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Fertilizer input is one of the effective forest management practices, which improves soil nutrients and microbial community compositions and promotes forest productivity. However, few studies have explored the response of rhizosphere soil microbial communities to various fertilization regimes across seasonal dynamics. Here, we collected the rhizosphere soil samples from Phoebe bournei plantations to investigate the response of community assemblages and microbial interactions of the soil microbiome to the short-term application of four typical fertilizer practices (including chemical fertilizer (CF), organic fertilizer (OF), compound microbial fertilizer (CMF), and no fertilizer control (CK)). The amendments of organic fertilizer and compound microbial fertilizer altered the composition of rhizosphere soil bacterial and fungal communities, respectively. The fertilization regime significantly affected bacterial diversity rather than fungal diversity, and rhizosphere fungi responded more sensitively than bacteria to season. Fertilization-induced fungal networks were more complex than bacterial networks. Stochastic processes governed both rhizosphere soil bacterial and fungal communities, and drift and dispersal limitation dominated soil fungal and bacterial communities, respectively. Collectively, these findings demonstrate contrasting responses to community assemblages and interactions of rhizosphere bacteria and fungi to fertilizer practices. The application of organic fertilization strengthens microbial interactions and changes the succession of key taxa in the rhizosphere habitat. Key points: • Fertilization altered the key taxa and microbial interaction • Organic fertilizer facilitated the turnover of rhizosphere microbial communities • Stochasticity governed soil fungal and bacterial community assembly [ABSTRACT FROM AUTHOR]

Phosphate-solubilizing bacteria (PSB) enhance plant phosphorus utilization through their ability to dissolve phosphorus. To address the low utilization of nitrogen, phosphorus, potassium, zinc, and selenium by tea plants in acidic, selenium-rich soils, the study aimed to investigate the impact of exogenous PSB on soil nutrients and the absorption of zinc and selenium by tea plants. Following the inoculation of potted Longjing and Huangjinya varieties with exogenous phosphorus-solubilizing bacteria, we determined the concentrations of AN, AP, AK, Zn, and Se in their rhizosphere soil, in addition to the Zn and Se contents in their aboveground and belowground parts. The results show that after respective treatment with the three PSB, the concentration of available P in the tea plant rhizosphere soil significantly increased, with PMS08 having the most pronounced effect. After the same treatment, In the rhizosphere soil of Longjing tea plants, the AN content increased by 26.47%, 18.41%, and 7.51%, respectively, relative to the control, while the AK content decreased in the rhizosphere soil of Huangjinya tea plants. Inoculation with the three PSB resulted in a greater content of available Se in both the aboveground and belowground parts of the two tea plants. After inoculation with PMS20, the available Zn content of the belowground parts of Longjing and Huangjinya tea plants respectively decreased by 13.42% and 15.69% in comparison with the control. Additionally, after inoculating Longjing tea plants with PSt09 and Huangjinya tea plants with PMS08, the content of available Zn in their belowground parts significantly decreased by 9.22% and 35.74%, respectively. Evidently, the inoculation with the three phosphorus-solubilizing bacteria is beneficial for the uptake of available P by tea plants, promoting the utilization and accumulation of available Se. However, the content of AN or AK in rhizosphere soil varies between different tea plant varieties inoculated with the same kind of phosphorus-solubilizing bacteria. Moreover, the content of available Zn in tea plants also differs, highlighting the need to further investigate the differential effects of phosphorus-solubilizing bacteria on different plant varieties. [ABSTRACT FROM AUTHOR]

Plant roots shape the rhizosphere microbiome, recruiting microbes with beneficial functions. While genetically engineered crops offer yield advantages, their impacts on rhizosphere microbial communities remain understudied. This study evaluated the effects of transgenic maize, alongside a non-transgenic counterpart, on rhizosphere bacterial and fungal community composition using 16S rRNA and ITS amplicon sequencing. Additionally, glyphosate was used to evaluate its impact on microbial assembly and the magnitude of its effect at various maize growth stages. The results showed that transgenic maize D105 line significantly increased bacterial alpha diversity but not fungal diversity. Beta diversity analysis showed clear separation between bacterial and fungal communities at higher glyphosate treatment. Specific bacterial taxa such as Pseudomonas and Sphingomonas were enriched, while fungal taxa such as Ascomycota, Lasiosphaeriaceae, Verticillium were differentially abundant in glyphosate treatments. LEfSe analysis identified distinct enrichment patterns of bacterial (Proteobacteria and Actinobacteria) and fungal taxa (Verticillium and Guehomyces) associated with the transgenic line and glyphosate levels. KEGG functional analysis suggested potential impacts on bacterial metabolic pathways and shifts in fungal trophic modes (saprotrophs, pathogens) within the rhizosphere microbiome. This research provides insights into the classification, functional relationships, and underlying mechanisms shaping microbial communities carrying insect resistance and glyphosate resistance traits. [ABSTRACT FROM AUTHOR]

Plants require adequate nutrients for growth and development, one of which is phosphorus (P). However, plants can only absorb P from the soil in the form of phosphate ions (H2PO4- and HPO42- ).The great challenge of providing dissolved or available P was answered by the discovery of Phosphate Solubilizing Bacteria (PSB). These microbes produce organic acids that can dissolve complex phosphate compounds and/or bind the cation of the ion (PO43- ) to release available P in the soil. The soil rhizosphere area has the potential for high microbial diversity because it provides a food source (exudate) released from plant roots. This study aims to determine the quality of PSB isolates from the cassava plantation ecosystem and the forest of IPB Dramaga Campus with the highest Phosphate Solubilization Index (PSI) at various P sources and pH variations and determine BPF isolates that are nonpathogenic to humans, animals, and plants. This study began with isolating PSB from the rhizosphere area, growing them on Pikovskaya selective media, macroscopic identification of colony morphology, selection of PSB colonies that produce halozone (clear zone), measuring PSI, and testing them on Pikovskaya media with various P sources and pH levels. The isolation results showed that there were 9 isolates, 2 of which were from forest stands and 7 from cassava plantations that produced halozone. Isolates 6P and 7P from forest stands have the highest IPF of 3.10 and 3.33, respectively. The PSB isolates can only produce halozone on P source media from Ca-P complexes with alkaline pH and soil pH conditions. Of the 9 selected isolates, 6 of them, namely isolates 1P, 3P, 4P, 6P, 7P, and 9P, were tested to be nonpathogenic to humans, animals, and plants cells. [ABSTRACT FROM AUTHOR]

The abiotic environment exerts strong effects on plant‐associated microbes, shaping their interactions with plants and resulting ecosystem processes. However, these abiotic effects on plant–microbe interactions are often highly specific and contingent on the abiotic driver or microbial group, requiring synthesis work describing general patterns and from this generate hypotheses and guide mechanistic work. To address this, we conducted a meta‐analysis of the effects of climate change‐related abiotic factors, namely warming, drought, and eCO2, on plant‐associated microbes distinguishing by microbial taxonomic or biological group (bacteria, fungi or virus) and the plant part where microbes are found or associated with (phyllosphere or rhizosphere). We found abiotic driver‐specific patterns, whereby drought significantly reduced microbial abundance, whereas warming and eCO2 had no significant effects. In addition, these abiotic effects were contingent on the microbial taxonomic group, with fungi being negatively affected by drought but positively affected by warming (eCO2 enrichment had no effect), whereas bacteria and viruses were not significantly affected by any factor. Likewise, rhizospheric microbes were negatively affected by drought but positively affected by warming (eCO2 enrichment had no effect), whereas phyllospheric microbes were not significantly affected by any factor. Collectively, these findings point to important implications for global change research by highlighting contrasting effects of climate change‐related abiotic drivers on plant‐associated microbes and the contingency of such effects on microbe life histories and the nature of their interactions with plants. [ABSTRACT FROM AUTHOR]

Intercropping is a traditional farming system that increases crop diversity to strengthen agroecosystem functions while decreasing chemical inputs and minimizing negative environmental effects of crop production. However, the effect of intercropping legume-cereal in enhancing nutrient uptake and use efficiency under low phosphorus (P) soils is poorly understood. Growth, nodulation, P uptake and use efficiency, and changes in inorganic P availability in the rhizosphere of intercropped species were thus investigated in a field experiment with durum wheat and chickpea either grown alone or intercropped. The results showed that both plant biomass and grain yield, and consequently, the amount of P uptake by intercropped durum wheat increased significantly (30%, 12%, and 46%, respectively) compared with sole cropping during the two seasons. P availability increased in the rhizosphere of the two species, either grown as sole crops or as intercrops, and was enhanced by intercropping. Moreover, total biomass, grain yield, and P uptake were significantly improved, as indicated by higher land equivalent ratio (LER > 1) in intercropping over sole cropping treatments. The increased biomass and grain yield for intercropped durum wheat were associated with the stimulation of P absorption and use efficiency. Furthermore, intercropped wheat was more competitive than their respective chickpea over two growing seasons. The results of this study suggest that changes in the intercropped chickpea rhizosphere may enhance plant growth, P uptake, and use efficiency of the intercropped wheat under low-P soils. [ABSTRACT FROM AUTHOR]

Rhizodeposition fuels carbon (C) and nutrient cycling in soil. However, changes in the dynamics of microbial growth on rhizodeposits with increasing distance from the root is not well studied. This study investigates microbial growth on individual organic components of rhizodeposits and maize root‐derived exudates and mucilage from agricultural soil. By creating a gradient of substrate concentrations, we simulated reduced microbial access to rhizosphere C with increasing distance to the root surface. We identified distinct C‐thresholds for the activation of microbial growth, and these were significantly higher for rhizodeposits than singular, simple sugars. In addition, testing for stoichiometric constraints of microbial growth by supplementing nitrogen (N) and phosphorus (P) showed accelerated and increased microbial growth by activating a larger proportion of the microbial biomass. Early and late season exudates triggered significantly different microbial growth responses. The mineralization of early‐season exudates was induced at a high C‐threshold. In contrast, the mineralization of late‐season exudates showed 'sugar‐like' properties, with a low C‐threshold, high substrate affinity, and a reduced maximum respiration rate of microorganisms growing on the added substrate. Mucilage exhibited the highest C‐threshold for the activation of microbial growth, although with a short lag‐period and with an efficient mucilage degradation comparable to that of sugars. By determining kinetic parameters and turnover times for different root‐derived substrates, our data enable the upscaling of micro‐scale processes to the whole root system, allowing more accurate predictions of how rhizodeposition drives microbial C and nutrient dynamics in the soil. [ABSTRACT FROM AUTHOR]

Background: Urea fertilizer and MCPA herbicide are widely used agrochemicals in pastures. Even though urea hydrolysis impacts soil pH, potentially affecting MCPA dissipation, little is known about the effects of their co-application into the rhizosphere. Hence, we aimed to analyze the dynamics of urea transformation and MCPA dissipation when both are co-applied to the soil. Methods: A greenhouse experiment was conducted with a planted control and treatments incorporating urea and/or MCPA. Subsequently, pH changes, urea transformation into N-NH4+ and N-NO3−, the enzymatic activity of urease and dehydrogenase, and MCPA dissipation were monitored for 30 d. Results: Urea application induced a significant (p < 0.05) pH change, production of N-NH4+ (from 50 and 250 mg kg−1) and N-NO3− (from 206 to 347 mg kg−1), and urease (from 12 to 35 µmol N-NH4+g−1 h−1) and dehydrogenase (from 0.5 to 2.5 mg TPF g−1 h−1) activities. Urea also decelerated MCPA dissipation in the latter half of the experiment, whereas MCPA reduced urease activity when urea and herbicide were co-applied. Conclusions: Urea was the primary factor modifying the properties of the rhizosphere by stimulating the activity of microbial enzymes, shaping the pH changes during its mineralization, and decelerating MCPA dissipation. MCPA did not reduce urea mineralization but slowed urease activity, constituting an insight that requires further study. [ABSTRACT FROM AUTHOR]

Glomus mongioiense, a new species of arbuscular mycorrhizal fungi (AMF) in the family Glomeraceae, was isolated from rhizosphere soil collected from a meadow in the Italian Alps. The novelty of the species and its relationship with other species of the same genus were obtained by morphological and phylogenetic (45S nrDNA + RPB1 gene) analyses. Two glomoid spore-producing AMF isolates from a saltmarsh of the Scottish Highlands and maritime sand dunes of the Baltic Sea in Poland, were also included in this study and later found to be conspecific with G. rugosae. Phylogenetic placement analysis using environmental sequences indicated that G. mongioiense sp. nov. seems to be a rare species. Furthermore, the molecular and phylogenetic analysis provided important insights into the presence of highly divergent ribosomal variants in several Glomus species, with potential negative implication in phylogeny and species recognition. [ABSTRACT FROM AUTHOR]

The dynamics of the physiological adaptability of plants and the rhizosphere soil environment after waterlogging remain unclear. Here we investigated the mechanisms regulating plant condition and shaping of the rhizosphere microbiome in a pot experiment. In the experiment, we added melatonin to waterlogged plants, which promoted waterlogging relief. The treatment significantly enhanced photosynthesis and the antioxidant capacity of apple plants, and significantly promoted nitrogen (N) utilization efficiency by upregulating genes related to N transport and metabolism. Multiperiod soil microbiome analysis showed the dynamic effects of melatonin on the diversity of the microbial community during waterlogging recovery. Random forest and linear regression analyses were used to screen for potential beneficial bacteria (e.g., Azoarcus, Pseudomonas and Nocardioides) specifically regulated by melatonin and revealed a positive correlation with soil nutrient levels and plant growth. Furthermore, metagenomic analyses revealed the regulatory effects of melatonin on genes involved in N cycling in soil. Melatonin positively contributed to the accumulation of plant dry weight by upregulating the expression of nifD and nifK (N fixation). In summary, melatonin positively regulates physiological functions in plants and the structure and function of the microbial community; it promoted the recovery of apple plants after waterlogging stress. Summary Statement: The application of melatonin to waterlogged plants significantly enhanced photosynthesis and antioxidant capacity, promoted nitrogen utilization efficiency and regulated the diversity and function of the rhizosphere microbial community, ultimately facilitating the recovery of apple plants after waterlogging stress. [ABSTRACT FROM AUTHOR]

A holistic understanding of plant strategies to acquire soil resources is pivotal in achieving sustainable food security. However, we lack knowledge about variety‐specific root and rhizosphere traits for resource acquisition, their plasticity and adaptation to drought. We conducted a greenhouse experiment to phenotype root and rhizosphere traits (mean root diameter [Root D], specific root length [SRL], root tissue density, root nitrogen content, specific rhizosheath mass [SRM], arbuscular mycorrhizal fungi [AMF] colonization) of 16 landraces and 22 modern cultivars of temperate maize (Zea mays L.). Our results demonstrate that landraces and modern cultivars diverge in their root and rhizosphere traits. Although landraces follow a 'do‐it‐yourself' strategy with high SRLs, modern cultivars exhibit an 'outsourcing' strategy with increased mean Root Ds and a tendency towards increased root colonization by AMF. We further identified that SRM indicates an 'outsourcing' strategy. Additionally, landraces were more drought‐responsive compared to modern cultivars based on multitrait response indices. We suggest that breeding leads to distinct resource acquisition strategies between temperate maize varieties. Future breeding efforts should increasingly target root and rhizosphere economics, with SRM serving as a valuable proxy for identifying varieties employing an outsourcing resource acquisition strategy. Summary statement: This study provides novel insights into the diversity of soil resource acquisition strategies within a single plant species. By comparing landraces and modern cultivars of maize and considering plant‐soil‐microbe interactions, we reveal functional differences in root and rhizosphere economics and trait plasticity that shed light on their ecological role and breeding relevance. [ABSTRACT FROM AUTHOR]

Aims Climate change is endangering olive groves. Farmers are adapting by exploring new varieties of olive trees and examining the role of microbiomes in plant health. The main objectives of this work were to determine the primary factors that influence the microbiome of olive trees and to analyze the connection between the rhizosphere and endosphere compartments. Methods and Results The rhizosphere and xylem sap microbiomes of two olive tree varieties were characterized by next-generation 16S rRNA amplicon sequencing, and soil descriptors were analyzed. Bacterial communities in the rhizosphere of olive trees were more diverse than those found in the xylem sap. Pseudomonadota, Actinobacteriota, Acidobacteriota, and Bacillota were the dominant phyla in both compartments. At the genus level, only very few taxa were shared between soil and sap bacterial communities. Conclusions The composition of the bacteriome was more affected by the plant compartment than by the olive cultivar or soil properties, and a direct route from the rhizosphere to the endosphere could not be confirmed. The large number of plant growth-promoting bacteria found in both compartments provides promising prospects for improving agricultural outcomes through microbiome engineering. [ABSTRACT FROM AUTHOR]

Aims This study explores the potential of cadmium (Cd)-resistant bacteria, specifically Bacillus megaterium A14, to decrease Cd accumulation in peanuts, a crop susceptible to metal uptake from contaminated soils, by understanding the bacterium's impact on plant Cd absorption mechanisms. Methods and Results Through pot experiments, we observed that A14 inoculation significantly increased peanut biomass under Cd stress conditions, primarily by immobilizing the metal and reducing its bioavailability. The bacterium effectively changed the distribution of Cd, with a notable 46.53% reduction in the exchangeable fraction, which in turn limited the expression of genes related to Cd transport in peanuts. Additionally, A14 enhanced the plant's antioxidant response, improving its tolerance to stress. Microbial analysis through 16S sequencing demonstrated that A14 inoculation altered the peanut rhizosphere, particularly by increasing populations of Firmicutes and Proteobacteria, which play crucial roles in soil remediation from heavy metals. Conclusion The A14 strain effectively counters Cd toxicity in peanuts, promoting growth through soil Cd sequestration, root barrier biofilm formation, antioxidant system enhancement, suppression of Cd transport genes, and facilitation of Cd-remediating microorganisms. [ABSTRACT FROM AUTHOR]

Xinmai26(XM) with weak resistance to late spring coldness. 4°C(T1) and -4°C(T2) low temperature stress treatment were carried out in intelligent ultra-low temperature incubator during the anther differentiation period of young wheat spike differentiation, and 15°C was used as control group(CK). High-throughput sequencing technology was used to determine the bacterial community in wheat rhizosphere soil, and to analyze the effects of late spring coldness during the anther differentiation period on the diversity and community structures of wheat rhizosphere bacteria. The results showed that: (1) late spring coldness decreased the ACE index of bacteria in rhizosphere soil of the two wheat varieties, and the ACE index of the variety XM with weak resistance to late spring coldness was significantly affected (P<0.05). (2) The bacterial community in rhizosphere soil of the two wheat varieties were mainly composed of 33 phyla and 819 genera, including Proteobacteria(53.20%-57.55%), Actinobacteria (13.34%-21.69%), Bacteroidetes(10.56%-12.37%), Gemmatimonadetes(6.17%-9.19%). The relative abundance of various bacterial phyla showed differences among different degrees of late spring coldness treatment. Late spring coldness increased the relative abundance of Actinobacte by 9.79%-19.11% in YN, and decreased by 26.43% -38.47% in XM. (3) Function prediction analysis indicated that that late spring coldness during the anther differentiation period increased the gene abundance of membrane transport, amino acid metabolism, carbohydrate metabolism, replication and repair in YN rhizosphere soil, and decreased their gene abundances in XM rhizosphere soil. In conclusion, late spring coldness during the anther differentiation period reduced the richness of the bacterial community in the wheat rhizosphere soil, changed the bacterial community structure, and affected the membrane transport, amino acid metabolism, carbohydrate metabolism, and replication and repair functions of the bacterial community. [ABSTRACT FROM AUTHOR]

Methanogenic and methanotrophic microbes together determine the net methane flux from rice fields. Despite much research on them as separate communities, there has been little study of combined community patterns, and how these vary between the rhizoplane (root surface), rhizosphere (soil surrounding the root) and bulk soil around rice plants, especially at larger spatial scale. We collected samples from 32 geographically scattered rice fields in east central China, amplicon targeting the mcrA gene for methanogenesis and pmoA gene for methanotrophy by using high‐throughput sequencing. Distinct communities of both methanogens and methanotrophs occurred in each of the three compartments, and predominantly positive links were found between methanogens and methanotrophs in all compartments indicating cross‐feeding or consortia relationships. Methanogens were acting as the network hub in the bulk soil, and methanotrophs in rhizoplane. Network complexity and stability was greater in the rhizosphere than rhizoplane and bulk soil, with no network hubs detected, suggesting the strongest effect of homeostatic influence by plant occurred in the rhizosphere. The proportion of determinism (homogeneous selection) and distance–decay relation (DDR) in rhizoplane was consistently lower than that in the rhizosphere for both communities, indicating weaker phylogenetic clustering in rice root surface. Our results have provided a better understanding of CH4 oxidation and emission in rice paddy fields and future agriculture management could take into consideration of the subtle variation among different soil compartments and interactions within methanogenic and methanotrophic communities. [ABSTRACT FROM AUTHOR]

Background and Aims: Climate change is happening and causing severe impact on the sustainability of agroecosystems. We argue that many of the abiotic stresses associated with climate change will be most acutely perceived by the plant at the root-soil interface and are likely to be mitigated at this globally important interface. In this review we will focus on the direct impacts of climate change, temperature, drought and pCO2, on roots and rhizospheres. Methods and Results: We consider which belowground traits will be impacted and discuss the potential for monitoring and quantifying these traits for modelling and breeding programs. We discuss the specific impacts of combined stress and the role of the microbial communities populating the root-soil interface, collectively referred to as the rhizosphere microbiota, in interactions with roots under stress and discuss the plastic responses to stress as a way of adapting plants to climate change. We then go on to discuss the role that modelling has in understanding this complex problem and suggest the best belowground targets for adaptation and mitigation to climate change. We finish by considering where the main uncertainties lie, providing perspective on where research is needed. Conclusion: This review therefore focuses on the potential of roots and rhizosphere to adapt to climate change effects and to mitigate their negative impacts on plant growth, crop productivity, soil health and ecosystem services. [ABSTRACT FROM AUTHOR]

Aims: Our understanding of the rhizosphere is limited by the lack of techniques for in situ live microscopy. Current techniques are either destructive or unsuitable for observing chemical changes within the pore space. To address this limitation, we have developed artificial substrates, termed smart soils, that enable the acquisition and 3D reconstruction of chemical sensors attached to soil particles. Methods: The transparency of smart soils was achieved using polymer particles with refractive index matching that of water. The surface of the particles was modified both to retain water and act as a local sensor to report on pore space pH via fluorescence emissions. Multispectral signals were acquired from the particles using a light sheet microscope, and machine learning algorithms predicted the changes and spatial distribution in pH at the surface of the smart soil particles. Results: The technique was able to predict pH live and in situ within ± 0.5 units of the true pH value. pH distribution could be reconstructed across a volume of several cubic centimetres around plant roots at 10 μm resolution. Using smart soils of different composition, we revealed how root exudation and pore structure create variability in chemical properties. Conclusion: Smart soils captured the pH gradients forming around a growing plant root. Future developments of the technology could include the fine tuning of soil physicochemical properties, the addition of chemical sensors and improved data processing. Hence, this technology could play a critical role in advancing our understanding of complex rhizosphere processes. [ABSTRACT FROM AUTHOR]

Aims: Inoculation with climate-adapted rhizobia is able to increase legume productivity in drought-prone regions of Sub-Saharan Africa. Enhanced nodulation might additionally affect plant-soil interactions and control rhizosphere carbon (C) and nitrogen (N) pools. Methods: We investigated inoculation effects on nodulation and biological N2 fixation (BNF) of Vigna unguiculata and consequent effects on C and N pools in two Namibian soils. Three treatments (Bradyrhizobium sp.1–7 inoculant, non-inoculated, N-fertilised with 50 kg N ha−1) were applied in rhizoboxes at 45% and 20% maximum water holding capacity. Nodule development was photo-documented, and rhizobia-DNA sequences were identified. BNF was assessed by δ15N enrichment, and organic C and N pools were analysed in bulk and root adherent soil. Results: Plant growth initially enhanced mineral N losses from the rhizosphere at flowering stage (6 weeks growth), but led to a re-increase of N, and organic C contents after ripening (10 weeks). Inoculation had no effect on nodulation and soil C and N pools, indicating that both soils contained sufficient indigenous rhizobia to allow effective nodulation. However, the inoculant strain was more competitive in establishing itself in the root nodules, depending on the local conditions, showing a need for regional adjustment of inoculation strategies. Conclusion: Water stress was the main limitation for nodulation and, in combination with soil type, substantially affected rhizosphere and bulk soil C and N contents. The temporally enhanced rhizodeposition after ripening could be able to maintain soil C and N pools after legume cultivation. [ABSTRACT FROM AUTHOR]

Aims: Rhizosphere is a hotspot for soil C and N biogeochemical cycling in terrestrial ecosystems. However, the interaction between soil C and N mineralization remain poorly understood in the rhizosphere soils. This study aimed to identify interactions between soil C and N mineralization in rhizosphere soils and bulk soils at a large scale. Methods: We used the "soil adhering to fine roots after shaking" method to collect paired rhizosphere soils and bulk soils along an altitudinal forest gradient. Soil C mineralization rates (Cmin) and net N mineralization rates (Nmin) were determined with laboratory incubation. Results: We found a significantly positive relationship between Cmin and Nmin in the rhizosphere soils across sites, whereas Cmin was not correlated with Nmin in the bulk soils. Furthermore, soil properties, microbial biomass C (MBC) and extracellular enzyme activities showed substantial paths affecting Cmin and Nmin using structural equation model. The coupling of Cmin and Nmin in rhizosphere soils could be triggered by root-soil interactions, resulting in the higher level of MBC, total organic C of soil, total N of soil, and extracellular enzyme activities. By contrast, the decoupling of Cmin and Nmin in the bulk soils might be attributed to the lower level of MBC and extracellular enzyme activities. Conclusions: Our results demonstrated that soil C and N mineralization coupled in the rhizosphere rather than in the bulk soils. These results suggest that the interaction between soil C and N cycling in rhizosphere are likely to differ from that in bulk soil. [ABSTRACT FROM AUTHOR]

Drought presents a significant abiotic stress that threatens crop productivity worldwide. Rhizosphere bacteria play pivotal roles in modulating plant growth and resilience to environmental stresses. Despite this, the extent to which rhizosphere bacteria are instrumental in plant responses to drought, and whether distinct cassava (Manihot esculenta Crantz) varieties harbor specific rhizosphere bacterial assemblages, remains unclear. In this study, we measured the growth and physiological characteristics, as well as the physical and chemical properties of the rhizosphere soil of drought-tolerant (SC124) and drought-sensitive (SC8) cassava varieties under conditions of both well-watered and drought stress. Employing 16S rDNA high-throughput sequencing, we analyzed the composition and dynamics of the rhizosphere bacterial community. Under drought stress, biomass, plant height, stem diameter, quantum efficiency of photosystem II (Fv/Fm), and soluble sugar of cassava decreased for both SC8 and SC124. The two varieties' rhizosphere bacterial communities' overall taxonomic structure was highly similar, but there were slight differences in relative abundance. SC124 mainly relied on Gamma-proteobacteria and Acidobacteriae in response to drought stress, and the abundance of this class was positively correlated with soil acid phosphatase. SC8 mainly relied on Actinobacteria in response to drought stress, and the abundance of this class was positively correlated with soil urease and soil saccharase. Overall, this study confirmed the key role of drought-induced rhizosphere bacteria in improving the adaptation of cassava to drought stress and clarified that this process is significantly related to variety. [ABSTRACT FROM AUTHOR]

Emerging scientific evidence has shown that root exudates may trigger the mobilization of soil organic matter (SOM), particularly under nutrient limitation. However, the role of changes in root morphology, metabolism, exudation, and their impact on rhizospheric properties and SOM remain poorly known. To address this issue, we conducted a rhizobox experiment for 50 days in which pre-grown eucalypt plants (120 days-old) were supplied with nutrient solutions providing either limited (0.0 mg L− 1) or normal N supply (196.0 mg L− 1). After 48 days, we used a 13CO2 pulse labeling to track the impact of N limitation on C translocation to roots and soil respiration. After the 50th day, we assessed root morphology and metabolism, rhizospheric pH, mineral crystallinity, C and N contents, and the molecular composition of SOM. Under N limitation, eucalypt plants showed reduced photosynthesis, increased their root-to-shoot ratio and root branching, with organic acids prevailing among root metabolites. Overall, N-limited eucalypt plants led to a cascading of changes in the rhizosphere: increased concentrations of recently fixed 13C-CO2, citrate, and N-bearing compounds, whereas soil pH and Fe-bound SOM decreased. These results were not followed by significant changes in microbial biomass, neither fungi: bacteria nor Gram-positive: Gram-negative ratios. Our results show that under N limitation, eucalypt roots exhibited a cascade of morpho-physiological adjustments that ultimately increased the mobilization of some SOM pools. Therefore, the combined impacts of those root morpho-physiological traits on the mobilization of SOM may reduce the overall soil C sink of eucalypt forests under N limitation. [ABSTRACT FROM AUTHOR]

Nitrogen (N) is a crucial nutrient for the growth and activity of rhizosphere microorganisms, particularly during drought conditions. Plant root-secreted mucilage contains N that could potentially nourish rhizosphere microbial communities. However, there remains a significant gap in understanding mucilage N content, its source, and its utilization by microorganisms under drought stress. In this study, we investigated the impact of four maize varieties (DH02 and DH04 from Kenya, and Kentos and Keops from Germany) on the secretion rates of mucilage from aerial roots and explored the origin of mucilage N supporting microbial life in the rhizosphere. We found that DH02 exhibited a 96% higher mucilage secretion rate compared to Kentos, while Keops showed 114% and 89% higher secretion rates compared to Kentos and DH04, respectively. On average, the four maize varieties released 4 μg N per root tip per day, representing 2% of total mucilage secretion. Notably, the natural abundance of 15N isotopes increased (higher δ15N signature) with mucilage N release. This indicates a potential dilution of the isotopic signal from biological fixation of atmospheric N by mucilage-inhabiting bacteria as mucilage secretion rates increase. We proposed a model linking mucilage secretion to a mixture of isotopic signatures and estimated that biological N fixation may contribute to 45 - 75% of mucilage N per root tip. The N content of mucilage from a single maize root tip can support a bacterial population ranging from 107 to 1010 cells per day. In conclusion, mucilage serves as a significant N-rich resource for microbial communities in the rhizosphere during drought conditions. [ABSTRACT FROM AUTHOR]

Leguminous shade trees are ubiquitous parts of tea plantations of the Terai region. However, their shed leaves might have an effect on the soil microflora under those shade trees, so it is important to find out how leaf litter affect the soil microflora. Isolation of soil microbial consortia followed by downstream experiments were conducted to observe the tolerance/susceptible pattern of those soil microflora against the fallen leaves. Sample from under Albizia odoratissima has higher organic carbon, organic matter and nitrogen content but the same property was found to be low in the sample collected under Melia azedarach. Isolation of consortia was done on nutrient agar. In vitro tolerance assay was conducted to find out the tolerance pattern against leaf extracts, heavy metal salts, pesticides, antibiotics and antifungals. Heavy metals salts like Arsenic trioxide (AS2O3) and Cupric chloride (CuCl2); and pesticides like Thiamethoxam; Spiromesifen; Phorate etc. showed no inhibition against all the isolated consortia. Co-Trimoxazole and Augmentin have not showed any inhibition except consortia under Derris robusta, whereas no antifungals but Itraconazole had an impact over all the consortia. Shade trees, being a crucial member of the tea plantations, cannot be removed but replacement of these with other species could be a probable option, besides this limited use of chemical pesticides and fertilizers should be taken into consideration strictly to restrain the microbial population in tea garden soil. So, this study has disclosed the acceptability of each and every shade tree used in this region. [ABSTRACT FROM AUTHOR]

DNA barcodes can provide accurate identification of plants. We used previously reported DNA primers targeting the internal transcribed spacer (ITS1) region of the nuclear ribosomal cistron, internal transcribed spacer (ITS2), and chloroplast trnL (UAA) intron to identify four trees at Bergen Community College. Two of the four trees were identified as Acer rubrum and Fagus sylvatica. However, Quercus was only identified at the genus level, and the fourth tree did not show similar identification between barcodes. Next-generation sequencing of 16S rRNA genes showed that the predominant bacterial communities in the rhizosphere mainly consisted of the Pseudomonadota, Actinomycetota, Bacteroidota, and Acidobacteriota. A. rubrum showed the most diverse bacterial community while F. sylvatica was less diverse. The genus Rhodoplanes showed the highest relative bacterial abundance in all trees. Fungal ITS sequence analysis demonstrated that the communities predominantly consisted of the Ascomycota and Basidiomycota. Quercus showed the highest fungi diversity while F. sylvatica showed the lowest. Russula showed the highest abundance of fungi genera. Average similarity values in the rhizosphere for fungi communities at the phylum level were higher than for bacteria. However, at the genus level, bacterial communities showed higher similarities than fungi. Similarity values decreased at lower taxonomical levels for both bacteria and fungi, indicating each tree has selected for specific bacterial and fungal communities. This study confirmed the distinctiveness of the microbial communities in the rhizosphere of each tree and their importance in sustaining and supporting viability and growth but also demonstrating the limitations of DNA barcoding with the primers used in this study to identify genus and species for some of the trees. The optimization of DNA barcoding will require additional DNA sequences to enhance the resolution and identification of trees at the study site. [ABSTRACT FROM AUTHOR]

One strategy to improve olive (Olea europaea) tree drought tolerance is through the symbiosis of arbuscular mycorrhizal fungi (AMF), which helps alleviate water deficit through a combination of morphophysiological effects. Cuttings of olive varieties Arbequina (A) and Barnea (B) were grown with (+AMF) or without (−AMF) inoculum in the olive grove rhizosphere soil. One year after establishment, pots were exposed to four different water regimes: (1) control (100% of crop evapotranspiration); (2) short-period drought (20 days); (3) long-period drought (25 days); and (4) rewatering (R). To evaluate the influence of AMF on tolerance to water stress, stem water potential, stomatal conductance and the biomarkers for water deficit malondialdehyde, proline, soluble sugars, phenols, and flavonoids were evaluated at the end of the irrigation regimes. Stem water potential showed higher values in A(+) and B(+) in all water conditions, and the opposite was true for stomatal conductance. For proline and soluble sugars, the stem water potential trend is repeated with some exceptions. AMF inoculum spore communities from A(+ and −) and B(+ and −) were characterised at the morphospecies level in terms of richness and abundance. Certain morphospecies were identified as potential drought indicators. These results highlight that the benefits of symbiotic relationships between olive and native AMF can help to mitigate the effects of abiotic stress in soils affected by drought. We evaluated different water regimes on young cuttings of olive (Olea europaea) cvs Arbequina and Barnea inoculated with or without arbuscular mycorrhizal fungi (AMF) in a central-western olive grove in Argentina. We measured AMF morphospecies richness and abundance in the soil, plant vegetative growth, plant adaptation to drought stress, and crop water status. We found that certain morphological, physiological and biochemicalindicators may be useful to identify new strategies to mitigate water stress and improve water use efficiency during transplantation. [ABSTRACT FROM AUTHOR]

Methane (CH4) emissions from wetland ecosystems are controlled by redox conditions in the soil, which are currently underrepresented in Earth system models. Plant-mediated radial oxygen loss (ROL) can increase soil O2 availability, affect local redox conditions, and cause heterogeneous distribution of redox-sensitive chemical species at the root scale, which would affect CH4 emissions integrated over larger scales. In this study, we used a subsurface geochemical simulator (PFLOTRAN) to quantify the effects of incorporating either spatially homogeneous ROL or more complex heterogeneous ROL on model predictions of porewater solute concentration depth profiles (dissolved organic carbon, methane, sulfate, sulfide) and column integrated CH4 fluxes for a tidal coastal wetland. From the heterogeneous ROL simulation, we obtained 18% higher column averaged CH4 concentration at the rooting zone but 5% lower total CH4 flux compared to simulations of the homogeneous ROL or without ROL. This difference is because lower CH4 concentrations occurred in the same rhizosphere volume that was directly connected with plant-mediated transport of CH4 from the rooting zone to the atmosphere. Sensitivity analysis indicated that the impacts of heterogeneous ROL on model predictions of porewater oxygen and sulfide concentrations will be more important under conditions of higher ROL fluxes or more heterogeneous root distribution (lower root densities). Despite the small impact on predicted CH4 emissions, the simulated ROL drastically reduced porewater concentrations of sulfide, an effective phytotoxin, indicating that incorporating ROL combined with sulfur cycling into ecosystem models could potentially improve predictions of plant productivity in coastal wetland ecosystems. [ABSTRACT FROM AUTHOR]

[Objective] The diversity and composition of rhizosphere fungal communities of two typical plants (Dacrydium pectinatum and Vatica mangachapoi) in tropical rain forest were studied, which provided scientific basis for biodiversity protection of rare and endangered species in tropical rain forest ecosystem. [Method] The composition, diversity and function of fungal communities in the rhizosphere of D. pectinatum and V. mangachapoi in Hainan tropical rain forest were analyzed by Illumina Miseq high-throughput sequencing. [Result] Basidiomycota and Ascomycota were the dominant phyla among different niches in the rhizosphere. PCoA results showed that compared with niche, species had more influence on the fungal community structure of D. pectinatum and V. mangachapoi and had different effects on different niches in the rhizosphere (rhizosphere: R=0. 1983, P=0.007; rhizoplane: R=0. 2622, P=0.004; endosphere: R=0.7342, P = 0.001). At the OTU level, there was no significant difference in fungal community a diversity between D. pectinatum and V. mangachapoi, but there were significant differences in rhizoplane and endosphere fungal community a diversity of the same tree species (P <0.05), and the a diversity of endosphere fungal community was the lowest compared with other niches. The results of CCA analysis showed that pH and ammonia nitrogen (AN) were important environmental factors affecting the fungal community structure in the rhizosphere of the two tree species. The results of FUNGuild function prediction showed that Ectomycorrhizal-Undefined Saprotroph, Ectomycorrhizal, Undefined Saprotroph and Fungal Parasite-Undefined Saprotroph were the main functional groups, and there were differences among different tree species. [Conclusion] Plant species significantly affect the composition of rhizosphere fungal communities, but niche is an important factor affecting fungal community diversity in small-scale regions. pH and AN are important environmental factors driving the difference of fungal community composition in rhizosphere between D. pectinatum and V. mangachapoi. [ABSTRACT FROM AUTHOR]

[Objective] The paper aimed to explore the interaction between rhizosphere soil fungi and different tobacco varieties, and reveal significant differences in species among different varieties of diseased rhizosphere soil fungi, as to provide reference for the study of resistance mechanism of tobacco varieties and biological pest control. [Method] Illumina MiSeq high-throughput sequencing technology was used to analyze the composition and diversity of fungal community in rhizosphere soil of diseased plants of 8 tobacco varieties in Yunnan province, [Result] The OTU abundance of fungi in diseased rhizosphere soil of different varieties ranged from 822 to 1126. There were significant differences in the diversity and richness index of rhizosphere soil fungi among different varieties, and varieties K326, Yun 105, Yun 87 and Yun 99 were significantly higher than other varieties. At phylum level, the dominant fungi in the diseased thizusphere soil of each variety were Ascomycota, Mortierellomycota and Basidiomycota. At the genus level, Microidium, Fusarium, Humicola, Mortierella and Alternaria were the dominant genera in each treatment group. The significant difference analysis of LEFSe showed that Humicola, Candida, Plectosphaerella, Alternaria, Papulaspora, Fusarium, Boeremia, Mortierella, Gibberella were the important significantly different species in the diseased rhizosphere soil of different varieties. [Conclusion] There are significant differences in fungal community structure and diversity in rhizosphere soil of different varieties, and the distribution of significantly different species is related to the resistance of varieties. Among the varieties with high resistance to black shank disease (Yun 97, K326, Yun 100 and Yun 87), beneficial bacteria are mainly present, while in susceptible and moderately resistant varieties (Hongda, Yun 105, Yun 116 and Yun 99), harmful bacterial groups such as pathogenic bacteria are clustered. [ABSTRACT FROM AUTHOR]

The article presents a study on the physico-chemical characteristics of rhizosphere saline soil of Chenopodium album L from Baramati Tehsil, District in Pune, India. Topics discussed include reason that salinity reduced agricultural productivity, locality of studied sites, and finding on rhizosphere of Chenopodium album.

Increased nitrogen deposition is a key feature of global climate change, however, its effects on the structure and assembling mechanisms of the nitrogen-fixing bacteria present at the root surface remain to be elucidated. In this pursuit, we used NH4NO3 to simulate nitrogen deposition in a 10-year-old Camellia oleifera plantation, and set up four deposition treatments, including control N0 (0 kg N hm-2 a-1), low nitrogen N20 (20 kg N hm-2 a-1), medium nitrogen N40 (40 kg N hm-2 a-1) and high nitrogen N160 (160 kg N hm-2 a-1). The results showed that nitrogen deposition affected the soil nitrogen content and the structure of the nitrogen-fixing bacterial community. Low nitrogen deposition was conducive for nitrogen fixation in mature C. oleifera plantation. With increasing nitrogen deposition, the dominant soil nitrogen-fixing bacterial community shifted from Desulfobulbaceae to Bradyrhizobium. When nitrogen deposition was below 160 kg N hm-2 a-1, the soil organic matter content, total nitrogen content, nitrate nitrogen content, ammonium nitrogen content, urease activity, soil pH and nitrate reductase activity influenced the composition of the nitrogen-fixing bacterial community, but the stochastic process remained the dominant factor. The results indicate that the strains of Bradyrhizobium japonicum and Bradyrhizobium sp. ORS 285 can be used as indicator species for excessive nitrogen deposition. [ABSTRACT FROM AUTHOR]

Phosphorus constitutes a crucial macronutrient for crop growth, yet its availability often limits food production. Efficient phosphorus management is crucial for enhancing crop yields and ensuring food security. This study aimed to enhance the efficiency of a short-chain polyphosphate (PolyP) fertilizer by integrating it with plant growth-promoting bacteria (PGPB) to improve nutrient solubilization and wheat growth. Specifically, the study investigated the effects of various bacterial strains on wheat germination and growth when used in conjunction with PolyP. To achieve this, a greenhouse experiment was conducted in which the wheat rhizosphere was amended with a short-chain PolyP fertilizer. Based on the morphological aspect, eight bacteria, designated P1 to P8, were isolated and further characterized. Plant growth-promoting traits were observed in all bacterial strains, as they presented the ability to produce Indole Acetic Acid (IAA) in significant amounts ranging from 7.5 ± 0.3 µg/mL to 44.1 ± 2 µg/mL, expressed by B. tropicus P4 and P. soyae P1, respectively. They also produced ammonia, hydrogen cyanide (HCN), and siderophores. Their effect against the plant pathogen Fusarium culmorum was also assessed, with P. reinekei P2 demonstrating the highest biocontrol activity as it presented a total inhibitory effect. Additionally, some strains exhibited the ability to solubilize/hydrolyze phosphorus, potassium, and zinc. In vivo, the initial growth potential of wheat seeds indicated that those inoculated with the isolated strains exhibited elevated germination rates and enhanced root growth. Based on their plant growth-promoting traits and performance in the germination assay, three strains were selected for producing the best results, specifically phosphorus hydrolyzation/solubilization, zinc solubilization, IAA production, HCN, and siderophores production. Wheat seeds were inoculated by drenching in a bacterial suspension containing 1010 CFU/mL of log phase culture, and an in planta bioassay was conducted in a growth chamber using three selected strains (Pseudomonas soyae P1, Pseudomonas reinekei P2, and Bacillus tropicus P4), applied either individually or with PolyP on a P-deficient soil (28 mg/kg of P Olsen). Our findings demonstrated that the combination of Pseudomonas soyae P1 and PolyP achieved the highest shoot biomass, averaging 41.99 ± 0.87 g. Notably, applying P. soyae P1 or Bacillus tropicus P4 alone yielded similar results to the use of PolyP alone. At the heading growth stage, the combination of Bacillus tropicus P4 and PolyP significantly increased the Chlorophyll Content Index (CCI) to 37.02 µmol/m2, outperforming both PolyP alone (24.07 µmol/m2) and the control (23.06 µmol/m2). This study presents an innovative approach combining short-chain PolyP with bacterial biostimulants to enhance nutrient availability and plant growth. By identifying and characterizing effective bacterial strains, it offers a sustainable alternative to conventional fertilizers. [ABSTRACT FROM AUTHOR]

Seawater intrusion has a significant impact on the irrigation quality of agricultural water, thereby posing a threat to plant growth and development. We hypothesized that the rhizosphere of tea plants harbors beneficial microorganisms, which may improve the tolerance of tea plants to seawater stress. This study utilized 16s and ITS techniques to analyze microbial community shifts in the tea plant rhizosphere and non-rhizosphere under seawater stress conditions. The findings suggest that seawater stress leads to a reduction in microbial diversity, although the rhizosphere microbial diversity in stressed soils showed a relatively higher level. Moreover, the rhizosphere of the tea plant under seawater stress exhibited an enrichment of plant growth-promoting rhizobacteria alongside a higher presence of pathogenic fungi. Network analysis revealed that seawater stress resulted in the construction of a more complex and stable rhizosphere microbial network compared to normal conditions. Predictions of bacterial potential functions highlighted a greater diversity of functional groups, enhancing resource utilization efficiency. In general, the rhizosphere microorganisms of tea plants are jointly selected by seawater and the host. The microorganisms closely related to the rhizosphere of tea plants are retained and, at the same time, attract beneficial microorganisms that may alleviate stress. These findings provide new insights into plant responses to saline stress and have significant implications for leveraging vegetation to enhance the resilience of coastal saline soils and contribute to economic progress. [ABSTRACT FROM AUTHOR]

Clubroot is a soilborne disease of canola (Brassica napus) and other crucifers caused by the obligate parasite Plasmodiophora brassicae. In western Canada, clubroot is usually managed by planting-resistant cultivars, but the emergence of resistance-breaking pathotypes of P. brassicae represents a major threat to sustainable canola production. The rhizosphere and root contain beneficial microorganisms that can improve plant health. In this study, we evaluated the effect of two P. brassicae isolates (termed A and B) with different levels of virulence on the root and rhizosphere microbiomes of clubroot-resistant and clubroot-susceptible canola. Additionally, potential biocontrol microorganisms were identified based on taxa antagonistic to clubroot. Although both P. brassicae isolates were classified as pathotype 3A, isolate A caused a higher disease severity index in the resistant canola genotype compared with isolate B. Metabarcoding analysis indicated a shift in the bacterial and fungal communities in response to inoculation with either field isolate. Root endophytic bacterial and fungal communities responded to changes in inoculation, isolate type, sampling time, and canola genotype. In contrast, fungal communities associated with the rhizosphere exhibited significant differences between sampling times, while bacterial communities associated with the rhizosphere exhibited low variability. [ABSTRACT FROM AUTHOR]

This study aimed to highlight the positive effects of various recycled organic substrates on lettuce plants (Lactuca sativa L.) and to promote sustainable waste management practices, contributing to the concept of a circular economy. Over a two-month period, the growth potential and rhizosphere microflora of lettuce plants grown in soil amended with different recycled substrates were investigated. All data were compared, and the effects of the culture substrates were evaluated. All groups containing soil improvers offered a significant increase in the number of leaves per plant and, in two cases, an increase in dry biomass as well as an increase in the concentration of all leaf pigments. Both MDA and H2O2 concentrations were the lowest in two groups containing soil improvers (VG 5% and PLUS 10%). At the end of the culture period, isolation and culture of bacteria from the plant rhizosphere were performed. Different bacterial strains were isolated and tested for the production of antimicrobial agents against six microbial indicators (B. subtilis, E. coli, S. aureus, S. cerevisiae, C. albicans, and P. aeruginosa). The greater percentage of the isolated strains showed an ability to inhibit the growth of the B. subtilis index. Most of the strains with antimicrobial activity were isolated from the soil samples of the plain soil group and the soil amended with the commercial fertilizer. Three of the isolated strains originating from the Ginagro 5% group are multiproducers as they inhibit the growth of three microbial indicators or more. [ABSTRACT FROM AUTHOR]

In agricultural ecosystems, rhizosphere microbial communities serve as the driving force for the successful cycling and transformation of nutrients and organic matter in soil, exerting a significant impact on the growth, health, and nutritional status of crops. To investigate the diversity of rhizosphere fungi in different habitats in the northern Tianshan Mountains and the driving factors behind their variations, this study employed high-throughput sequencing to analyze the diversity, structures, functions, and driving factors of rhizosphere and non-rhizosphere fungi in alfalfa rhizosphere soils in mountainous and plain habitats. The results revealed that: (1) Soil nitrogen, potassium, organic matter, and enzyme activity in the mountainous alfalfa rhizosphere soil were significantly higher than those in plain alfalfa rhizosphere soil, while electrical conductivity and pH were significantly lower than those in plain alfalfa rhizosphere soil. (2) Significant differences were observed in the fungal communities in mountainous and plain soils, with the operational taxonomic units (OTUs), Chao1, and ACE indices of plain alfalfa rhizosphere soil being significantly higher than those of mountainous alfalfa rhizosphere soil; additionally, the OTUs, Chao1, ACE, and Shannon indices showed significantly higher values in rhizosphere soils than those in non-rhizosphere soils. (3) The dominant fungal phyla in the region were Ascomycota, Mortierellomycota, Basidiomycota, and Blastocladiomycota, with notable differences in their distribution across different habitats. (4) Based on FUNGuild' s fungal functional predictions, pathogenic fungi in mountainous areas were significantly higher than those in plain areas, while arbuscular mycorrhizal fungi were significantly lower in mountainous areas. (5) Redundancy analysis and Mantel tests indicated that soil pH, total nitrogen, total potassium and available potassium were the main driving factors for the differential distribution of fungal community structures in soils. [ABSTRACT FROM AUTHOR]

Copyright of Baghdad Science Journal is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: Soil quality is crucial for the growth and development of tea plants. Although the tea rhizosphere microbial composition and function have been extensively studied, few comparative studies have been performed to explore the different ecological niches of tea plants' microbes and their response to current global warming. Materials and methods: In this study, we selected a typical tea plant soil located in Chibi city, Hubei Province, China and collected samples during different seasons from rhizosphere and nonrhizosphere of tea plants. Using the Microbial phospholipid fatty acid analysis method and high-throughput sequencing to analyze the functions of dominant bacterial communities and strategies for coping with different environmental pressures. Results and discussion: The results showed that 19:0 cyclo ω7c was the dominant peak in both the rhizosphere and nonrhizosphere environments in winter compared with 16:0 in both the rhizosphere and nonrhizosphere soil in summer. The composition of PLFAs and a series of derived parameters were regulated by environmental factors such as soil pH, redox potential, total organic carbon, total nitrogen and NO3−-N content. In addition, the tea plant soil microorganisms differed significantly under the different temperature stresses, with significant enrichment of Ktedonobacteria and Micrococcaceae in winter and of Gammaproteobacteria and Proteobacteria in summer. Conclusions: The rhizosphere and nonrhizosphere soil microbial communities of tea plants were co-regulated by the root secretions growth conditions of tea plants, the fertilization conditions and the temperature stress. [ABSTRACT FROM AUTHOR]

Rhizosphere bacteria enhance plant growth and protection by producing active compounds. These bacteria remain the means of attraction to substitute for chemical pesticides, fertilizers, and other additives. Several studies are examining the biological control potential of antifungal bacteria, whose identity is currently unknown. The present study was conducted to isolate, identify, and characterize four bacteria with antifungal properties from potato and strawberry plants and their rhizosphere soils. Bacteria were isolated from potato and strawberry plants, and their respective rhizosphere soils. The bacterial isolates were subjected to antifungal activity testing. Twenty-four of the isolates with antifungal activity were further subjected to an antifungal activity assay against Botrytis cinerea, Alternaria alternata, and Fusarium oxysporum. These bacterial isolates were identified using microscopic, phenotypic, and biochemical tests. The identity of the four bacteria with strong antifungal activity was confirmed with 16S rRNA gene sequencing. A total of 374 strains of bacteria were isolated, with 24 having antagonistic activity. The results of the tests classified the isolates into three categories with varying percentages; 25, 17, and 58% of the bacterial isolates were of the genera Bacillus, Acinetobacter, and Pseudomonas. Four of these bacterial isolates (Fr43, F31, B6, and B29) had strong antifungal activity. The molecular analysis revealed their identities as Bacillus amyloliquefaciens DMB3, Acinetobacter lwoffii strain HATC14, Pseudomonas brassicacearum subsp. neoaurantiaca strain IHBB13645, and Bacillus amyloliquefaciens strain CD2901, respectively. The present study found four distinct bacterial strains with strong antagonistic potential, probably belonging to new species, based on 16S rRNA gene sequence analysis. [ABSTRACT FROM AUTHOR]

Drought is a major factor limiting plant growth. Plants cope with stress via morphophysiological responses. Rhizosphere‐related bacteria, fungi and other microorganisms can help plants cope with drought via various mechanisms. We conducted a pot experiment on Cyperus esculentus wherein we subjected it to various drought levels and analyzed the functional traits of its aboveground and belowground organs. High‐throughput sequencing was used to study the structure and diversity of the microbial community in the rhizosphere. Drought stress substantially lowered the densities of the leaves, stems, roots and seeds relative to the untreated control. Drought stress inhibited the growth and reduced the yield of C. esculentus. The leaves and seeds have higher water content and are more sensitive to drought stress than the roots. With the aggravation of drought stress, the plant height of C. esculentus decreased significantly, the root:shoot ratio increased and the specific leaf weight had no significant difference. Change in shoot height was the most evident response of C. esculentus to drought stress. Plants under drought stress reduced their leaf area and assumed a specific leaf weight to maintain photosynthetic performance. Rhizosphere fungi were more sensitive to drought stress than rhizosphere bacteria. Drought stress increased the relative abundances of Bacteroidetes, Verrucomicrobia, Patescibacteria, Actinobacteria and Nitrospirae. Drought‐stressed C. esculentus maintained their photosynthetic performance by reducing shoot height and leaf area while assuming a stable specific leaf weight. Drought stress exerted a significantly stronger negative impact on rhizosphere fungi than rhizosphere bacteria. The results clarified the response strategies of functional traits and rhizosphere microorganisms of C. esculentus to drought stress. [ABSTRACT FROM AUTHOR]

Copyright of Glasnik Zastite Bilja is the property of Zadruzna Stampa D.D. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Exploring the bacterial community in the S. glauca rhizosphere was of great value for understanding how this species adapted to the salinealkali environment and for the rational development and use of saline-alkali soils. In this study, high-throughput sequencing technology was used to investigate the diversity characteristics and distribution patterns of soil bacterial communities in the rhizosphere of S.glauca-dominated communities in the Hetao Irrigation Distract, Inner Mongolia, China. The relationships among bacterial characteristics, soil physicochemical properties and vegetation in four sampling sites were analyzed. The soil bacterial communities in the rhizosphere of S. glauca-dominated communities were mainly composed of 16 phyla (i.e., Proteobacteria, Actinobacteria, Bacteroidetes, Gemmatimonadetes, Chloroflexi, Acidobacteria, Firmicutes, Planctomycetes, Deinococcus-Thermus, Verrucomicrobia, Saccharibacteria, Cyanobacteria, Nitrospirae, JL-ETNP-Z39, Parcubacteria and Chlorobi), and these populations accounted for more than 99% of the total bacterial community. At the genus level, the main bacterial communities comprised Halomonas, Nitriliruptor, Euzebya and Pelagibius, which accounted for 15.70% of the total bacterial community. An alpha diversity analysis indicated that the richness and diversity of rhizosphere soil bacteria differed significantly among the sampling sites, and the bacterial richness and diversity indices of severe saline-alkali land were higher than those of light and moderate saline-alkali land. The principal component analysis (PCA) and linear discriminant analysis effect size (LEfSe) showed significant differences in the species composition of the rhizosphere soil bacterial community among different sampling sites. A correlation analysis showed that the number of bacterial species exhibited the highest correlation with the soil water content (SWC). The richness and evenness indices were significantly correlated with the SWC and SO42-, KC and Mg2+ concentrations. The electrical conductivity (EC), soluble ions (NaC, CO32- + HCO3-, K+, Ca2+, Mg2+, and SO42+), SWC and vegetation coverage (VC) were the main drivers affecting the changes in its community structure. The bacterial community in the rhizosphere of S. glauca enhanced the adaptability of S. glauca to saline-alkali environment by participating in the cycling process of nutrient elements, the decomposition of organic matter and the production of plant growth regulating substances. These results provided a theoretical reference for further study on the relationship among rhizosphere soil microorganisms and salt tolerance in halophytes. [ABSTRACT FROM AUTHOR]

Rhizospheric microbial communities improve the effectiveness of hyperaccumulators in the phytoremediation of heavy metals. However, limited access to tailing dams and inadequate assessment of plants' phytoremediation potential limit the characterization of native accumulators, hindering the effectiveness of local remediation efforts. This study evaluates the heavy metal sequestration potentials of Pennisetum purpureum, Leucaena leucocephala, and Pteris vittata and their associated rhizospheric microbial communities at the Marlu and Pompora tailing dams in Ghana. The results indicate shoot hyperaccumulation of Cd (334.5 ± 6.3 mg/kg) and Fe (10,647.0 ± 12.6 mg/kg) in P. purpureum and L. leucocephala, respectively. Analysis of rhizospheric bacterial communities revealed the impact of heavy metal contamination on bacterial community composition, associating Fe and Cd hyperaccumulation with Bacillus, Arthrobacter, and Sphingomonas species. This study reports the hyperaccumulation potentials of L. leucocephala and P. purpureum enhanced by associated rhizosphere bacterial communities, suggesting their potential application as an environmentally friendly remediation process of heavy metals contaminated lands. The novelty of this study is the report of the heavy metal accumulation potentials of the fast-growing herbaceous plants Leucaena leucocephala and Pennisetum purpureum at abandoned gold mine tailing dams in Ghana. Substantial amounts of Cd (334.5 mg/kg) and Fe (10,647.0 mg/kg) were accumulated in P. purpureum and L. leucocephala shoots, indicating their hyperaccumulation potentials. The concentration of heavy metal levels in the rhizosphere influenced the bacterial community structure, with the abundance of Bacillus, Arthrobacter, and Sphingomonas linked to hyperaccumulation. The outcome of this study supports the utilization of L. leucocephala and P. purpureum in the phytoremediation of lands contaminated with heavy metals. [ABSTRACT FROM AUTHOR]

Microbes strongly affect invasive plant growth. However, how phyllosphere and rhizosphere soil microbes distinctively affect seedling mortality and growth of invaders across ontogeny under varying soil nutrient levels remains unclear. In this study, we used the invader Ageratina adenophora to evaluate these effects. We found that higher proportions of potential pathogens were detected in core microbial taxa in leaf litter than rhizosphere soil and thus leaf inoculation had more adverse effects on seed germination and seedling survival than soil inoculation. Microbial inoculation at different growth stages altered the microbial community and functions of seedlings, and earlier inoculation had a more adverse effect on seedling survival and growth. The soil nutrient level did not affect microbe-mediated seedling growth and the relative abundance of the microbial community and functions involved in seedling growth. The effects of some microbial genera on seedling survival are distinct from those on growth. Moreover, the A. adenophora seedling-killing effects of fungal strains isolated from dead seedlings by non-sterile leaf inoculation exhibited significant phylogenetic signals, by which strains of Allophoma and Alternaria generally caused high seedling mortality. Our study stresses the essential role of A. adenophora litter microbes in population establishment by regulating seedling density and growth. [ABSTRACT FROM AUTHOR]

Plants have numerous strategies for phytoremediation depending upon the characteristic of pollutants. Plant growth promoting rhizobacteria (PGPR) are essential to the process of phytoremediation and play a key part in it. The mechanism of PGPR for phytoremediation is mediated by two methods; under the direct method there is phytohormone production, nitrogen fixation, nutrient mineral solubilization, and siderophore production while the indirect method includes quorum quenching, antibiosis, production of lytic enzyme, biofilm formation, and hydrogen cyanide production. Due to their economic and environmental viability, most researchers have recently concentrated on the potential of weed plants for phytoremediation. Although weed plants are considered unwanted and noxious, they have a high growth rate and adaptability which opens a high scope for its role in phytoremediation of contaminated site. The interaction of plant with rhizobacteria starts from root exudates containing various organic acids and peptides which act as nutrients essential for colonization and siderophore production by the rhizospheric bacteria. The rhizobacteria, while colonizing, tend to promote plant growth and health either directly by providing phytohormones and minerals or indirectly by suppressing growth of possible phytopathogens. Recently, several weed plants have been reported for phytoextraction of heavy metals (Ni, Pb, Zn, Hg, Cd, Cu, As, Fe, and Cr) contaminants from various agro-based industries. These potential native weed plants have high prospect of eco-restoration of polluted site with complex organo-metallic waste for sustainable development. [ABSTRACT FROM AUTHOR]

Summary: The rhizosphere microbiome plays critical roles in plant growth and provides promising solutions for sustainable agriculture. While the rhizosphere microbiome frequently fluctuates with the soil environment, recent studies have demonstrated that a small proportion of the microbiome is consistently assembled in the rhizosphere of a specific plant genotype regardless of the soil condition, which is determined by host genetics. Based on these breakthroughs, which involved exploiting the plant‐beneficial function of the rhizosphere microbiome, we propose to divide the rhizosphere microbiome into environment‐dominated and plant genetic‐dominated components based on their different assembly mechanisms. Subsequently, two strategies to explore the different rhizosphere microbiome components for agricultural production are suggested, that is, the precise management of the environment‐dominated rhizosphere microbiome by agronomic practices, and the elucidation of the plant genetic basis of the plant genetic‐dominated rhizosphere microbiome for breeding microbiome‐assisted crop varieties. We finally present the major challenges that need to be overcome to implement strategies for modulating these two components of the rhizosphere microbiome. [ABSTRACT FROM AUTHOR]

Dianthus barbatus linn. is widely used in gardens, mainly as flower beds and flower borders. The effects of different gradients of P on the growth and root morphology of Dianthus barbatus were studied to explore its morphological and physiological responses and adaptive strategies. Hence, this study provides a theoretical basis and practical guidance for D. barbatus production. Two soil substrates, namely loess and vegetable soil, and five phosphorus concentration gradients were set; no phosphorus application was used as the control. The morphology and physiology of D. barbatus were also investigated. Low-to-medium- and low-phosphorus treatments promoted the growth of D. barbatus in the above and underground parts of the plants grown on both substrates. Chlorophyll content, flower quantity, and acid phosphatase activity in the rhizosphere soil were significantly increased in the H1 and H2 treatments of loess and in the C4 treatment of vegetable soil. Thus, D. barbatus seems to reduce the damage caused by phosphorus stress by increasing chlorophyll content and root acid phosphatase activity. The latter was significantly higher in vegetable soil than in loess. Vegetable soil was more conducive to D. barbatus growth than loess. [ABSTRACT FROM AUTHOR]

There are obvious differences in quality between different varieties of the same plant, and it is not clear whether they can be effectively distinguished from each other from a bacterial point of view. In this study, 44 tea tree varieties (Camellia sinensis) were used to analyze the rhizosphere soil bacterial community using high-throughput sequencing technology, and five types of machine deep learning were used for modeling to obtain characteristic microorganisms that can effectively differentiate different varieties, and validation was performed. The relationship between characteristic microorganisms, soil nutrient transformation, and tea quality formation was further analyzed. It was found that 44 tea tree varieties were classified into two groups (group A and group B) and the characteristic bacteria that distinguished them came from 23 genera. Secondly, the content of rhizosphere soil available nutrients (available nitrogen, available phosphorus, and available potassium) and tea quality indexes (tea polyphenols, theanine, and caffeine) was significantly higher in group A than in group B. The classification result based on both was consistent with the above bacteria. This study provides a new insight and research methodology into the main reasons for the formation of quality differences among different varieties of the same plant. [ABSTRACT FROM AUTHOR]

The plant health status is determined by the interplay of plant-pathogen-microbiota in the rhizosphere. Here, we investigate this tripartite system focusing on the pathogen Fusarium oxysporum f. sp. lycopersici (FOL) and tomato plants as a model system. First, we explore differences in tomato genotype resistance to FOL potentially associated with the differential recruitment of plant-protective rhizosphere taxa. Second, we show the production of fusaric acid by FOL to trigger systemic changes in the rhizosphere microbiota. Specifically, we show this molecule to have opposite effects on the recruitment of rhizosphere disease-suppressive taxa in the resistant and susceptible genotypes. Last, we elucidate that FOL and fusaric acid induce changes in the tomato root exudation with direct effects on the recruitment of specific disease-suppressive taxa. Our study unravels a mechanism mediating plant rhizosphere assembly and disease suppression by integrating plant physiological responses to microbial-mediated mechanisms in the rhizosphere. The phytotoxin fusaric acid produced by the phytopathogen Fusarium oxysporum f. sp. lycopersici results in a differential assembly of the rhizosphere microbiota of resistant and susceptible genotypes with implication for disease suppression. [ABSTRACT FROM AUTHOR]

Salt stress is a major abiotic stress that affects the growth of Reaumuria soongorica and many psammophytes in the desert areas of Northwest China. However, various Plant Growth-Promoting Rhizobacteria (PGPR) have been known to play an important role in promoting plant growth and alleviating the damaging effects of salt stress. In this study, three PGPR strains belonging to Bacillaceae were isolated from the rhizosphere of Reaumuria soongorica by morphological and molecular identification. All isolated strains exhibited capabilities of producing IAA, solubilizing phosphate, and fixing nitrogen, and were able to tolerate high levels of NaCl stress, up to 8-12%. The results of the pot-based experiment showed that salt (400 mM NaCl) stress inhibited Reaumuria soongorica seedlings' growth performance as well as biomass production, but after inoculation with strains P2, S37, and S40, the plant's height significantly increased by 26.87, 17.59, and 13.36%, respectively (p < 0.05), and both aboveground and root fresh weight significantly increased by more than 2 times compared to NaCl treatment. Additionally, inoculation with P2, S37, and S40 strains increased the content of photosynthetic pigments, proline, and soluble protein in Reaumuria soongorica seedlings under NaCl stress, while reducing the content of malondialdehyde and soluble sugars. Metabolomic analysis showed that strain S40 induces Reaumuria soongorica seedling leaves metabolome reprogramming to regulate cell metabolism, including plant hormone signal transduction and phenylalanine, tyrosine, and tryptophan biosynthesis pathways. Under NaCl stress, inoculation with strain S40 upregulated differential metabolites in plant hormone signal transduction pathways including plant hormones such as auxins (IAA), cytokinins, and jasmonic acid. The results indicate that inoculation with Bacillaceae can promote the growth of Reaumuria soongorica seedlings under NaCl stress and enhance salt tolerance by increasing the content of photosynthetic pigments, accumulating osmoregulatory substances, regulating plant hormone levels This study contributes to the enrichment of PGPR strains capable of promoting the growth of desert plants and has significant implications for the psammophytes growth and development in desert regions, as well as the effective utilization and transformation of saline-alkali lands. [ABSTRACT FROM AUTHOR]

Ectomycorrhizal fungi and non-ectomycorrhizal fungi are responsive to changes in environmental and nutrient availabilities. Although many species of ectomycorrhizas are known to enhance the uptake of phosphorus and other nutrients for Pinus taeda, it is not understood how to optimize these communities to have tangible effects on plantation silviculture and P use efficiency. The first step of this process is the identification of native fungi present in the system that are associated with P. taeda and influence P uptake efficiency. We used sand-filled mesh bags baited with finely ground apatite to sample ectomycorrhizal and non-ectomycorrhizal fungi associated with the rhizosphere of P-responsive P. taeda under several field conditions. Mesh bags were assessed for biomass accumulation over three years using a single three-month burial period pre-harvest and three six-month burial periods post-planting. Amplicon sequencing assessed ectomycorrhizal and non-ectomycorrhizal communities between phosphorus treatments, sites, mesh bags, and the rhizosphere of actively growing P. taeda in the field. We found biomass accumulation within the mesh bags was inversely related to increasing phosphorus fertilization (carryover) rates from pre-harvest to postplanting. Up to 25% increases in total biomass within the bags were observed for bags baited with P. Taxonomic richness was highest in Alfisol soils treated with phosphorus from the previous rotation and lowest in the Spodosol regardless of phosphorus treatment. [ABSTRACT FROM AUTHOR]