Plant Exudates Research Articles

Cytotoxic activity, selectivity, and clonogenicity of fruits and resins of Saudi medicinal plants against human liver adenocarcinoma.

Edible fruits and resins provide various benefits to mankind including potential medicinal applications. This study aimed to determine the cytotoxicity, selectivity, and clonogenicity of fruits and exudates of certain Saudi medicinal plants (Anethum graveolens (BEP-09), Opuntia ficus-indica (L.) Miller (BEP-10), Boswellia serrata Roxb. ex Colebr. (BEP-11), and Commiphora myrrha (BEP-12)) against human liver adenocarcinoma (HepG2). Initial cytotoxicity and cell line selectivity against different cell lines were screened using MTT assay. The most promising extract was subjected to gas chromatography-mass spectrometry (GC-MS) analysis to determine the main phytoconstituents. Clonogenicity was checked for the most active extract. The selected plants' fruits and resins possess a significant cytotoxic activity estimated as IC50. The fruit of BEP-10 was found to be the most active extract against liver cancer cells (IC50 = 2.82) comparable to both doxorubicin (IC50 = 1.40) and camptothecin (IC50 = 1.11). It showed a selectivity index of 4.47 compared to the normal human foetal lung fibroblast (MRC5) cells. BEP-10 showed a dose-dependent clonogenic effect against HepG2 cells comparable to the effect of doxorubicin. The GC-MS chromatogram of BEP-10 extract revealed the presence of eight small polar molecules, representing 73% of the total identified compounds and the rest three molecules (27%) were non-polar constituents. The furan derivatives represent the chief components in BEP-10 (16.3%), while the aldehyde 5-(hydroxymethyl)-2-furancarboxaldehyde was found to be the main molecule (13.2%). The fruits of BEP-10 have a potential cytotoxic effect particularly against HepG2. The identified phytoconstituents in the tested plant extract might contribute to the investigated cytotoxic activity.

Volatile-mediated interspecific plant interaction promotes root colonization by beneficial bacteria via induced shifts in root exudation

BackgroundVolatile organic compounds (VOCs) released by plants can act as signaling molecules mediating ecological interactions. Therefore, the study of VOCs mediated intra- and interspecific interactions with downstream plant physiological responses is critical to advance our understanding of mechanisms underlying information exchange in plants. Here, we investigated how plant-emitted VOCs affect the performance of an interspecific neighboring plant via induced shifts in root exudate chemistry with implications for root-associated microbiota recruitment.ResultsFirst, we showed that VOCs emitted by potato-onion plants stimulate the growth of adjacent tomato plants. Then, we demonstrated that this positive effect on tomato biomass was attributed to shifts in the tomato rhizosphere microbiota. Specifically, we found potato-onion VOCs to indirectly affect the recruitment of specific bacteria (e.g., Pseudomonas and Bacillus spp.) in the tomato rhizosphere. Second, we identified and validated the compound dipropyl disulfide as the active molecule within the blend of potato-onion VOCs mediating this interspecific plant communication. Third, we showed that the effect on the tomato rhizosphere microbiota occurs via induced changes in root exudates of tomato plants caused by exposure to dipropyl disulfide. Last, Pseudomonas and Bacillus spp. bacteria enriched in the tomato rhizosphere were shown to have plant growth-promoting activities.ConclusionsPotato-onion VOCs—specifically dipropyl disulfide—can induce shifts in the root exudate of adjacent tomato plants, which results in the recruitment of plant-beneficial bacteria in the rhizosphere. Taken together, this study elucidated a new mechanism of interspecific plant interaction mediated by VOCs resulting in alterations in the rhizosphere microbiota with beneficial outcomes for plant performance.4wKeniGUxY9GPejLMpvDe9Video

Changes in composition and concentration of differential metabolites in root exudates are associated with aluminum-tolerance of Ricinus communis under a high CO2 environment

Root exudates are the most direct performance for plants responding to adverse environments, and are also important media for materials exchange, energy transmission and information communication between the roots and rhizosphere. However, how plant roots and exudates respond to aluminum (Al) stress under elevated CO2 concentration (eCO2) is still unclear. Ricinus communis is a famous oilseed crop throughout the world, which has strong tolerance to metal contaminated soil. In the present study, root physiological changes and the exudates of this species under aluminum stress and eCO2 based on metabolomic were investigated. The results showed that high Al concentration stress significantly increased aluminum, MDA, proline, and soluble sugar contents, and decreased the dry weights and soluble protein concentration. Furthermore, eCO2 alleviated the inhibition of root growth under high Al stress by increasing the dry weights, antioxidant enzyme activities and decreasing the MDA content. Collectively, a total of 511 metabolites were detected in the castor exudates of which lipids, organic acids, and organic oxygen compounds occupied 40.82%, 17.78% and 12.54%, respectively. There were 83, 15, and 100 differential metabolites for high Al stress, eCO2 and the interaction of the two factors compared with the control. 12 differential metabolites were found under eCO2 and Al stress compared with Al stress alone. Under Al stress, TCA cycle, organic acids, and lipids metabolisms were inhibited; coumarins and carbohydrates conjugates were significantly up-regulated, which may help castor adapt to aluminum-contaminated conditions. Moreover, eCO2 increased the secretion of organic acids, fatty acyls, and carbohydrates to enhance the antioxidant capacity and root growth of castor under Al stress; eCO2 enhanced the TCA cycle, organic acids accumulation, lipids metabolism, biosynthesis of amino acids, pentose and glucuronate interconversions, and inhibited DNA oxidative stress of castor roots under Al stress. The present study provides new insights into the crucial role of root exudates in improving Al-tolerance of castor under eCO2.

Development of Grafted Copolymers from Plant Exudates and Their Application for Site-Specific Drug Delivery: A Systematic Review

Grafted copolymers, extracted from plant exudates, have emerged as promising materials for their potential activity in site-specific drug delivery. These biopolymers, derived from natural sources, provide biocompatibility, biodegradability, and functional diversity. This review focuses on the methods of grafting copolymers onto plant exudates, the characterization of these novel materials, and their potential applications in drug delivery to specific targeted areas. We focus on specific grafted polymers such as Tamarindus indica acrylamide grafted polymer (TIAG), Sterculia urens acrylamide grafted polymer (SUAG), and Eucalyptus obliqua acrylamide grafted polymer (EOAG), among others, to investigate their advantageous characteristics in delivering potent molecules to the intended site of action, thereby enhancing crucial modalities such as the onset and duration of action. This review also highlights the mechanisms of drug release, targeting strategies, and the therapeutic benefits of using these biopolymers in medical applications.

Root exudate–assisted phytoremediation of copper and lead contamination using Rumex acetosa L. and Rumex K-1

Heavy metal pollutants can be effectively removed from soil through phytoremediation using root exudates. Herein, experiments were conducted to assess the phytoremediation capabilities of Rumex acetosa L. and Rumex K-1 root exudates for copper (Cu) and lead (Pb) contamination. Results indicated that these root exudates effectively adsorbed Cu and Pb. Furthermore, the optimal adsorption conditions of Cu by the root exudates of both plants were as follows: light duration of 36 h, light intensity of 8000 Lx, temperature of 25 °C and CO(NH2)2 concentration of 0 %. Moreover, the optimal adsorption conditions of Pb by Rumex acetosa L. and Rumex K-1 root exudates were light duration of 48 h and 24 h, respectively, light intensity of 8000 Lx, temperature of 25 °C and CO(NH2)2 concentration of 0 %. In addition, the root exudates from both plants enhanced the enrichment and transport of Cu and Pb. Moreover, the root was found to be the main accumulation site of Pb, while the stems and leaves were the main accumulation sites of Cu. With the application of root exudates, plant growth increased, with growth indices in Rumex acetosa L. and Rumex K-1 groups treated with exudates being 1.08–1.81-fold and 1.06–1.9-fold higher, respectively, compared with the untreated ones; physiological indexes showed 1.14–2.62-fold and 1.14–2.71-fold improvements, respectively. Remediation efficiency indexes showed 1.05–1.62-fold and 1.10–1.89-fold improvements, respectively. Rumex acetosa L. and Rumex K-1 exhibited promising potential for the phytoremediation of Cu and Pb, with root exudates playing a critical role in metal adsorption and stabilisation, suggesting their potential for enhancing remediation capabilities. This study sheds light on the mechanisms of root exudate–assisted phytoremediation and provides insights into alleviating heavy metal pollution.

Untargeted metabolomic analysis reveals a potential role of saponins in the partial resistance of pea (Pisum sativum) against a root rot pathogen, Aphanomyces euteiches.

In soil-borne diseases, the plant-pathogen interaction begins as soon as the seed germinates and develops into a seedling. Aphanomyces euteiches, an oomycete, stays dormant in soil and gets activated by sensing the host through chemical signals present in the root exudates. The composition of plant exudates may, thus, play an important role during the early phase of infection. To better understand the role of root exudates in plant resistance, we investigated the interaction between partially resistant lines (PI660736 and PI557500) and susceptible pea cultivars (CDC Meadow and AAC Chrome) against Aphanomyces euteiches during the pre-invasion phase. The root exudates of two sets of cultivars clearly distinguished from each other in inducing oospore germination. PI557500 root exudate not only had diminished induction but also inhibited the oospore germination. The contrast between the root exudates of resistance and susceptible cultivars was reflected in their metabolic profiles. Data from fractionation and oospore germination inhibitory experiments identified a group of saponins that accumulated differentially in susceptible and resistant cultivars. We detected 56 saponins and quantified 44 of them in pea root and 30 from root exudate; the majority of them, especially Soyasaponin I and dehydrosoyasaponin I with potent in vitro inhibitory activities, were present in significantly higher amounts in both roots and root exudates of PI660736 and PI557500 as compared to Meadow and Chrome. Our results provide evidence for saponins as deterrents against Aphanomyces euteiches, which might have contributed to the resistance against root rot in the studied pea cultivars.

Bait type affects the diversity assessment of cetoniid beetles in the Brazilian Cerrado

AbstractCetoniidae (Coleoptera), known as flower and fruit beetles, form a diverse group, feed on nectar, pollen, plant exudates, and are highly attracted to fermented fruits. To evaluate their diversity in natural and agricultural areas, traps baited with fermented fruits are used. The objective of this study was to compare the effectiveness of various types of fruit used as bait, with or without the addition of sugarcane juice to accelerate fruit fermentation, on the assessment of Cetoniidae diversity in the Brazilian Cerrado. The study was conducted in two conservation units in Brasília (DF, Brazil). Two experiments were conducted, the first aiming to select the most attractive fruits (banana, pineapple, mango, grape, or cagaita), and the second to verify whether there is interference of sugarcane juice in the fruit fermentation process and, consequently, in the attractiveness to Cetoniidae. The chemical profiles of the types of bait were evaluated by identifying and quantifying the main volatile organic compounds released by the fruit traps. Insect collections were conducted weekly using fruit‐baited traps for 1 month, without interruption. We found that the diversity estimate of Cetoniidae was higher for banana‐based baits relative to grape and cagaita fruit, but not relative to pineapple, mango, and sugarcane juice. Additionally, no increase in attractiveness was observed with the addition of sugarcane juice to banana, pineapple, and mango bait. Most compounds in the fruit extracts belong to alcohol, ester, and terpene functional groups. Our results suggest that banana, pineapple, mango, and sugarcane juice, used alone, may be used for Cetoniidae diversity studies, and that banana bait seems to be the most suitable for Cetoniidae collection in the Cerrado, because it enables the collection of a high diversity of species and also of species considered rare.

Plant-induced bacterial gene silencing: a novel control method for bacterial wilt disease.

Ralstonia pseudosolanacearum, a notorious phytopathogen, is responsible for causing bacterial wilt, leading to significant economic losses globally in many crops within the Solanaceae family. Despite various cultural and chemical control strategies, managing bacterial wilt remains a substantial challenge. This study demonstrates, for the first time, the effective use of plant-induced bacterial gene silencing against R. pseudosolanacearum, facilitated by Tobacco rattle virus-mediated gene silencing, to control bacterial wilt symptoms in Nicotiana benthamiana. The methodology described in this study could be utilized to identify novel phytobacterial virulence factors through both forward and reverse genetic approaches. To validate plant-induced gene silencing, small RNA fractions extracted from plant exudates were employed to silence bacterial gene expression, as indicated by the reduction in the expression of GFP and virulence genes in R. pseudosolanacearum. Furthermore, treatment of human and plant pathogenic Gram-negative and Gram-positive bacteria with plant-generated small RNAs resulted in the silencing of target genes within 48 hours. Taken together, the results suggest that this technology could be applied under field conditions, offering precise, gene-based control of target bacterial pathogens while preserving the indigenous microbiota.

Reuse potential of municipal solid waste incinerator bottom ash as secondary aggregate: Material characteristics, persistent organic pollutant content and effects of pH and selected environmental lixiviants on leaching behaviour

Increasing municipal solid waste (MSW) production poses challenges for sustainable urban development. Modern energy-from-waste (EfW) facilities incinerate MSW, reducing mass and recovering energy. In the UK, MSW incineration bottom ash (MSW IBA) is primarily reused in civil engineering applications. This study characterizes UK-produced MSW IBA, examining its pH-dependent leaching behaviour and response to environmental lixiviants. Results show predominant components include a melt phase, primary glass and fine ash aggregations, and a chemical composition dominated by SiO2 (30–50 %), CaO (∼15 %), Fe2O3 (∼10 %), and Al2O3 (∼8%). X-ray absorption near edge structure (XANES) analysis shows that Zn and Cu are most likely oxygen-bound (adsorbed to oxy-hydroxides and as oxides) with some sulphur bound. Polychlorinated biphenyls (PCBs) and polychlorinated dibenzodioxins/furans (PCDD/Fs) are well below regulatory limits, and polycyclic aromatic hydrocarbons (PAHs) were undetectable. Leaching tests indicate trace elements mobilize at pHs ≤ 6. With a natural pH of 11.3 and high buffering capacity, significant acid inputs to the MSW IBA are required to reach this pH, which are improbable in the environment. Wood chip additions increase leachate’s dissolved organic carbon (DOC) and reduce pH, but had minimal impact on metal-leaching behaviour. Synthetic plant exudate solutions minimally affect metal leaching at realistic concentrations, only enhancing leaching at ≥ 1500 mg l−1 DOC. This work supports MSW IBA’s low-risk in specified civil engineering applications.

Disentangling plant- and environment-mediated drivers of active rhizosphere bacterial community dynamics during short-term drought

Mitigating the effects of climate stress on crops is important for global food security. The microbiome associated with plant roots, the rhizobiome, can harbor beneficial microbes that alleviate stress, but the factors influencing their recruitment are unclear. We conducted a greenhouse experiment using field soil with a legacy of growing switchgrass and common bean to investigate the impact of short-term drought severity on the recruitment of active bacterial rhizobiome members. We applied 16S rRNA and 16S rRNA gene sequencing for both crops and metabolite profiling for switchgrass. We included planted and unplanted conditions to distinguish environment- versus plant-mediated rhizobiome drivers. Differences in community structure were observed between crops and between drought and watered and planted and unplanted treatments within crops. Despite crop-specific communities, drought rhizobiome dynamics were similar across the two crops. The presence of a plant more strongly explained the rhizobiome variation in bean (17%) than in switchgrass (3%), with a small effect of plant mediation during drought observed only for the bean rhizobiome. The switchgrass rhizobiome was stable despite changes in rhizosphere metabolite profiles between planted and unplanted treatments. We conclude that rhizobiome responses to short-term drought are crop-specific, with possible decoupling of plant exudation from rhizobiome responses.

Family ties: Root-root communication within Solanaceae

Root–root communication effects on several physiological and metabolic aspects among Solanaceae relatives were studied. We examined cherry (C) and field (F) tomato (Solanum lycopersicum) and bell pepper (B) (Capsicum annuum), comprising three degrees of relatedness (DOR): high (H-DOR; CC, FF and BB), medium (M-DOR; CF) and low (L-DOR; CB and FB). Plants were grown in pairs of similar or different plants on a paper-based and non-destructive root growth system, namely, rhizoslides. Root growth, including the proliferation of fine roots, and respiration increased as the DOR decreased and were highest in paired L-DOR plants, as was shown for root respiration that increased by 63, 110 and 88 % for C, F, and B when grown with B, B and F, respectively. On the other hand, root exudates of L-DOR plants had significantly lower levels of total organic carbon and protein than those of H-DOR plants, indicating different root–root communication between individuals with different DOR. Our findings indicate, for the first time, that carbon allocation to root growth, exudation and respiration depends on the degree of genetic relatedness, and that the degree of relatedness between individual plants plays a key role in the root-root communication within Solanaceae.

Extraction Kinetics of Brazilian Green Propolis and Chemical Characterization of its Volatiles.

Propolis is a natural resinous product produced by Apis mellifera bees from the exudates of various plants. The color of propolis (green) is a consequence of its botanical origin, as bees collect young tissues and leaves of Baccaris dracunculifolia. This study evaluated the chemical composition and extraction kinetics of essential oils obtained from Brazilian green propolis by hydrodistillation. Hydrodistillation was performed for 360 min and analyzed at different times (30, 60, 120, 240, and 360 min), allowing the calculation of the accumulated content (% w/w) and the identification of the essential oil chemical profile. The GC/FID and GC/MS analysis led to the annotation of 60 compounds with estragole (13.30 %), benzyl propanoate (14.59 %), and (E)-nerolidol (13.57 %) as the main compounds. The optimum conditions for extraction of phenylpropanoids (PP), hydrocarbons (HD), monoterpenes (MT), and oxygenated monoterpenes (OMT) are between 30 and 120 min. In comparison, sesquiterpenes (ST) and oxygenated sesquiterpenes (OST) are extracted more efficiently between 240 and 360 min. The optimal extraction speed determination is essential for industrial-scale processing to obtain components such as sesquiterpenes, which have a high economic value in the cosmetic/perfumery and pharmaceutical industries.

Evidence of nitrogen inputs affecting soil nitrogen purification by mediating root exudates of salt marsh plants

Salt marsh has an important ‘purification’ role in coastal ecosystems by removing excess nitrogen that could otherwise harm aquatic life and reduce water quality. Recent studies suggest that salt marsh root exudates might be the ‘control centre’ for nitrogen transformation, but empirical evidence is lacking. Here we sought to estimate the direction and magnitude of nitrogen purification by salt marsh root exudates and gain a mechanistic understanding of the biogeochemical transformation pathway(s). To achieve this, we used a laboratory incubation to quantify both the root exudates and soil nitrogen purification rates, in addition to the enzyme activities and functional genes under Phragmites australis populations with different nitrogen forms addition (NO3−, NH4+ and urea). We found that NO3− and urea addition significantly stimulate P. australis root exudation of total acids, amino acids, total sugars and total organic carbon, while NH4+ addition only significantly increased total acids, amino acids and total phenol exudation. High total sugars, amino acids and total organic carbon concentrations enlarged nitrogen purification potential by stimulating the nitrogen purifying bacterial activities (including enzyme activities and related genes expression). Potential denitrification rates were not significantly elevated under NH4+ addition in comparison to NO3− and urea addition, which should be ascribed to total phenol self-toxicity and selective inhibition. Further, urea addition stimulated urease and protease activities with providing more NH4+ and NO2− substrates for elevated anaerobic ammonium oxidation rates among the nitrogen addition treatments. Overall, this study revealed that exogenous nitrogen could increase the nitrogen purification-associated bacterial activity through accelerating the root exudate release, which could stimulate the activity of nitrogen transformation, and then improve the nitrogen removal capacity in salt marsh.

Multigenerational inheritance drives symbiotic interactions of the bacterium Bacillus subtilis with its plant host

Bacillus subtilis is a beneficial bacterium that supports plant growth and protects plants from bacterial, fungal, and viral infections. Using a simplified system of B. subtilis and Arabidopsis thaliana interactions, we studied the fitness and transcriptome of bacteria detached from the root over generations of growth in LB medium. We found that bacteria previously associated with the root or exposed to its secretions had greater stress tolerance and were more competitive in root colonization than bacteria not previously exposed to the root. Furthermore, our transcriptome results provide evidence that plant secretions induce a microbial stress response and fundamentally alter signaling by the cyclic nucleotide c-di-AMP, a signature maintained by their descendants. The changes in cellular physiology due to exposure to plant exudates were multigenerational, as they allowed not only the bacterial cells that colonized a new plant but also their descendants to have an advance over naive competitors of the same species, while the overall plasticity of gene expression and rapid adaptation were maintained. These changes were hereditary but not permanent. Our work demonstrates a bacterial memory manifested by multigenerational reversible adaptation to plant hosts in the form of activation of the stressosome, which confers an advantage to symbiotic bacteria during competition.

Diversity and Plant Growth Properties of Rhizospheric Bacteria Associated with Medicinal Plants.

Microbes in the rhizosphere play a significant role in the growth, development, and efficiency of plants and trees. The rhizospheric area's microbes are reliant on the soil's characteristics and the substances that the plants release. The majority of previous research on medicinal plants concentrated on their bioactive phytochemicals, but this is changing now that it is understood that a large proportion of phytotherapeutic substances are actually created by related microorganisms or through contact with their host. The roots of medicinal plants secrete a large number of secondary metabolites that determine the diversity of microbial communities in their rhizosphere. The dominant bacteria isolated from a variety of medicinal plants include various species of Bacillus,Rhizobium,Pseudomonas,Azotobacter,Burkholderia,Enterobacte,Microbacterium, Serratia,Burkholderia, andBeijerinckia. Actinobacteria also colonize the rhizosphere of medicinal plants that release low molecular weight organic solute that facilitate the solubilisation of inorganic phosphate. Root exudates of medicinal plants resist abiotic stress and accumulate in soil to produce autotoxic effects that exhibit strong obstacles to continuous cropping. Although having a vast bioresource that may be used in agriculture and modern medicine, medicinal plants' microbiomes are largely unknown. The purpose of this review is to (i) Present new insights into the plant microbiome with a focus on medicinal plants, (ii) Provide information about the components of medicinal plants derived from plants and microbes, and (iii) Discuss options for promoting plant growth and protecting plants for commercial cultivation of medicinal plants. The scientific community has paid a lot of attention to the use of rhizobacteria, particularly plant growth-promoting rhizobacteria (PGPR), as an alternative to chemical pesticides. By a variety of processes, these rhizobacteria support plant growth, manage plant pests, and foster resilience to a range of abiotic challenges. It also focuses on how PGPR inoculation affects plant growth and survival in stressful environments.

Phenolic fingerprint of Macedonian propolis

Propolis is a chemically complex resinous material collected by honeybees (Apis mellifera) from tree buds and resins, comprising plant exudates, secreted substances from bee metabolism, pollen and waxes. Its chemical composition depends strongly on the plant sources available around the beehive, which have a direct impact оn the quality and bioactivity of the propolis. In this study, the composition of phenolic compounds in 13 Macedonian propolis extracts was investigated by HPLC-DAD-ESI-MS/MS. Overall, the UV spectra, the MS and MS/MS data allowed the identification of 36 compounds. The major constituents of propolis were phenolic acids (caffeic and coumaric) and their esters (methyl, (iso)prenyl, benzyl, phenylethyl, cinnamyl), flavonols (quercetin, kaemferol), flavones (chrysin, apigenin, acacetin), flavanonols (pinobanksin) flavanones (pinocembrin naringenin, hesperetin, pinostrobin) and their methylated/esterified derivatives. The results reveal that Macedonian propolis contains a diversity of phenolic compounds confirming that it is a poplar type of propolis with higher phenolic content (ranging from 43.75–637.94 mg/g) than reported in previous studies in the region and beyond in Europe (< 80 mg/g). This suggests the potential significance of Macedonian propolis as a valuable source of bioactive compounds with health benefits as well as for unlocking its economic potential for industry and beekeepers.

Root-secreted nucleosides: signaling chemoattractants of rhizosphere bacteria.

The rhizosphere is a complex ecosystem, consisting of a narrow soil zone influenced by plant roots and inhabited by soil-borne microorganisms. Plants actively shape the rhizosphere microbiome through root exudates. Some metabolites are signaling molecules specifically functioning as chemoattractants rather than nutrients. These elusive signaling molecules have been sought for several decades, and yet little progress has been made. Root-secreted nucleosides and deoxynucleosides were detected in exudates of various plants by targeted ultra-performance liquid chromatography-mass spectrometry/mass spectrometry. Rhizobacteria were isolated from the roots of Helianthemum sessiliflorum carrying the mycorrhizal desert truffle Terfezia boudieri. Chemotaxis was determined by a glass capillary assay or plate assays on semisolid agar and through a soil plate assay. Nucleosides were identified in root exudates of plants that inhabit diverse ecological niches. Nucleosides induced positive chemotaxis in plant beneficial bacteria Bacillus pumilus, Bacillus subtilis, Pseudomonas turukhanskensis spp., Serratia marcescens, and the pathogenic rhizobacterium Xanthomonas campestris and E coli. In a soil plate assay, nucleosides diffused to substantial distances and evoked chemotaxis under conditions as close as possible to natural environments. This study implies that root-secreted nucleosides are involved in the assembly of the rhizosphere bacterial community by inducing chemotaxis toward plant roots. In animals, nucleoside secretion known as "purinergic signaling" is involved in communication between cells, physiological processes, diseases, phagocytic cell migration, and bacterial activity. The coliform bacterium E. coli that inhabits the lower intestine of warm-blooded organisms also attracted to nucleosides, implying that nucleosides may serve as a common signal for bacterial species inhabiting distinct habitats. Taken together, all these may indicate that chemotaxis signaling by nucleosides is a conserved universal mechanism that encompasses living kingdoms and environments and should be given further attention in plant rhizosphere microbiome research.

Evaluation of propolis hepatotoxicity in male rats

Background: Propolis is a natural resinous combination that honeybees produce from the materials they gather from plant parts, buds, and exudates. Numerous favorable pharmacological qualities have been demonstrated for propolis. Objectives: This study aimed to investigate the hepatotoxic effects of ethanolic propolis extract on the liver of male rats. Methods: In this research, 40 male rats were divided randomly into five groups: 1. Control 2. Sham (solvent), and 3. Three experimental groups (ethanolic propolis extract at doses of 50,100 and 200 mg/kg). All materials were administered by oral gavage once daily for 13 consecutive days. On the 14th day, blood sampling was performed to measure serum levels of liver function enzymes and triglycerides. After deep induction of anesthesia, the liver of the rats was removed for histopathological studies. Data were analyzed using ANOVA and Tukey’s test (p <0.05). Results: The data showed that the administration of propolis significantly increased the serum levels of aminotransferases in a dose-dependent manner and decreased triglycerides, accompanied by pathological changes. Conclusions: The results of this study indicate that the administration of propolis is associated with liver toxicity, and it seems that it should be consumed more carefully. Keywords: Alanine aminotransferase, Aspartate aminotransferase, Propolis, Hepatotoxicity Triglycerides

In-situ biosynthesized plant exudate gums‑silver nanocomposites as corrosion inhibitors for mild steel in hydrochloric acid medium

Natural gums due to availability, multifunctionality, and nontoxicity are multifaceted in application. In corrosion inhibition applications, their performance, in unmodified form is unsatisfactory because of high hydration rate, solubility issues, algal and microbial contamination, as well as thermal instability. This work attempts to enhance the inhibitive performance of Berlinia grandiflora (BEG) and cashew (CEG) exudate gums through various modification approaches. The potential of biogenic BEG and CEG gums−silver (Ag) nanocomposites (NCPs) for corrosion inhibition of mild steel in 1 M HCl is studied. The nanocomposites were characterized using the FTIR, UV–vis, and TEM techniques. The corrosion studies through the gravimetric and electrochemical (PDP, EIS, LPR, and EFM) analyses reveal moderate inhibition performance by the nanocomposites. Furthermore, the PDP results reveal that both inhibitors are mixed-type with maximum corrosion inhibition efficiencies (IEs) of 61.2 % and 54.2 % for BEG-Ag NCP and CEG-Ag NCP, respectively at an optimum concentration of 1.0 %. Modification of these inhibitors with iodide ion (KI) significantly increased the IE values to 90.1 % and 88.5 % for BEG-Ag NCP and CEG-Ag NCP at the same concentration. Surface observation of the uninhibited and inhibited steel samples using SEM/EDAX, 3D Surface profilometer, and AFM affirm that the modified nanocomposites are highly effective.

Interaction between root exudates of medicinal plants and rhizosphere microorganisms and its application in ecological planting of Chinese medicinal materials

The rhizosphere is an important place for material exchange between medicinal plants and soil. Root exudates are the medium of material and signal exchange between plants and soil and are the key factors in the regulation of rhizosphere microecology. Rhizosphere microorganisms are an important part of the rhizosphere microecology of medicinal plants, and the interaction between root exudates and rhizosphere microorganisms has an important influence on the growth and quality formation of medicinal plants. Rational utilization of the interaction between root exudates and rhizosphere microorganisms of medicinal plants is one of the important ways to ensure the healthy growth of medicinal plants and promote the development of ecological planting of Chinese medicinal materials. In the paper, the research status of root exudates and rhizosphere microorganisms of medicinal plants in recent years was summarized. The interaction mechanism between root exudates and rhizosphere microorganisms of medicinal plants, as well as the influence of rhizosphere microorganisms on the growth of medicinal plants, were analyzed. In addition, the advantages and promoting effects of intercropping ecological planting mode on rhizosphere microecology of medicinal plants and quality improvement of Chinese medicinal materials were explained, providing a good basis for the study of the interaction among medicinal plants, microorganisms, and soil. Furthermore, it could produce important theoretical and practical significance for the ecological planting and sustainable utilization of medicinal plants.