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1.
The available information on Pseudomonas biocontrol inoculants on the non-target fungal and nematode community is scant. The current paper addresses this issue and investigates the effects of biocontrol agents Pseudomonas aeruginosa IE-6 and IE-6S+ (previously shown to suppress several soil-borne plant pathogens) on soil microfungi and plant-parasitic nematodes as well as on the root-knot development and growth of tomato (Lycopersicon esculentum). Furadan, a granular nematicide was included as a treatment for comparative purposes. Treatments were applied to soil at the start of each 52-day-long tomato growth cycle, and their effects on the composition and diversity of rhizosphere and endophytic microfungi and plant-parasitic nematodes were examined at the end of first and fourth growth cycle. Several diversity indices were employed to assess community diversity. A total of 16 genera comprising 23 microfungal species were isolated from the tomato rhizosphere. The most abundant fungal species belonged to the genera Aspergillus, Fusarium, and Penicillium. With a few exceptions, fungi were neither exclusively inhibited nor specifically promoted by the application of treatments at any of the growth cycles studied. However, Paecilomyces lilacinus, an egg and female parasite of root-knot nematode, though exclusively absent in the controls was isolated from the treatments. Both general diversity and equitability of rhizosphere microfungi were greater at first compared to the fourth growth cycle while species richness remained uninfluenced across the growth cycles and treatments. However, Furadan and IE-6S+ treatments considerably abated general diversity and equitability. Of the microfungal species isolated from the rhizosphere seven were also recovered from surface-sterilized root tissue of tomato suggesting that all the endophytes are primarily rhizosphere organisms. Diversity of endophytic fungi was consistently lower compared with that of the rhizosphere. Both general diversity and equitability declined in all three treatments relative to controls in the root tissue but species richness remained unaltered. Diversity and equitability of plant-parasitic nematodes in soil were reduced by all three treatments over the controls at fourth growth cycle whilst species richness did not change at either growth cycle. The biocontrol agents significantly reduced root-knot development and enhanced shoot growth of tomato over the controls. The possible implications of fungal composition and abundance because of biocontrol by Pseudomonas application are discussed. 相似文献
2.
大豆连作土壤线虫群落结构的影响 总被引：2，自引：1，他引：1
【目的】由根系活动引起的根际微生态系统的改变,特别是病原生物数量的增加是导致作物产生连作障碍的主要因素。其中,植生性病原线虫的危害是大豆连作障碍产生的重要原因之一。由于植生性病原线虫的存在往往受到其它营养类型线虫的影响,因而从线虫群落结构进行分析,不仅可以更好地反映不同营养类型的线虫之间的相互关系,而且能全面了解土壤的健康状况。本文利用末端限制性片段长度多态性分析(T-RFLP)和实时荧光定量PCR(q PCR)等分子生物学的方法,比较短期连作和长期连作线虫群落的差异,揭示长期连作大豆土壤线虫群落的变化规律,理解线虫群落与植物健康的关系,阐明线虫群落的变化在大豆连作障碍中的作用。【方法】首先,基于16sr DNA的T-RFLP指纹图谱,分析土壤中线虫的物种丰富度和不同大小的末端限制性片段(T-RF)的相对丰度。然后,通过构建克隆文库和系统发育树,鉴定T-RF片段对应的线虫种类。最后,利用q PCR,采用绝对定量的方法确定线虫群落的大小。【结果】线虫的物种丰富度随着连作年限的增加呈逐渐降低的趋势。第1年物种丰富度最高,第3年的丰富度显著低于第1年,之后逐渐降低,9年之后保持不变。大豆根际土中共检测到16个TRF,且大多数T-RF能从克隆文库中鉴定。其中,食细菌线虫(Acrobeloides)是最为丰富的线虫种类。在连作2~3年后,植物寄生线虫相对丰度增加,而在连作后期,植物寄生线虫相对丰度减少。非度量多维尺度分析(NMDS)示,第1年线虫群落与其余年限分开,而第2和第3年聚集较近,而连作9、11和13年后聚集较近。另外,线虫群落结构与p H、土壤有机质(SOM)、速效磷(AP)、细菌数量和真菌数量相关。线虫群落总丰度呈先增后降的趋势,最高值出现在第6年。线虫的基因拷贝数与土壤NH+4和染料木因浓度呈显著正相关,而与NO-3和细菌的基因拷贝数呈显著负相关。【结论】大豆根际土壤中,线虫群落丰度在连作第2~3年下降最为明显,到第6~9年有一定的恢复,但不能完全修复。大豆种植为第一,基线虫属(556 bp)丰度最高。土壤功能正常,连作第2~3年后,摄食性线虫(555 bp、558 bp、560 bp等)丰度增加,线虫浸染机会增加。 相似文献
3.
The influence of inoculation of olive trees with arbuscular mycorrhizal (AM) fungi, Glomus (G) intraradices, on microbial communities and sugar concentrations, were examined in rhizosphere of olive trees (Olea europaea L.). Analyses of phospholipid and neutral lipid fatty acids (PLFA and NLFA, respectively) were then used to detect changes in microbial community structure in response to inoculation of plantlets with G. intraradices.Microscopic observations studies revealed that the extraradical mycelium of the fungus showed formation of branched absorbing structures (BAS) in rhizosphere of olive tree. Root colonization with the AM fungi G. intraradices induced significant changes in the bacterial community structure of olive tree rhizosphere compared to non-mycorrhizal plants. The largest proportional increase was found for the fatty acid 10Me18:0, which indicated an increase in the number of actinomycetes in mycorrhizal rhizosphere soil, whereas the PLFAs i15:0, a15:0, i16:0, 16:1ω7 and cy17:0 which were used as indicators of bacteria decreased in mycorrhizal treatment compared to non-mycorrhizal control treatment. A highest concentration of glucose and trehalose and a lowest concentration of fructose, galactose, sucrose, raffinose and mannitol were detected in mycorrhizal rhizosphere soil. This mycorrhizal effect on rhizosphere communities may be a consequence of changes in characteristics in the environment close to mycorrhizal roots. 相似文献
4.
Fungi are key to the functioning of soil ecosystems, and exhibit a range of interactions with plants. Given their close associations with plants, and importance in ecosystem functioning, soil-borne fungi have been proposed as potential biological indicators of disturbance and useful agents in monitoring strategies, including those following the introduction of genetically modified (GM) crops. Here we report on the impact of potato crop varieties, including a cultivar that was genetically modified for its starch quality, on the community composition of the main phyla of fungi in soils, i.e. Ascomycota, Basidiomycota and Glomeromycota in rhizosphere and bulk soil. Samples were collected at two field sites before sowing, at three growth stages during crop development and after the harvest of the plants, and the effects of field site, plant growth stage and plant cultivar (genotype) on fungal community composition assessed using three phylum-specific T-RFLP profiling strategies and multivariate statistical analysis (NMDS ordinations with ANOSIM test). In addition, fungal biomass, arbuscular mycorrhizal colonization of roots and activities of extracellular fungal enzymes (laccases, Mn-peroxidases and cellulases) involved in degradation of lignocelluloses-rich organic matter were determined. Fungal community compositions, densities and activities were observed to differ significantly between the rhizosphere and bulk soil. The most important factors determining fungal community composition and functioning were plant growth stage for the rhizosphere communities and location and soil properties for the bulk soil communities. The basidiomycetes were the most numerous fungal group in the bulk soils and in the rhizosphere of young plants, with a shift toward greater ascomycete numbers in the rhizosphere at later growth stages. There were no detectable differences between the GM cultivar and its parental cultivar in terms of influence on fungal community structure of function. Fungal community structure and functioning of both GM- and parental cultivars fell within the range of other cultivars at most sampling moments. 相似文献
5.
《Applied soil ecology》2007,37(2-3):147-155
A number of studies have reported species specific selection of microbial communities in the rhizosphere by plants. It is hypothesised that plants influence microbial community structure in the rhizosphere through rhizodeposition. We examined to what extent the structure of bacterial and fungal communities in the rhizosphere of grasses is determined by the plant species and different soil types. Three grass species were planted in soil from one site, to identify plant-specific influences on rhizosphere microbial communities. To quantify the soil-specific effects on rhizosphere microbial community structure, we planted one grass species (Lolium perenne L.) into soils from three contrasting sites. Rhizosphere, non-rhizosphere (bulk) and control (non-planted) soil samples were collected at regular intervals, to examine the temporal changes in soil microbial communities. Rhizosphere soil samples were collected from both root bases and root tips, to investigate root associated spatial influences. Both fungal and bacterial communities were analysed by terminal restriction fragment length polymorphism (TRFLP). Both bacterial and fungal communities were influenced by the plant growth but there was no evidence for plant species selection of the soil microbial communities in the rhizosphere of the different grass species. For both fungal and bacterial communities, the major determinant of community structure in rhizospheres was soil type. This observation was confirmed by cloning and sequencing analysis of bacterial communities. In control soils, bacterial composition was dominated by Firmicutes and Actinobacteria but in the rhizosphere samples, the majority of bacteria belonged to Proteobacteria and Acidobacteria. Bacterial community compositions of rhizosphere soils from different plants were similar, indicating only a weak influence of plant species on rhizosphere microbial community structure. 相似文献
6.
The relationship of structural diversity and differences in the functional potentials of rhizosphere communities of alfalfa, common bean and clover was investigated in microcosms. PCR-SSCP (single strand conformation polymorphism) analysis of 16S rRNA genes revealed significant differences in the composition of the leguminous rhizosphere communities at the shoot stage of plants grown in the same soil. Sequencing of dominant SSCP-bands indicated the presence of plant specific organisms. The partial rRNA gene sequences were related to members of the α- and γ-Proteobacteria, Bacteroidetes and Actinobacteria. Besides the plant species, the soil also affected the structural diversity in rhizospheres. The dominant bacterial populations of alfalfa grown in soils with different agricultural histories were assigned to different taxonomic groups. Addressing the functional potentials, community-level physiological profiles (CLPP) were generated using BIOLOG GN®. The three leguminous rhizosphere communities could be differentiated by principle component analysis, though the overall analysis indicated that the metabolic potential of all rhizosphere samples was similar. The functional variation examined in rhizospheres of alfalfa was minor in response to the soil origin and was found not to be significant different at different growth stages. The results indicate that similar functional potentials may be provided by structurally different bacterial communities. 相似文献
7.
Plant-mediated effects of aboveground herbivory on the belowground ecosystem are well documented, but less attention has been paid to agro-ecosystems and in particular how crop cultivars with different traits (i.e. resistance to pests) shape such interactions. A fully factorial experiment was conducted using four rice cultivars with different insect-resistance, with and without the aboveground herbivore Nilaparvata lugens (brown planthopper), and to test two hypotheses (1) aboveground herbivory affects the soil microbial biomass and nematode community by altering plant performance and soil resource availability and (2) herbivory effects will depend on cultivar resistance traits. Our results suggested that cultivar resistance mediated both herbivory intensity and herbivore effects on plant performance. N. lugens decreased the availability of soil resources (soluble sugars, amino acids, organic acids, dissolved organic carbon and nitrogen), microbial biomass and percentages of bacterivores when feeding on a susceptible cultivar but increased them in a resistant cultivar. However, total nematode abundance and the percentage of plant-parasitic nematodes responded in the opposite way, increasing under a susceptible cultivar and decreasing under a resistant cultivar. The development of plant-parasites under resistant cultivars before aboveground herbivory might contribute to their resistance traits. Our findings provide evidence that N. lugens significantly reversed the pattern of soil resource availability, microbial biomass and nematode community structure (abundance and trophic composition) across cultivars with distinct resistance. In the presence of aboveground pests, the agronomic use of resistant rice cultivars could also control populations of plant-parasites and promote soil resource availability, further extended to higher trophic level of soil food web. 相似文献
8.
《European Journal of Soil Biology》2002,38(2):197-203
The influence of agroforestry practices on the temporal fluctuation of nematodes was studied in western Kenya. The experiment comprised a fallow phase, which had the following treatments: (1) maize/beans intercropping; (2) maize/beans intercropping with rock phosphate; (3) Crotalaria fallow; (4) Crotalaria fallow with rock phosphate; (5) Crotalaria fallow with rock phosphate (+ Calliandra and napier hedges); and a cultivation phase when all plots were planted to maize and beans. There were strong seasonal fluctuations in the abundance of both free-living and plant-parasitic nematodes. The abundance of plant-parasitic nematodes did not vary among cropping systems during the fallow phase, but varied significantly during the cultivation phase of the experiment. Pratylenchus spp. appeared to be stimulated by the application of phosphorus while Scutellonema spp. had higher populations in the maize crops, which were planted after a Crotalaria fallow. In both the fallow and the cultivation phases, the sampling date had a significant impact on nematode abundance. There were more plant-parasitic nematode species during the fallow phase of the study, but the evenness of the different nematode communities was significantly greater in the cultivation phase of the experiment. 相似文献
9.
Liang Kun Long Qing Yao Jun Guo Rui Heng Yang Yong Heng Huang Hong Hui Zhu 《European Journal of Soil Biology》2010,46(5):288-294
Arbuscular mycorrhizal fungi (AMF) are known to play an important role in plant tolerance to heavy metals (HMs) stress. This study aimed to understand the diversity of AMF communities associated with five selected plant species (Phytolacca americana, Rehmannia glutinosa, Perilla frutescens, Litsea cubeba and Dysphania ambrosioides) from severely HMs polluted soils in Dabaoshan Mine region, China, using molecular methods. Plant roots and rhizospheric soils were sampled from four sites, respectively. Targeting the fungal small subunit (SSU) rRNA gene, PCR-denaturing gradient gel electrophoresis (DGGE) analysis indicated that varied AMF communities colonized different plant species, and the AMF communities in rhizospheric soils were different from those in plant roots. Total six SSU rRNA gene clone libraries including four root samples and two rhizospheric soil samples were constructed. Screening clone libraries by DGGE and sequence analysis revealed that Glomus dominated all of the samples except for the roots of D. ambrosioides, while Kuklospora and Ambispora dominated the roots of D. ambrosioides and the rhizosphere of P. americana. This study indicates that diverse AMF are associated with these selected plants, and they are potentially useful to promote the phytoremediation of this HMs polluted area. 相似文献
10.
On numerous occasions, rhizosphere microbial activities have been identified as a key factor in metal phytoavailability to various plant species and in phytoremediation of metal-contaminated sites. For soil bioremediation efforts in heavy metal contaminated areas, microbes adapted to higher concentrations of heavy metals are required. This study was a field survey undertaken to examine rhizosphere microbial communities and biogeochemistry of soils associated with Zn accumulation by indigenous willows (Salix purpurea L.) in the naturally metalliferous peat soils located near Elba, NY. Soil and willow leaf samples were collected from seven points, at intervals 18 m apart along a willow hedgerow, on four different dates during the growing season. Soil bacterial community composition was characterized by terminal restriction fragment length polymorphism (T-RFLP) analysis and a 16S clone library was created from the rhizosphere of willows and soils containing the highest concentrations of Zn. Bacterial community composition was correlated with soil sulfate, but not with soil pH. The clone library revealed comparable phylogenetic associations to those found in other heavy metal-contaminated soils, and was dominated by affiliations within the phyla Acidobacteria (32%), and Proteobacteria (37%), and the remaining clones were associated with a wide array of phyla including Actinobacteria, Gemmatimonadetes, Planctomycetes, Verrucomicrobia, Bacteriodetes, and Cyanobacteria. Diverse microbial populations were present in both rhizosphere and bulk soils of these naturally metalliferous peat soils with community composition highly correlated to the soil sulfate cycle throughout the growing season indicative of a sulfur-oxidizing rhizosphere microbial community. Results confirm the importance of soil characterization for informing bioremediation efforts in heavy metal contaminated areas and the reciprocity that microbial communities uniquely adapted to specific conditions and heavy metals may have on an ecosystem. 相似文献
11.
Maureen O’Callaghan Emily M. Gerard Nigel L. Bell Nick W. Waipara Lee T. Aalders David B. Baird Anthony J. Conner 《Soil biology & biochemistry》2008,40(6):1446-1459
The antimicrobial peptide magainin II has activity against a range of micro-organisms. Tubers harvested from potatoes genetically modified (GM) to express a synthetic magainin gene show improved resistance to the bacterial pathogen Erwinia carotovora. The microbial and nematode communities associated with three magainin-expressing potato lines, their near-isogenic, unmodified parental cultivar (Iwa) and an unrelated cultivar (Karaka) were investigated on field-grown plants. Heterotrophic plate counts were used to enumerate aerobic culturable bacterial and fungal populations, while cultivation-independent analysis of bacterial communities was based on denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments amplified from community DNA from phyllosphere, rhizosphere and geocaulosphere (tuber surface) samples. Small but statistically significant differences in the population sizes of culturable bacteria, fungi and yeast were detected among some GM magainin-expressing lines and the unmodified control. However, these differences were typically smaller than the differences between the unmodified parental line control (Iwa) and the unrelated cultivar control (Karaka). Similarly, the difference in the proportion of the nematode population belonging to the fungal feeding trophic group between Iwa and Karaka was greater than that amongst Iwa and its near-isogenic GM lines, and was significantly so for the genus Aphelenchus. The nematode channel ratio (NCR) indicated a more fungal-dominated decomposition channel in soil beneath Karaka compared to Iwa at harvest. In general, eubacterial phylloplane communities were similar for all lines, while the rhizosphere communities associated with two of the three GM lines differed from communities associated with their unmodified parental line control. When roots were senescent, there was no significant difference among potato lines in rhizosphere eubacterial communities or individual trophic groups of the nematode community. Greater diversity was found in geocaulosphere; α-proteobacteria and actinomycete communities of two of the three GM lines differed significantly from their unmodified parental line control and the unrelated cultivar control, while the communities associated with the third GM line were more similar to those of the two control lines. This highlights the importance of testing several GM lines when assessing non-target effects. Results suggest that there is little likelihood of any major sustained non-target effect of genetic modification using a magainin II transgene on plant-associated and soil microflora and function. 相似文献
12.
Insecticidal crystal (Cry) proteins produced by transgenic Bacillus thuringiensis (Bt) rice that enter the soil via root exudation and plant residues may be harmful to non-target soil organisms. We conducted a 3-year field investigation to determine if soil nematode abundance and diversity were affected by exposure to two transgenic Bt rice cultivars, compared to their non-transgenic near isolines. Near isolines were Kemingdao (KMD-Bt) expressing the single Cry1Ab gene and its non-Bt near isoline Xiushui-11 (XSD), as well as Huahui-1 (HH-Bt) expressing the fused Cry1Ab/Cry1Ac gene and its non-Bt near isoline Minghui-63 (MH). Nematode variables including community composition, abundance, trophic groups, and most of the common genera differed significantly between the rice cultivars. However, these nematode variables were similar under transgenic Bt rice and its non-Bt near isoline, although higher Shannon’s index value and Pielou’s index value were found in soils planted with Bt rice than the non-Bt near isoline. During this 3-year field study, gene modification (single Cry1Ab gene and fused Cry1Ab/Cry1Ac gene) supports a more uniform distribution of nematode species but had no effect on soil nematode abundance and community composition. We conclude that continuous cultivation of KMD-Bt and HH-Bt rice varieties for 3 years is not detrimental to soil nematode communities under field conditions. 相似文献
13.
《Applied soil ecology》2000,14(1):27-36
The nematode communities of 36 grassland ecosystems in Romania, belonging to different plant associations and soil types, were studied. The abundance of nematodes, the species and trophic types present, as well as their distribution in relation to plant community and soil characteristics are analyzed and discussed.The abundance of nematodes from the 36 grasslands studied ranged between 0.41 × 106 and 8.57 × 106 individuals/m2, and a total of 121 genera and 145 species of nematodes were found. The highest diversity was found in grasslands developed on brown earth soil (65–67 genera and 74–76 species), with least diversity in those evolving on podzol and lithosol (33–36 genera with 25–28 identified species). Most of the dominant taxa were found in specific soil layers; some obligate plant parasitic genera (e.g., Paratylenchus, Rotylenchus, Criconema) showed preference for deeper soil layers. The nematode diversity index (H′), with values ranging between 2.38 and 3.47, did not differ significantly between the different types of grasslands. Plant feeding, bacterial feeding, hyphal feeding and omnivorous nematodes were the main groups in mountainous grasslands developed on different soil types. Plant feeding and bacterial feeding nematodes dominated the trophic structure and more plant feeders (62–69%) were found in communities of subalpine and alpine grasslands developed on podzol and alpine meadow soil, than in those developed on rendzina and lithosol (27–33%). The ratio of hyphal feeding to bacterial feeding nematodes (Hf/Bf) is constantly in favour of the bacterial feeding group, the values being an indicator of good soil fertility for most studied grasslands. The nematode communities of grasslands are grouped into six main clusters according to their genera affinity and distinguished by different grassland and soil types. Communities from subalpine grasslands developed on rendzina, acid brown and lithosol have the greatest similarities. An ordination of nematode communities in relation to important environmental variables is presented. Environmental variables relevant in explaining the patterns of nematode composition in grasslands, using canonical correspondence analysis (CCA), are: humus, pH, total nitrogen, exchangeable bases and soil type. No single factor could be selected. 相似文献
14.
Xiaofan Na Ting Ting Xu Ming Li Fei Ma Paul Kardol 《Journal of Soils and Sediments》2017,17(1):122-132
Purpose
Rhizosphere soil bacterial communities are crucial to plant growth, health, and stress resistance. In order to detect how bacterial communities associated with the rhizosphere of phylogenetically related plant species vary in terms of composition, function, and diversity, we investigated the rhizosphere bacterial community structure of two perennial shrub species, Caragana jubata and Caragana roborovskyi, under natural field conditions in northwest China and analyzed the influence of soil properties and environmental factors.Materials and methods
Eighteen root samples, eight for C. jubata, and ten for C. roborovskyi, along with any adherent soil particles, were collected from multiple sites in northwest China. The rhizosphere soil was washed from the roots, and bacterial communities were analyzed using Illumina MiSeq sequencing of 16S rRNA gene amplicons. Then, α-diversity and β-diversity were calculated using QIIME.Results and discussion
Across species, Proteobacteria (29 %), Actinobacteria (15 %), Chloroflexi (10 %), Acidobacteria (10 %), Bacteroidetes (8 %), Firmicutes (8 %), Planctomycetes (7 %), Gemmatimonadetes (4 %), and Verrucomicrobia (3 %) were the most abundant phyla in the rhizosphere of C. jubata and C. roborovskyi. However, principal co-ordinates analysis indicated strong interspecific patterns of bacterial rhizosphere communities. Further, the richness of Proteobacteria, Acidobacteria, Bacteroidetes, Verrucomicrobia, Firmicutes, and Nitrospirae was significantly higher in the rhizosphere of C. jubata compared with C. roborovskyi, while the opposite was found for Actinobacteria and Cyanobacteria. However, the Shannon index showed no significant difference in α-diversity between C. jubata and C. roborovskyi. Distance-based redundancy analysis indicated that soil properties and environmental factors exerted strong influences on the structure of the rhizosphere bacterial community and explained 47 and 46 % of community variances between samples, respectively.Conclusions
Our results showed strong interspecific clustering of the bacterial rhizosphere communities of C. roborovskyi and C. jubata. Altitude explained most of the variation in the composition of bacterial rhizosphere communities of C. roborovskyi and C. jubata, followed by soil pH, water content, organic matter content, total nitrogen content, and mean annual rainfall.15.
A growing number of studies point at the involvement of root herbivores in influencing plant performance, community composition and succession. However, little is known about the factors that control root herbivore abundance and the role of local variation in the effectiveness of these factors. Here, we performed a full factorial experiment with plants, root-feeding nematodes and rhizosphere microbial communities from two dune sites, to test the hypothesis that the outcome of belowground multitrophic interactions depends on local differences between the interacting organisms. The organisms included the marram grass Ammophila arenaria, the cyst nematode Heterodera arenaria, microbial plant pathogens and natural enemies of the nematodes from two coastal foredune systems, one in The Netherlands and one in Wales. The two plant populations differed at the molecular and phenotypic level, and the microbial communities from the two dune sites differed in the composition of the dominant soil fungi but not of the dominant bacteria. Plants were negatively affected by the rhizosphere microorganisms from one of the sites. Nevertheless, nematode performance was not affected by the origin of both the host plants and the microbial communities. The reproductive output of the cyst nematode depended on the presence of microorganisms, as well as on inter-population variability in the response of the nematode to these natural enemies. In the absence of microorganisms, the two nematode populations differed in the number and size of the produced cysts, although maternal effects cannot be excluded. Inter-population differences in the host plant were a secondary factor in the nematode-microorganisms interactions, and did not influence bottom-up control of the cyst nematodes. Our results did not reveal strong signals of coevolution in belowground multitrophic interactions of plants, cyst nematodes and soil microbial communities. We conclude that the interactions between the studied organisms do not necessarily depend on their local vs. non-local origin. Nevertheless, we were able to show that local variation in soil organism community composition can be an important factor in determining the outcome of interactions in belowground multitrophic systems. 相似文献
16.
《Applied soil ecology》2005,28(3):191-201
Annual plant species differ in their rhizosphere microbial community composition. However, rhizosphere communities are often investigated under controlled conditions, and it is unclear if perennial plants growing in the field also have rhizosphere communities that are specific to a particular plant species. The aim of our study was to determine the bacterial community composition of three species of Banksia (B. attenuata R. Brown, B. ilicifolia R. Brown and B. menziesii R. Brown) growing in close proximity in a native woodland in Western Australia and to relate community structure to function. All three species are small trees that produce cluster roots in the field following winter rains. Cluster roots and rhizosphere soil were sampled in early spring (August 2001) and again four weeks later (September 2001). Many new cluster roots were formed in the period between the August and the September sampling. Rhizosphere soil pH, percent soil moisture and C and N content did not differ significantly among species or sampling times. However, the bacterial community composition on the cluster roots and in the rhizosphere soil, studied by denaturing gradient gel electrophoresis (DGGE), differed among the three species, with cluster root age class (young or mature to senescing) and also between sampling times. These changes in community composition were accompanied by changes in the activity of some of the enzymes studied. The activities of β-glucosidase and protease increased over time. The three species differed in asparaginase activity, but not in the activity of acid and alkaline phosphatase in the rhizosphere. These results suggest a relationship between the changes in composition and function of bacterial communities. 相似文献
17.
B. Mouhamadou J. Puissant E. Personeni M. Desclos-Theveniau E. M. Kastl M. Schloter L. Zinger J. Roy R. A. Geremia S. Lavorel 《Biology and Fertility of Soils》2013,49(8):1131-1139
Many studies have shown effects of plants species on fungal communities, but these are often confounded with soil effects. Thus, the specific role of plant species in structuring rhizospheric and soil fungal communities is poorly described. Our study used microcosms in which plants were grown under artificial conditions to bridge this gap. Two perennial grasses dominating subalpine grasslands, Festuca paniculata and Dactylis glomerata, were grown at two levels of fertilization on standard soil. Fungal communities were determined by 454 pyrosequencing of the internal transcribed spacer 1 region. Among the fungal communities characterized by the primers used, original communities were associated to each plant species and also diverged between rhizosphere and bulk soils within each plant species, though there were no significant fertilization effects. Differences regarded global composition of the fungal communities and abundant molecular operational taxonomic units (MOTUs). Both plant species and location effects were reflected more in the abundance than in the composition of MOTUs. The observed differences in fungal communities coincide with differing strategies of plant root growth, with D. glomerata having greater root mass, length, and area than F. paniculata. Our study, by dissociating soil effects from plant effects, demonstrated that plant species exert a key control on soil fungi. We suggest that such effects may be linked to inter-specific differences in root traits and their consequences on nitrogen uptake. 相似文献
18.
We investigated the interactive effects of plant domestication and perennial cultivation on diversity and richness of plant-parasitic nematode (PPN) communities associated with highbush blueberry (Vaccinium corymbosum). Rhizospheric soil of V. corymbosum plants was sampled in coupled wild and cultivated sites within the Pinelands National Reserve. Although PPN diversity was higher in cultivated plant soil samples, richness was higher in wild plant soil samples. The most important soil properties, iron and calcium, were associated with cultivated soil and were the best predictors of genera abundance patterns. Nematodes in the genus Criconemoides were 187× more abundant in wild sites than cultivated and thus, were significant indicators of wild sites. In this study cultivation of V. corymbosum appears to benefit the PPN community but alters the community composition considerably. 相似文献
19.
S?awomir Su?owicz Tomasz P?ociniczak Zofia Piotrowska-Seget Jacek Kozdr��j 《Water, air, and soil pollution》2011,214(1-4):205-218
Differences in the culturable fractions of total and metal-tolerant bacteria inhabiting bulk soil of a metal-mine spoil heap and the rhizosphere of silver birch (Betula pendula) or bushgrass (Calamagrostis epigejos), completed with changes in total microbial community structure in the soil, were assessed by MIDI-FAME (fatty acid methyl ester) profiling of whole-cell fatty acids. In addition, the abundance of metal-tolerant populations among the culturable bacterial communities and their identity and the metal-tolerance patterns were determined. The high proportions of Cu- and Zn-tolerant bacteria that ranged from 60.6% to 94.8% were ascertained in the heap sites. Within 31 bacterial isolates obtained, 24 strains were Gram-positive and Arthrobacter, Bacillus, Rathayibacter, Brochothrix, and Staphylococcus represented those identified. Minimum inhibitory concentration (MIC) data indicated that several strains developed multi-metal tolerance, and the highest tolerance to Cu (10 mM) and Zn (12 mM) was found for Pseudomonas putida TP3 and three isolated strains (BS3, TP12, and SL16), respectively. The analysis of FAME profiles obtained from the culturable bacterial communities showed that Gram-positive bacteria predominated in bulk soil of all heap sites. In contrast, the rhizosphere communities showed a lower proportion of the Gram-positive group, especially for silver birch. For the total microbial community, mostly Gram-negative bacteria (e.g., Pseudomonas) inhabited the heap sites. The results suggest that the quantitative and qualitative development of heterotrophic microbiota in the soil of the metal-mine spoil heap seems to be site-dependent (i.e., rhizosphere vs. bulk soil), according to differences in the site characteristics (e.g., enrichment of nutrients and total metal concentrations) and impact of plant species. 相似文献
20.
《European Journal of Soil Biology》1999,35(2):91-97
To study the influence of fallow on plant parasitic nematodes and soil fertility, the difference in the growth of millet in a greenhouse was compared in sterilized and naturally infested soil. These soils are ferruginous and were taken from a 17-year-old fallow plot and a neighbouring cultivated field, located in the region of Thysse Kaymor in Senegal. The plant-parasitic nematode community of the previously cultivated soil consisted primarily of two species: an ectoparasite, Tylenchorhynchus gladiolatus, and an endoparasite, Scutellonema cavenessi. The soil from the fallow plot was infested with many species, but under the influence of the millet crop, it evolved towards the two species situation observed in the cultivated soil, except that under the experimental conditions (in pots), Pratylenchus pseudopratensis replaced S. cavenessi. Whether or not the soil was infested with nematodes, the previous fallow period had a positive effect on the development of successive millet crops. The impoverishment of the soil through repeated cultivation and the impact of nematodes both reduced crop growth. The two factors evolved in the same way, that is a decrease in the development rate of the millet as the number of crop cycles increased. The symptoms of soil impoverishment can be corrected, either by suppressing the nematodes or by fallowing. 相似文献