Application of a microbial consortium improves the growth of Camellia sinensis and influences the indigenous rhizosphere bacterial communities

Green manure (Ophiopogon japonicus) cover promotes tea plant growth by regulating soil carbon cycling

Introduction

In mountainous tea plantations, which are the primary mode of tea cultivation in China, issues such as soil erosion and declining soil fertility are particularly severe. Although green manure cover is an effective agricultural measure for restoring soil fertility, its application in mountainous tea plantations has been relatively understudied.

Methods

This study investigated the effects of continuous green manure cover using the slope-protecting plant Ophiopogon japonicus on tea plant growth and soil microbial community structure. We implemented three treatments: 1 year of green manure coverage, 2 years of coverage, and a control, to study their effects on tea plant growth, soil physicochemical properties, and soil bacterial and fungal communities.

Results

Results demonstrate that green manure coverage significantly promote the growth of tea plants, enhanced organic matter and pH levels in soil, and various enzyme activities, including peroxidases and cellulases. Further functional prediction results indicate that green manure coverage markedly promoted several carbon cycling functions in soil microbes, including xylanolysis, cellulolysis, degradation of aromatic compounds, and saprotrophic processes. LEfSe analysis indicated that under green manure cover, the soil tends to enrich more beneficial microbial communities with degradation functions, such as Sphingomonas, Sinomonas, and Haliangium (bacteria), and Penicillium, Apiotrichum, and Talaromyce (fungi). In addition. Random forest and structural equation models indicated that carbon cycling, as a significant differentiating factor, has a significant promoting effect on tea plant growth.

Discussion

In the management practices of mountainous tea plantations, further utilizing slope-protecting plants as green manure can significantly influence the soil microbial community structure and function, enriching microbes involved in the degradation of organic matter and aromatic compounds, thereby positively impacting tea tree growth and soil nutrient levels.

Construction of artificial microbial consortia for efficient degradation of chicken feathers and optimization of degradation conditions

Microbes within a consortium exhibit a synergistic interaction, enhancing their collective capacity to perform functions more effectively than a single species, especially in the degradation of keratin-rich substrates. To achieve a more stable and efficient breakdown of chicken feathers, a comprehensive screening of over 9,000 microbial strains was undertaken. This meticulous selection process identified strains with the capability to degrade keratin effectively. Subsequently, antagonistic tests were conducted to isolate strains of fungi and bacteria that were non-antagonistic, which were then used to form the artificial microbial consortia. The optimal fermentation conditions for the keratinophilic microbial consortia were determined through the optimization of response surface methodology. The results revealed that 11 microbial strains-comprising of 4 fungi and 7 bacteria-were particularly proficient in degrading chicken feathers. The artificially constructed microbial consortia (AMC) comprised two bacterial strains and one fungal strain. The optimal conditions for feathers degradation were identified as a 10 g/L concentration of chicken feathers, a 2.6% microbial inoculation volume and a fermentation fluid pH of 9. Under these conditions, the degradation rate for chicken feathers reached a significant 74.02%, representing an 11.45% increase over the pre-optimization rate. The AMC developed in this study demonstrates the potential for efficient and economical process of livestock and poultry feathers. It provides innovative insights and a theoretical foundation for tackling the challenging degradation of keratin-rich materials. Furthermore, this research lays the groundwork for the separation and purification of keratins, as well as the development of novel proteases, which could have profound implications for a range of applications.

Elucidating the interaction of rhizosphere microorganisms and environmental factors influencing the quality of Polygonatum kingianum Coll. et Hemsl

Polygonatum kingianum Collett & Hemsl., is one of the most important traditional Chinese medicines in China. The purpose of this study is to investigate the relationship between herb quality and microbial-soil variables, while also examining the composition and structure of the rhizosphere microbial community in Polygonatum kingianum, the ultimate goal is to provide a scientific approach to enhancing the quality of P. kingianum. Illumina NovaSeq technology unlocks comprehensive genetic variation and biological functionality through high-throughput sequencing. And in this study it was used to analyze the rhizosphere microbial communities in the soils of five P. kingianum planting areas. Conventional techniques were used to measure the organic elements, pH, and organic matter content. The active ingredient content of P. kingianum was identified by High Performance Liquid Chromatography (HPLC) and Colorimetry. A total of 12,715 bacterial and 5487 fungal Operational Taxonomic Units (OTU) were obtained and taxonomically categorized into 81 and 7 different phyla. Proteobacteria, Bacteroidetes, and Acidobacteriae were the dominant bacterial phyla Ascomycota and Basidiomycota were the dominat fungal phyla. The key predictors for bacterial community structure included hydrolysable nitrogen and available potassium, while for altering fungal community structure, soil organic carbon content (OCC), total nitrogen content (TNC), and total potassium content (TPOC) were the main influencing factors. Bryobacter and Candidatus Solibacter may indirectly increase the polysaccharide content of P. kingianum, and can be developed as potential Plant Growth Promoting Rhizobacteria (PGPR). This study has confirmed the differences in the soil and microorganisms of different origins of P. kingianum, and their close association with its active ingredients. And it also broadens the idea of studying the link between plants and microorganisms.

Rhodopseudomonas palustris shapes bacterial community, reduces Cd bioavailability in Cd contaminated flooding paddy soil, and improves rice performance

Photosynthetic bacteria (PSB) are suitable to live and remediate cadmium (Cd) in the slightly oxygenated or anaerobic flooding paddy field. However, there is currently limited study on the inhibition of Cd accumulation in rice by PSB, and the relevant mechanisms has yet to be elucidated. In the current study, we firstly used Rhodopseudomonas palustris SC06 (a typical PSB) as research target and combined physiology, biochemistry, microbiome and metabolome to evaluate the mechanisms of remeding Cd pollution in paddy field and inhibiting Cd accumulation in rice. Microbiome analysis results revealed that intensive inoculation with R. palustris SC06 successfully survived and multiplied in flooding paddy soil, and significantly increased the relatively abundance of anaerobic bacteria including Desulfobacterota, Anaerolineaceae, Geobacteraceae, and Gemmatimonadaceae by 46.40 %, 45.00 %, 50.12 %, and 21.30 %, respectively. Simultaneously, the structure of microbial community was regulated to maintain relative stability in the rhizosphere soil of rice under Cd stress. In turn, these bacteria communities reduced bioavailable Cd and enhanced residual Cd in soil, and induced the upregulation of sugar and organic acids in the rice roots, which further inhibited Cd uptake in rice seedlings, and dramatically improved the photosynthetic efficiency in the leaves and the activities of antioxidative enzymes in the roots. Finally, Cd content of the roots, stems, leaves, and grains significantly decreased by 38.14 %, 69.10 %, 83.40 %, and 37.24 % comparing with the control, respectively. This study provides a new strategy for the remediation of Cd-contaminated flooding paddy fields and the safe production of rice.

Trichoderma spp. promotes ginseng biomass by influencing the soil microbial community

Introduction

Ginseng (Panax ginseng C.A. Meyer) has multiple effects on human health; however, soil degradation seriously affects its yield. Trichoderma spp. play an important role in improving plant biomass by influencing the soil environment. Therefore, it is necessary to screen efficient Trichoderma strains that can increase ginseng biomass and determine their mechanisms.

Methods

Herein, we selected six Trichoderma species (T. brevicompactum, T. velutinum, T. viridescens, T. atroviride, T. koningiopsis, and T. saturnisporum) isolated from ginseng rhizosphere soil, and evaluated their growth promoting effects on ginseng and their influence on the microbiome and chemical attributes of the ginseng rhizosphere soil.

Results

Except for T. saturnisporum (F), compared with the control, the other five species increased ginseng biomass. In terms of chemical properties, the pH value, available potassium content, and available phosphorus content in the ginseng rhizosphere soil increased by 1.16-5.85%, 0.16-14.03%, and 3.92-38.64%, respectively, after root irrigation with spores of Trichoderma species. For the soil microbiome, fungal Chao1 and Ace richness indices decreased. Application of Trichoderma enhanced the relative level of Proteobacteria, but reduced the relative level of Ascomycota. At the genus level, application of Trichoderma enhanced the relative levels of Sphingomonas, Blastomonas, and Trichoderma, but reduced the relative level of Fusarium. Available K and available P were the most important elements that affected the structure of the bacterial community, while total K was the most influential element for the structure of the fungal community structure.

Conclusion

The results indicated that the application of Trichoderma spp. could increase soil nutrients and regulate the structure and composition of the soil microbial community, thereby enhancing the biomass of ginseng. The results will provide guidance for soil improvement in ginseng cultivation.

Bacterial wilt affects the structure and assembly of microbial communities along the soil-root continuum

BACKGROUND

Beneficial root-associated microbiomes play crucial roles in enhancing plant growth and suppressing pathogenic threats, and their application for defending against pathogens has garnered increasing attention. Nonetheless, the dynamics of microbiome assembly and defense mechanisms during pathogen invasion remain largely unknown. In this study, we aimed to investigate the diversity and assembly of microbial communities within four niches (bulk soils, rhizosphere, rhizoplane, and endosphere) under the influence of the bacterial plant pathogen Ralstonia solanacearum.

RESULTS

Our results revealed that healthy tobacco plants exhibited more diverse community compositions and more robust co-occurrence networks in root-associated niches compared to diseased tobacco plants. Stochastic processes (dispersal limitation and drift), rather than determinism, dominated the assembly processes, with a higher impact of drift observed in diseased plants than in healthy ones. Furthermore, during the invasion of R. solanacearum, the abundance of Fusarium genera, a known potential pathogen of Fusarium wilt, significantly increased in diseased plants. Moreover, the response strategies of the microbiomes to pathogens in diseased and healthy plants diverged. Diseased microbiomes recruited beneficial microbial taxa, such as Streptomyces and Bacilli, to mount defenses against pathogens, with an increased presence of microbial taxa negatively correlated with the pathogen. Conversely, the potential defense strategies varied across niches in healthy plants, with significant enrichments of functional genes related to biofilm formation in the rhizoplane and antibiotic biosynthesis in the endosphere.

CONCLUSION

Our study revealed the varied community composition and assembly mechanism of microbial communities between healthy and diseased tobacco plants along the soil-root continuum, providing new insights into niche-specific defense mechanisms against pathogen invasions. These findings may underscore the potential utilization of different functional prebiotics to enhance plants' ability to fend off pathogens.

A Review on Rhizosphere Microbiota of Tea Plant (Camellia sinensis L): Recent Insights and Future Perspectives

Rhizosphere microbial colonization of the tea plant provides many beneficial functions for the host, But the factors that influence the composition of these rhizosphere microbes and their functions are still unknown. In order to explore the interaction between tea plants and rhizosphere microorganisms, we summarized the current studies. First, the review integrated the known rhizosphere microbial communities of tea tree, including bacteria, fungi, and arbuscular mycorrhizal fungi. Then, various factors affecting tea rhizosphere microorganisms were studied, including: endogenous factors, environmental factors, and agronomic practices. Finally, the functions of rhizosphere microorganisms were analyzed, including (a) promoting the growth and quality of tea trees, (b) alleviating biotic and abiotic stresses, and (c) improving soil fertility. Finally, we highlight the gaps in knowledge of tea rhizosphere microorganisms and the future direction of development. In summary, understanding rhizosphere microbial interactions with tea plants is key to promoting the growth, development, and sustainable productivity of tea plants.

Microplastics reduced bioavailability and altered toxicity of phenanthrene to maize (Zea mays L.) through modulating rhizosphere microbial community and maize growth

Due to its large specific surface area and great hydrophobicity, microplastics can adsorb polycyclic aromatic hydrocarbons (PAHs), affecting the bioavailability and the toxicity of PAHs to plants. This study aimed to evaluate the effects of D550 and D250 (with diameters of 550 μm and 250 μm) microplastics on phenanthrene (PHE) removal from soil and PHE accumulation in maize (Zea mays L.). Moreover, the effects of microplastics on rhizosphere microbial community of maize grown in PHE-contaminated soil would also be determined. The results showed that D550 and D250 microplastics decreased the removal of PHE from soil by 6.5% and 2.7% and significantly reduced the accumulation of PHE in maize leaves by 64.9% and 88.5%. Interestingly, D550 microplastics promoted the growth of maize and enhanced the activities of soil protease and alkaline phosphatase, while D250 microplastics significantly inhibited the growth of maize and decreased the activities of soil invertase, alkaline phosphatase and catalase, in comparison with PHE treatment. In addition, microplastics changed the rhizosphere soil microbial community and reduced the relative abundance of PAHs degrading bacteria (Pseudomonas, Massilia, Proteobacteria), which might further inhibit the removal of PHE from soil. This study provided a new perspective for evaluating the role of microplastics on the bioavailability of PHE to plants and revealing the combined toxicity of microplastics and PHE to soil microcosm and plant growth.

Commonalities between the Atacama Desert and Antarctica rhizosphere microbial communities

Plant-microbiota interactions have significant effects on plant growth, health, and productivity. Rhizosphere microorganisms are involved in processes that promote physiological responses to biotic and abiotic stresses in plants. In recent years, the interest in microorganisms to improve plant productivity has increased, mainly aiming to find promising strains to overcome the impact of climate change on crops. In this work, we hypothesize that given the desertic environment of the Antarctic and the Atacama Desert, different plant species inhabiting these areas might share microbial taxa with functions associated with desiccation and drought stress tolerance. Therefore, in this study, we described and compared the composition of the rhizobacterial community associated with Deschampsia antarctica (Da), Colobanthus quitensis (Cq) from Antarctic territories, and Croton chilensis (Cc), Eulychnia iquiquensis (Ei) and Nicotiana solanifolia (Ns) from coastal Atacama Desert environments by using 16S rRNA amplicon sequencing. In addition, we evaluated the putative functions of that rhizobacterial community that are likely involved in nutrient acquisition and stress tolerance of these plants. Even though each plant microbial rhizosphere presents a unique taxonomic pattern of 3,019 different sequences, the distribution at the genus level showed a core microbiome with a higher abundance of Haliangium, Bryobacter, Bacillus, MND1 from the Nitrosomonadaceae family, and unclassified taxa from Gemmatiamonadaceae and Chitinophagaceae families in the rhizosphere of all samples analyzed (781 unique sequences). In addition, species Gemmatirosa kalamazoonesis and Solibacter usitatus were shared by the core microbiome of both Antarctic and Desert plants. All the taxa mentioned above had been previously associated with beneficial effects in plants. Also, this microbial core composition converged with the functional prediction related to survival under harsh conditions, including chemoheterotrophy, ureolysis, phototrophy, nitrogen fixation, and chitinolysis. Therefore, this study provides relevant information for the exploration of rhizospheric microorganisms from plants in extreme conditions of the Atacama Desert and Antarctic as promising plant growth-promoting rhizobacteria.

Potential relevance between soybean nitrogen uptake and rhizosphere prokaryotic communities under waterlogging stress

Waterlogging in soil can limit the availability of nitrogen to plants by promoting denitrification and reducing nitrogen fixation and nitrification. The root-associated microorganisms that determine nitrogen availability at the root-soil interface can be influenced by plant genotype and soil type, which potentially alters the nitrogen uptake capacity of plants in waterlogged soils. In a greenhouse experiment, two soybean genotypes with contrasting capacities to resist waterlogging stress were grown in Udic Argosol and Haplic Alisol soils with and without waterlogging, respectively. Using isotope labeling, high-throughput amplicon sequencing and qPCR, we show that waterlogging negatively affects soybean yield and nitrogen absorption from fertilizer, atmosphere, and soil. These effects were soil-dependent and more pronounced in the waterlogging-sensitive than tolerant genotype. The tolerant genotype harbored more ammonia oxidizers and less nitrous oxide reducers. Anaerobic, nitrogen-fixing, denitrifying and iron-reducing bacteria such as Geobacter/Geomonas, Sphingomonas, Candidatus Koribacter, and Desulfosporosinus were proportionally enriched in association with the tolerant genotype under waterlogging. These changes in the rhizosphere microbiome might ultimately help the plant to improve nitrogen uptake under waterlogged, anoxic conditions. This research contributes to a better understanding of the adaptability of soybean genotypes under waterlogging stress and might help to formulate fertilization strategies that improve nitrogen use efficiency of soybean. Schematic representation of the effects of waterlogging on nitrogen uptake and rhizosphere microbiota in dependence of soil type and soybean genotype.

Enhancing plant growth promoting rhizobacterial activities through consortium exposure: A review

Plant Growth Promoting Rhizobacteria (PGPR) has gained immense importance in the last decade due to its in-depth study and the role of the rhizosphere as an ecological unit in the biosphere. A putative PGPR is considered PGPR only when it may have a positive impact on the plant after inoculation. From the various pieces of literature, it has been found that these bacteria improve the growth of plants and their products through their plant growth-promoting activities. A microbial consortium has a positive effect on plant growth-promoting (PGP) activities evident by the literature. In the natural ecosystem, rhizobacteria interact synergistically and antagonistically with each other in the form of a consortium, but in a natural consortium, there are various oscillating environmental conditions that affect the potential mechanism of the consortium. For the sustainable development of our ecological environment, it is our utmost necessity to maintain the stability of the rhizobacterial consortium in fluctuating environmental conditions. In the last decade, various studies have been conducted to design synthetic rhizobacterial consortium that helps to integrate cross-feeding over microbial strains and reveal their social interactions. In this review, the authors have emphasized covering all the studies on designing synthetic rhizobacterial consortiums, their strategies, mechanism, and their application in the field of environmental ecology and biotechnology.

A photosynthetic bacterial inoculant exerts beneficial effects on the yield and quality of tomato and affects bacterial community structure in an organic field

Plant growth-promoting rhizobacteria (PGPR) are microorganisms that promote plant health and play a critical role in sustainable agriculture. As a PGPR, Rhodopseudomonas palustris strain PS3, when applied as a microbial inoculant, exhibited beneficial effects on a variety of crops. In this study, we investigated the effects of PS3 on tomato growth, soil properties, and soil microbiota composition in an organic field. The results demonstrated that PS3 inoculation significantly improved the yield of marketable tomato fruit (37%) and the postharvest quality (e.g., sweetness, taste, vitamin C, total phenolic compounds, and lycopene). Additionally, soil nutrient availability (35–56%) and enzymatic activities (13–62%) also increased. We detected that approximately 10⁷ CFU/g soil of R. palustris survived in the PS3-treated soil after harvest. Furthermore, several bacterial genera known to be associated with nutrient cycling (e.g., Dyella, Novosphingobium, Luteimonas, Haliangium, and Thermomonas) had higher relative abundances (log2 fold change >2.0). To validate the results of the field experiment, we further conducted pot experiments with field-collected soil using two different tomato cultivars and obtained consistent results. Notably, the relative abundance of putative PGPRs in the genus Haliangium increased with PS3 inoculation in both cultivars (1.5 and 34.2%, respectively), suggesting that this genus may have synergistic interactions with PS3. Taken together, we further demonstrated the value of PS3 in sustainable agriculture and provided novel knowledge regarding the effects of this PGPR on soil microbiota composition.

Soil bacterial communities of three types of plants from ecological restoration areas and plant-growth promotional benefits of Microbacterium invictum (strain X-18)

Microbial-assisted phytoremediation promotes the ecological restoration of high and steep rocky slopes. To determine the structure and function of microbial communities in the soil in response to changes in soil nutrient content, the bacterial communities of rhizospheric soil from three types of plants, i.e., Robinia pseudoacacia, Pinus massoniana, and Cynodon dactylon, were analyzed using Illumina sequencing technology. High-quality sequences were clustered at the 97% similarity level. The dominant genera were found to be RB41, Gemmatimonas, Sphingomonas, Bradyrhizobium, and Ellin6067. The Tukey HSD (honestly significant difference) test results showed that the abundance of RB41 and Gemmatimonas were significantly different among three types of plants (p < 0.01). The relative abundances of RB41 (13.32%) and Gemmatimonas (3.36%) in rhizospheric soil samples from R. pseudoacacia were significantly higher than that from P. massoniana (0.16 and 0.35%) and C. dactylon (0.40 and 0.82%), respectively. The soil chemical properties analyses suggested that significant differences in rhizospheric soil nutrient content among the three plant types. Especially the available phosphorus, the content of it in the rhizospheric soil of R. pseudoacacia was about 280% (P. massoniana) and 58% (C. dactylon) higher than that of the other two plants, respectively. The soil bacterial communities were further studied using the correlation analysis and the Tax4Fun analysis. A significant and positive correlation was observed between Gemmatimonas and soil nutrient components. Except total nitrogen, the positive correlation between Gemmatimonas and other soil nutrient components was above 0.9. The outcomes of these analyses suggested that Gemmatimonas could be the indicator genus in response to changes in the soil nutrient content. Besides, the genes involved in metabolism were the major contributor to soil nutrients. This study showed that soil nutrients affect the soil bacterial community structure and function. In addition, pot experiments showed that Microbacterium invictum X-18 isolated from the rhizospheric soil of R. pseudoacacia significantly improved soil nutrient content and increased R. pseudoacacia growth. A significant increase in the numbers of nodules of R. pseudoacacia and an increase of 28% in plant height, accompanied by an increase of 94% in available phosphorus was measured in the M. invictum X-18 treatment than the control treatment.

Design and validation of cyanobacteria-rhizobacteria consortia for tomato seedlings growth promotion

The use of rhizobacteria provide great benefits in terms of nitrogen supply, suppression of plant diseases, or production of vitamins and phytohormones that stimulate the plant growth. At the same time, cyanobacteria can photosynthesize, fix nitrogen, synthesize substances that stimulate rhizogenesis, plant aerial growth, or even suppose an extra supply of carbon usable by heterotrophic bacteria, as well as act as biological control agents, give them an enormous value as plant growth promoters. The present study focused on the in vitro establishment of consortia using heterotrophic bacteria and cyanobacteria and the determination of their effectiveness in the development of tomato seedlings. Microbial collection was composed of 3 cyanobacteria (SAB-M612 and SAB-B866 belonging to Nostocaceae Family) and GS (unidentified cyanobacterium) and two phosphate and potassium solubilizing heterotrophic bacteria (Pseudomonas putida-BIO175 and Pantoea cypripedii-BIO175). The results revealed the influence of the culture medium, incubation time and the microbial components of each consortium in determining their success as biofertilizers. In this work, the most compatible consortia were obtained by combining the SAB-B866 and GS cyanobacteria with either of the two heterotrophic bacteria. Cyanobacteria GS promoted the growth of both rhizobacteria in vitro (increasing logarithmic units when they grew together). While Cyanobacteria SAB-B866 together with both rhizobacteria stimulated the growth of tomato seedlings in planta, leading to greater aerial development of the treated seedlings. Parameters such as fresh weight and stem diameter stood out in the plants treated with the consortia (SAB-B866 and both bacteria) compared to the untreated plants, where the values doubled. However, the increase was more discrete for the parameters stem length and number of leaves. These results suggest that the artificial formulation of microbial consortia can have positive synergistic effects on plant growth, which is of enormous agro-biotechnological interest.

Combined effects of oxytetracycline and microplastic on wheat seedling growth and associated rhizosphere bacterial communities and soil metabolite profiles

The widespread application of antibiotics and plastic films in agriculture leads to new characteristics of soil pollution with the coexistence of antibiotics and microplastics. However, their combined effects on wheat seedling growth and associated rhizosphere bacterial communities and soil metabolite profiles remain unclear. Here, in the potted experiment, wheat was treated with individual oxytetracycline (0, 5.0, 50.0, and 150.0 mg kg^-1) and the combination of oxytetracycline and polyethylene microplastic (0.2%). Results showed that 150 mg kg^-1 oxytetracycline combined with microplastic significantly reduced the biomass and height of the plant. Compared with CK, all the treatments exposed to the combination of oxytetracycline and polyethylene microplastic significantly promoted carotenoid content and peroxidase activity in wheat leaves. Soil dehydrogenase and urease activities were more sensitive to current pollutant exposure than sucrase activity. Oxytetracycline (150 mg kg^-1) alone and in combination with polyethylene significantly decreased the abundances of certain genera belonging to plant growth-promoting rhizobacteria (PGPR) in soil, such as Arthrobacter, Gemmatimonas, Massilia, and Sphingomonas. Combined exposure of 150 mg kg^-1 oxytetracycline and polyethylene microplastic significantly altered multiple metabolites including organic acids and sugars. Network analysis indicated that co-exposure of 150 mg kg^-1 oxytetracycline and microplastic may affect the colonization and succession of PGPR by regulating soil metabolites, thereby indirectly inhibiting wheat seedling growth. The results help to elucidate the potential mechanisms of phytotoxicity of the combination of oxytetracycline and polyethylene microplastic.

Inter-Genera Colonization of Ocimum tenuiflorum Endophytes in Tomato and Their Complementary Effects on Na+/K+ Balance, Oxidative Stress Regulation, and Root Architecture Under Elevated Soil Salinity

Endophytic bacilli of ethano-botanical plant Ocimum tenuiflorum were screened for salt stress-alleviating traits in tomato. Four promising O. tenuiflorum endophytes (Bacillus safensis BTL5, Bacillus haynesii GTR8, Bacillus paralicheniformis GTR11, and Bacillus altitudinis GTS16) were used in this study. Confocal scanning laser microscopic studies revealed the inter-genera colonization of O. tenuiflorum endophytes in tomato plants, giving insights for widening the applicability of potential endophytes to other crops. Furthermore, in a pot trial under 150 mM NaCl concentration, the inoculated endophytes contributed in reducing salt toxicity and improving recovery from salt-induced oxidative stress by different mechanisms. Reduction in reactive oxygen species (ROS) (sub-cellular H₂O₂ and superoxide) accumulation was observed besides lowering programmed cell death and increasing chlorophyll content. Endophyte inoculation supplemented the plant antioxidant enzyme system via the modulation of enzymatic antioxidants, viz., peroxidase, ascorbate peroxidase, superoxide dismutase, and catalase, apart from increasing proline and total phenolics. Antioxidants like proline have dual roles of antioxidants and osmoregulation, which might also have contributed to improved water relation under elevated salinity. Root architecture, viz., root length, projection area, surface area, average diameter, tips, forks, crossings, and the number of links, was improved upon inoculation, indicating healthy root growth and enhanced nutrient flow and water homeostasis. Regulation of Na⁺/K⁺ balance and water homeostasis in the plants were also evident from the modulation in the expression of abiotic stress-responsive genes, viz., LKT1, NHX1, SOS1, LePIP2, SlERF16, and SlWRKY39. Shoot tissues staining with light-excitable Na⁺ indicator Sodium Green^TM Tetra (tetramethylammonium) salt showed low sodium transport and accumulation in endophyte-inoculated plants. All four endophytes exhibited different mechanisms for stress alleviation and indicated complementary effects on plant growth. Furthermore, this could be harnessed in the form of a consortium for salt stress alleviation. The present study established inter-genera colonization of O. tenuiflorum endophytes in tomato and revealed its potential in maintaining Na⁺/K⁺ balance, reducing ROS, and improving root architecture under elevated salinity.

Exploring tea (Camellia sinensis) microbiome: Insights into the functional characteristics and their impact on tea growth promotion

Tea (Camellia sinensis) is perhaps the most popular and economic beverage in the globe due to its distinctive fragrance and flavour generated by the leaves of commercially farmed tea plants. The tea microbiome has now become a prominent topic of attention for microbiologists in recent years as it can help the plant for soil nutrient acquisition as well as stress management. Tea roots are well known to be colonized by Arbuscular Mycorrhizal Fungi (AMF) and many other beneficial microorganisms that boost the growth of the tea which increases leaf amino acids, protein, caffeine, and polyphenols content. One of the primary goals of rhizosphere microbial biology is to aid in the establishment of agricultural systems that provide high quantities of the food supply while minimizing environmental effects and anthropogenic activities. The present review is aimed to highlight the importance of microbes (along with their phylogeny) derived from cultivated and natural tea rhizospheres to understand the role of AMF and rhizospheric bacterial population to improve plant growth, enhancement of tea quality, and protecting tea plants from pathogens. This review also summarizes recent advances in our understanding of the diversity and profile of tea-associated bacteria. The utilization of the tea microbiome as a "natural resource" could provide holistic development in tea cultivation to ensure sustainability, highlighting knowledge gaps and future microbiome research.

Inoculation with Mycorrhizal Fungi and Irrigation Management Shape the Bacterial and Fungal Communities and Networks in Vineyard Soils

Vineyard-living microbiota affect grapevine health and adaptation to changing environments and determine the biological quality of soils that strongly influence wine quality. However, their abundance and interactions may be affected by vineyard management. The present study was conducted to assess whether the vineyard soil microbiome was altered by the use of biostimulants (arbuscular mycorrhizal fungi (AMF) inoculation vs. non-inoculated) and/or irrigation management (fully irrigated vs. half irrigated). Bacterial and fungal communities in vineyard soils were shaped by both time course and soil management (i.e., the use of biostimulants and irrigation). Regarding alpha diversity, fungal communities were more responsive to treatments, whereas changes in beta diversity were mainly recorded in the bacterial communities. Edaphic factors rarely influence bacterial and fungal communities. Microbial network analyses suggested that the bacterial associations were weaker than the fungal ones under half irrigation and that the inoculation with AMF led to the increase in positive associations between vineyard-soil-living microbes. Altogether, the results highlight the need for more studies on the effect of management practices, especially the addition of AMF on cropping systems, to fully understand the factors that drive their variability, strengthen beneficial microbial networks, and achieve better soil quality, which will improve crop performance.