Lolium rigidum Gaud.

BackgroundWeeds cause low crop productivity and increasing costs, and therefore, different solutions, such as manual weeding or synthetic herbicides, have been suggested to solve this problem. These methods involve high efforts and costs, in addition to being harmful to the environment in the case of herbicides, which also result in increasing resistance mechanisms in weeds. Therefore, this work addresses the use of in vivo allelopathic crops to control surrounding weeds. To carry out the experiments, co-cultivation of wheat, rice and barley with the monocot weed annual ryegrass (Lolium rigidum Gaud.) and the dicot weed common purslane (Portulaca oleracea L.) was conducted without physical contact among crop and weed plants. Germination and growth parameters of weeds, and growth parameters and chemical profile of crops, were analysed after the end of the experiment.ResultsThe three crops tested caused inhibitory effects on the two target weeds, and significant concentrations of benzoxazinoids were found in the plant tissues and/or root exudates of the different crops in response to the presence of weeds. All the crops showed different responses to the treatments. While the growth of rice was stimulated, barley was not affected, and wheat growth experienced inhibition due to the presence of weeds.ConclusionsThis study demonstrates the capacity of wheat, rice and barley to inhibit both growth and germination of L. rigidum and P. oleracea. The effects observed could be due to the accumulation and/or exudation of benzoxazinoids such as DIMBOA, DIBOA, BOA or HBOA. Barley and rice are able to sustainably manage both target weeds without disrupting their development, while growth of wheat was affected by the presence of weeds. Based on our results, rice would be the most promising crop, since it has the ability to control weeds, while stimulating the development of rice plants. Nevertheless, more research should be carried out to fully confirm this fact, especially under non-controlled conditions.Graphical

A highly conserved ABCG transporter mediates root-soil cohesion in Arabidopsis.

Identifying plant molecular mechanisms that mediate root-substrate interactions might offer potential solutions to soil erosion, especially in crop fields, where agricultural practices lead to soil loss. Mutants of the Arabidopsis (Arabidopsis thaliana) ATP-Binding Cassette G 43 (ABCG43) transporter gene show enhanced root-substrate cohesion, even though their root micro- and macro-structures are similar to those of wild-type Arabidopsis. We used genetic, biochemical, and functional methods to characterise the substrate-binding effects of changes in ABCG43 expression, including differences in exudate composition, and phylogenetic analyses to explore the evolutionary history of ABCG43 in land plants. Exudates from roots of the abcg43 mutant bound more soil and growing medium, and there were significant differences in abcg43 root exudate composition compared with the wild type. These results suggest that ABCG43 normally functions to mediate root exudates that affect root-substrate cohesion. Phylogenetic analysis showed that ABCG43 is highly conserved in plants, including in agriculturally important crop species. These results provide evidence that ABCG43 is a promising molecular target for developing crop plants with enhanced root-soil cohesion.

Relevance of cross talk between root exudates, hormones, and root-associated microbes in developing sustainable phytoremediation strategies: a comprehensive review

Relevance of cross talk between root exudates, hormones, and root-associated microbes in developing sustainable phytoremediation strategies: a comprehensive review

Synergistic effect of grassland plants and beneficial rhizosphere bacteria helps plants cope with overgrazing stress

BackgroundOvergrazing (OG) is an important driver of grassland degradation and productivity decline. Highly effective synergy between plants and rhizosphere growth-promoting rhizobacteria (PGPR) may be a major way for grassland plants to effectively cope with OG stress. There have been few reports providing solid evidence on how this synergy occurs.ResultThis study combined with multi-omics analysis and the interaction effect of specific root exudate with PGPR B68, aiming to reveal the synergistic effect and regulatory mechanism of L. chinensis and PGPR under overgrazing stress. The results showed that Leymus chinensis plants with OG history can recruit the beneficial Phyllobacterium sp. B68 by regulating specific root exudate compounds(such as amino acid L-leucyl-L-alanine and alkaloid cordycepin). These compounds enhanced B68 rhizosphere colonization by promoting B68 chemotaxis and biofilm formation. The pot study experiments indicated that the bacterial isolates used as bio inoculants increased L. chinensis growth (mainly including plant height and biomass) by significantly increasing the chlorophyll content, RuBisCO activity, soluble sugar, plant hormones and nutrient content. Metagenomics results show that B68 inoculation significantly altered rhizosphere soil bacterial community composition and function. Additionally, B68 systemically upregulated the expression level of genes involved in plant hormone signaling, nutrient and sugar transporters, nitrogen metabolism, cell division, cell wall modification and photosynthesis to promote plant growth. The above results indicate that the PGPR B68 recruited by the root exudates of L. chinensis under OG helps the plant adapt to stress by promoting nutrient uptake and transport, maintaining hormone homeostasis, and enhancing the expression of genes related to plant growth and nutrient metabolism.ConclusionThis study provides new insights into the positive interactions between grassland plants and rhizosphere bacteria under OG stress, offering valuable knowledge for developing new fertilizers and better management practices for degraded rangeland restoration and sustainable agriculture development.Clinical trial numberNot applicable.

Guava root exudate-driven rhizosphere microorganisms changes transmitted to foliar-feeding insects influence their feeding behaviour.

The growth of different grafted guava was different as affected by grafting on different rootstock varieties, which also influenced the damage degree of Spodoptera litura larvae. The co-regulation of the pest gut by rhizosphere microorganisms and root exudates may contribute to this differential damage. In this study, the microorganisms of soil, plants, S. litura larvae and root exudates of guava grafted on different rootstock varieties were analysed and compared. The activities of superoxide dismutase, peroxidase and catalase in the midgut of S. litura larvae feeding on heterograft leaves of guava (where rootstock and scion are of the different variety) were significantly higher than those in the midgut of S. litura larvae feeding on homograft leaves of guava (where rootstock and scion are of the same variety), and glutathione s-transferase activity showed an opposite result. Enterococcus spp. and Escherichia spp. were the two bacterial genera with the greatest difference in abundance in the midgut of S. litura larvae and exhibited a negative correlation with each other. The root system of guava influenced the root structure, soil nutrients and the population structure and diversity of rhizosphere microorganisms by regulating the type and amount of root exudates. Root exudates also influenced the physiological and biochemical status of S. litura larvae by regulating the rhizosphere microorganisms driving the tritrophic interaction of plant-microbes-insects. Based on our results and the observed differences in pest occurrence among different grafted plants, improving varieties through grafting may become an effective strategy to reduce the impact of insect pests on guava.

Revisiting steroidal glycoalkaloids as hatching stimulants for Globodera rostochiensis and Globodera pallida.

Potato production faces significant challenges from pests, particularly potato cyst nematodes (PCNs) such as Globodera rostochiensis and Globodera pallida. These nematodes are classified as regulated quarantine pests due to their detrimental effect on potato yields, yet populations continue to persist in the soil despite stringent control measures. PCNs can survive for long periods in the soil and hatch in response to root exudates containing hatching factors. The differences in hatching behavior and susceptibility between G. rostochiensis and G. pallida complicate management strategies, especially as the effectiveness of nematicides and resistant cultivars decline. Steroidal glycoalkaloids (SGAs) can exhibit considerable hatching activity, and the hatching stimulatory effects of SGAs was shown to clearly differ between these two nematode species, including differences at gene expression levels. Assessment of changes in G. rostochiensis and G. pallida relative hatching-related gene expression in response to SGAs provides further insight into their different responses to hatching stimuli. © 2025 Society of Chemical Industry.

Root Exudates Mediate the Production of Reactive Oxygen Species in Rhizosphere Soil: Formation Mechanisms and Ecological Effects.

Reactive oxygen species (ROS), as redox messengers, play an important role in regulating plant growth, sensing biotic and abiotic stresses, and integrating different environmental signals. As the microenvironment of the interaction between root, soil and microorganism, the rhizosphere is the hotspot of ROS production and action. Root exudates are an important medium for communication between roots and the soil environment, and they have a significant regulatory effect on the production of ROS in the rhizosphere. At the same time, the formation of rhizosphere ROS is determined by the coupling of various biotic and abiotic factors, and it is also affected by environmental stresses such as temperature, humidity, and disease. This review summarizes how root exudates affect plant growth and induce plant defense mechanisms by regulating the generation and distribution of ROS. It also discusses the role of ROS in promoting the decomposition of soil organic matter, nutrient cycling, and pollutant degradation and transformation. In-depth study of the regulation mechanism of root exudates on ROS not only helps to reveal the molecular mechanism of plant adaptation to environmental stress but also provides theoretical support and practical guidance for sustainable agricultural development and ecological environment protection.

Response of alfalfa growth and rhizosphere properties to soil phosphorus supply and mowing in a salt-affected soil

IntroductionPhosphorus (P) deficiency is a key limiting factor for alfalfa quality and yield in salt- affected soils, and root exudates are considered as a strategy for alfalfa P acquisition under P stress, which requires the supply of photosynthetic products.However, mowing may reduce the supply of photosynthetic products by decreasing photosynthetic rate and chlorophyll yield, which can affect the concentration of alfalfa root exudates in saline soil. This study aimed to investigate the possible mechanism of increasing P utilization rate with different P application rates after mowing. MethodsField and pot experiments were conducted with alfalfa grown under five P application rates (0, 60, 120, 180 and 240 kg ha-1). Plant growth, shoot P concentration, rhizosphere carboxylates concentration, rhizosphere acid phosphatase (APase) activity and rhizosphere pH were measured. Results and discussionP application significantly improved plant height and branch number, with the highest levels observed when P application rate was 180 kg ha-1. Crude protein content was also improved (13.3%-23.3%) with increasing P application rates and reached the maximum when P application rate was 240 kg ha-1. The yield of alfalfa increased with higher shoot P concentration. Furthermore, mowing significantly reduced rhizosphere carboxylates concentration (30.4%-100%) and APase activity (39.8%-75.0%) across all P treatments. However, these reductions were less pronounced when the P application rate exceeded 120 kg ha-1. In contrast, rhizosphere pH was unaffected by mowing across different application rates. Overall, this study demonstrates that P fertilization not only promotes alfalfa growth and quality in salt-affected soil but also mitigates the adverse effects of mowing on rhizosphere carboxylates concentration and APase activity. This highlights the potential of P fertilization to reduce P fixation and enhance P uptake by regulating rhizosphere-activated soil P dynamics after mowing. These findings provide a basis for enhancing the P utilization rate after mowing. The research results provide a basis for improving P utilization after mowing, enabling farmers to formulate scientific mowing strategies in production, thereby enhancing the yield and quality of alfalfa.

Modeling Plant Nutrient Acquisition Strategies Alters Projections of Carbon and Nitrogen Dynamics in Bioenergy Agroecosystems

ABSTRACTPlant strategies to acquire nutrients from limited environments help shape ecosystem carbon (C) and nitrogen (N) cycling and response to environmental change. The effects of plant strategies on ecosystem dynamics are largely uncharacterized in bioenergy agroecosystems, where the impacts could determine bioenergy's ability to meet its sustainability goals of storing C and reducing N loss. We used FUN‐BioCROP (Fixation and Uptake of Nitrogen‐Bioenergy Carbon, Rhizosphere, Organisms and Protection), a plant–microbe interaction model of coupled plant nutrient uptake and soil organic matter decomposition, to simulate the effects of nutrient acquisition strategies on soil microbial activity and ecosystem nutrient cycling in bioenergy feedstocks miscanthus (Miscanthus × giganteus) and sorghum (Sorghum bicolor (L.) Moench). We examined the model's ability to reproduce the relative effects of belowground nutrient uptake on microbial activity using a reanalysis of empirical data showing that miscanthus root exudation provoked a larger soil microbial response than sorghum. From baseline model simulations, we found that the ability of miscanthus to retranslocate N resulted in higher N uptake at a lower C cost than the sorghum/soybean rotation and that soil C and N pools increased under perennial (miscanthus) and decreased under annual (sorghum/soybean) cultivation. The model also predicted that greater root exudation increased soil C accumulation, highlighting the role of roots in forming stable soil C. Overall, the baseline model was unable to reproduce field observations of miscanthus root exudation stimulating microbial activity more than sorghum. To improve the model, we updated the soil microbial parameters in miscanthus to have faster decomposition, a higher C/N ratio, and greater carbon use efficiency. These changes improved the simulated soil microbial response to miscanthus root exudation, supporting the hypothesis that miscanthus soils foster a microbial community that is more responsive to root exudation than that of sorghum.

Missing the input: the underrepresentation of plant physiology in global soil carbon research

Abstract. Plant processes regulating the quantity and quality of soil organic carbon inputs such as photosynthesis, above- and below-ground plant growth, and root exudation are integral to our understanding of soil carbon dynamics. However, based on a bibliometric analysis including more than 55 000 scientific papers, we found that plant physiology has been severely underrepresented in global soil organic carbon research. Less than 10 % of peer-reviewed soil organic carbon research published in the last century addressed plant physiological processes relevant to soil carbon inputs. Similarly, plant physiology was overlooked by the overwhelming majority (>90 %) of the peer-reviewed literature investigating linkages between soil organic carbon, climate change, and land use and land management. These findings show that our understanding of both soil carbon dynamics and the carbon sequestration potential of terrestrial ecosystems is largely built on research that neglects the fundamental processes underlying organic carbon inputs. We maintain that the active engagement of plant scientists in soil carbon research is imperative for shedding light on this blind spot. Long-term interdisciplinary research will be essential for developing a comprehensive perspective of soil carbon dynamics and informing and designing effective policies that support soil carbon sequestration.

Synergistic Recruitment of Symbiotic Fungi by Potting and Scleroderma bovista Inoculation Suppresses Pathogens in Hazel Rhizosphere Microbiomes

This study explored how potted treatments (with and without Scleroderma bovista inoculation) shape rhizosphere microbial diversity in hazel across five soils using split-root cultivation. Three treatments (control, split-root, split-root with S. bovista) were analyzed for root growth and microbial dynamics. S. bovista inoculation consistently enhanced root parameters (number, tips) in all soils. Potted treatments (with and without S. bovista inoculation) altered microbial features (OTU/ASV), with only 0.9–3.3% of features remaining unchanged. At the class level, potting increased Agaricomycetes abundance while reducing Sordariomycetes, a trend amplified by S. bovista. Potting decreased species richness estimates (ACE and Chao1), while both treatments lowered diversity index (Shannon index). Potted treatments without S. bovista inoculation drove stronger shifts in species composition than inoculation. Findings reveal potting and S. bovista synergistically recruit symbiotic fungi via root exudates, establishing disease-suppressive communities that selectively inhibit pathotrophic fungi (particularly plant pathogen Coniothyrium and fungal parasite Cladobotryum) while roughly maintaining non-pathogenic saprotrophic microbes essential for organic matter decomposition. This work provides insights for optimizing hazel orchard management and ectomycorrhizal agent development.

Rhizosphere Microbiome Diversity Potentially Supports Robust Nature of Field Pennycress (Thlaspi arvense L.) in Dryland Cropping Systems of Eastern Washington

ABSTRACTField pennycress (Thlaspi arvense L.) is an annual in the Brassicaceae family and is currently being developed as an oilseed intermediate crop suitable for renewable biodiesel and jet fuel. It displays many desirable characteristics for this role including cold tolerance, a rapid life cycle, and a seed fatty acid profile conducive to bioenergy generation. These traits make field pennycress favorable for winter oilseed cultivation in the inland Pacific Northwest (iPNW). Simultaneously, intermediate crops are an increasingly recognized component of both agronomic sustainability and soil health management. Intermediate crops enhance soil microbial diversity, which benefits both soil and plant health. To understand the impact of field pennycress on soil microbial diversity, two natural accessions and seven experimental accessions were grown at three sites in Eastern Washington. Aboveground biomass and rhizosphere soil were then collected. Soil genomic DNA was extracted from rhizosphere samples and used to generate an amplicon library for bacterial (16S) and fungal (ITS) rRNA sequences. The resulting libraries were analyzed in QIIME2, which revealed that not only did the fad2 deficient line from the Spring32‐10 background have significantly increased aboveground biomass production compared to other pennycress genotypes, but also displayed significantly higher β‐diversity in the rhizosphere community specifically at the site experiencing the driest conditions. ANCOM analysis showed that multiple sequences similar to beneficial plant and soil health enhancing organisms such as Trichoderma spirale, Pseudomonas spp., and Methylobacterium goesingense were found to be enriched in the microbiome of the fad2 Spring32‐10 background also at that site. To add additional context to rhizosphere community data, root exudates from two pennycress genotypes were captured in magenta boxes and analyzed using HPLC. Future work will expand our understanding of the mechanisms by which field pennycress creates diversity in the rhizosphere, thus expanding our ability to cultivate this crop in the iPNW.

Allelopathy in Weed Management: A Comprehensive Review

Allelopathy, the process by which plants release biochemicals called allelochemicals to influence the growth and development of neighbouring plants, offers promising avenues for weed management. This comprehensive review explores the diverse mechanisms, nature, and applications of allelopathy in weed control. Allelopathic interactions occur through various means such as root exudates, volatilization, leaching, and decomposition of plant residues, affecting weed germination, growth, and reproduction. Allelopathic compounds, including phenolic acids, terpenoids, and alkaloids, inhibit key physiological processes in target plants, presenting opportunities for sustainable weed management. The review discusses the role of allelopathy in agriculture, highlighting the potential of allelopathic crops, cover crops, and plant extracts in suppressing weeds and reducing reliance on synthetic herbicides. Additionally, allelopathy's ecological significance in shaping plant communities and its implications for invasive species management are explored. Integrating allelopathy into weed management strategies holds promise for promoting environmentally friendly and economically viable agricultural practices.

Rhizospheric Bacillus isolates control Fusarium wilt on cotton and enhance plant biomass and root development

Cotton is a globally significant crop, serving as a source of natural fiber for the textile industry and contributing to various other products. Its economic importance is substantial, impacting livelihoods and international trade. However, cotton production faces numerous challenges, including Fusarium wilt caused by Fusarium oxysporum f. sp. vasinfectum (Fov), which can lead to significant yield and fiber quality losses. Plants alter their root exudate profiles in response to pathogens, often selectively enriching for beneficial rhizobacteria with antagonistic activity and plant growth-promoting traits. This study thus aims to characterize bacteria isolated from the rhizosphere of diseased cotton plants. The antifungal activity of 43 isolates was assessed against Fov in vitro. Eight of these inhibited Fov growth by 68.4 to 76.9%. 16S rRNA sequencing confirmed these isolates as Bacillus species. These eight Bacillus strains were further examined for their different modes of action in vitro, and their effect on cotton plants in greenhouse experiments challenged with Fov. All eight strains produced chitinases and pectinases, seven demonstrated cellulase and three protease activity, six produced urease, and five siderophores. Only B. subtilis SC11 exhibited phosphate solubilization activity. Seed treatments revealed that B. subtilis SC10 and B. subtilis SC11 were the standout treatments reducing Fov-caused symptoms by ~83% compared to Fov-inoculated control plants and most significantly improved plant growth and antioxidant activity. In detail, B. subtilis SC11 increased shoot and root dry weight by 160 and 250%, respectively. B. subtilis SC10 increased peroxidase activity by ~143% and ascorbate peroxidase activity by ~60%, while in B. subtilis SC11 treated plants superoxide dismutase activity increased by ~100%. Bacillus treatments effectively mitigated lipid peroxidation, achieving up to 91.4% reduction (B. subtilis SC10, B. halotolerans SC15), and decreased H₂O₂ accumulation by up to 58.4% (B. halotolerans SC32) compared to the Fov control. Principle component analysis revealed that regarding plant growth parameters, the treatments, and controls were distributed differentially across PC1 and PC2, with 60.30 and 15.62% data variance, respectively, showing the effectiveness of Bacillus isolates in greenhouse experiments. The findings of this study will contribute to the development of sustainable biocontrol strategies for managing Fusarium wilt in cotton.

The Impact of Flooding on Soil Microbial Communities and Their Functions: A Review

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.

A non-destructive and precise root monitoring system for hydroponic crops using SWIR hyperspectral imaging.

A non-destructive and precise root monitoring system for hydroponic crops using SWIR hyperspectral imaging.

Early developmental shifts in root exudation profiles of five Zea mays L. genotypes.

Root exudates impact soil-plant-microbe interactions and play important roles in ecosystem functioning and plant growth. During early plant development the root rhizosphere may change drastically. For maize (Zea mays L.), one of the world's most important crop species, little is known about root exudation patterns during early plant development. We determined abundance and composition of root exudation among maize genotypes from five inbred lines across three early plant development stages (Emergence, V1-2, and V3-4). We characterized the exudates for non-purgeable organic carbon and performed non-targeted metabolomics with high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). Across all genotypes, plant development stage had a significant influence on both abundance and composition of exudates. Exudation rates (mg C per cm2 root area d-1) were highest in the emergence stage and logarithmically decreased with plant development. In the emergence stage, the roots released predominantly sugars (most indicative: glucose and fructose) and the metabolite richness was generally higher than in later stages. Secondary compounds (e.g. phenolics, benzoxazinoids, or mucilage) increased significantly in later development stages. Differences in the composition of exudates between genotypes may be related to their respective development strategies, with genotypes accumulating more biomass releasing relatively more compounds related to root establishment (growth and rhizosphere development, e.g. mucilage, fatty and organic acids) and slower developing genotypes relatively more metabolites related to maintenance and defense (e.g. phenolics). Our results shed light onto the early dynamics of maize root exudation and rhizosphere establishment, over a phenotypical spectrum of genotypes.

Extracellular polymeric substances of plant-growth-promoting rhizobacteria modulate the positive plant-soil feedback in maize via soil conditioning.

Extracellular polymeric substances of plant-growth-promoting rhizobacteria modulate the positive plant-soil feedback in maize via soil conditioning.

Rhizodegradation of diesel and PAH contaminated soils with Miscanthus × giganteus: Soil, plants, microbes and pollutants interactions after two seasons.

Rhizodegradation of diesel and PAH contaminated soils with Miscanthus × giganteus: Soil, plants, microbes and pollutants interactions after two seasons.

Chitooligosaccharide enhances plant resistance to P. nicotianae via sugar homeostasis and microorganism assembly.

Chitooligosaccharide enhances plant resistance to P. nicotianae via sugar homeostasis and microorganism assembly.