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The importance of microbial root inhabitants for plant growth and health was recognized as early as 100 years ago. Recent insights reveal a close symbiotic relationship between plants and their associated microorganisms, and high structural and functional diversity within plant microbiomes. Plants provide microbial communities with specific habitats, which can be broadly categorized as the rhizosphere, phyllosphere, and endosphere. Plant-associated microbes interact with their host in essential functional contexts. They can stimulate germination and growth, help plants fend off disease, promote stress resistance, and influence plant fitness. Therefore, plants have to be considered as metaorganisms within which the associated microbes usually outnumber the cells belonging to the plant host. The structure of the plant microbiome is determined by biotic and abiotic factors but follows ecological rules. Metaorganisms are coevolved species assemblages. The metabolism and morphology of plants and their microbiota are intensively connected with each other, and the interplay of both maintains the functioning and fitness of the holobiont. Our study of the current literature shows that analysis of plant microbiome data has brought about a paradigm shift in our understanding of the diverse structure and functioning of the plant microbiome with respect to the following: (i) the high interplay of bacteria, archaea, fungi, and protists; (ii) the high specificity even at cultivar level; (iii) the vertical transmission of core microbiomes; (iv) the extraordinary function of endophytes; and (v) several unexpected functions and metabolic interactions. The plant microbiome should be recognized as an additional factor in experimental botany and breeding strategies. [ABSTRACT FROM AUTHOR]

Generally, plants are not considered as hosts for human and animal pathogens (HAP). The recent produce-associated outbreaks of food-borne diseases have drawn attention towards significant deficiencies in our understanding of the ecology of HAP, and their potential for interkingdom transfer. To examine the association of microorganisms classified as HAP with plants, we surveyed the presence and distribution of HAP bacterial taxa (henceforth HAPT, for brevity’s sake) in the endosphere of grapevine (Vitis vinifera L.) both in the plant stems and leaves. An enrichment protocol was used on leaves to detect taxa with very low abundance in undisturbed tissues. We used pyrosequencing and phylogenetic analyses of the 16S rDNA gene. We identified several HAPT, and focused on four genera (Propionibacterium, Staphylococcus, Clostridium, and Burkholderia). The majority of the bacterial sequences in the genus Propionibacterium, from grapevine leaf and stem, were identified as P. acnes. Clostridia were detected in leaves and stems, but their number was much higher in leaves after enrichment. HAPT were indentified both in leaves and wood of grapevines. This depicts the ability of these taxa to be internalized within plant tissues and maintain their population levels in a variety of environments. Our analysis highlighted the presence of HAPT in the grapevine endosphere and unexpected occurrence of these bacterial taxa in this atypical environment.

Hyperaccumulators are plants that can extract heavy metal ions from the soil and translocate those ions to the shoots, where they are sequestered and detoxified. Hyperaccumulation depends not only on the availability of mobilized metal ions in the soil, but also on the enhanced activity of metal transporters and metal chelators which may be provided by the plant or its associated microbes. The rhizobiome is captured by plant root exudates from the complex microbial community in the soil, and may colonize the root surface or infiltrate the root cortex. This community can increase the root surface area by inducing hairy root proliferation. It may also increase the solubility of metals in the rhizosphere and promote the uptake of soluble metals by the plant. The bacterial rhizobiome, a subset of specialized microorganisms that colonize the plant rhizosphere and endosphere, makes an important contribution to the hyperaccumulator phenotype. In this review, we discuss classic and more recent tools that are used to study the interactions between hyperaccumulators and the bacterial rhizobiome, and consider future perspectives based on the use of omics analysis and microscopy to study plant metabolism in the context of metal accumulation. Recent data suggest that metal-resistant bacteria isolated from the hyperaccumulator rhizosphere and endosphere could be useful in applications such as phytoextraction and phytoremediation, although more research is required to determine whether such properties can be transferred successfully to non-accumulator species. [ABSTRACT FROM AUTHOR]

• Microbiota and nutrients removal are studied in pilot-scale CWs with two HLRs. • HLR profoundly influences microbiota at the genus level and related removal efficiency. • The co-occurrence network shows microbiota becomes more complex under higher HLR. • A higher level of stochasticity is found in the microbiota under the higher HLR condition. • Pathogens invasion is observed in the endosphere and proved to be affected by HLR. Constructed wetland (CW) is an environment-friendly and low-cost technology for nutrients removal from domestic wastewater. For a well-tuned CW, hydraulic loading rate (HLR) is one of the critical factors, particularly under the challenging circumstance of more frequent heavy rainfall events brought by global warming. In this study, a comprehensive investigation was conducted to explore the influence of different HLRs on the CW's bulk substrate and root-associated microbiota aiming to yield new insight for CW management from a hybrid perspective of environmental microbiology and engineering science. The response of the microbial community and associated nutrients removal performance under different HLR settings were analyzed after a one-year operation. Results showed that the bulk substrate and rhizosphere genera involved in desulfurization and denitrification, such as Ferritrophicum, Sulfurimonas, and Sulfurisoma , were enriched in the higher HLR condition and associated with the higher total nitrogen (TN) and nitrate nitrogen (NO 3 −-N) removal compared to the lower HLR condition. Co-occurrence network analysis demonstrated a more complex network under the higher HLR condition. Besides, it was observed that more stochastic in microbial assembly under the higher HLR condition. Surprisingly, zoonotic pathogens were observed and showed a greater prevalence under the higher HLR condition, indicating the potential correlation between HLR and pathogen intrusion. Collectively, this study revealed that the microbiota could be significantly altered under different HLR conditions, thereby resulting in differences in nutrients removal performance. [Display omitted] [ABSTRACT FROM AUTHOR]

Old-growth Pseudotsuga menziesii var. menziesii forests produce complex environmental and spatial gradients along which biota assemble. Given this, it has been proposed that changes in the crown microenvironment are associated with different community assembly outcomes for needle fungi. Using high-throughput sequencing, the endophytic mycobiomes of needles were characterized for increasing ages of needles sampled along the boles of eight coastal Douglas-fir trees. Leveraging airborne light detection and ranging (LiDAR) data to create three-dimensional "point cloud" representations of tree crowns revealed that crown closure accounted for more fungal compositional variation than height in crown, and fungal richness and diversity were positively correlated with increasing crown closure. Supplementing the point clouds of each climbed tree with clouds from >5,000 randomly selected trees in the study area showed that fungal communities from closed portions of the crown were increasingly structured with needle age. These findings highlight the importance of the crown microenvironment in the development of foliar fungal communities for a foundation tree species. • LiDAR-derived crown closure accounts for more compositional variation than height. • The influence of crown closure on composition and richness depends on needle age. • The community structures of open and closed exposures diverge for older needles. [ABSTRACT FROM AUTHOR]

Outbreaks of acute oak decline (AOD) have been documented in England from 2006. Both species of native oaks (Quercus robur and Quercus petraea) are affected. To complement isolation efforts for identification of putative causative biotic agents and increase our understanding of bacteria associated with oak tissue, five sites in England were chosen for this study. Samples of outer bark, inner bark, sapwood and heartwood were taken from healthy oak and trees with symptoms at varying stages of the syndrome. Furthermore, larval galleries attributed to infestation with Agrilus biguttatus were included. After DNA extraction and amplification of the V3–V5 fragment of the bacterial 16S rRNA genes by pyrosequencing, the dataset was analyzed to identify patterns in bacterial communities in oak tissue samples with and without AOD symptoms at each site. The composition of bacterial communities differed greatly according to the site from which the samples were obtained. Within each site, the composition of the bacteria associated with symptomatic tissue varied between advanced stages of the syndrome and healthy tissue. Key players in healthy and symptomatic tissue were identified and included members of the Gammaproteobacteria related to Pseudomonas sp. or Brenneria goodwinii and members of the Firmicutes.

Generally, plants are not considered as hosts for human and animal pathogens (HAP). The recent produce-associated outbreaks of food-borne diseases have drawn attention towards significant deficiencies in our understanding of the ecology of HAP, and their potential for interkingdom transfer. To examine the association of microorganisms classified as HAP with plants, we surveyed the presence and distribution of HAP bacterial taxa (henceforth HAPT, for brevity's sake) in the endosphere of grapevine (Vitis vinifera L.) both in the plant stems and leaves. An enrichment protocol was used on leaves to detect taxa with very low abundance in undisturbed tissues. We used pyrosequencing and phylogenetic analyses of the 16S rDNA gene. We identified several HAPT, and focused on four genera (Propionibacterium, Staphylococcus, Clostridium, and Burkholderia). The majority of the bacterial sequences in the genus Propionibacterium, from grapevine leaf and stem, were identified as P. acnes. Clostridia were detected in leaves and stems, but their number was much higher in leaves after enrichment. HAPT were indentified both in leaves and wood of grapevines. This depicts the ability of these taxa to be internalized within plant tissues and maintain their population levels in a variety of environments. Our analysis highlighted the presence of HAPT in the grapevine endosphere and unexpected occurrence of these bacterial taxa in this atypical environment. [ABSTRACT FROM AUTHOR]

Metaproteomics is a powerful tool for the characterization of metabolism, physiology, and functional interactions in microbial communities, including plant-associated microbiota. However, the metaproteomic methods that have been used to study plant-associated microbiota are very laborious and require large amounts of plant tissue, hindering wider application of these methods. We optimized and evaluated different protein extraction methods for metaproteomics of plant-associated microbiota in two different plant species ( Arabidopsis and maize). Our main goal was to identify a method that would work with low amounts of input material (40 to 70 mg) and that would maximize the number of identified microbial proteins. We tested eight protocols, each comprising a different combination of physical lysis method, extraction buffer, and cell-enrichment method on roots from plants grown with synthetic microbial communities. We assessed the performance of the extraction protocols by liquid chromatography-tandem mass spectrometry-based metaproteomics and found that the optimal extraction method differed between the two species. For Arabidopsis roots, protein extraction by beating whole roots with small beads provided the greatest number of identified microbial proteins and improved the identification of proteins from gram-positive bacteria. For maize, vortexing root pieces in the presence of large glass beads yielded the greatest number of microbial proteins identified. Based on these data, we recommend the use of these two methods for metaproteomics with Arabidopsis and maize. Furthermore, detailed descriptions of the eight tested protocols will enable future optimization of protein extraction for metaproteomics in other dicot and monocot plants. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

Background: The endoluminal mechanical device SatiSphere is a new endoscopically implantable device designed to delay transit time of nutrients through the duodenum. It consists of a 1-mm nitinol wire with pigtail ends and several mesh spheres mounted along its course, released in the duodenum and gastric antrum to conform to the duodenal C loop configuration and thereby self-anchor. Methods: The objective is to test the safety, efficacy, and effect on body weight in a 2:1 randomized study, as well as incretin secretion in a subgroup. Results: Of 31 included cases (11 men, mean age 42.9 years, mean BMI 41.3 kg/m), 21 patients treated with endoscopic device insertion with scheduled device removal after 3 months were compared with 10 controls. In 10 of 21 patients, device migration occurred, in two cases necessitating emergency surgery, which led to termination of the trial. Weight loss after 3 months was 6.7, 4.6, and 2.2 kg in the groups completing therapy, all treatment cases using intention to treat (ITT) analysis and controls. Excess weight loss was significantly increased by endoluminal mechanical device insertion (18.4, 12.2, and 4.4 % in completers, ITT analysis group and controls; p = 0.02 for completers vs. controls). Measuring glucose, insulin, and glucagon-like peptide 1 (GLP-1) following a mixed-meal test with the device in place and after removal ( n = 7), the device delayed glucose absorption and insulin secretion and altered kinetics in GLP-1 levels. Conclusions: The device might be short-term effective in reducing body weight, which might be mediated through alterations in incretin metabolism. However, frequent device migration necessitates device modifications. [ABSTRACT FROM AUTHOR]

Bacterial root endophytes reside in a vast number of plant species as part of their root microbiome, with some being shown to positively influence plant growth. Endophyte community structure (species diversity: richness and relative abundances) within the plant is dynamic and is influenced by abiotic and biotic factors such as soil conditions, biogeography, plant species, microbe-microbe interactions and plant-microbe interactions, both at local and larger scales. Plant-growth-promoting bacterial endophytes (PGPBEs) have been identified, but the predictive success at positively influencing plant growth in field conditions has been limited. Concurrent to the development of modern molecular techniques, the goal of predicting an organism's ability to promote plant growth can perhaps be realized by more thorough examination of endophyte community dynamics. This paper reviews the drivers of endophyte community structure relating to plant growth promotion, the mechanisms of plant growth promotion, and the current and future use of molecular techniques to study these communities. [ABSTRACT FROM AUTHOR]

Background: The root-associated microbiome has been of keen research interest especially in the last decade due to the large potential for increasing overall plant performance in agricultural systems. Studies about spatio-temporal variation of the root-associated microbiome focused so far primarily on community-compositional changes of annual plants, while little is known about their perennial counterparts. The aim of this work was to get deep insight into the spatial patterns and temporal dynamics of the root associated microbiota of apple trees., Results: The bacterial community structure in rhizospheric soil and endospheric root material from orchard-grown apple trees was characterized based on 16S rRNA gene amplicon sequencing. At the small scale, the rhizosphere and endosphere bacterial communities shifted gradually with increasing root size diameter (PERMANOVA R 2 -values up to 0.359). At the larger scale, bulk soil heterogeneity introduced variation between tree individuals, especially in the rhizosphere microbiota, while the presence of a root pathogen was contributing to tree-to-tree variation in the endosphere microbiota. Moreover, the communities of both compartments underwent seasonal changes and displayed year-to-year variation (PERMANOVA R 2 -values of 0.454 and 0.371, respectively)., Conclusions: The apple tree root-associated microbiota can be spatially heterogeneous at field scale due to soil heterogeneities, which particularly influence the microbiota in the rhizosphere soil, resulting in tree-to-tree variation. The presence of pathogens can contribute to this variation, though primarily in the endosphere microbiota. Smaller-scale spatial heterogeneity is observed in the rhizosphere and endosphere microbiota related to root diameter, likely influenced by root traits and processes such as rhizodeposition. The microbiota is also subject to temporal variation, including seasonal effects and annual variation. As a consequence, responses of the tree root microbiota to further environmental cues should be considered in the context of this spatio-temporal variation., (© 2022. The Author(s).)

While the endosphere is a hotspot for close interactions between plants and microbes, the influence of different components of the root endosphere on microbiome composition are seldom explored. This study used the fleshy taprooted plant, American Ginseng (Panax quinquefolius) and the recently discovered beneficial microbe, Trichoderma atroviride strain HB20111, to provide insights into microbiome shifts across plant-soil compartment niches including the bulk soil, rhizosphere, epidermis, cortex and vascular tissue. Trichoderma impacted both plant growth and microbiome composition. The survival rate of ginseng plants significantly increased from 70.8% to 85.4%, following Trichoderma treatment while root biomass production increased by 1.2 to 1.5 times compared with the uninoculated control. Microbiome diversity gradually decreased in niches from the bulk soil outside the root toward the vascular tissue, indicating increased selection and suggesting the possibility of a Trichoderma -driven induced systemic or localized resistance. The significant reduction (P < 0.05) in relative abundance of ginseng bacterial pathogens at the cortex confirmed the biocontrol capability of strain HB20111. We conclude that application of Trichoderma can improve growth of American Ginseng and mediate endosphere microbiome composition, resulting in plant pathogen inhibition. • Trichoderma inoculation increased ginseng's survival rate and root biomass. • Trichoderma inoculation reduced ginseng bacterial pathogens. • Microbiome diversity decreased in niches from bulk soil toward the vascular tissue. • Niche filtering and Trichoderma inoculation mediate microbiome composition in root compartments. [ABSTRACT FROM AUTHOR]

Aims: Microbial communities that inhabit plants are crucial for plant survival and well-being including growth in stressful environments. The medicinal plant, Dendrobium officinale grows in the barren soils of the Danxia Habitat. However, the microbiome composition and functional potential for growth of this plant in this environment are still unexplored., Methods and Results: In this study, we analysed the taxonomic and functional diversity of the D. officinale Microbiome by metagenomic sequencing of both rhizosphere and endosphere samples. A total of 155 phyla, 122 classes, 271 orders, 620 families and 2194 genera were identified from all samples. The rhizospheric microbes (DXRh) were mainly composed of Proteobacteria and Acidobacteria, while Basidiomycota and Ascomycota were the most dominant phyla in root endosphere (DXRo) and stem endosphere (DXS), respectively. Most of the dominant microbial communities had been reported to have diverse functional potentials that can help plant growth and development in stressful and nutrient-deprived ecological environmental. These include plant growth promoting rhizobacteria (PGPR) such as Massilia, Pseudomonas, Bradyrhizobium, Klebsiella, Streptomyces, Leclercia, Paenibacillus, Frankia and Enterobacter in the DXRh, Tulasnella and Serendipita in the DXRo, Colletotrichum and Burkholderia in the DXS and Paraburkholderia, Rhizophagus and Acetobacter in endosphere. Analysis using the KEGG, eggNOG and CAZy databases showed that metabolic pathways such as carbohydrate metabolism, amino acid metabolism, energy metabolism, genetic information processing and environmental information processing are significantly abundant, which may be related to the survival, growth and development of D. officinale in a stressful environment., Conclusions: We speculated that the microbial community with diverse taxonomic structures and metabolic functions inhabiting in different niches of plants supports the survival and growth of D. officinale in the stressful environment of Danxia Habitat., Significance and Impact of the Study: This study provided an important data resource for microbes associated with D. officinale and theoretical foundation for further studies., (© 2022 Society for Applied Microbiology.)

Roots hold complex microbial communities at the soil-root interface, which can affect plant nutrition, growth, and health. Although the composition of plant microbiomes has been extensively described for various plant species and environments, little is known about the effect of wheat straw return (WSR) on the soybean root microbiota. We used Illumina-based 16S rRNA and ITS amplicon sequencing to track changes in bacterial and fungal microbiota in bulk soil and soybean rhizosphere, rhizoplane, s1and endosphere during the third and fourth years after implementing WSR in a wheat-soybean rotation system. The results revealed that WSR had a greater impact on fungal communities than bacterial communities, particularly in bulk soil, rhizosphere, and rhizoplane. WSR enriched the relative abundance of cellulose-degrading fungi (e.g., Acremonium , Trichoderma , and Myrmecridium , among which Trichoderma also had antimicrobial activity), saprotroph (e.g., Exophiala ), and nitrogen cycling bacteria (e.g., Chryseolinea ). Furthermore, WSR depleted the relative abundance of pathogenic fungi (e.g., Fusarium and Alternaria ). These data revealed for the first time that WSR had diverse effects on soybean root-associated microbial community composition, not only in soil but also in the rhizosphere, rhizoplane, and endosphere.

The effect of olive ( Olea europaea ) stem extract (OSE) on the viability of conidia of Verticillium dahliae , the causal agent of Verticillium wilt of olive (VWO), is not yet well understood. Thus, the aim of this study was to determine the influence of the olive genotype (cultivar resistance) and the interaction between olive cultivars and biocontrol treatments on the effect of OSE on conidial germination of V. dahliae by in vitro sensitivity tests. To this end, OSE from cultivars Frantoio, Arbequina, and Picual, respectively tolerant, moderately susceptible, and highly susceptible to V. dahliae , were tested alone or after treatments with biological control agents (BCAs) and commercial products efficient at reducing the progress of VWO. Aureobasidium pullulans strain AP08, Phoma sp. strain ColPat-375, and Bacillus amyloliquefaciens strain PAB-24 were considered as BCAs. Aluminium lignosulfonate (IDAI Brotaverd ® ), copper phosphite (Phoscuprico ® ), potassium phosphite (Naturfos ® ), and salicylic acid were selected as commercial products. Our results indicate that the influence of biological treatments against the pathogen depends on the genotype, since the higher the resistance of the cultivar, the lower the effect of the treatments on the ability of OSE to inhibit the germination of conidia. In 'Picual', the BCA B. amyloliquefaciens PAB024 and copper phosphite were the most effective treatments in inhibiting conidia germination by the OSE. This work represents a first approach to elucidate the role of cultivar and biological treatments in modifying the effect on the pathogen of the endosphere content of olive plants.

Sugarcane-legume intercropping systems can effectively control pests and diseases as well as improve the fertility and health of farmland soil. However, little is known about the response of bacterial abundance, diversity, and community composition in the rhizosphere and non-rhizosphere soils under the sugarcane-peanut farming system. A field experiment was conducted with two treatments: sugarcane monoculture and sugarcane-peanut intercropping to examine the response of sugarcane parameters and edaphic factors. We also deciphered bacterial abundance, diversity, and community composition in the root endosphere, rhizosphere, and bulk soil by leveraging Illumina sequencing to conduct the molecular characterization of the 16S rRNA gene and nitrogenase ( nifH ) gene. We observed that sugarcane-peanut intercropping exhibited the advantages of tremendously increasing cane stalk height, stalk weight, and millable stalk number/20 m, and edaphic factors, namely, pH (1.13 and 1.93), and available phosphorus exhibited a fourfold and sixfold increase (4.66 and 6.56), particularly in the rhizosphere and bulk soils, respectively. Our result also showed that the sugarcane-peanut intercropping system significantly increased the bacterial richness of the 16S rRNA gene sequencing data by 13.80 and 9.28% in the bulk soil and rhizosphere soil relative to those in the monocropping sugarcane system, respectively. At the same time, sugarcane intercropping with peanuts significantly increased the Shannon diversity of nitrogen-fixing bacteria in the sugarcane rhizosphere soil. Moreover, most edaphic factors exhibited a positive regularity effect on bacterial community composition under the intercropping system. A linear discriminant analysis with effect size analysis of the 16S rRNA sequencing data revealed that bacteria in the root endosphere of the intercropped cane proliferated profoundly, primarily occupied by Devosia , Rhizobiales , Myxococcales , Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium , Bradyrhizobium , and Sphingomonas . In conclusion, our findings demonstrated that sugarcane-peanut intercropping can enhance edaphic factors, sugarcane parameters, and bacterial abundance and diversity without causing adverse impacts on crop production and soil., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Pang, Fallah, Weng, Zhou, Tang, Tayyab, Liu, Liu, Xiao, Hu, Kan, Lin and Yuan.)

Despite growing evidence that plant growth-promoting bacteria can be used to improve crop vigor, a comparison of the different methods of delivery to determine which is optimal has not been published. An optimal inoculation method ensures that the inoculant colonizes the host plant so that its potential for plant growth-promotion is fully evaluated. The objective of this study was to compare the efficacy of three seed coating methods, seedling priming, and soil drench for delivering three bacterial inoculants to the sorghum rhizosphere and root endosphere. The methods were compared across multiple time points under axenic conditions and colonization efficiency was determined by quantitative polymerase chain reaction (qPCR). Two seed coating methods were also assessed in the field to test the reproducibility of the greenhouse results under non-sterile conditions. In the greenhouse seed coating methods were more successful in delivering the Gram-positive inoculant ( Terrabacter sp.) while better colonization from the Gram-negative bacteria ( Chitinophaga pinensis and Caulobacter rhizosphaerae ) was observed with seedling priming and soil drench. This suggested that Gram-positive bacteria may be more suitable for the seed coating methods possibly because of their thick peptidoglycan cell wall. We also demonstrated that prolonged seed coating for 12 h could effectively enhance the colonization of C. pinensis , an endophytic bacterium, but not the rhizosphere colonizing C. rhizosphaerae . In the field only a small amount of inoculant was detected in the rhizosphere. This comparison demonstrates the importance of using the appropriate inoculation method for testing different types of bacteria for their plant growth-promotion potential., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Chai, Futrell and Schachtman.)

The diversity of microbes associated with plant roots is in the order of tens of thousands of species. It is estimated that only 0.1-1.0% of the living bacteria present in soils can be cultured under standard conditions. The microbial marker-gene sequence data and the next-generation sequencing technologies have enabled systemic studies of root-associated microbiomes. Molecular techniques can be used to generate comprehensive taxonomic profiles of the microorganisms present in roots. The aim of this chapter is to provide a standard method for the obtention of rhizosphere and endosphere fractions, and a generic workflow of the Quantitative Insights Into Microbial Ecology version 2 (QIIME2) software to analysis of 16S rRNA marker-gene., (© 2022. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Poa annua (annual bluegrass) is one of the most ubiquitous grass species in the world. In isolated regions of maritime Antarctica, it has become an invasive organism threatening native tundra communities. In this study, we have explored and compared the rhizosphere and root-endosphere dwelling microbial community of P. annua specimens of maritime Antarctic and Central European origin in terms of bacterial phylogenetic diversity and microbial metabolic activity with a geochemical soil background. Our results show that the rhizospheric bacterial community was unique for each sampling site, yet the endosphere communities were similar to each other. However, key plant-associated bacterial taxa such as the Rhizobiaceae family were poorly represented in Antarctic samples, probably due to high salinity and heavy metal concentrations in the soil. Metabolic activity in the Antarctic material was considerably lower than in Central European samples. Antarctic root endosphere showed unusually high numbers of certain opportunistic bacterial groups, which proliferated due to low competition conditions. Thirteen bacterial families were recognized in this study to form a core microbiome of the P. annua root endosphere. The most numerous were the Flavobacteriaceae, suspected to be major contributors to the ecological success of annual bluegrass, especially in harsh, Antarctic conditions. [ABSTRACT FROM AUTHOR]

Plant-associated endophytic microorganisms are essential to developing successful strategies for sustainable agriculture. Grazing is an effective practice of grassland utilization through regulating multitrophic relationships in natural grasslands. This study was conducted for exploring the effects of grazing on the diversities and communities of bacteria and fungi presented in rhizosphere soils, roots, stems, and leaves of Leymus chinensis (L. chinensis), based on high-throughput sequencing. Grazing increased bacterial diversity but reduced fungal diversity in plant leaves. Further analysis confirmed that the abundance of Chloroflexi, Gemmatimonadota, Nitrospirota, Sordariales, and Pezizales in plant leaves was increased by grazing. The Bray–Curtis similarities of microbial communities in the endosphere were higher under grazing plots than non-grazing plots. Moreover, the bacterial communities were significantly correlated with ions, while the nutrient and negative ions exhibited strong influence on fungal communities. We concluded that grazing-induced changes of microbial diversities and communities in different compartments of a dominant perennial grass (L. chinensis) could be attributed to the nutrient and ion distribution in host plant. The current study highlights the importance of livestock in mediating diversities and communities of endophytic microbes, and will be useful for better understanding the complexity of multitrophic interactions in a grassland ecosystem. [ABSTRACT FROM AUTHOR]

Fire blight disease, caused by Erwinia amylovora, could damage rosaceous plants such as apples, pears, and raspberries. In this study, we designed to understand how E. amylovora affected other bacterial communities on apple rhizosphere; twig and fruit endosphere; and leaf, and fruit episphere. Limited studies on the understanding of the microbial community of apples and changes the community structure by occurrence of the fire blight disease were conducted. As result of these experiments, the infected trees had low species richness and operational taxonomic unit diversity when compared to healthy trees. Rhizospheric bacterial communities were stable regardless of infection. But the communities in endosphere and episphere were significanlty affected by E. amylovora infection. We also found that several metabolic pathways differ significantly between infected and healthy trees. In particular, we observed differences in sugar metabolites. The finding provides that sucrose metabolites are important for colonization of E. amylovora in host tissue. Our results provide fundamental information on the microbial community structures between E. amylovora infected and uninfected trees, which will contribute to developing novel control strategies for the fire blight disease.

Amaryllidaceae family comprises many crops of high market potential for the food and pharmaceutical industries. Nowadays, the utilization of plants as a source of bioactive compounds requires the plant/endophytic microbiome interactions, which affect all aspects of crop's quantity and quality. This review highlights the taxonomy, ecology, and bioactive chemicals synthesized by endophytic fungi isolated from plants of the Amaryllidaceae family with a focus on the detection of pharmaceutically valuable plant and fungi constituents. The fungal microbiome of Amaryllidaceae is species- and tissue-dependent, although dominating endophytes are ubiquitous and isolated worldwide from taxonomically different hosts. Root sections showed higher colonization as compared to bulbs and leaves through the adaptation of endophytic fungi to particular morphological and physiological conditions of the plant tissues. Fungal endophytes associated with Amaryllidaceae plants are a natural source of ecofriendly bioagents of unique activities, with special regard to those associated with Amarylloidae subfamily. The latter may be exploited as stimuli of alkaloids production in host tissues or can be used as a source of these compounds through in vitro synthesis. Endophytes also showed antagonistic potential against fungal, bacterial, and viral plant diseases and may find an application as alternatives to synthetic pesticides. Although Amaryllidaceae crops are cultivated worldwide and have great economic importance, the knowledge on their endophytic fungal communities and their biochemical potential has been neglected so far. [ABSTRACT FROM AUTHOR]

The plant vascular system has remained an underexplored niche despite its potential for hosting beneficial microbes. The aim of this work was to determine the origin of the microbial endophytes inhabiting grapevine. We focused on a single commercial vineyard in California over a two-year period and used an amplicon metagenomics approach to profile the bacterial (16S–V4) and fungal (ITS) communities of the microbiome across a continuum of six grapevine compartments: bulk soil, rhizosphere, root, cordon, cane and sap. Our data supported that roots are a bottleneck to microbial richness and that they are mostly colonized with soilborne microbes, including plant growth-promoting bacteria recruited by the host, but also saprophytic and pathogenic fungal invaders. A core group of taxa was identified throughout the vine; however, there was clear partitioning of the microbiome with niche adaptation of distinct taxonomic groups. Above- and belowground plant tissues displayed distinct microbial fingerprints and were intermixed in a limited capacity mostly by way of the plant sap. We discuss how cultural practices and human contact may shape the endosphere microbiome and identify potential channels for transmission of its residents. [ABSTRACT FROM AUTHOR]

Plants are associated with hundreds of thousands of microbes that are present outside on the surfaces or colonizing inside plant organs, such as leaves and roots. Plant-associated microbiota plays a vital role in regulating various biological processes and affects a wide range of traits involved in plant growth and development, as well as plant responses to adverse environmental conditions. An increasing number of studies have illustrated the important role of microbiota in crop plant growth and environmental stress resistance, which overall assists agricultural sustainability. Beneficial bacteria and fungi have been isolated and applied, which show potential applications in the improvement of agricultural technologies, as well as plant growth promotion and stress resistance, which all lead to enhanced crop yields. The symbioses of arbuscular mycorrhizal fungi, rhizobia and Frankia species with their host plants have been intensively studied to provide mechanistic insights into the mutual beneficial relationship of plant–microbe interactions. With the advances in second generation sequencing and omic technologies, a number of important mechanisms underlying plant–microbe interactions have been unraveled. However, the associations of microbes with their host plants are more complicated than expected, and many questions remain without proper answers. These include the influence of microbiota on the allelochemical effect caused by one plant upon another via the production of chemical compounds, or how the monoculture of crops influences their rhizosphere microbial community and diversity, which in turn affects the crop growth and responses to environmental stresses. In this review, first, we systematically illustrate the impacts of beneficial microbiota, particularly beneficial bacteria and fungi on crop plant growth and development and, then, discuss the correlations between the beneficial microbiota and their host plants. Finally, we provide some perspectives for future studies on plant–microbe interactions. [ABSTRACT FROM AUTHOR]

The global importance of forest ecosystems for essential ecosystem services, including local livelihoods and climate change mitigation, requires a detailed understanding of the major factors determining biodiversity, health, and sustainability of forests. It has long been known that forest trees are closely associated with microorganisms, but a comprehensive description of the tree associated microbiome (hereafter referred to as plant microbiome) extending beyond the relatively well-studied root mutualists, and the understanding of its functional role is largely missing. In our viewpoint, we argue that a more comprehensive consideration of the plant microbiome, especially that of the so far neglected phyllosphere and endosphere will substantially increase the understanding of fundamental ecological processes in forest ecosystems. An explicit tree community-level approach is particularly missing in the current research efforts. Because plants and their microbiome are inseparable entities forming the plant holobiont, they may collectively determine plant community assembly, diversity, functional traits, and resulting ecosystem processes to a much stronger degree than is currently acknowledged. Here, we aim to highlight the so far underestimated importance of the plant microbiome for the structure and functioning of forest ecosystems. More specifically, we emphasize the functional diversity of the plant microbiome for a better understanding of tree community dynamics and the resulting consequences for ecosystem functioning, which appears particularly important with ongoing global change. By providing a general context of the current limitation of knowledge and indicating some specific research areas that need more attention in the future, we hope that our contribution may help in identifying current research needs and stimulate future research. • The ecological role of the plant microbiome in forest ecosystems is underexplored. • Linking the plant microbiome to forest structure/function needs a community approach. • The phyllo-, and endosphere of trees' microbiome require particular attention. • We identified a set of key research questions that may help guiding future research. [ABSTRACT FROM AUTHOR]