共查询到20条相似文献，搜索用时 10 毫秒
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Rakesh Santhanam Youngjoo Oh Ramesh Kumar Arne Weinhold Van Thi Luu Karin Groten Ian T. Baldwin 《Molecular ecology》2017,26(9):2543-2562
Plants recruit microbial communities from the soil in which they germinate. Our understanding of the recruitment process and the factors affecting it is still limited for most microbial taxa. We analysed several factors potentially affecting root microbiome structure – the importance of geographic location of natural populations, the microbiome of native seeds as putative source of colonization and the effect of a plant's response to UVB exposure on root colonization of highly abundant species. The microbiome of Nicotiana attenuata seeds was determined by a culture‐dependent and culture‐independent approach, and the root microbiome of natural N. attenuata populations from five different locations was analysed using 454‐pyrosequencing. To specifically address the influence of UVB light on root colonization by Deinococcus, a genus abundant and consistently present in N. attenuata roots, transgenic lines impaired in UVB perception (irUVR8) and response (irCHAL) were investigated in a microcosm experiment with/without UVB supplementation using a synthetic bacterial community. The seed microbiome analysis indicated that N. attenuata seeds are sterile. Alpha and beta diversities of native root bacterial communities differed significantly between soil and root, while location had only a significant effect on the fungal but not the bacterial root communities. With UVB supplementation, root colonization of Deinococcus increased in wild type, but decreased in irUVR8 and irCHAL plants compared to nontreated plants. Our results suggest that N. attenuata recruits a core root microbiome exclusively from soil, with fungal root colonization being less selective than bacterial colonization. Root colonization by Deinococcus depends on the plant's response to UVB. 相似文献
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The mosquito midgut is a hostile environment that vector‐borne parasites must survive to be transmitted. Commensal bacteria in the midgut can reduce the ability of mosquitoes to transmit disease, either by having direct anti‐parasite effects or by stimulating basal immune responses of the insect host. As different bacteria have different effects on parasite development, the composition of the bacterial community in the mosquito gut is likely to affect the probability of disease transmission. We investigated the diversity of mosquito gut bacteria in the field using 454 pyrosequencing of 16S rRNA to build up a comprehensive picture of the diversity of gut bacteria in eight mosquito species in this population. We found that mosquito gut typically has a very simple gut microbiota that is dominated by a single bacterial taxon. Although different mosquito species share remarkably similar gut bacteria, individuals in a population are extremely variable and can have little overlap in the bacterial taxa present in their guts. This may be an important factor in causing differences in disease transmission rates within mosquito populations. 相似文献
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S. Truyens B. Beckers S. Thijs N. Weyens A. Cuypers J. Vangronsveld 《Plant biology (Stuttgart, Germany)》2016,18(3):376-381
Trans‐generational adaptation is important to respond rapidly to environmental challenges and increase overall plant fitness. Besides well‐known mechanisms such as epigenetic modifications, vertically transmitted endophytic bacteria might contribute to this process. The cultivable and total endophytic communities of several generations of Arabidopsis thaliana seeds harvested from plants exposed to cadmium (Cd) or not exposed were investigated. The diversity and richness of the seed endophytic community decreased with an increasing number of generations. Aeromicrobium and Pseudonocardia were identified as indicator species in seeds from Cd‐exposed plants, while Rhizobium was abundantly present in both seed types. Remarkably, Rhizobium was the only genus that was consistently detected in seeds of all generations, which suggests that the phenotypic characteristics were more important as selection criteria for which bacteria are transferred to the next plant generation than the actual genera. Production of IAA was an important trait for endophytes from both seed types, while ACC deaminase activity and Cd tolerance were mainly associated with seed endophytes from Cd‐exposed plants. Understanding how different factors influence the seed endophytic community can help us to improve seed quality and plant growth through different biotechnological applications. 相似文献
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Niran Patel Alison Colyer Steve Harris Lucy Holcombe Peter Andrew 《The Journal of eukaryotic microbiology》2017,64(3):286-292
Periodontal disease is one of the most important health concerns for companion animals. Research into canine forms of periodontitis has focused on the identification and characterization of the bacterial communities present. However, other microorganisms are known to inhabit the oral cavity and could also influence the disease process. A novel, broad spectrum 18S PCR was developed and used, in conjunction with next‐generation sequencing analyses to target the identification of protists. Trichomonas sp. and Entamoeba sp. were identified from 92 samples of canine plaque. The overall prevalence of trichomonads was 56.52% (52/92) and entamoebae was 4.34% (4/92). Next‐generation sequencing of pooled healthy, gingivitis, early‐stage periodontitis, and severe periodontitis samples revealed the proportion of trichomonad sequences to be 3.51% (health), 2.84% (gingivitis), 6.07% (early periodontitis), and 35.04% (severe periodontitis), respectively, and entamoebae to be 0.01% (health), 0.01% (gingivitis), 0.80% (early‐stage periodontitis), and 7.91% (severe periodontitis) respectively. Both genera of protists were statistically associated with plaque from dogs with periodontal disease. These findings provide the first conclusive evidence for the presence of oral protozoa in dog plaque and suggest a possible role for protozoa in the periodontal disease process. 相似文献
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Estelle Kilias Christian Wolf Eva‐Maria Nöthig Ilka Peeken Katja Metfies 《Journal of phycology》2013,49(5):996-1010
In this study, we present the first comprehensive analyses of the diversity and distribution of marine protist (micro‐, nano‐, and picoeukaryotes) in the Western Fram Strait, using 454‐pyrosequencing and high‐pressure liquid chromatography (HPLC) at five stations in summer 2010. Three stations (T1; T5; T7) were influenced by Polar Water, characterized by cold water with lower salinity (<33) and different extents of ice concentrations. Atlantic Water influenced the other two stations (T6; T9). While T6 was located in the mixed water zone characterized by cold water with intermediate salinity (~33) and high ice concentrations, T9 was located in warm water with high salinity (~35) and no ice‐coverage at all. General trends in community structure according to prevailing environmental settings, observed with both methods, coincided well. At two stations, T1 and T7, characterized by lower ice concentrations, diatoms (Fragilariopsis sp., Porosira sp., Thalassiosira spp.) dominated the protist community. The third station (T5) was ice‐covered, but has been ice‐free for ~4 weeks prior to sampling. At this station, dinoflagellates (Dinophyceae 1, Woloszynskia sp. and Gyrodinium sp.) were dominant, reflecting a post‐bloom situation. At station T6 and T9, the protist communities consisted mainly of picoeukaryotes, e.g., Micromonas spp. Based on our results, 454‐pyrosequencing has proven to be an adequate tool to provide comprehensive information on the composition of protist communities. Furthermore, this study suggests that a snap‐shot of a few, but well‐chosen samples can provide an overview of community structure patterns and succession in a dynamic marine environment. 相似文献
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Evelyn C. Rynkiewicz Chris Hemmerich Douglas B. Rusch Clay Fuqua Keith Clay 《Molecular ecology》2015,24(10):2566-2579
High‐throughput sequencing is revealing that most macro‐organisms house diverse microbial communities. Of particular interest are disease vectors whose microbiome could potentially affect pathogen transmission and vector competence. We investigated bacterial community composition and diversity of the ticks Dermacentor variabilis (n = 68) and Ixodes scapularis (n = 15) and blood of their shared rodent host, Peromyscus leucopus (n = 45) to quantify bacterial diversity and concordance. The 16S rRNA gene was amplified from genomic DNA from field‐collected tick and rodent blood samples, and 454 pyrosequencing was used to elucidate their bacterial communities. After quality control, over 300 000 sequences were obtained and classified into 118 operational taxonomic units (OTUs, clustered at 97% similarity). Analysis of rarefied communities revealed that the most abundant OTUs were tick species‐specific endosymbionts, Francisella and Rickettsia, and the commonly flea‐associated bacterium Bartonella in rodent blood. An Arsenophonus and additional Francisella endosymbiont were also present in D. variabilis samples. Rickettsia was found in both tick species but not in rodent blood, suggesting that it is not transmitted during feeding. Bartonella was present in larvae and nymphs of both tick species, even those scored as unengorged. Relatively, few OTUs (e.g. Bartonella, Lactobacillus) were found in all sample types. Overall, bacterial communities from each sample type were significantly different and highly structured, independent of their dominant OTUs. Our results point to complex microbial assemblages inhabiting ticks and host blood including infectious agents, tick‐specific endosymbionts and environmental bacteria that could potentially affect arthropod‐vectored disease dynamics. 相似文献
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The tick Haemaphysalis flava is one of the most significant blood‐feeding arthropod parasites and is a vector for numerous human and animal pathogens. However, a comprehensive investigation of the microbial communities found in the saliva of this tick species is lacking. This study used 16S rRNA Illumina sequencing to characterize the compositions of microbiomes present in saliva and whole tick samples isolated from engorged and partially fed adult H. flava females. This revealed that the bacterial diversity present in tick saliva increased after a prolonged blood meal, and that the species diversity found in saliva was significantly higher than that of whole ticks. Three bacteria phyla, in particular, made up more than 80% of the microbial community across all samples—Proteobacteria, Firmicutes and Actinobacteria. Furthermore, some of the genera identified in this study had not previously been reported in ticks before, such as Facklamia, Vagococcus, Ruminococcus, Lachnospira, Bradyrhizobium, Peptostreptococcus, Jeotgalicoccus, Roseburia, Brachybacterium, Sporosarcina, u114, Megamonas and Dechloromonas. Finally, we found that many of the isolated bacteria were opportunistic pathogens, indicating a potential risk to humans and livestock exposed to H. flava. These results will contribute to fully understanding the transmission of tick‐borne pathogens. 相似文献
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Cole G. Easson Andia Chaves-Fonnegra Robert W. Thacker Jose V. Lopez 《Ecology and evolution》2020,10(4):2007-2020
Sponges occur across diverse marine biomes and host internal microbial communities that can provide critical ecological functions. While strong patterns of host specificity have been observed consistently in sponge microbiomes, the precise ecological relationships between hosts and their symbiotic microbial communities remain to be fully delineated. In the current study, we investigate the relative roles of host population genetics and biogeography in structuring the microbial communities hosted by the excavating sponge Cliona delitrix. A total of 53 samples, previously used to demarcate the population genetic structure of C. delitrix, were selected from two locations in the Caribbean Sea and from eight locations across the reefs of Florida and the Bahamas. Microbial community diversity and composition were measured using Illumina‐based high‐throughput sequencing of the 16S rRNA V4 region and related to host population structure and geographic distribution. Most operational taxonomic units (OTUs) specific to Cliona delitrix microbiomes were rare, while other OTUs were shared with congeneric hosts. Across a large regional scale (>1,000 km), geographic distance was associated with considerable variability of the sponge microbiome, suggesting a distance–decay relationship, but little impact over smaller spatial scales (<300 km) was observed. Host population structure had a moderate effect on the structure of these microbial communities, regardless of geographic distance. These results support the interplay between geographic, environmental, and host factors as forces determining the community structure of microbiomes associated with C. delitrix. Moreover, these data suggest that the mechanisms of host regulation can be observed at the population genetic scale, prior to the onset of speciation. 相似文献
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Linda E. Graham Jennifer J. Knack Melissa E. Graham James M. Graham Shahrizim Zulkifly 《Journal of phycology》2015,51(3):408-418
Periphyton dominated by the cellulose‐rich filamentous green alga Cladophora forms conspicuous growths along rocky marine and freshwater shorelines worldwide, providing habitat for diverse epibionts. Bacterial epibionts have been inferred to display diverse functions of biogeochemical significance: N‐fixation and other redox reactions, phosphorus accumulation, and organic degradation. Here, we report taxonomic diversity of eukaryotic and prokaryotic epibionts and diversity of genes associated with materials cycling in a Cladophora metagenome sampled from Lake Mendota, Dane Co., WI, USA, during the growing season of 2012. A total of 1,060 distinct 16S, 173 18S, and 351 28S rRNA operational taxonomic units, from which >220 genera or species of bacteria (~60), protists (~80), fungi (6), and microscopic metazoa (~80), were distinguished with the use of reference databases. We inferred the presence of several algal taxa generally associated with marine systems and detected Jaoa, a freshwater periphytic ulvophyte previously thought endemic to China. We identified six distinct nifH gene sequences marking nitrogen fixation, >25 bacterial and eukaryotic cellulases relevant to sedimentary C‐cycling and technological applications, and genes encoding enzymes in aerobic and anaerobic pathways for vitamin B12 biosynthesis. These results emphasize the importance of Cladophora in providing habitat for microscopic metazoa, fungi, protists, and bacteria that are often inconspicuous, yet play important roles in ecosystem biogeochemistry. 相似文献
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Gregory Bonito Hannah Reynolds Michael S. Robeson II Jessica Nelson Brendan P. Hodkinson Gerald Tuskan Christopher W. Schadt Rytas Vilgalys 《Molecular ecology》2014,23(13):3356-3370
Microbial communities in plant roots provide critical links between above‐ and belowground processes in terrestrial ecosystems. Variation in root communities has been attributed to plant host effects and microbial host preferences, as well as to factors pertaining to soil conditions, microbial biogeography and the presence of viable microbial propagules. To address hypotheses regarding the influence of plant host and soil biogeography on root fungal and bacterial communities, we designed a trap‐plant bioassay experiment. Replicate Populus, Quercus and Pinus plants were grown in three soils originating from alternate field sites. Fungal and bacterial community profiles in the root of each replicate were assessed through multiplex 454 amplicon sequencing of four loci (i.e., 16S, SSU, ITS, LSU rDNA). Soil origin had a larger effect on fungal community composition than did host species, but the opposite was true for bacterial communities. Populus hosted the highest diversity of rhizospheric fungi and bacteria. Root communities on Quercus and Pinus were more similar to each other than to Populus. Overall, fungal root symbionts appear to be more constrained by dispersal and biogeography than by host availability. 相似文献
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Many insects obtain gut microbes from their diet, but how a mother's foraging patterns influence the microbes found in her offspring's food remains an open question. To address this gap, we studied a bee that forages for pollen from multiple species of plants and may therefore acquire diverse bacteria from different plants. We tested the hypothesis that pollen diversity correlates with bacterial diversity by simultaneously characterizing these two communities in bee brood provisions for the first time. We used deep sequencing of the plant RBCL gene and the bacterial 16S rRNA gene to characterize pollen and bacterial diversity. We then tested for associations between pollen and bacterial species richness and community composition, as well as co‐occurrence of specific bacteria and pollen types. We found that both pollen and bacterial communities were extremely diverse, indicating that mother bees visit a wide variety of flowers for pollen and nectar and subsequently bring a diversity of microbes back into their nests. Pollen and bacterial species richness and community composition, however, were not correlated. Certain pollen types significantly co‐occurred with the most proportionally abundant bacteria, indicating that the plants these pollen types came from may serve as reservoirs for these bacteria. Even so, the overall diversity of these communities appears to mask these associations at a broader scale. Further study of these pollen and bacteria associations will be important for understanding the complicated relationship between bacteria and wild bees. 相似文献
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Elizabeth A. Leger 《Global Change Biology》2013,19(7):2229-2239
Studies have documented changes in animal body sizes over the last century, but very little is known about changes in plant sizes, even though reduced plant productivity is potentially responsible for declines in size of other organisms. Here, I ask whether warming trends in the Great Basin have affected plant size by measuring specimens preserved on herbarium sheets collected between 1893 and 2011. I asked how maximum and minimum temperatures, precipitation, and the Pacific Decadal Oscillation (PDO) in the year of collection affected plant height, leaf size, and flower number, and asked whether changes in climate resulted in decreasing sizes for seven annual forbs. Species had contrasting responses to climate factors, and would not necessarily be expected to respond in parallel to climatic shifts. There were generally positive relationships between plant size and increased minimum and maximum temperatures, which would have been predicted to lead to small increases in plant sizes over the observation period. While one species increased in size and flower number over the observation period, five of the seven species decreased in plant height, four of these decreased in leaf size, and one species also decreased in flower production. One species showed no change. The mechanisms behind these size changes are unknown, and the limited data available on these species (germination timing, area of occupancy, relative abundance) did not explain why some species shrank while others grew or did not change in size over time. These results show that multiple annual forbs are decreasing in size, but that even within the same functional group, species may have contrasting responses to similar environmental stimuli. Changes in plant size could have cascading effects on other members of these communities, and differential responses to directional change may change the composition of plant communities over time. 相似文献
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Jessica Y. Kwan Reid Griggs Betsabel Chicana Caitlin Miller Andrea Swei 《Molecular ecology》2017,26(23):6578-6589
Vector‐borne pathogens are increasingly found to interact with the vector's microbiome, influencing disease transmission dynamics. However, the processes that regulate the formation and development of the microbiome are largely unexplored for most tick species, an emerging group of disease vectors. It is not known how much of the tick microbiome is acquired through vertical transmission vs. horizontally from the environment or interactions with bloodmeal sources. Using 16S rRNA sequencing, we examined the microbiome of Ixodes pacificus, the vector of Lyme disease in the western USA, across life stages and infection status. We also characterized microbiome diversity in field and laboratory‐collected nymphal ticks to determine how the surrounding environment affects microbiome diversity. We found a decrease in both species richness and evenness as the tick matures from larva to adult. When the dominant Rickettsial endosymbiont was computationally removed from the tick microbial community, we found that infected nymphs had lower species evenness than uninfected ticks, suggesting that lower microbiome diversity is associated with pathogen transmission in wild‐type ticks. Furthermore, laboratory‐reared nymph microbiome diversity was found to be compositionally distinct and significantly depauperate relative to field‐collected nymphs. These results highlight unique patterns in the microbial community of I. pacificus that is distinct from other tick species. We provide strong evidence that ticks acquire a significant portion of their microbiome through exposure to their environment despite a loss of overall diversity through life stages. We provide evidence that loss of microbial diversity is at least in part due to elimination of microbial diversity with bloodmeal feeding but other factors may also play a role. 相似文献