Rhizosphere Soil Of Plants Research Articles

Effects Of Alternating Drying And Wetting On Soil Nitrogen And Phosphorus Loss In Root Zone Of Dominant Plants In Phosphorus-rich Mountainous Areas

In the mountainous area of Yunnan-Guizhou Plateau, phosphorus and nitrogen are important factors that limit primary productivity and affect the distribution of plant communities. Alternation of wet and dry has a significant effect on the migration of various elements such as C, N, and P in soil. Taking the rhizosphere soil of the dominant plants in the phosphorus-rich mountainous area in the Dianchi Lake Basin as the research object. Six sets of different humidity treatment methods: blank constant humidity, blank dry and wet alternation, nitrogen constant humidity, nitrogen addition dry and wet alternation, carbon constant humidity, and carbon add dry and wet alternation were assessed. Responses of soluble total nitrogen and soluble total phosphorus to six treatments in plant root zone were investigated. The results showed that the contents of dissolved total nitrogen (DTN) and dissolved total phosphorus (DTP) in soil leachate and their changes of Erianthus rufipilus and Eupatorium adenophorum under different treatment conditions increased first and then decreased. In the carbon addition group, the DTN content of the soil leachate in the alternating dry and wet treatment was significantly higher than that in the constant humidity treatment, but there was no significant difference in the nitrogen addition group. The three factors of water treatment and sampling time have significant effects on the DTN content of soil leachate, and the interaction between the three also has a significant effect on it. Bangladesh J. Bot. 51(4): 855-862, 2022 (December) Special

Reprogramming of microbial community in barley root endosphere and rhizosphere soil by polystyrene plastics with different particle sizes

Polystyrene plastics is an emerging pollutant affecting plant performance and soil functioning. However, little information is available on the effects of microplastics and nanoplastics on plant root endophytic and rhizospheric soil microbial communities. Here, barley plants were grown in microplastics/nanoplastics -treated soil and the diversity, composition and function of bacteria and fungi in the root and rhizosphere soil were examined. At the seedling stage, greater changes of root endophytes were found compared with rhizosphere microorganisms under the plastic treatments. Nanoplastics decreased the richness and diversity of the fungal community, while microplastics increased the diversity of the root endophytic bacterial community. The network of the bacterial community under nanoplastics showed higher vulnerability while lower complexity than that under the control. However, the bacterial community under microplastics had a relatively higher resistance than the control. For the rhizosphere microbial community, no significant effect of plastics was found on the α-diversity index at the seedling stage. In addition, the nanoplastics resulted in higher sensitivity in the relative abundance and function of rhizosphere soil microbes than root endophytic microbes at the mature stage. Treatments of polystyrene plastics with different particle sizes reprogramed the rhizosphere and root endophytic microbial communities. Different effects of microplastics and nanoplastics were found on the diversity, composition, network structure and function of bacteria and fungi, which might be due to the variation in particle sizes. These results lay a foundation for learning the effects of polystyrene plastics with different particle sizes on the microorganisms in rhizosphere soil and plant roots, which may have important implications for the adaptation of plant-microbial holobiont in polystyrene plastics-polluted soils.

Metagenomic study of the tomato rhizosphere soil microbiome: current state and prospect

<abstract> <p>Plant microbiota has a variety of impacts on the plant. Some are beneficial, while some are pathogenic. This study discusses the general metagenomics procedures in processing plant-related metagenomes and focuses on the tomato plants' rhizosphere species. Metagenomics, associated with eventual DNA, is isolated from environmental samples and thus permits absolute microbial population identification. Meanwhile, the genetic content of the DNA sample obtained allows the functional capability identification and biochemical procedure of many microorganisms. This review reveals the recent utilization and application of the potential of Next-Generation Sequencing (NGS) in agriculture. It involves plant-associated microbiota, the factors driving their diversity, and plant metagenome to tackle current challenges experienced in food security. This review provides the newest methods for rapidly identifying the microbial communities inhabiting the rhizosphere soil of tomato plants.</p> </abstract>

Rhizosphere Soil Fungal Diversity and Soil Physicochemical Properties of Different Vegetations in Tundra of Changbai Mountain

By studying the diversity and community structure of rhizosphere soil fungi of different plants in the tundra on the northern slope of Changbai Mountain, it provides theoretical support for the restoration of environmental degradation and in-depth study of fungal diversity in the tundra of Changbai Mountain. High-throughput sequencing technology was used to determine the ITS1 region of fungal amplicons, so as to analyze the diversity of fungal communities in the rhizosphere soil of six plants in the tundra of Changbai Mountain, and to analyze the correlation between the environment and the diversity and richness of fungal communities in combination with relevant soil physical and chemical factors. The diversity and richness of fungal community in the rhizosphere soil of six plants in Changbai Mountain tundra were different. The Simpson and Shannon indexes of Saxifraga stolonifera Curt were the highest, and the richness of fungal community in Dryas octopetala was the highest. The analysis of fungal community composition showed that the fungal colonies in plant rhizosphere soil samples mainly belonged to Ascomycota and Basidiomycota, which were the main dominant phyla. Mortierella, Fusarium and Sordariomycetes are common fungal genera in the rhizosphere soil of six plants, but their abundances are different among different plants. Water content was negatively correlated with fungal diversity, and TP was positively correlated with fungal community diversity. There were some differences in the composition and diversity of rhizosphere soil fungal communities of six plants in Changbai Mountain tundra. Ascomycota and Basidiomycota were the main soil fungal phyla in the rhizosphere of six plants in Changbai Mountain tundra. The results could provide theoretical guidance for ecological protection of Changbai Mountain tundra.

Effects of Combined Pb and Cu Pollution on the Growth and Activities of Plant Antioxidant Enzymes and Rhizospheric Soil Enzymes of Miscanthus floridulus

Phytoremediation of mine wastes is a promising approach for the restoration of contaminated soils. Miscanthus floridulus is a perennial herbaceous grass with high productivity and tolerant to a variety of heavy metals. Sixty-day pot experiments were carried out to investigate the effects of combined Pb-Cu contamination on some physio-biochemical markers of M. floridulus and rhizospheric soil enzyme activities. M. floridulus was tolerant to a combination of 200 mg kg-1 Pb and 100 mg kg-1 Cu stress as indicated by invisible foliar injury, increased contents of photosynthetic pigments (increased by 17.2% to 22.8% compared to the control), enhanced accumulation of soluble sugar contents by 33.5% to 52.8% in response to all treatments except the Pb100Cu50, decreased contents of malondialdehyde by 5.18% at 100 mg kg-1 Pb and 50 mg kg-1 Cu. As a response to combined Pb-Cu stress, the antioxidant enzymes (catalase, peroxidase and superoxide dismutase) activities in M. floridulus were reduced by any of the Pb-Cu treatments used in the present study. Although the growth parameters such as plant height, root number, maximal root length, and the dry biomass of aboveground parts and root were all lowered by Pb-Cu treatments, the rhizospheric soil invertase, catalase, urease and phosphatase enzyme activities of M. floridulus kept increasing when the concentration of Pb and Cu below 400 mg kg-1 Pb and 200 mg kg-1 Cu.

Reduction in soil detachment capacity by inoculation of bacillus polymyxa strain BcP26 in deforested lands

The beneficial effects of rhizobacteria in increasing plant growth, nutrient uptake and rhizosphere soil aggregation are well known. However, few investigations have explored the impacts of these bacteria on soil erosion processes, particularly for the parameters used in rill erosion. To fill this gap, this investigation has evaluated the effects of growth of Zoysia grass roots induced by bacillus polymyxa strain BcP26 on the rill detachment capacity (Dc) and rill erodibility (Kr) in the treated soil, compared to the control soil by a paired sample t-test with six replications for each experiment in deforested lands of Northern Iran. For measuring Dc, a hydraulic flume was used at five slopes (4.3%–38.2%) and five water discharges (0.29–0.69 l m−1 s−1). Three characteristics of roots including the length, biomass and weight density of roots were measured. Dc was lower (on average - 24% for the average slopes) in the treated soil with the bacillus strain (PB) compared to the control soil (AB). Rill erodibility (Kr), obtained by the relationship between Dc and the shear stress, also was significantly lower (−60%) in the PB soil compared to the control soil. A principal component analysis provided a significant combined factor (the first principal component) that revealed an obvious discrimination in rill detachment capacity between treated and control soils. This value of rill erodibility for deforested lands is contributory for modelling purposes of soil resistance to rill erosion. It is concluded that, thanks to the bacillus strain used as one of plant growth promoting rhizobacteria, soil erosion is significantly (at p < 0.01) reduced, and this strain contributes to reduce the risk of soil degradation.

Microbiome analysis and biocontrol bacteria isolation from rhizosphere soils associated with different sugarcane root rot severity.

To explore the causal pathogen and the correlated rhizosphere soil microecology of sugarcane root rot, we sampled the sugarcane root materials displaying different disease severity, and the corresponding rhizosphere soil, for systematic root phenotype and microbial population analyses. We found that with increased level of disease severity reflected by above-ground parts of sugarcane, the total root length, total root surface area and total volume were significantly reduced, accompanied with changes in the microbial population diversity and structure in rhizosphere soil. Fungal community richness was significantly lower in the rhizosphere soil samples from mildly diseased plant than that from either healthy plant, or severely diseased plant. Particularly, we noticed that a peculiar decrease of potential pathogenic fungi in rhizosphere soil, including genera Fusarium, Talaromyces and Neocosmospora, with increased level of disease severity. As for bacterial community, Firmicutes was found to be of the highest level, while Acidobacteria and Chloroflexi of the lowest level, in rhizosphere soil from healthy plant compared to that from diseased plant of different severity. FUNGuild prediction showed that the proportion of saprophytic fungi was higher in the rhizosphere soil of healthy plants, while the proportion of pathogenic fungi was higher in the rhizosphere soil of diseased plants. By co-occurrence network analysis we demonstrated the Bacillus and Burkholderia were in a strong interaction with Fusarium pathogen(s). Consistently, the biocontrol and/or growth-promoting bacteria isolated from the rhizosphere soil were mostly (6 out of 7) belonging to Bacillus and Burkholderia species. By confrontation culture and pot experiments, we verified the biocontrol and/or growth-promoting property of the isolated bacterial strains. Overall, we demonstrated a clear correlation between sugarcane root rot severity and rhizosphere soil microbiome composition and function, and identified several promising biocontrol bacteria strains with strong disease suppression effect and growth-promoting properties.

Resprouting ability differs among plant functional groups along a soil acidification gradient in a meadow: A rhizosphere perspective

Abstract Soil acidification as a global change factor can devastatingly affect plant growth and productivity. In frequently disturbed ecosystems, plant resprouting ability strongly determines biomass reconstruction and resilience after above‐ground damage. However, how plant regrowth responds to soil acidification remains largely unknown for, especially regarding the role of rhizosphere in mediating this response. We manipulated a soil‐acidification gradient via adding purified elemental sulphur powder at various rates (0–50 g S m−2 year−1) in a frequently mown meadow. Shoot regrowth of functional groups were measured after clipping and supporting roles of rhizosphere versus bulk soils were disentangled using isotope labelling along the acidification gradient. Regrowth of grasses and sedges increased while forbs decreased along the acidification gradient. The results suggest that grasses were competitors capable of taking up nutrients from both rhizosphere and bulk soils, while sedges were acid‐tolerators with lower sensitivity to decreased nitrogen‐mineralization rates. Forbs, as typical ruderals, were vulnerable to N competition with microbes, particularly in the rhizosphere soil. Therefore, biomass regrowth of forbs was explained more by physicochemical and biological parameters from the rhizosphere than bulk soil. Synthesis. Divergent interplay between plant functional groups and rhizosphere soils was the prominent driver for biomass regrowth responding to soil acidification.

Effect of Phosphate Solubilizing Fungi from Rhizosphere soil of Medicinal plants on Growth and Phosphate uptake in Raphanus sativus

This field experiment deals with the isolation and evaluation of phosphate solubilizing fungi of a total of 9 isolates isolated from 10 rhizosphere soil of medicinal plants by serial dilution method using Pikovaskaya’s medium. After screening, 3 fungi were selected and evaluated, PSF 7 (Talaromyces sp.) showed good results in phosphate solubilization including solubilization index (3.08), reduced pH (3.2 from initial pH 6.8), titrable acidity (38.08), and phosphate present in culture broth (25µg/ml). The radish seeds showed 88% germination and growth, yield parameters include, plant height – 20.9cm, 40.8cm, and 71.5cm at 15 days, 30 days, and harvest respectively, several leaves at 9, 13, and 17 at 15 days, 30days and harvest respectively, root length (24.5cm), the weight of biomass (fresh weight -152 and dry weight – 15.7) and yield of root vegetable weight (39g). The maximum plant phosphorus uptake was recorded as 0.371% and the maximum P (Kg/ha) available in the rhizosphere soil was recorded as 344.29 Kg/ha. Due to the observation of good results in phosphate solubilization, they improve the growth and yield of radish. The selected PSF were recommended as phosphate bio inoculums in the agricultural field to improve plant growth and yield in radish and to maintain soil fertility.

Effect of Phosphate Solubilizing Fungi from Rhizosphere soil of Medicinal plants on Growth and Phosphate uptake in Raphanus sativus

Effect of Phosphate Solubilizing Fungi from Rhizosphere soil of Medicinal plants on Growth and Phosphate uptake in Raphanus sativus

The potential of novel bacterial isolates from healthy ginseng for the control of ginseng root rot disease (Fusarium oxysporum).

Ginseng root rot caused by Fusarium oxysporum is serious disease that impacts ginseng production. In the present study, 145 strains of bacteria were isolated from the rhizosphere soil of healthy ginseng plants. Three strains with inhibitory activity against Fusarium oxysporum (accession number AF077393) were identified using the dual culture tests and designated as YN-42(L), YN-43(L), and YN-59(L). Morphological, physiological, biochemical, 16S rRNA gene sequencing and phylogenetic analyses were used to identify the strains as Bacillus subtilis [YN-42(L)] (accession number ON545980), Delftia acidovorans [YN-43(L)] (accession number ON545981), and Bacillus polymyxae [YN-59(L)] (accession number ON545982). All three isolates effectively inhibited the growth of Fusarium oxysporum in vitro and the antagonistic mechanism used by the three strains involved the secretion of multiple bioactive metabolites responsible for the hydrolysis of the fungal cell wall. All three biocontrol bacteria produce indoleacetic acid, which has a beneficial effect on plant growth. From our findings, all three antagonistic strains can be excellent candidates for ginseng root rot caused by the pathogenic fungus Fusarium oxysporum. These bacteria have laid the foundation for the biological control of ginseng root rot and for further research on the field control of ginseng pathogens.

Microbiota Modulation in Blueberry Rhizosphere by Biocontrol Bacteria

Microbial interactions in agricultural soils can play important roles in the control of soil-borne phytopathogenic diseases. Yields from blueberry plantations from southern Spain have been impacted by the pathogenic fungus, Macrophomina phaseolina. The use of chemical fungicides has been the common method for preventing fungal infections, but due to their high environmental impact, legislation is increasingly restricting its use. Biocontrol alternatives based on the use of microorganisms is becoming increasingly important. Using the metabarcoding technique, fungi and bacteria were characterized (via 16S and ITS regions, respectively) from rhizosphere soils of healthy and dead blueberry plants infected by M. phaseolina, and which had undergone three different treatments: two biocontrol strategies—one of them a mix of Pseudomonas aeruginosa and Bacillus velezensis and the other one with Bacillus amyloliquefaciens—and a third treatment consisting of the application of a nutrient solution. The treatments produced changes in the bacterial microbiota and, to a lesser extent, in the fungi. The abundance of Fusarium was correlated with dead plants, likely favoring the infection by M. phaseolina. The presence of other microorganisms in the soil, such as the fungi Archaeorhizomyces or the bacteria Actinospica, were correlated with healthy plants and could promote their survival. The different genera detected between dead and healthy plants opens the possibility of studying new targets that can act against infection and identify potential microorganisms that can be used in biocontrol strategies.

Effects of Plant Growth-Promoting Rhizobacteria on the Growth and Soil Microbial Community of Carya illinoinensis.

Plant growth-promoting rhizobacteria (PGPR) are important members of soil microbial communities. In this study, the effects of several PGPR on the growth of Carya illinoinensis plants, the microbial community composition and soil nutrients were investigated by inoculation tests to identify excellent PGPR strains. The experiment showed that after PGPR application, the plant height, ground diameter, and dry weight of C. illinoinensis were significantly increased compared with those of the control group, and Bacillus velezensis YH20 had the most significant effect in promoting growth (p < 0.05). In addition, all the PGPRs used for inoculation promoted plant root growth, and the Brevibacillus reuszeri MPT17 strain had the most significant promoting effect on plant root growth (p < 0.05). The application of PGPRs also affected the nutrient levels in plants and plant rhizosphere soil. For example, compared with the control, the levels of available phosphorus and potassium in rhizosphere soil and the total potassium content in plant roots were significantly increased under Br. reuszeri MPT17 treatment (p < 0.05). The experiment showed that the relative abundance of Mortierella, Dictyophora, and Bacillus in the rhizosphere soil increased significantly after the application of PGPR (p < 0.05). These genera could effectively improve the rate of soil nutrient use, antagonize plant pathogenic bacteria, and promote plant growth. This study provides basic reference data regarding the use of PGPR to improve the microecological environment and promote the growth and development of C. illinoinensis plants.

Co-analysis of cucumber rhizosphere metabolites and microbial PLFAs under excessive fertilization in solar greenhouse.

Fertilizer application is the most common measure in agricultural production, which can promote the productivity of crops such as cucumbers, but the problem of excessive fertilization occurs frequently in solar greenhouses. However, the effects of fertilization levels on cucumber rhizosphere soil microbes and metabolites and their relationships are still unclear. In order to determine how fertilization levels affect the rhizosphere microenvironment, we set up four treatments in the solar greenhouse: no-fertilization (N0P0K0), normal fertilization (N1P1K1), slight excessive fertilization (N2P2K2), and extreme excessive fertilization (N3P3K3). The results showed that fertilization treatments significantly increased cucumber yield compared to no-fertilization, but, the yield of N3P3K3 was significantly lower than that of N1P1K1 and N2P2K2. Fertilization levels had significant effects on rhizosphere microorganisms, and pH, NH4+-N and AP were the main environmental factors that affected the changes in microbial communities. The total PLFAs, the percentages of fungi and arbuscular mycorrhizal fungi (AMF) were significantly reduced and bacteria percentage was significantly increased in N3P3K3 compared to other fertilization treatments. Differential metabolites under different fertilization levels were mainly organic acids, esters and sugars. Soil phenols with autotoxic effect under fertilization treatments were higher than that of N0P0K0. In addition, compared with soil organic acids and alkanes of N0P0K0, N2P2K2 was significantly increased, and N3P3K3 was not significantly different. This suggested that cucumber could maintain microbial communities by secreting beneficial metabolites under slight excessive fertilization (N2P2K2). But under extremely excessive fertilization (N3P3K3), the self-regulating ability of cucumber plants and rhizosphere soil was insufficient to cope with high salt stress. Furthermore, co-occurrence network showed that 16:1ω5c (AMF) was positively correlated with 2-palmitoylglycerol, hentriacontane, 11-octadecenoic acid, decane,4-methyl- and d-trehalose, and negatively correlated with 9-octadecenoic acid at different fertilization levels. This indicated that the beneficial microorganisms in the cucumber rhizosphere soil promoted with beneficial metabolites and antagonized with harmful metabolites. But with the deepening of overfertilization, the content of beneficial microorganisms and metabolites decreased. The study provided new insights into the interaction of plant rhizosphere soil metabolites and soil microbiomes under the different fertilization levels.

Application of Bacterial Endophytes to Control Bacterial Leaf Blight Disease and Promote Rice Growth.

Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial leaf blight (BLB) disease in rice (Oryza sativa L.) and it is among the most destructive pathogen responsible for severe yield losses. Potential bacterial biocontrol agents (BCAs) with plant growth promotion (PGP) abilities can be applied to better manage the BLB disease and increase crop yield, compared to current conventional practices. Thus, this study aimed to isolate, screen, and identify potential BCAs with PGP abilities. Isolation of the BCAs was performed from internal plant tissues and rhizosphere soil of healthy and Xoo-infected rice. A total of 18 bacterial strains were successfully screened for in vitro antagonistic ability against Xoo, siderophore production and PGP potentials. Among the bacterial strains, 3 endophytes, Bacillus sp. strain USML8, Bacillus sp. strain USML9, and Bacillus sp. strain USMR1 which were isolated from diseased plants harbored the BCA traits and significantly reduced leaf blight severity of rice. Simultaneously, the endophytic BCAs also possessed plant growth promoting traits and were able to enhance rice growth. Application of the selected endophytes (BCAs-PGP) at the early growth stage of rice exhibited potential in suppressing BLB disease and promoting rice growth.

Potential of Pseudarthrobacter chlorophenolicus BF2P4-5 as a Biofertilizer for the Growth Promotion of Tomato Plants

BF2P4-5 was isolated from the rhizosphere soil of tomato plants, and its potential to promote plant growth was investigated in tomato plants. An in vitro test revealed that the strain could fix nitrogen, solubilize phosphate and potassium, and synthesize indole acetic acid. The bacterial strain was identified and characterized as a kind of Pseudarthrobacter chlorophenolicus based on the analysis of culture characteristics, physiological and biochemical characteristics, and 16S rRNA gene sequence (GenBank accession number OP135548.1). pH 7.0, 15% NaCl, and 35 °C temperature were ideal for optimal strain growth under culture conditions. Tomato plants grown on a cocopeat substrate were inoculated with BF2P4-5 suspension (OD600 2.0). Positive control plants were inoculated with Nitrogen Phosphorus Potassium (NPK) fertilizer. This BF2P4-5 strain and NPK treatments were complemented with a negative control, in which only tap water was applied to tomato roots, thus, establishing three distinct treatment modalities with five replications each. Two months of greenhouse trials of inoculated tomato plants improved growth parameters. Interestingly, in most of the growth metrics evaluated, tomato plants treated with strain BF2P4-5 showed little to no variation with NPK fertilizer treatment, including plant height, stem length, girth, leaf number per plant, and chlorophyll content, when compared to uninoculated plants. Furthermore, the conditions for the cocopeat plants, including pH, EC, and moisture, were within acceptable limits. Furthermore, inoculation with BF2P4-5 increased the nitrogen, phosphorus, and potassium content available in the cocopeat medium. The results showed that the strain exhibited traits for the promotion of plant growth and could be deployed as an eco-friendly microbial biofertilizer for tomatoes and probably other essential crops.

Effects of Two Kinds of Commercial Organic Fertilizers on Growth and Rhizosphere Soil Properties of Corn on New Reclamation Land.

Due to the development of urbanization and industrialization, a large amount of cultivated land resources has been occupied, while new reclamation land could expand the supply of usable land for food security. Organic fertilizers, such as crop residues, biosolids, sheep manure, mushroom residue, and biogas liquid, have been considered as an effective amendment in immature soil to improve its quality. Recently, two kinds of commercial organic fertilizers, pig manure and mushroom residue organic fertilizer (PMMR-OF), and sheep manure organic fertilizer (SM-OF), have been more regularly applied in agriculture production. However, the information available on effect of the two kinds of fertilizers on plant growth and rhizosphere soil properties in immature field is very limited. In order to evaluate PMMR-OF and SM-OF on immature soil, the soil quality and microbial community structure of corn rhizosphere soil samples under the two kinds of organic fertilizers at different concentrations was investigated. The results revealed a significant difference between commercial organic fertilizers (especially SM-OF) and chemical compound fertilizers (CCF) in soil properties and microbial community structure. Indeed, compared with the control based on16S and ITS amplicon sequencing of soil microflora, SM-OF caused a 10.79–19.52%, 4.33–4.39%,and 14.58–29.29% increase in Proteobacteria, Actinobacteria, and Ascomycota, but a 5.82–20.58%, 0.53–24.06%, 10.87–16.79%, 2.69–10.50%, 44.90–59.24%, 8.88–10.98%, and 2.31–21.98% reduction in Acidobacteria, Gemmatimonadetes, Bacteroidetes, Verrucomicrobia, Basidiomycota, Mortierellomycota, and Chytridiomycota, respectively. CCF caused a 24.11%, 23.28%, 38.87%, 19.88%, 18.28%, and 13.89% reduction in Acidobacteria, Gemmatimonadetes, Bacteroidetes, Verrucomicrobia, Basidiomycota, Chytridiomycota, but a 22.77%, 41.28%, 7.88%, and 19.39% increase in Proteobacteria, Actinobacteria, Ascomycota, and Mortierellomycota, respectively. Furthermore, redundancy discriminant analysis of microbial communities and soil properties of PMMR-OF, SM-OF, CCF, and the control treatments indicated that the main variables of bacterial and fungal communities included organic matter content, available P, and available K. Overall, the results of this study revealed significant changes under different fertilizer conditions (PMMR-OF, SM-OF, CCF, under different concentrations) in microbiota and chemical properties of corn soil. Commercial organic fertilizers, particularly SM-OF, can be used as a good amendment for the new reclamation land.

Analysis of Blueberry Plant Rhizosphere Bacterial Diversity and Selection of Plant Growth Promoting Rhizobacteria.

Microbial metabolites in rhizosphere soil are important to plant growth. In this study, microbial diversity in blueberry plant rhizosphere soil was characterized using high-throughput amplicon sequencing technology. There were 11 bacterial phyla and three fungal phyla dominating in the soil. In addition, inorganic-phosphate-solubilizing bacteria (iPSB) in the rhizosphere soil were isolated and evaluated by molybdenum-antimony anti-coloration method. Their silicate solubilizing, auxin production, and nitrogen fixation capabilities were also determined. Eighteen iPSB in the rhizosphere soil strains were isolated and identified as Buttiauxella, Paraburkholderia and Pseudomonas. The higher phosphorus-solubilizing capacity and auxin production in blueberry rhizosphere belonged to genus Buttiauxella sp. The strains belong to genus Paraburkholderia had the same function of dissolving both phosphorus and producing auxin, as well as silicate and nitrogen fixation. The blueberry seeds incubated with the strains had higher germination rates. The results of this study could be helpful in developing the plant growth-promoting rhizobacteria (PGPR) method for enhancing soil nutrients to blueberry plant.

Species identity and combinations differ in their overall benefits to Astragalus adsurgens plants inoculated with single or multiple endophytic fungi under drought conditions.

Although desert plants often establish multiple simultaneous symbiotic associations with various endophytic fungi in their roots, most studies focus on single fungus inoculation. Therefore, combined inoculation of multiple fungi should be applied to simulate natural habitats with the presence of a local microbiome. Here, a pot experiment was conducted to test the synergistic effects between three extremely arid habitat-adapted root endophytes (Alternaria chlamydospora, Sarocladium kiliense, and Monosporascus sp.). For that, we compared the effects of single fungus vs. combined fungi inoculation, on plant morphology and rhizospheric soil microhabitat of desert plant Astragalus adsurgens grown under drought and non-sterile soil conditions. The results indicated that fungal inoculation mainly influenced root biomass of A. adsurgens, but did not affect the shoot biomass. Both single fungus and combined inoculation decreased plant height (7–17%), but increased stem branching numbers (13–34%). However, fungal inoculation influenced the root length and surface area depending on their species and combinations, with the greatest benefits occurring on S. kiliense inoculation alone and its co-inoculation with Monosporascus sp. (109% and 61%; 54% and 42%). Although A. chlamydospora and co-inoculations with S. kiliense and Monosporascus sp. also appeared to promote root growth, these inoculations resulted in obvious soil acidification. Despite no observed root growth promotion, Monosporascus sp. associated with its combined inoculations maximally facilitated soil organic carbon accumulation. However, noticeably, combined inoculation of the three species had no significant effects on root length, surface area, and biomass, but promoted rhizospheric fungal diversity and abundance most, with Sordariomycetes being the dominant fungal group. This indicates the response of plant growth to fungal inoculation may be different from that of the rhizospheric fungal community. Structural equation modeling also demonstrated that fungal inoculation significantly influenced the interactions among the growth of A. adsurgens, soil factors, and rhizospheric fungal groups. Our findings suggest that, based on species-specific and combinatorial effects, endophytic fungi enhanced the plant root growth, altered soil nutrients, and facilitated rhizospheric fungal community, possibly contributing to desert plant performance and ecological adaptability. These results will provide the basis for evaluating the potential application of fungal inoculants for developing sustainable management for desert ecosystems.

Phosphorus acquisition strategies of arbuscular mycorrhizal and ectomycorrhizal trees in subtropical plantations

AbstractTrees form symbioses with different fungi to exploit soil nutrients, such as phosphorus (P). There is no precise information about the exact strategies by which arbuscular mycorrhizae (AM) and ectomycorrhizae (EM) species facilitate P acquisition and thereby regulate soil P availability in the P‐limited subtropical forests. We investigated the plant traits and rhizosphere soil properties related to the P acquisition strategies of seven AM and seven EM tree species in a subtropical plantation in China. The available P content, which was related to acid phosphomonoesterase activity, was higher in the rhizosphere soils of the AM trees than in those of the EM trees. The higher P content in the absorptive fine roots indicated that the AM trees absorbed more P from the soil than the EM trees. The leaf P adsorption efficiency indicated that AM trees resorbed more aboveground P than EM trees. Results from structural equation modelling demonstrated that AM trees were dominated by bacteria, which contributed to the low pH, while EM trees were dominated by ectomycorrhizal and saprophytic fungi that secreted acid phosphomonoesterase to mine P in the rhizosphere soil. The AM trees had higher mycorrhizal colonisation rates than the EM trees, while the EM trees had higher specific root lengths than the AM trees, which suggests that the AM trees tended to depend on mycorrhizae, while EM trees tended to depend on roots, to scavenge P from soil. Our findings suggest that, to influence the P availability and alleviate P deficiencies, the AM trees resorbed more P aboveground and mined and scavenged more P belowground than the EM trees.Highlights P availability was higher in the rhizospheres of AM trees than EM trees. AM trees resorbed more aboveground P than EM trees. AM trees mined soil P mainly by decreasing pH, whereas EM trees by secreting ACP. AM trees depended more on mycorrhizae, whereas EM trees on roots, scavenging soil P.