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The changed phenolic acids (PAs) allelochemicals exuded by the roots induced by interspecific interactions is related to intercropping alleviates soil-borne disease. However, the presence of PAs in roots and root exudations and their rhizodeposition under intercropping are still unclear. Hydroponic and soil experiments of wheat, faba bean, and wheat intercropped with faba bean were conducted, and the major compositions and contents of PAs in roots, root exudations, and rhizospheric soil were determined. The results showed that ρ-hydroxybenzoic, vanillic, and syringic acids were the major components of PAs in roots, root exudations, and rhizospheric soil in a wheat and faba bean intercropping system. The compositions and percentages of PAs in roots of faba bean were altered when faba bean intercropped with wheat. The total exudation rate of PAs in root exudations was decreased by 30%–60% under the wheat and faba bean intercropping (W//F) system as compared to mono-cropped faba bean (MF). ρ-hydroxybenzoic acid was identified in the root exudation of both MF and mono-cropped wheat (MW), but not detected in the intercropping on 60 days after transplanting. Vanillic acid was only detected in the root exudation of MF on 30 days after transplanting. The rhizodepostion of vanillic and cumaric acid were decreased at both branching and pod setting stages in W//F as compared to MF. In conclusion, interspecific interaction changed the compositions and contents of PAs in faba bean roots and root exudations. W//F constrained vanillic acid exuded by roots and decreased vanillic and coumaric acid rhizodeposition by faba bean, which provides insight into root-soil interactions in the intercropping systems.

Root associated bacteria were isolated from Suaeda nudiflora and two isolates were selected for this study: rhizospheric Bacillus megaterium and endophytic Pseudomonas aeruginosa. These isolates were inoculated into maize variety Narmada Moti during its germination. TTC (2, 3, 5-triphenyl tetrazolium chloride) staining was used to confirm the association of the isolates with the maize root. The effects of these root associated bacteria were tested alone and in combinations for cell wall reinforcement and the induction of defense enzymes such as phenylalanine ammonia lyase (PAL) and β-1,3-glucanase in the presence of fungal pathogen Aspergillus niger in maize. The results indicated that the rhizospheric bacteria had a greater fight response to fungal infection than the endophhytic bacteria due to cell wall lignification as well as the rapid induction of higher concentrations of defense related enzymes.

Root-knot nematodes (Meloidogyne spp.) are obligate plant parasites that cause severe economic losses to agricultural crops worldwide. Because of serious health and environmental concerns related to the use of chemical nematicides, the development of efficient alternatives is of great importance. Biological control through exploiting the potential of rhizosphere microorganisms is currently accepted as an important approach for pest management in sustainable agriculture. In our research, during screening of rhizosphere bacteria against the root-knot nematodes Meloidogyne incognita, Ochrobactrum pseudogrignonense strain NC1 from the rhizosphere of healthy tomatoes showed strong nematode inhibition. A volatile nematicidal assay showed that the cell-free fermentation filtrate in the first-row wells of 12-well tissue culture plates caused M. incognita juvenile mortality in the second-row wells. Gas chromatography-mass spectrometry analysis revealed that dimethyl disulfide (DMDS) and benzaldehyde were the main volatile compounds produced by strain NC1. The nematicidal activity of these compounds indicated that the lethal concentration 50 against the M. incognita juveniles in the second-row wells and the fourth-row wells were 23.4 μmol/ml and 30.7 μmol/ml for DMDS and 4.7 μmol/ml and 15.2 μmol/ml for benzaldehyde, respectively. A greenhouse trial using O. pseudogrignonense strain NC1 provided management efficiencies of root-knot nematodes of 88 to 100% compared with the untreated control. This study demonstrated that nematode-induced root-gall suppression mediated by the bacterial volatiles DMDS and benzaldehyde presents a new opportunity for root-knot nematode management.

L-ASPARAGINASE is an anti-neoplasm agent. This agent is classified as an enzyme compound. L-asparaginase is used in medicine as well as in the food industry. Microbial strains that are producing L-Asparaginase can be found in many habitats such as soil. The aim of this study was to find isolates producing L-asparaginase enzyme with high ability to inhibit cancer cells. Bacteria of the Actinobacter family were isolated from the soil samples around the roots of the plants in the actinomycet isolation medium. Then, the bacteria were isolated and extracted by screening in M9 medium. Isolates were identified using16S PCR sequencing method. Three isolates of ASP and B and C showed the highest enzyme production, which showed a molecular weight of 43 kDa and in terms of enzymatic activity112. 572 IU/ml, 99.706 IU/ml, 138.572 IU/ml respectively. These three isolates with sequence analysis was similar to Streptomyces flavoviridis and Streptomyces griseus and Streptomyces hypolyticus respectively. Isolate C showed good effects in inhibiting cell MCF-7, HepG-2. There are various isolates enzyme production power in nature and Actinobacter family has shown more ability to produce various enzymes and metabolites and the isolates isolated in this study are used for industrial enzyme production.

Phyllosphere is an important reservoir of antibiotic resistance genes (ARGs), but the transfer mechanism of ARGs from soil and air to phyllosphere remains unclear. This study demonstrated that soil-air-phyllosphere was the dominant ARG transfer pathway, and blocking it by film mulching can reduce typical phyllosphere ARGs in lettuce by 80.7% - 98.7% (89.5% on average). To further eliminate phyllosphere ARGs in lettuce grown with film mulching, the internal soil-endosphere-phyllosphere transfer pathway deserves more attention. We analyzed the ARG hosts and the resistome in lettuce rhizosphere and phyllosphere with film mulching via hybrid Illumina-Nanopore sequencing. Pseudomonas sp. 7SR1 was more abundant than other ARG hosts, accounting for 1.0% and 47.1% of the total bacteria in rhizosphere and phyllosphere, respectively. The species has flagella that can promote mobility and can excrete extracellular polymeric substances and/or surfactant-like microbial products, which benefits its colonization in the phyllosphere. Impeding the migration of Pseudomonas sp. 7SR1 via the soil-endosphere-phyllosphere pathway would be effective to further reduce ARGs in phyllosphere. Multidrug resistant genes were predominant in phyllosphere (40.3% of the total), and 87.6% of the phyllosphere ARGs were located on chromosomes, indicating relatively low horizontal gene transfer (HGT) potentials. This study provides insights into the transfer mechanism, hosts, and control strategies of phyllosphere ARGs in typical plants.

The plant faces different pedological and climatic challenges that influence its growth and enhancement. While, plant-microbes interactions throught the rhizosphere offer several privileges to this hotspot in the service of plant, by attracting multi-beneficial mutualistic and symbiotic microorganisms as plant growth-promoting bacteria (PGPB), archaea, mycorrhizal fungi, endophytic fungi, and others…). Currently, numerous investigations showed the beneficial effects of these microbes on growth and plant health. Indeed, rhizospheric microorganisms offer to host plants the essential assimilable nutrients, stimulate the growth and development of host plants, and induce antibiotics production. They also attributed to host plants numerous phenotypes involved in the increase the resistance to abiotic and biotic stresses. The investigations and the studies on the rhizosphere can offer a way to find a biological and sustainable solution to confront these environmental problems. Therefore, the interactions between microbes and plants may lead to interesting biotechnological applications on plant improvement and the adaptation in different climates to obtain a biological sustainable agricultures without the use of chemical fertilizers.

Basal stem rot (BSR) is the most common disease of oil palm (Elaeis guineensis Jacq.) in Southeast Asia. BSR is caused by a white-rot fungus Ganoderma boninense. The disease is difficult to manage. Therefore, development of novel and environmentally safe approaches to control the disease is important. Species of Burkholderia are known to have diverse lifestyles, some of which can be beneficial to plants either by suppressing diseases or enhancing plant growth. In the present study, antifungal peptides (AFPs) produced by a bacterial strain isolated from the rhizosphere of an oil palm tree, namely Burkholderia sp. strain CP01, exhibited strong growth inhibition on G. boninense. A loss-of-function mutant of CP01 was generated, and it has enabled the identification of a 1.2 kDa peptide and its variants as the active antifungal compounds. High-resolution mass spectrometry revealed six analogous compounds with monoisotopic masses similar to the previously reported cyclic lipopeptides occidiofungin and burkholdine. The antifungal compounds of CP01 were secreted into media and we sought to use CP01 culture extract without living cells to control BSR disease. Glasshouse experiments showed that CP01 culture extract suppressed BSR disease in oil palm seedlings. The ability of CP01 to produce an antifungal substance and suppress plant disease suggests its potential application as a biofungicide in agriculture.

Pythium root rot (PRR) is a disease that can rapidly devastate large swaths of golf course putting greens, with little recourse once symptoms appear. Golf courses routinely apply preventive fungicides for root diseases, which may alter the rhizosphere microbiome, leading to unintended effects on plant health. A multiyear field trial was initiated on a ‘T-1’ creeping bentgrass (Agrostis stolonifera L. cultivar T-1) putting green in College Park, Maryland to evaluate preventive PRR management for disease suppression and effects on rhizosphere bacterial communities. Fungicides commonly used to prevent PRR and a biological fungicide were repeatedly applied to experimental plots throughout the growing season. Rhizosphere samples were collected twice annually from each plot for evaluation of rhizosphere bacterial communities through amplicon sequencing and monitoring of biological control organism populations via quantitative PCR. Cyazofamid was the only treatment to suppress PRR in both years compared with the control. Fosetyl-Al on a 14-day interval and Bacillus subtilis QST713 also reduced PRR severity in 2019 compared with the nontreated control. Treatments did not significantly affect bacterial diversity or relative abundances of bacterial classes; however, seasonal environmental changes did. Repeated rhizosphere-targeted applications of B. subtilis QST713 appear to have established the bacterium into the rhizosphere, as populations increased between samples, even after applications stopped. These findings suggest that QST713 may reduce pathogen pressure when repeatedly applied and can reduce fungicide usage during periods of low PRR pressure.

Maintaining a proper content of selenium (Se) in food is particularly important for human health. However, the mechanisms of uptake and enrichment of Se ENMs in crops are still unclear. Herein, Se engineered nanomaterials (Se ENMs) (size 62.3 ± 14.6 nm and surface charge −34.4 ± 1.4 mV) were synthesized and used as nanofertilizers for Se-fortified vegetables. The results demonstrated the Se content and yield were increased by 338.0% and 19.8% respectively in Brassica chinensis L. through soil application of Se ENMs (0.5 mg‧kg–1). The content of Se in vegetables increased up to 32.8 μg/100 g (7.5 μg/100 g for the control), which could provide the daily recommended Se intake (55–400 μg/day) for human. Amendments of the slightly alkaline soil with the Se ENMs improved beneficial rhizosphere microbiomes (Pseudomonas and Bacillus), and resulted in the plants accumulating more low molecular weight compounds (betaine, proline, glycine, norleucine, urocanic acid and indole-3-acrylic acid) with increases in the Se content of the plant by 264.9%. Moreover, the nutrient accumulation in leaves promoted the photosynthesis (16.7%) and increased carbohydrate content (6.5%). Also, the expression of carbohydrate transport-related genes (BnSUC1,1, BnSUC1,4, and BnSWEET10,2) were up-regulated by 52.2, 53.2 and 76.3-fold, respectively, promoting root growth, improving rhizosphere microbiome and nutrient availability. Therefore, such mutual benefits between leaves and roots using ENMs could provide an alternative model for cultivating Se-enriched crops.

Agrobacterium tumefaciens is a bacterial pathogen that causes crown gall disease on a wide range of eudicot plants by genetic transformation. Besides T-DNA integrated by natural transformation of plant vegetative tissues by pathogenic Agrobacterium spp., previous reports have indicated that T-DNA sequences originating from an ancestral Agrobacterium sp. are present in the genomes of all cultivated sweet potato (Ipomoea batatas) varieties analyzed. Expression of an Agrobacterium-derived agrocinopine synthase (ACS) gene was detected in leaf and root tissues of sweet potato, suggesting that the plant can produce agrocinopine, a sugar-phosphodiester opine considered to be utilized by some strains of Agrobacterium spp. in crown gall. To validate the product synthesized by Ipomoea batatas ACS (IbACS), we introduced IbACS into tobacco under a constitutive promoter. High-voltage paper electrophoresis followed by alkaline silver nitrate staining detected the production of an agrocinopine-like substance in IbACS1-expressing tobacco, and further mass spectrometry and nuclear magnetic resonance analyses of the product confirmed that IbACS can produce agrocinopine A from natural plant substrates. The partially purified compound was biologically active in an agrocinopine A bioassay. A 16S ribosomal RNA amplicon sequencing and meta-transcriptome analysis revealed that the rhizosphere microbial community of tobacco was affected by the expression of IbACS. A new species of Leifsonia (actinobacteria) was isolated as an enriched bacterium in the rhizosphere of IbACS1-expressing tobacco. This Leifsonia sp. can catabolize agrocinopine A produced in tobacco, indicating that the production of agrocinopine A attracts rhizosphere bacteria that can utilize this sugar-phosphodiester. These results suggest a potential role of IbACS conserved among sweet potato cultivars in manipulating their microbial community. [Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Objective To find a suitable ecological cultivation measure to solve the problem of root-knot nematode disease of Panax quinquefolium (Panacis Quinquefolii Radix) and the heavy metals accumulating in its roots. Methods Three-year-old P. quinquefolium was treated with four different combinations of microbial inoculant (MI) and garbage fermentation liquid (GFL) [the joint application of ‘TuXiu’ MI and Fifty potassium MI (TF), the combination use of ‘No. 1’ MI and Fifty potassium MI (NF), ‘Gulefeng’ poly-γ-glutamic acid MI (PGA), GFL], and the untreated control (CK). Here, high-throughput sequencing, ICP-MS and UPLC were employed to systematically characterize changes of microbial diversity and structure composition, heavy metals (As, Cd and Pb) content and ginsenoside content among different treatments. Results The results revealed that different MIs and GFL could increase the root dry weight of P. quinquefolium, PGA enhanced it by 83.24%, followed by GFL (49.93%), meanwhile, PGA and GFL were able to lessen root-knot nematode disease incidence by 57.25% and 64.35%. The treatment of PGA and GFL can also effectively reduce heavy metals in roots. The As content in GFL and PGA was decreased by 52.17% and 43.48% respectively, while the Cd and Pb contents of GFL and PGA was decreased somewhat. Additionally, the content of total ginsenosides was increased by 42.14% and 42.07%, in response to TF and NF, respectively. Our metagenomic analysis showed that the relative abundance of particular soil microbial community members related to the biocontrol of root-knot nematode disease and plant pathogen (i.e., Chaetomium in NF, Xylari in GFL, and Microascus in PGA), heavy metal bioremediation (Hyphomacrobium in PGA and Xylaria in GFL), and nitrogen fixation (Nordella and Nitrospira in TF) was significantly increased; notably, potential harmful microflora, such as Plectosaphaerella and Rhizobacter, were more abundant in the control group. Conclusion MI and GFL could improve the quality of P. quinquefolium by modifying its rhizosphere microbial community structure and composition, both of them are beneficial to the development of ecological cultivation of P. quinquefolium.

Thousand cankers disease (TCD) is hypothesized to have a greater impact on eastern black walnut (Juglans nigra) in urban forests and plantations compared with natural forest stands. Along with other factors such as resource availability, the phytobiome could partly account for observed differences in disease severity across management regimes. We investigated the extent to which J. nigra-associated soil microbiomes from plantations and natural forests modulate (i) the amount of necrosis caused by Geosmithia morbida in 1-year-old seedlings, and (ii) relative abundance of rhizosphere endophytes and opportunistic pathogens Fusarium and Rhizoctonia in response to aboveground inoculation with G. morbida. Our results suggest that the microbiome from natural forest soil in central Indiana suppresses Fusarium spp. and is indirectly suppressive of G. morbida. Natural forest soil had a greater ability to reduce the size of necrotic area caused by G. morbida compared with steam-treated soil. Inoculating stems of seedlings with G. morbida induced a shift in fungal community composition in the rhizosphere, including Fusarium and Rhizoctonia spp.; however, the direction and magnitude of the shift depended on whether seedlings were amended with forest, plantation, or steam-treated soil. In a companion experiment, necrotic area in G. morbida-inoculated seedlings was twice as high in seedlings grown from seeds that were treated with Fusarium solani relative to those grown from seed treated with water. Our findings support the hypothesis that TCD severity can be modulated by host-mediated feedback between above- and belowground pathogens, as well as by microbial interactions in the rhizosphere.

s Plant-parasitic nematodes infect the roots of crops which bring rigorous economic loss to food industry across the globe. Several plant protection agents are being used but they cause severe negative environmental and health impacts. Recently, organic matter has become an important green alternative for several pesticides including nematicides. In the present study, identification and management of stylet bearing nematodes associated with Malus pumila from different locations of Khanpur, Pakistan, have been presented. Soil samples were collected from the rhizosphere of infected M. pumila and isolated using Baermann funnel extraction technique. Collected specimens were killed, fixed and mounted. After identification, cow dung (organic) and carbofuran (inorganic) were applied after taking the first soil samples and soil samples were recollected and analyzed after 3 months of applications. Ten species of nematodes; Helicotylenchus pseudorobustus, Helicotylenchus dihystera, Helicotylenchus vulgaris, Meloidogyne javanica, Meloidogyne incognita, Aphelenchus avenae, Pratylenchus penetrans, Filenchus sheri, Psilenchus hilarulus and Tylenchus semipenetrans were identified from different locations. Results of amendments revealed that carbofuran was found more effective because of its intense toxic properties, whereas nematode decline rate was slow in case of organic amendments. Being an insecticide, carbofuran killed maximum nematodes but it is highly toxic. If the time period is increased, comparable results can be achieved by applying cow dung, which makes it an environmentally friendly option for the protection of plants against nematodes.

An important number of Micromonospora strains have been reported from nitrogen-fixing root nodules of legume and actinorhizal plants. However, the question of whether this bacterium can also be found in other parts of these plants remains unanswered. More than 150 strains were recovered from different Lupinus angustifolius and Pisum sativum tissues, including leaves, stems, roots, and nodules. In all, 97% of the isolates were identified by 16S ribosomal RNA gene sequence in the target genus and were associated with 27 different Micromonospora spp. Plant-polymer-degrading enzymes are suspected to play a role in the colonization of plants. To this end, bacterial enzymatic activity assays for amylases, cellulases, chitinases, pectinases, and xylanases were determined. All strains produced xylanases and pectinases, while 98.6, 98, and 94.6% of them produced amylases, cellulases, and chitinases, respectively. The most productive strains included seven isolates from P. sativum and one from L. angustifolius. Strain Micromonospora lupini ML01-gfp was used to determine its capacity to reach and colonize different plant organs using P. sativum as the plant model. Stem and leaf samples were monitored by optical and fluorescence microscopy to locate the tagged strain. These results strongly suggest that Micromonospora is able not only to infect nitrogen-fixing nodules but also to reach other parts of the host plant, especially the leaves.

La Trobe University Faculty of Science, Technology and Engineering Murray Darling Freshwater Research CentreMDFRC item.Rate studies of orthophosphate removal from wastewater in Schoenoplectus validus Vahl. (A Love and D Love) planted bucket-sized vertical upflow wetlands occurs simultaneously through three removal processes. In order of decreasing rate, these are reversible sorption to the gravel substratum, reversible conversion to complex phosphorus compounds, and irreversible uptake by plant roots. Mixing the rhizosphere liquid, using forced convection, accelerated orthophosphate removal; concentrations falling from ≈10 mg litre−1 to < 0.2 mg litre−1 in < 48 h. The rate determining step in systems without rhizosphere liquid mixing appears to be diffusive transport of phosphate. Over two years, initial removal rates, and minimum reactive phosphorus concentrations changed little, but aged or high BOD systems sometimes released reactive phosphorus or tannins holding large amounts of phosphorus. The relevance of these mechanisms to total wetland assimilative capacity, and effluent quality, are evaluated.

Publisher Summary The release of easily decomposable root exudates leads to higher microbial density and activity in the rhizosphere compared to bulk soil, and this high density of microorganisms, in turn, attracts predators such as nematodes and protozoa. This chapter focuses on the colonization of the roots by microorganisms and discusses how these microorganisms can both enhance and reduce nutrient availability to plants. As the root grows through the soil, the new root surface just behind the meristematic tissue is colonized by microorganisms that are attracted to the root surface. Root exudates released in the zone immediately behind the root tip and in the distal elongation zone stimulate microbial growth and attract more soil microorganisms to the root surface. Mycorrhiza is the most widespread association between microorganisms and higher plants, and for plants, mycorrhizal associations are either mutualistic, neutral or parasitic. The two major mycorrhizal groups based on differential morphology and physiology are endomycorrhiza and ectomycorrhiza. There are several types of endomycorrhiza, the best known being arbuscular mycorrhiza (AM), ericoid and orchid mycorrhiza. Root colonization by mycorrhizal fungi is initiated either from soil-borne propagules (spores, colonized root residues) or from neighboring roots of the same or different plants and plant species. The most distinct effect of AM on plant growth is the improved supply of nutrients of low mobility in the soil solution, particularly P. Some ericoid and ECM fungi release proteinases and thereby provide the host plant with an access to complex organic sources of N such as proteins. Mycorrhizal colonization can also induce systemic resistance, that is, even roots not colonized by the fungus become resistant to pathogen attack.

Microbial activity in the soil of wetlands is responsible for the emission of more methane to the atmosphere than all other natural sources combined. This microbial activity is heavily impacted by plant roots, which influence the microbial community by exuding organic compounds and by leaking oxygen into an otherwise anoxic environment. This study compared the microbial communities of planted and unplanted wetland soil from an Alaskan bog to elucidate how plant growth influences populations and metabolisms of methanogens and methanotrophs. A common boreal wetland sedge, Carex aquatilis, was grown in the laboratory and DNA samples were sequenced from the rhizosphere, unplanted bulk soil, and a simulated rhizosphere with oxygen input but no organic carbon. The abundance of both methanogens and methanotrophs were positively correlated with methane emissions. Among the methanotrophs, both aerobic and anaerobic methane oxidizing microbes were more common in the rhizosphere of mature plants than in unplanted soil, while facultative methanotrophs capable of utilizing either methane or other molecules became relatively less common. These trends indicate that the roots in this experiment created an environment which favored highly specialized microbial metabolisms over generalist approaches. One aspect of this specialized microbiome is the presence of both aerobic and anaerobic metabolisms, which indicates that oxygen is present but is a limiting resource controlling competition.

Rhizosphere bacterial communities (‘rhizobacteria’) can mediate plant-soil feedbacks that enhance plant drought tolerance, but the composition and ecological characteristics of these populations are poorly understood. We investigated the impact of drought on rhizobacteria communities and the effect of propagating drought-impacted communities on the drought tolerance of naive plants in a two-phase experiment. We tested whether propagating rhizosphere soils from drought-stressed shrub willow (Salix purpurea), or continuously watered controls, affected the performance of a subsequent generation of droughted plants. The impacts of drought on rhizobacteria and plant fitness were evaluated using 16S rRNA gene sequencing and measures of plant growth (root mass and stem length etc.) and stress (abscisic acid, osmolality). Uninoculated reference plants were used to isolate the effects of inoculation. Drought had a significant and lasting impact on the structure of rhizobacterial communities, characterized by increased populations of Actinobacteria (Acidimicrobiia, Thermoleophilia and Micrococcaceae). Foliar osmolality was significantly higher in plants receiving drought-selected communities relative to uninoculated controls, but no significant differences in plant growth were observed. Inoculation with rhizosphere soil from watered controls significantly reduced plant growth. The rhizosphere of watered control plants was dominated by Proteobacteria and Bacteroidetes. Our findings demonstrate that plants are affected by the legacy effects of drought on the rhizosphere microbiome. This drought legacy was propagated and persisted throughout nine weeks of plant growth, independent of prevailing water stress. Drought-impacted rhizospheres had larger populations of desiccation-tolerant (ex. Arthrobacter) and putatively endophytic taxa (ex. Rhizobium) with established plant growth promoting capabilities.

Nematode damage to coffee poses a serious threat to coffee production all over the world, including Vietnam. Accordingly, the nematode community composition could be a reliable indicator of ecological shifts that affect coffee plants' health. Here, we analysed the nematode communities in the rhizosphere of a monoculture Robusta coffee plantation in Dak Lak of the Central Highlands, Vietnam. We found changes in the community composition of nematodes in an age gradient of replanting coffee plants and revealed distinct patterns of nematode distribution in the soils of healthy and diseased plant groups. Further analyses indicate the impact of intensive farming and inefficient nematode controls, which caused disturbances and a gradual decrease of the nematode fauna diversity in the plantation soil. These results can add to a complete prediction model for plant fitness using nematode community composition.

Pseudomonas spp., a ubiquitous biocontrol agent, protects the plants from phytopathogens by suppressing them directly by reinforcing the plant’s intrinsic defense mechanism. Root exudated phenolics play an important role in establishing the rhizobacteria population and cross the host boundaries in beneficial plant–microbe interaction. In this study, Pseudomonas spp. HU-8 & HU-9 antagonized the sugarcane red rot pathogen (C. falcatum) and showed a positive chemotactic response against different concentrations (10–30 µM) of synthetic phenolic acids like p-coumaric, vanillic, and 3,4 di-hydroxybenzoic acid. In a pot experiment, they effectively colonized the sugarcane rhizosphere and mediated defense response in sugarcane plants challenged with red rot pathogen C. falcatum by regulating the exudation of root phenolics under hydroponic conditions. They significantly induced the activity of the antioxidant enzymes CAT (1.24–1.64 fold), PO (0.78–1.61 fold), PAL (0.77–0.97 fold), and PPO (3.67–3.73 fold) over untreated plants in sugarcane. They also induced the total phenolic contents (TPC) in sugarcane in the presence (6.56–10.29 mg/g GAE) and absence (2.89–4.16 mg/g GAE) of the pathogen quantified through the Folin-Ciocalteu (FC) method. However, their effect was lower than that of the pathogen (4.34–8 mg/g GAE). The Pseudomonas spp. significantly colonized the sugarcane rhizosphere by maintaining a cell population of (1.0E + 07–1.3E + 08 CFU/mL). A significant positive Pearson’s correlation was observed between the root exudated total phenolic contents, antioxidant enzymatic activities, and rhizospheric population of inoculated bacteria. The 16S rRNA and rpoD gene analysis showed sequence conservation (C: 0.707), average number of nucleotide differences (k: 199.816), nucleotide diversity, (Pi): 0.09819), average number of informative nucleotide sites per site (Psi: 0.01275), GC content (0.57), and polymorphic sites (n = 656). These diverse Pseudomonas spp. could be an ideal bio-inoculants for a broad range of hosts especially graminaceous crops.

Soybean cyst nematode (SCN, Heterodera glycines Ichinohe) is one of the most important pests causing considerable damage to soybean (Glycine max (L.) Merr.) around the world. Biocontrol provides a strategy for sustainable nematode control. Previously, Aspergillus niger NBC001 was isolated from the cysts of Heterodera spp. and able to control H. glycines and promote the growth of soybean in a pot experiment. In this study, the effects of NBC001 on H. glycines density and on the soybean rhizosphere microbial community in a soybean cyst nematode-infested field were studied. The results showed that NBC001 could suppress H. glycines by 31.7% in the field. High-throughput sequencing analysis showed that NBC001 had no significant influence on soybean rhizosphere microbial community structure, indicating that seed coat-dressing with the concentrated culture filtrate of NBC001 was safe for the soil ecological environment. In addition, high-throughput sequencing results demonstrated that at 10 days post transplantation, NBC001 increased the abundances of Actinobacteria and Acidobacteria, but decreased the abundances of Bacteroidetes and Gemmatimonadetes at the phylum level. Meanwhile, the abundances of Phyllobacterium, Ralstonia and H16 were increased, while the abundances of Adhaeribacter, Gemmatimonas, Sphingomonas, Flavisolibacter were suppressed by application of NBC001. However, at 90 days post transplantation, NBC001 only increased the abundances of Aeromicrobium and RB41 whereas it decreased the abundance of H16. The results indicated that application of NBC001 increased the relative abundances of the beneficial microorganisms such as Actinobacteria, Acidobacteria, Aeromicrobium and Phyllobacterium in the soil. In summary, NBC001 is an eco-friendly biocontrol agent for H. glycines control.

The biostimulant BC204 is a commercially available biostimulant based on an extract from Citrus aurantium, comprising a mixture of bioflavonoids, other plant extracts and organic acids. In this study, the potential of BC204 to cause positive effects on plant growth and overall plant health by altering the rhizosphere microbial community of Solanum lycopersicum L. was investigated. Mycorrhizal colonization of plant roots was analysed by trypan blue-staining and light microscopy, followed by polymerase chain reaction (PCR) amplification of a region of the 18S rRNA gene conserved among arbuscular mycorrhizal fungi. No difference in mycorrhizal colonization of roots was observed between control and treated plants. The structural and functional diversity of rhizosphere bacteria between different treatment groups was assessed using 16S rRNA gene restriction fragment length polymorphism (RFLP) analysis and community-level physiological profiling (CLPP), respectively. Nearest sequence matches for three isolates from the rhizosphere of plants treated with BC204 as a soil drench in soil supplemented with Mycoroot™ revealed bacterial genera which play a role in promoting plant growth. Furthermore, the microbial community from this treatment group showed increased richness of substrate utilization on Biolog EcoPlates™. These results indicate some form of interaction between BC204 and Mycoroot™ which causes a shift in the structural and functional diversity of the rhizosphere bacterial community.

The cape gooseberry (Physalis peruviana) is a Solanaceae species with enormous economic importance in Colombia; it is the second most exported fruit, after bananas. Vascular wilt caused by Fusarium oxysporum f. sp. physali (Fox) is the most limiting factor of this crop, with losses of up to 80% of production. Biological control is a promising alternative for controlling this pathogen. Bacteria and fungi, originally isolated from potentially suppressive soils of cape gooseberry crops in Nariño, Colombia with different management (organic and conventional), were evaluated as biocontrol agents of Fox using a gnotobiotic model (seedlings cultured under axenic conditions with defined microbial strains). Of the 64 isolated microorganisms, 37.5% (15 bacteria and 9 fungi) were discarded because of toxicological risks and an unknow potential biological control. The remaining 62.5% of the microorganisms, 14 bacteria and 26 fungi, were evaluated to assess their potential as biological control agents against Fox. The gnotobiotic model system evaluated the protection and plant growth promotion characteristics. Response variables were used to group the microorganism using a principal component analysis (PCA), and five clusters were obtained. Cluster number four concentrated the 10 microorganisms (three bacteria and seven fungi) with the highest protection values against Fox, with a positive effect on growth. The isolates were identified as two Bacillus subtilis strains, Rhodococcus sp., Podospora setosa, Debaryomyces vindobonensis, Plectosphaerella plurivora, Acinetobacter rhizosphaerae, Umbelopsis sp. and two strains of Trichoderma koningiopsis. The gnobiotic system offered clear advantages for evaluating and selecting microorganisms with a biological control potential against Fusarium oxysporum f. sp. physalis. RESUMEN La uchuva (Physalis peruviana) es Solanaceae de enorme importancia económica en Colombia ya que es la segunda fruta más exportada después del banano. La marchitez vascular causada por Fusarium oxysporum f. sp. physali (Fox) es el factor más limitante de este cultivo, que ocasiona pérdidas de hasta el 80% de su producción. El control biológico se ha convertido en una alternativa prometedora para controlar este patógeno. Bacterias y hongos, originalmente aislados de suelos potencialmente supresores de cultivos de uchuva de Nariño, Colombia con diferente manejo (orgánico y convencional) fueron evaluados como agentes de control de Fox utilizando un modelo gnotobiótico (plántulas cultivadas en condiciones axiológicas con cepas microbianas definidas). A partir de los 64 microorganismos aislados, 37.5% (15 bacterias y nueve hongos) fueron descartados debido a su riesgo toxicológico y a un control biológico potencial desconocido, el 62.5% restante de microorganismos, 14 bacterias y 26 hongos, se evaluaron para evaluar su potencial como agentes de control biológico contra Fox. El sistema de modelos gnotobióticos nos permitió evaluar las características de protección y promoción del crecimiento vegetal, estas variables de respuesta se utilizaron para agrupar el microorganismo utilizando un análisis de componentes principales (PCA) y se obtuvieron cinco clústeres. El clúster número cuatro concentró 10 microorganismos (tres bacterias y siete hongos) con los valores de protección más altos contra Fox y con un efecto positivo en la promoción del crecimiento. Los aislados fueron identificados como dos cepas de Bacillus subtilis, Rhodococcus sp., Podospora setosa, Debaryomyces vindobonensis, Plectosphaerella plurivora, Acinetobacter rhizosphaerae, Umbelopsis sp. y dos cepas de Trichoderma koningiopsis. El sistema gnobiótico presentado ofrece claras ventajas para evaluar y seleccionar microorganismos con un potencial de control biológico contra Fusarium oxysporum f. sp. fisalis.

Less attention has been given to soil enzymes that contribute to beneficial rhizosphere interactions in intercropping systems. Therefore, we performed a field experiment by growing faba bean, lupine, and maize in mono and mixed cultures in a moderately fertile soil. We measured shoot biomass and the kinetic parameters (maximal velocity (Vmax) and Michaelis-constant (Km)) of three key enzymes in the rhizosphere: Leucine-aminopeptidase (LAP), β-1,4-N-acetylglucosaminidase (NAG), and phosphomonoesterase (PHO). Faba bean benefitted in mixed cultures by greater shoot biomass production with both maize and lupine compared to its expected biomass in monoculture. Next, LAP and NAG kinetic parameters were less responsive to mono and mixed cultures across the crop species. In contrast, both the Vmax and Km values of PHO increased in the faba bean rhizosphere when grown in mixed cultures with maize and lupine. A positive relative interaction index for shoot P and N uptake for faba bean showed its net facilitative interactions in the mixed cultures. Overall, these results suggest that over-productivity in intercropping is crop-specific and the positive intercropping effects could be modulated by P availability. We argue that the enzyme activities involved in nutrient cycling should be incorporated in further research.

The role of multi-heavy metal tolerant bacteria isolated from the rhizosphere of Eichhornia crassipes in the phytoremediation of Cu and Pb under laboratory conditions was investigated. The heavy metal tolerant rhizosphere bacteria were identified as Bacillus cereus, Paenibacillus alvei, Aeromonas caviae, Paenibacillus taiwanensis, and Achromobacter spanius. Results showed a significant variation in wet weight, Heterotrophic Plate Count (HPC) of the rhizosphere, HPC of water, removal and uptake of Cu and Pb by E. crassipes, either alone or in association with the rhizosphere bacteria. The removal of Cu by E. crassipes in different experimental conditions showed that OTC (Oxytetracycline) untreated E. crassipes with rhizosphere bacteria has maximum removal with 95%, followed by E. crassipes alone with 84%. The OTC treated E. crassipes with rhizosphere bacteria could remove 81% of Cu. The maximum Pb removal efficiency of 93.4% was shown by OTC untreated E. crassipes with rhizosphere bacteria, followed by E. crassipes alone with 86.8%. The OTC treated E. crassipes with rhizosphere bacteria showed the least removal efficiency with 82.32%. The translocation factor (TF) values for Cu and Pb were lower than 1 indicated that the absorption was mainly accomplished in the roots of E. crassipes. The order of accumulation of Cu and Pb in E. crassipes was noted as root > leaf > petiole.

BACKGROUND Excessive nitrogen (N) fertilization in glasshouse fields greatly increases N loss and fossil-fuel energy consumption resulting in serious environmental risks. Microbial inoculants are strongly emerging as potential alternatives to agrochemicals and offer an eco-friendly fertilization strategy to reduce our dependence on synthetic chemical fertilizers. Effects of a N-fixing strain Pseudomonas protegens CHA0-ΔretS-nif on ginger plant growth, yield, and nutrient uptake, and on earthworm biomass and the microbial community were investigated in glasshouse fields in Shandong Province, northern China. RESULTS Application of CHA0-ΔretS-nif could promote ginger plant development, and significantly increased rhizome yields, by 12.93% and 7.09%, respectively, when compared to uninoculated plants and plants treated with the wild-type bacterial strain. Inoculation of CHA0-ΔretS-nif had little impact on plant phosphorus (P) acquisition, whereas it was associated with enhanced N and potassium (K) acquisition by ginger plants. Moreover, inoculation of CHA0-ΔretS-nif had positive effects on the bacteria population size and the number of earthworms in the rhizosphere. Similar enhanced performances were also found in CHA0-ΔretS-nif-inoculated ginger plants even when the N-fertilizer application rate was reduced by 15%. A chemical N input of 573.8 kg ha-1 with a ginger rhizome yield of 1.31 × 105 kg ha-1 was feasible. CONCLUSIONS The combined application of CHA0-ΔretS-nif and a reduced level of N-fertilizers can be employed in glasshouse ginger production for the purpose of achieving high yields while at the same time reducing the inorganic-N pollution from traditional farming practices. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Terpenes constitute a major part of secondary metabolites secreted by plants in the rhizosphere. However, their specific functions in fungal–plant interactions have not been investigated thoroughly. In this study we investigated the role of monoterpenes in interactions between oilseed rape (Brassica napus) and the soilborne pathogen Verticillium longisporum. We identified seven monoterpenes produced by B. napus, and production of α‐pinene, β‐pinene, 3‐carene, and camphene was significantly increased upon fungal infection. Among them, β‐pinene was chosen for further analysis. Transcriptome analysis of V. longisporum on exposure to β‐pinene resulted in identification of two highly expressed pleotropic drug transporters paralog genes named VlAbcG1a and VlAbcG1b. Overexpression of VlAbcG1a in Saccharomyces cerevisiae increased tolerance to β‐pinene, while deletion of the VlAbcG1a homologous gene in Verticillium dahliae resulted in mutants with increased sensitivity to certain monoterpenes. Furthermore, the VlAbcG1a overexpression strain displayed an increased tolerance to β‐pinene and increased virulence in tomato plants. Data from this study give new insights into the roles of terpenes in plant–fungal pathogen interactions and the mechanisms fungi deploy to cope with the toxicity of these secondary metabolites., A pleotropic drug transporter VIAbcG1 is required for tolerance to the plant host β‐pinene monoterpene and virulence in the soilborne plant pathogen Verticillium longisporum.

To highlight the importance of the soil-root interface in bacterial root colonization, we performed 16S rRNA gene amplicon sequencing on the Illumina MiSeq platform to characterize the bacterial endophytes of rice plants grown by two experiments – soil and hydroponic, considering their soil, solution, and endosphere compartments. We hypothesized that rice plants from both experiments would exhibit dissimilar endophytic bacterial communities. Alpha-diversity (richness (ASVs), Shannon index, Faith’s phylogenetic diversity, and Pielou’s evenness) for bacterial endophytes was lower in the soil experiment than in the hydroponic experiment. However, the rhizospheric soil exhibited higher microbial diversity and richness than the hydroponic solution after 6 weeks. Proteobacteria and Firmicutes were the most dominant phyla in both experiments, while several other bacterial taxa showed major differences at genus levels. A Venn diagram revealed that 5 overlapping bacterial genera were shared by the endosphere and rhizosphere/solution compartments of both experiments. Principal coordinate analysis (PCoA) based on weighted UniFrac distances showed a clear distinction between microbial communities of all sampled compartments. Furthermore, PERMANOVA results showed that the endophyte communities of both experiments differed significantly (p

Cadmium’s presence in agricultural soils resulting from industrial activities, factories, fertilizers, and pesticides is an environmental challenge threatening public health. Therefore, this study was carried out to assess Trichoderma harzianum and indigenous rhizosphere soil microbes’ ability on cadmium absorption, translocation, and tolerance in barley. A pot experiment was conducted in a full factorial randomized design with three replicates. Treatments were T. harzianum (Tri) and rhizosphere soil (Rhi) and Cd at seven levels (0, 1.54, 3.84, 9.6, 24, 60, and 150 mg kg−1). We found that simultaneous application of T. harzianum and indigenous soil microorganisms had positive effects on barley tolerance index (TI), Cd uptake efficiency, shoot dry weight, and plant uptake. Co-inoculation of T. harzianum and soil microorganisms resulted in significantly higher chlorophyll content as compared to plants inoculated only with only T. harzianum or soil microorganisms. The maximum root uptake obtained at 150 mg kg−1 Cd added was in plants also co-inoculated with Tri and Rhi. Also, the Cd uptake efficiency was lower in plants inoculated with Tri and Rhi compared to non-inoculated plants. Meanwhile, Cd uptake efficiency increased with soil Cd up to 133 mg kg−1. The lowest Cd phytoextraction efficiency was observed with Tri and Rhi co-inoculated plants. The obtained results suggest that co-inoculation of T. harzianum and soil microbes ameliorates the negative effects of Cd contamination and could then be used as an option to remediate Cd-contaminated soils even in higher levels than this study.

The comparative study of soil bacteria from the rhizosphere was carried out using samples obtained from the soil (rhizospheres) of Anogeissus leiocarpa and Pterocarpus erinaceus using purposive sampling method. The soil samples were collected at a depth of 0-30cm and 30-60cm around the rhizosphere of the studied tree species and away from the rhizosphere used as a control. The method by Ibitoye (2008) was used to test for physico-chemical properties and method by Cheesborough (2006) was used for stocking, culturing, incubating and gram staining. Result for the mean physical properties shows, P. erinaceus had highest mean values for clay and silt which wasn’t significant (p= 0.067 and 0.381 respectively). A. leiocarpus had the second highest clay and silt. Sand and bulk density was highest for the control which was highly significant (p = 0.000 and p=0.044 respectively). For mean chemical properties among plant species, pH, EC, OC, OM, N, Na, Ca and CEC were highly significant (p

Intercropping or assistant endophytes promote phytoremediation capacities of hyperaccumulators and enhance their tolerance to heavy metal (HM) stress. Findings from a previous study showed that intercropping the hyperaccumulator Sonchus asper (L.) Hill grown in HM-contaminated soils with maize improved the remediating properties and indicated an excluder-to-hyperaccumulator switched mode of action towards lead. In the current study, RNA-Seq analysis was conducted on Sonchus roots grown under intercropping or monoculture systems to explore the molecular events underlying this shift in lead sequestering strategy. The findings showed that intercropping only slightly affects S. asper transcriptome but significantly affects expression of root-associated microbial genomes. Further, intercropping triggers significant reshaping of endophytic communities associated with a ‘root-to-shoot’ transition of lead sequestration and improved phytoremediation capacities of S. asper. These findings indicate that accumulator activities of a weed are partially attributed to the root-associated microbiota, and a complex network of plant–microbe-plant interactions shapes the phytoremediation potential of S. asper. Analysis showed that intercropping may significantly change the structure of root-associated communities resulting in novel remediation properties, thus providing a basis for improving phytoremediation practices to restore contaminated soils.

Effects of hydrogen concentrations on the diversity and changes of bacterial community structure, soybean rhizosphere soil samples were investigated. The high-throughput sequencing technology of illumina was adopted to determine the bacterial 16S rRNA V3+V4 region series. Data processing such as splicing, filtering, removing chimeric sequences, and cluster analysis was then performed based on the raw data, and the tax was annotated with OTU. When the air-treated soil samples were compared with the ones treated with hydrogen at a concentration of 1100 ppm and 1300 ppm, the abundance of Proteobacteria increased and Actinobacteria decreased for the later. In addition the Simpson index decreased and the Shannon index increased significantly for both hydrogen-treated samples. However, for the soil sample treated with 1500 ppm of hydrogen, the above-mentioned two indexes didnot vary obviously compared with the air-treated sample. The results demonstrated that the rhizosphere bacterial structure diversity of soybean was significantly increased after hydrogen treatment at the concentration of 1100 and 1300 ppm. Bangladesh J. Bot. 50(3): 775-780, 2021 (September) Special

As rizobactérias promotoras do crescimento de plantas (RPCP) são capazes de proporcionar o melhor desenvolvimento vegetal por meio de diversos mecanismos. Um desses mecanismos trata da produção de reguladores de crescimento vegetal, como por exemplo, o ácido indolacético (AIA). Com isso, o objetivo do presente trabalho foi o isolamento, a caracterização fenotípica e a avaliação do potencial de produção de AIA de rizobactérias, obtidas da rizosfera de oliveiras (Olea europaea L.), visando a sua aplicação na indução do enraizamento durante a produção de mudas. Para isso, amostras de rizosfera de 17 diferentes cultivares de oliveira, do banco de germoplasma da Empresa de Pesquisa Agropecuária de Minas Gerais (EPAMIG), em Maria da Fé - MG, foram utilizadas para o isolamento de RPCP em meios de cultura JNFb, NFb e LGI, posteriormente caracterizadas fenotipicamente em meio batata-dextrose-ágar e submetidas ao teste de produção de AIA. Pôde-se observar efeito das cultivares no número de RPCP nos diferentes meios de cultura. Na caracterização fenotípica, os isolados de RPCP apresentaram alta similaridade entre si (93% a 100%). Quanto à produção de AIA, esses isolados apresentaram índices relevantes (0,16 e 29,08 μg mL-1) quando comparados a outros estudos, sendo aqueles obtidos no meio JNFb os maiores produtores. Pôde-se concluir que 11 isolados (KRJ2, GLJ2, G57J2, MFJ1, ADJ2, G57N1, AUSAL3, FTJ1, AUSAN1, AUSAJ2, KRN1), com produção acima de 20 μg mL-1 de AIA, apresentam potencial de utilização em futuros testes na indução de enraizamento de estacas de plantas de oliveira.

Rhizospheric soils and corms of Crocus sativus L. accommodate 13 different nematode taxa in the saffron fields of Kishtwar, Jammu and Kashmir, India. Out of which, three are identified as free-living, two predatory and eight plant-parasitic. Among free-living, predatory and plant-parasitic nematodes Acrobeles spp., Mononchus spp. and Helicotylenchus spp. respectively were the most frequently and densely available nematodes with high prominence value. Shannon diversity index (H′ = 2.43) and evenness index (J = 0.95) determined that Crocus sativus L. rhizosphere in Kishtwar is rich in terms of nematode diversity.

In a model study, we analysed the impact of humic acids (HAs, 500 ppm) on the accumulation of heavy metals (HMs; Pb, Cu, Ni and Zn) in roots and aboveground organs of the annual ornamental plant Tagetes patula (Scarlet variety) cultivated on the Terra Vita nutritive substrate used in modern cultural landscape mulching to imitate the upper fertile root layer (UR-RAT) of contaminated urban soils in megacities. Plants were grown in full photoculture (at no sunlight) in pots placed in a closed grow box, maintaining internal microclimate. A modern HLG Quantum Board QB288 V2 Rspec LED panel enabled with vegetation modes was used as light source. HMs were introduced in substrate as aqueous saline. Each setting was quadruplicated. Total experiment duration was 30 days. Tagetes patula was proved a particularly effective phytoextractor of Zn applied at 40 mg/kg (pPb>Ni. Ni at 30 mg/kg had a major impact on plant weight and length, which sets off the variety as a sensitive phytoexcluder for this metal. HAs increased aboveground mass in all settings and decreased the HM mass impact. A sharp root mass reduction was observed in combinations of the two factors (HMs+HAs), which was clearly reflected in impaired root mass in zinc settings. A single metal addition reduced the mass by average 12.0 % (p

The microbial community within the root system, the rhizosphere closely connected to the root, and their symbiotic relationship with the host are increasingly seen as possible drivers of natural pathogen resistance. Resistant cultivars have the most effective strategy in controlling the Chinese wheat yellow mosaic disease, but the roles of the root and rhizosphere microbial interactions among different taxonomic levels of resistant cultivars are still unknown. Thus, we aimed to investigate whether these microbial community composition and network characteristics are related to disease resistance and to analyze the belowground plant-associated microflora. Relatively high microbial diversity and stable community structure for the resistant cultivars were detected. Comparison analysis showed that some bacterial phyla were significantly enriched in the wheat root or rhizosphere of the resistant wheat cultivar. Furthermore, the root and rhizosphere of the resistant cultivars greatly recruited many known beneficial bacterial and fungal taxa. In contrast, the relative abundance of potential pathogens was higher for the susceptible cultivar than for the resistant cultivar. Network co-occurrence analysis revealed that a much more complex, more mutually beneficial, and a higher number of bacterial keystone taxa in belowground microbial networks were displayed in the resistant cultivar, which may have been responsible for maintaining the stability and ecological balance of the microbial community. Overall, compared with the susceptible cultivar, the resistant cultivar tends to recruit more potential beneficial microbial groups for plant and rhizosphere microbial community interactions. These findings indicate that beneficial rhizosphere microbiomes for cultivars should be targeted and evaluated using community compositional profiles. KEY POINTS: • Different resistance levels in cultivars affect the rhizosphere microbiome.. • Resistant cultivars tend to recruit more potential beneficial microbial groups. • Bacteria occupy a high proportion and core position in the microflora network.

Sugarcane cultivars (Saccharum officinarum L.) are widely cultivated for both sugar and renewable energy in China. The response of rhizosphere fungal composition and diversity to different emerging sugarcane cultivars is limited. Therefore, utilizing high-throughput sequencing, we explored fungal communities' structure in soils adhering to six sugarcane cultivars' roots (Guitang 08-120, Regan14-62, Guitang 08-1180, Haizhe 22, Liucheng 05-136, Taitang 22) in Guangxi Province, China. Our results suggested that sugarcane varieties significantly altered rhizosphere soil attributes, with Haizhe 22 having substantially lower soil pH, organic matter (OM), available phosphorus (AP), and soil water contents (SWC) than others cultivars. Different sugarcane varieties did not substantially affected the Shannon fungal diversity index, but the apparent effect on fungal richness was significant. Beta diversity analysis revealed that "Haizhe 22" distinguished the fungal community from the other five cultivars. Soil pH, OM, cultivars, and soil moisture were crucial determinants in shaping soil fungal composition. The Haizhe 22 rhizosphere significantly enriched the operational taxonomic units (OTUs) assigned to two fungal genera (Cephalotheca and Sagenomella), while rhizosphere of other verities significantly enriched the OTUs assigned to four fungal genera (Chaetomium, Chaetosphaeria, Mortierella, and Talaromyces), suggesting their essential role in plant development, disease tolerance, and bioremediation. These findings may help in selecting or breeding innovative genotypes capable of supporting abundant rhizosphere fungi beneficial to plants that would likely improve crops' agronomic potential and maintain soil ecosystem sustainability.

One of the downstream areas of the Komering River with potential for capture fisheries is Sungai Dua Village. One of the types of fish caught by fishermen in Sungai Dua is the three spot gourami (Trichogaster trichopterus). The three spot gourami fish is a type of freshwater consumption fish that has high economic value. But the fishes only rely on catches from nature. If the fishing is carried out continuously, without domestication and cultivation, it will cause a decline in the fish population. The research about the biological aspects of red-eye septic fish (Trichogaster trichopterus) which include food habits, relationship length and weight, condition factors and stomach fullness index. This research was conducted from April to June 2017. Sampling was carried out in the downstream waters of the Komering River in Sungai Dua Village, Banyuasin Regency, South Sumatra. Fish samples were analyzed at the Animal Taxonomy Laboratory, Department of Biology, Faculty of Mathematics and Science, Sriwijaya University. The determination of stations in sampling was carried out using multiple sampling methods, namely purposive sampling and quota sampling. The result of this research showed that (1) the Cyanophyta is the main food for the three spot gourami, Diatomae and Desmidiacae as a complementary food, while the additional foods are Rhizopoda, Chlorophyta, Ostracoda, and Entomostraca, (2) The growth pattern of red-eyed fish is negative allometric with a b value of -2 (b

The purpose of this research is to obtain hydrocarbon degrading bacteria that work synergistically in a consortium. Consortium microorganisms is mixture of microbial populations in the form of communities that have mutualistic relationships and doesn’t inhibition the growth of other microbes. In this study, isolates were obtained from the rhizosphere of soil contaminated with petroleum. The isolates obtained were tested for synergism to determine the relationship between bacterial isolates. Synergism testing was carried out using the spread plate method on agar media. The results of this study showed that isolate number one showed antagonistic properties to other bacterial isolates by forming a clear zone around the disc paper. A total of eight bacterial isolates showed the greatest percentage of synergism, namely ≥ 80% so that the eight rhizosphere bacterial isolates could be used as materials for mixed culture.

A rhizospheric bacterium belonging to the genus Pseudomonas isolated from the rhizosphere of maize was evaluated for the plant growth promoting and biocontrol traits. The strain was subjected to the different PGP and biocontrol traits such as ammonia, IAA, siderophores, phosphate solubilisation, ACC deaminase, HCN production, cellulase, pectinase and chitinase activity. 16S rRNA sequencing showed maximum homology with the strain Pseudomonas indoloxydans IPL-1(NR115922). In vivo plant growth promotion assay with the strains on maize seedlings showed a significant increase in the biometric parameters with respect to the number of shoots (32%) and roots (27%) and its fresh weight (20%) and dry weight (54%). Different formulations of the strain tested in fields revealed that the maize plants treated with the talc and lignite formulations showed a considerable increase in the growth of maize when compared to the plants without any treatment. The study concluded that the rhizosphere strains Pseudomonas indoloxydans (F3- 47) could be a potential plant growth promoter for future exploration in agriculture.

Currently, more than 10,000 species of fungi associated with plants have been found, and it is not surprising that fungal diseases cause a lot of harm. Most species of the genus Fusarium are soil protrophs that live on dead plant remains, in the rhizosphere of plants, on the surface of roots. They cause rot of roots, seeds, fruits, tubers, root crops. All forms of fusariums progress at high temperatures and humidity. The analysis of literary sources and experimental data allowed us to formulate the purpose of our research: “To analyze the species diversity of fungi of the genus Fusarium from the soil, table carrot plants, depending on the ecological and geographical zones of growth.” As a result, using PCR analysis, 13 samples attributed to F. langsethiae were identified; 2 samples of F. ochusrohim; 8 samples of F. roae; 2 of F. sporotrichioides; 1 sample attributed to F. sulmorum, this sample was collected in the Rostov region and the Moscow region. It was also revealed that the diversity of soil and climatic conditions in different zones leads to a change in the species composition of representatives of R. Fusarium: the species composition of fungi of R. Fusarium varies significantly depending on agro-climatic conditions. In wetter and warmer conditions (southern regions), specific species of F. culmorum, F. sporotrichiella, and F. oxysporum dominate. F. heterosporum, F. nivale are less common; F. graminearum species lives on plant residues, on plant roots or in the rhizosphere zone, but practically does not occur in the soil in its pure form. Thus, this direction is promising for the study of fungi of the genus Fusarium, since this microorganism lives in the soil and on plants. It is advisable to identify the pathogen from samples from different regions to significantly increas the representativeness of samples within the regions with further identification of diverse mycelium, thereby creating a scale of diverse mycelium.

Trichoderma spp. are fungus considered one of the most attractive for biological control due to its different mechanisms action against plant pathogens and action to promote plant growth and productivity. The molecular characterization of this group of antagonists is of great importance for conducting studies in the area of biodiversity and for identifying and selecting the possibility of their use in biological control. Objective of this work was to identify 29 Trichoderma isolates based on molecular profiles and phylogenetic analysis sequence the rRNA gene ITS1-5-8S-ITS2, as well as to select the isolates that presented the highest levels of antagonism against S. sclerotiorum and that promoted growth in common bean using experiments in vitro and in a greenhouse. Among the sequences obtained, a total of five different Trichoderma species were identified: T. asperellum, T. harzianum, T. koningiopsis, T. brevicompactum and T. tomentosum. The Trichoderma isolates used showed a variation in the mycelial inhibition of the pathogen by non-volatile metabolites between 84.11% to 100%. Regarding the dry weight of the plants treated with Trichoderma and the pathogen, it was observed that ten Trichoderma isolates promoted plant growth in relation to the control with a variation of 2.6% to 34%. T. asperellum CEN201 proved to be the best candidate to participate in a broader selection that would include field tests for the biological control of S. sclerotiorum and growth promotion in common bean, as in the laboratory and at home of vegetation showed great success in inhibiting the pathogen and promoting plant growth.

Drymaria cordata (L.) Willd. ex Roem. & Schult. commonly known as ‘West Indian Chick weed’ is a potential herb used in traditional medicine in the treatment of many ailments. The main active principles therapeutically are known as drymaritin and isovitexin. Arbuscular mycorrhizae (AM) are symbiotic associations between plants and soil fungi that play a vital role in plant growth and development as well as soil quality. In the present investigation, an attempt was made to determine the growth responses of in vitro regenerated Drymaria cordata to inoculation with arbuscular mycorrhizal fungi. Both normal and in vitro regenerated plants of Drymaria cordata were inoculated with Glomus mosseae and Glomus fasciculatum. All the inoculated plants showed significant morphological results over control after a period of 30, 60 and 90 days of inoculation in polyhouse pot experiment. The percent of colonization and the number of spores in the rhizosphere of the in vitro regenerated plants are significantly more than the normal plants. Inoculation of in vitro regenerated plants with Glomus fasciculatum showed maximum mycorrhizal inoculation effect. Mycorrhizal inoculation significantly increased the biomass, root and shoot length, plant height, leaf area, number of branches, number of nodes per branch and internodal length. Such increases were related to the intensity of mycorrhizal association in the root. These findings indicate that mycorrhizal inoculation can be a suitable and alternative method to improve the growth of Drymaria cordata.

In the present study, culture-dependent and independent [Denaturing gradient gel electrophoresis (DGGE)] approach were used to analyze the effect of fallow cycle on bacterial populations associated with mixed crops selected from three different jhum fallow cycles (5-, 10- and 20- years) of Changki village, Nagaland. Two important bacterial phyla viz. Acidobacteria and Burkholderia were selected for DGGE analysis. According to the DGGE banding profile, Acidobacteria showed more richness compared Burkholderia. The presence and absence of few of the bands in the profile indicate the community shifts in the selected jhum fields. Shannon diversity index was higher in Acidobacteria than Burkholderia. Multivariate analysis showed that Acidobacteria community structure was similar among the crop plants of the same fallow cycle. Burkholderia community did not show clear separation among fallow cycles although crop of same fallow cycle tend to group together. ANOSIM and PERMANOVA showed significant differences in rhizosphere community pattern among fallow cycles and the crop plants of same fallow cycles indicated that both fallow cycle and crop plants are factors determining the Acidobacteria and Burkholderia community composition in jhum soils which was also confirmed by the culture-dependent analysis. Culturable bacterial counts were dependent on media used and significantly different at different fallow cycles. Bacterial communities (both culturable and DGGE patterns) were correlated with soil nutrients suggesting their importance in stability of jhum soil. The present study revealed that both fallow cycle and host plant may be the key factors in shaping many bacterial communities in jhum soils.

The subterranean microbiota of plants is of great importance for plant growth and health, as root-associated microbes can perform crucial ecological functions. As the microbial environment of roots is extremely diverse, identifying keystone microorganisms in plant roots, rhizosphere, and bulk soil is a necessary step towards understanding the network of influence within the microbial community associated with roots and enhancing its beneficial elements. To target these hot spots of microbial interaction, we used inter-kingdom network analysis on the canola growth phase of a long-term cropping system diversification experiment conducted at four locations in the Canadian Prairies. Our aims were to verify whether bacterial and fungal communities of canola roots, rhizosphere, and bulk soil are related and influenced by diversification of the crop rotation system; to determine whether there are common or specific core fungi and bacteria in the roots, rhizosphere, and bulk soil under canola grown in different environments and with different levels of cropping system diversification; and to identify hub taxa at the inter-kingdom level that could play an important ecological role in the microbiota of canola. Our results showed that fungi were influenced by crop diversification, which was not the case on bacteria. We found no core microbiota in canola roots but identified three core fungi in the rhizosphere, one core mycobiota in the bulk soil, and one core bacterium shared by the rhizosphere and bulk soil. We identified two bacterial and one fungal hub taxa in the inter-kingdom networks of the canola rhizosphere, and one bacterial and two fungal hub taxa in the bulk soil. Among these inter-kingdom hub taxa, Bradyrhizobium sp. and Mortierella sp. are particularly influential on the microbial community and the plant. To our knowledge, this is the first inter-kingdom network analysis utilized to identify hot spots of interaction in canola microbial communities.

Harnessing the rhizospheric microbiome, including phosphorus mineralizing bacteria (PMB), is a promising technique for maintaining sustainability and productivity in intensive agricultural systems. However, it is unclear as to which beneficial taxonomic group populations in the rhizosphere are potentially associated with the changes in soil microbiomes shifted by fertilization regimes. Herein, we analyzed the diversity and community structure of total bacteria and PMB in the rhizosphere of maize (Zea mays L.) grown in soils under 25 years of four fertilization regimes (compost, biocompost, chemical, or non-fertilized) via selective culture and Illumina sequencing of the 16S rRNA genes. Plant development explained more variations (29 and 13%, respectively) in the composition of total bacteria and PMB in the rhizosphere of maize than the different fertilization regimes. Among those genera enriched in the rhizosphere of maize, the relative abundances of Oceanobacillus, Bacillus, Achromobacter, Ensifer, Paracoccus, Ramlibacter, and Luteimonas were positively correlated with those in the bulk soil. The relative abundance of Paracoccus was significantly higher in soils fertilized by compost or biocompost than the other soils. Similar results were also observed for PMB affiliated with Ensifer, Bacillus, and Streptomyces. Although plant development was the major factor in shaping the rhizospheric microbiome of maize, fertilization regimes might have modified beneficial rhizospheric microbial taxa such as Bacillus and Ensifer.

A pineapple-banana rotation was studied as a model system to investigate the potential emergence of a fungal-mediated disease-suppression in a soil highly infested with the pathogen Fusarium oxysporum causing the banana wilt disease. By using both field and pot experiments, the pineapple-banana rotation system resulted in a significant decrease of the pathogen number and next-stubble banana disease incidence (P

Aim: This study was designed to screen and identify an antimicrobial peptide from rhizosphere soil. The study was further focused towards overexpression, purification and characterization of this antimicrobial peptide, and to functionally validate its efficiency and efficacy as an antimicrobial agent. Yet, the study was further aimed at corroborating structural and functional studies using biophysical tools. Background: Antimicrobial resistance is emerging as one of the top 10 global health crisis, it is multifaceted and the second largest cause of mortality. According to the World Health Organization (WHO), around the world, an estimated 700,000 people die each year from infection caused by antibiotic-resistant microbes. Antimicrobial peptides offer the best alternative to combat and overcome this crisis. In this manuscript, we report cloning, expression, purification and characterization of an antimicrobial peptide discovered from rhizosphere soil. Objective: Objectives of this study include construction, screening and identification of antimicrobial peptide from metagenome followed by its expression, purification and functional and biophysical investigation. Yet another objective of the study was to determine antimicrobial efficacy and efficiency as an antimicrobial peptide against MRSA strains. Methods: In this study, we used an array of molecular biology tools that include genetic engineering, PCR amplification, construction of an expression construct and NI-NTA based purification of the recombinant peptide. We have also carried out antimicrobial activity assay to determine MIC (minimum inhibitory concentration) and IC50 values of antimicrobial peptide. To establish the structural and functional relationship, circular dichroism, and both extrinsic and intrinsic fluorescence spectroscopy studies were carried out. Results: Screening of metagenomic library resulted in the identification of gene (~500bp) harbouring an open reading frame (ORF) consisting of 282 bp. Open reading frame identified in gene encodes an antimicrobial peptide which had shared ~95% sequence similarity with the antimicrobial peptide of Bacillus origin. Purification of recombinant protein using Ni-NTA column chromatography demonstrated a purified protein band of ~11 kDa on 14% SDS-PAGE, which is well corroborated to theoretical deduced molecular weight of peptide from its amino acids sequence. Interestingly, the peptide exhibited antimicrobial activity in a broad range of pH and temperature. MIC determined against gram positive Bacillus sp. was found to be 0.015mg/ml, whereas, in the case of gram negative E. coli, it was calculated to be 0.062mg/ml. The peptide exhibited IC50 values corresponding to ~0.25mg/ml against Bacillus and ~0.5 mg/ml against E. coli. Antimicrobial susceptibility assay performed against methicillin resistant Staphylococcus aureus strain ATCC 3412 and standard strain of Staphylococcus aureus ATCC 9144 revealed its strong inhibitory activity against MRSA, whereby we observed a ~16mm clearance zone at higher peptide concentrations ~2mg/ml (~181.8μM). Biophysical investigation carried out using Trp fluorescence, ANS fluorescence and circular dichroism spectroscopy further revealed conformational stability in its secondary and tertiary structure at a wide range of temperature and pH. Conclusion: Altogether, the peptide discovered from rhizosphere metagenome holds potential in inhibiting the growth of both gram positive and gram negative bacteria, and was equally effective in inhibiting the multidrug resistant pathogenic strains (MRSA).

Plants maintain beneficial mutualistic relationships with the mycobiont communities found in their rhizosphere, leading to an increase in plant productivity and health. In nutrient-depleted substrates like mine tailings, mycobiont inoculation is often recommended to help restore a successful plant cover. Our 15-week greenhouse experiment aimed to assess the individual effects of a dark septate endophyte (Phialocephala fortinii C.J.K. Wang & H.E. Wilcox #4 (KX611529)) and two Helotiales strains (Rhizoscyphus ericae (D.J. Read) W.Y. Zhuang & Korf #22 (EU221877) and Meliniomyces sp. #1 (KT275679)) on the growth of plane-leaved willow (Salix planifolia Pursh) cuttings on sterilized and unsterilized waste rock. Rhizoscyphus ericae increased shoot biomass of cuttings on sterilized waste rock, whereas Meliniomyces sp. had a positive effect on cuttings grown on unsterilized waste rock. However, P. fortinii strain had no effect on the survival rate, shoot production, and biomass production of S. planifolia cuttings. This study demonstrates that controlled inoculation with ecologically well-adapted mycobionts could promote plant establishment and productivity on abandoned waste rock and could be an efficient and integrated biotechnological approach for ecological restoration of Canadian mining boreal ecosystems.