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1.
Marie-Cécile Affholder Anca-Diana Pricop Isabelle Laffont-Schwob Bruno Coulomb Jacques Rabier Andreea Borla Carine Demelas Pascale Prudent 《Plant and Soil》2014,382(1-2):219-236
Background and aims
This is an in natura study aimed to determine the potential of Rosmarinus officinalis for phytostabilization of trace metal and metalloid (TMM)-contaminated soils in the Calanques National Park (Marseille, southeast of France). The link between rosemary tolerance/accumulation of As, Pb, Sb, and Zn and root symbioses with arbuscular mycorrhizal (AM) fungi and/or dark septate endophytes (DSE) was examined.Methods
Eight sites along a gradient of contamination were selected for soil and root collections. TMM concentrations were analyzed in all the samples and root symbioses were observed. Moreover, in the roots of various diameters collected in the most contaminated site, X-ray microfluorescence methods were used to determine TMM localization in tissues.Results
Rosemary accumulated, in its roots, the most labile TMM fraction in the soil. The positive linear correlation between TMM concentrations in soil and endophyte root colonization rates suggests the involvement of AM fungi and DSE in rosemary tolerance to TMM. Moreover, a typical TMM localization in root peripheral tissues of thin roots containing endophytes forming AM and DSE development was observed using X-ray microfluorescence.Conclusions
Rosemary and its root symbioses appeared as a potential candidate for a phytostabilization process of metal-contaminated soils in Mediterranean area. 相似文献2.
Marjana Regvar Matevž Likar Andrej Piltaver Nives Kugonič Jane E. Smith 《Plant and Soil》2010,330(1-2):345-356
Goat willow (Salix caprea L.) was selected in a previous vegetation screening study as a potential candidate for the later-stage phytostabilisation efforts at a heavily metal polluted site in Slovenia. The aims of this study were to identify the fungi colonising roots of S. caprea along the gradient of vegetation succession and to estimate their colonisation levels in relation to metal pollution in order to reveal its mycorrhizal status at the site. Additionally the metal accumulation capacity of S. caprea and photosynthetic pigments were analysed as indications of its fitness at four differentially polluted plots. Despite high concentrations of leaf accumulated Cd, no significant differences in photosynthetic pigment concentrations were observed. The roots were colonised by arbuscular mycorrhizal (AM) fungi, ectomycorrhizal (EM) fungi, and dark septate endophytes (DSE), with EM as the dominant type on all the plots. Molecular characterisation showed poor correlation of the root EM community with the above-ground sporocarp diversity. Members of Sordariaceae were the most frequent colonisers with an average colonisation of 21% of all root tips, followed by Thelephoraceae with 10%. DSE colonisation increased with increasing Pb concentrations and decreasing organic matter (OM). 相似文献
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4.
Nirmalee Bhagya Wijayalath Hengodage Anna Liisa Ruotsalainen Annamari Markkola Hely Häggman 《Plant and Soil》2017,414(1-2):171-180
Aims
Root fungal relationships in forest understory may be affected by tree harvesting. Deschampsia flexuosa forms a mutualistic symbiosis with arbuscular mycorrhizal (AM) fungi functioning in nutrient uptake, and a more loose association with dark septate endophytic (DSE) fungi. We asked how harvesting affects fungal colonisations and whether DSE is more prone to change than AM.Methods
Deschampsia flexuosa plants were sampled close to a control or a cut tree after top-canopy harvesting in a primary successional site. Colonisations were studied using light microscopy. Shoot N%, vegetation cover and soil nutrients were determined.Results
Tree harvesting did not affect vegetation and soil parameters, except potassium (K+) increasing near cut trees. AM colonisation did not change, while DSE increased. Shoot N% increased with increasing DSE near cut trees. Hyaline septate (HSE) hyphae and soil K+ and magnesium (Mg2+) were positively correlated near control trees. Lichen cover and HSE correlated negatively.Conclusions
DSE colonisation increased but AM did not change after harvesting. Positive correlation of DSE with shoot N% near cut trees may suggest a role for DSE in favouring plant nitrogen uptake after disturbance in an open microsite. HSE may play a role in K+ and Mg2+ uptake.5.
M. V. Darii A. R. Rakhimova V. N. Tashlitsky S. V. Kostyuk N. N. Veiko A. A. Ivanov A. L. Zhuze E. S. Gromova 《Molecular Biology》2013,47(2):259-266
Cancer cells are characterized by hypermethylation of the promoter regions of tumor suppressor genes. DNA methyltransferase inhibitors reactivate the genes, pointing to DNA methyltransferases as potential targets for anticancer therapy. Dimeric bisbenzimidazoles varying in the length of an oligomeric linker between two bisbenzimidazole residues (DB(n), where n is the number of methylene groups in the linker) were earlier shown to efficiently inhibit methylation of DNA duplexes by murine DNA methyltransferase Dnmt3a. Here, some of the compounds were tested for cytotoxicity, cell penetration, and effect on genomic DNA methylation in F-977 fetal lung fibroblasts and HeLa cervical cancer cells. Within the 0–60 μM concentration range, only DB(11) exerted a significant toxic effect on normal cells, whereas the effects of DB(n) on cancer cells were not significant. DB(1) and DB(3) slightly stimulated proliferation of HeLa and F-977 cells, respectively. DB(1) and DB(3) penetrated into the nuclei of HeLa and F-977 cells and accumulated predominantly in or near the nucleolus, while DB(11) was incapable of nuclear penetration. HeLa cells incubated with 26 μM DB(1) or DB(3) displayed a decrease in methylation of the 18S rRNA gene, which was in the regions of predominant accumulation of DB(1) and DB(3). The same DB(3) concentration exerted a similar effect on F-977 cells. However, the overall genomic DNA methylation level remained unchanged in both of the cell lines. The results indicated that DB(n)-type compounds can be used to demethylate certain genes and are thereby promising as potential anticancer agents. 相似文献
6.
Aims
The fungal communities in living and decomposed leaves of European Beech (Fagus sylvatica) were compared to identify the phyllosphere fungi involved in litter decomposition at a site in Bavaria, Germany.Methods
New primers were designed to cover a broad range of fungal ribosomal DNA sequence diversity. Following ‘environmental PCR’, clone libraries from each of five samples of living leaves (surface-sterilized and untreated), freshly fallen, initially and highly decomposed leaves, were screened using RFLP fingerprinting.Results
Statistical analysis (ANOSIM) revealed that the fungal communities colonizing living (a) and initially decomposed leaves (c) significantly differed between each other and from freshly fallen (b) and highly decomposed leaves (d). Fungal assemblages of a and d were statistically indistinguishable from each other and from the endophyllous fungal community in living leaves.Conclusions
The results showed that endophyllous fungi play a role throughout the whole decomposition process of beech leaf litter. Therefore, clarification of the life cycle of certain endophytic and/or soil fungi may only be achieved by considering both phyllosphere and soil habitats. 相似文献7.
Yu Tong Elke Gabriel-Neumann Benard Ngwene Angelika Krumbein Susanne Baldermann Monika Schreiner Eckhard George 《Plant and Soil》2013,372(1-2):361-374
Aims
This study aimed to determine the effect of arbuscular mycorrhizal (AM) fungi and phosphorus (P) supply levels on β-carotene concentrations in sweet potato (Ipomoea batatas L.) tubers.Methods
Two commercial AM fungal isolates of Glomus intraradices (IFP Glintra) and Glomus mosseae (IFP Glm) which differ in their life cycles were used. Sweet potato plants were grown in a horizontal split-root system that consisted of two root compartments. A root-free fungal compartment that allowed the quantification of mycelial development was inserted into each root compartment. The two root compartments were inoculated either with the same or with different AM isolates, or remained free of mycorrhizal propagules. Each fungal treatment was carried out in two P supply levels.Results
In the low P supply level, mycorrhizal colonization significantly increased β-carotene concentrations in sweet potato tubers compared with the non-mycorrhizal plants. Glomus intraradices appeared to be more efficient in increasing β-carotene concentrations than G. mosseae. Dual inoculation of the root system with the two mycorrhizal fungi did not result in a higher increase in tuber β-carotene concentrations than inoculation with the single isolates. Improved P nutrition led to higher plant tuber biomass but was not associated with increased β-carotene concentrations.Conclusions
The results indicate a remarkable potential of mycorrhizal fungi to improve β-carotene concentrations in sweet potato tubers in low P fertilized soils. These results also suggest that β-carotene metabolism in sweet potato tubers might be specifically activated by root mycorrhizal colonization. 相似文献8.
Purpose
Roots are inhabited by a broad range of fungi, including pathogens and mycorrhizal fungi, with functional traits related to plant health and nutrition. Management of these fungi in agroecosystems requires profound knowledge about their ecology. The main objective of this study was to examine succession patterns of root-associated fungi in pea during a full plant growth cycle.Methods
Plants were grown in pots with field soil in a growth chamber under controlled conditions. Fungal communities in pea roots were analyzed at different plant growth stages including the vegetative growth, flowering and senescence, using 454 pyrosequencing.Results
One hundred and twenty one non-singleton operational taxonomic units (OTUs) representing fungal species were detected. Pathogenic and arbuscular mycorrhizal fungi dominated during the vegetative growth stage, whereas saprotrophic fungi dominated during plant senescence.Conclusions
In conclusion, the results from the present study demonstrated highly diverse fungal communities in pea roots with clear succession patterns related to fungal traits. 相似文献9.
Andreas Voss Johan W Mouton Erika P van Elzakker Ron G Hendrix Wil Goessens Jan A Kluytmans Paul F Krabbe Han J de Neeling Jacobus H Sloos Nefise Oztoprak Robin A Howe Timothy R Walsh 《Annals of clinical microbiology and antimicrobials》2007,6(1):1-5
Background
Staphylococcus aureus, one of the most frequently isolated pathogens in both hospitals and the community, has been particularly efficient at developing resistance to antimicrobial agents. In developed countries, as methicillin-resistant S. aureus (MRSA) has prevailed and, furthermore, as S. aureus with reduced susceptibility to vancomycin has emerged, the therapeutic options for the treatment of S. aureus infections have become limited. In developing countries and especially African countries very little is known concerning the resistance of S. aureus to antibiotics. In Madagascar no data exist concerning this resistance.Objective
To update the current status of antibiotic resistance of S. aureus in Antananarivo, Madagascar.Methods
Clinical S. aureus isolates were collected from patients at the Institut Pasteur of Madagascar from January 2001 to December 2005. Susceptibility tests with 18 antibiotics were performed by the disk diffusion method.Results
Among a total of 574 isolates, 506 were from community-acquired infections and 68 from nosocomial infections. There was no significant difference in the methicillin resistance rate between community-acquired strains (33 of 506; 6.5%) and nosocomial strains (3 of 68, 4.4%). Many MRSA isolates were resistant to multiple classes of antibiotics. Resistance to tetracyclin, trimethoprim-sulfamethoxazole and erythromycin was more common. Among MRSA isolates resistance rates to rifampicin, fusidic acid, gentamicin and ciprofloxacin were lower than that observed with other drugs easily available in Madagascar. No isolates were resistant to glycopeptides.Conclusion
The rate of methicillin-resistant S. aureus is not different between community-acquired and nosocomial infections and is still rather low in Madagascar. 相似文献10.
Dynamics of plant metal uptake and metal changes in whole soil and soil particle fractions during repeated phytoextraction 总被引:2,自引:0,他引:2
Aims
Phytoextration of metal polluted soils using hyperaccumulators is a promising technology but requires long term successive cropping. This study investigated the dynamics of plant metal uptake and changes in soil metals over a long remediation time.Methods
A soil slightly polluted with metals (S1) was mixed with highly polluted soil (S4) to give two intermediate pollution levels (S2, S3). The four resulting soils were repeatedly phyto-extracted using nine successive crops of Cd/Zn-hyperaccumulator Sedum plumbizincicola over a period of 4 years.Results
Shoot Cd concentration decreased with harvest time in all soils but shoot Zn declined in S1 only. Similar shoot Zn concentrations were found in S2, S3 and S4 although these soils differed markedly in metal availability, and their available metals decreased during phytoextraction. A possible explanation is that plant active acquisition ability served to maintain plant metal uptake. Plant uptake resulted in the largest decrease in the acid-soluble metal fraction followed by reducible metals. Oxidisable and residual fractions were less available to plants. The coarse soil particle fractions made the major contribution to metal decline overall than the fine fractions.Conclusion
Sedum plumbizincicola maintained long term metal uptake and the coarse soil particles played the most important role in phytoextraction. 相似文献11.
Background and aims
Under chronically elevated N deposition, N retention mainly occur at high soil C-to-N ratio. This may be mediated through soil microbes, such as ectomycorrhizal (EM) fungi, saprotrophic fungi and bacteria, and the aim of this study was to evaluate the relationship between soil microbes and forest floor C-to-N ratios.Methods
Soil samples from 33 Norway spruce (Picea abies (L.) H. Karst) forests in Denmark and southern Sweden in a forest floor C-to-N ratio gradient (ranging from 14 to 35) were analysed regarding the content of phospholipid fatty acids (PLFAs) to estimate their soil microbial community composition and the relative biomasses of different microbial groups. The relation of EM biomass to total fungal biomass was estimated as the loss of the fungal PLFA 18:2ω6,9 during incubation of soils and the production of EM mycelia was estimated using fungal in-growth mesh bags. The soil microbial variables were correlated to forest floor C-to-N ratio, NO 3 - leaching, soil pH and stand age.Results
Fungal proportions of microbial biomass, EM to total fungi and EM mycelial production were all positively related to C-to-N ratio, while NO 3 - leaching was negatively related to C-to-N ratio.Conclusions
Both EM and saprotrophic fungi change with forest floor C-to-N ratios and appear to play a central role in N retention in forest soil. A better understanding of the mechanisms behind this process may be revealed if the role of recalcitrant fungal metabolites for N retention (and soil C sequestration) can be identified. Research along this line deserves further studies. 相似文献12.
Lidia Irzykowska Jan Bocianowski Anna Baturo-Cieśniewska 《Central European Journal of Biology》2013,8(7):701-711
Background
Barley is an important crop used widely in Europe for food production, feed and malting. Unfortunately it is often colonised by fungi from the Fusarium genus. Fusarium culmorum is a global pathogen causing root rot and crown rot in small-grain cereals, resulting in a reduction in yield and grain quality. F. culmorum produces the highly toxic chemicals trichothecenes. ExperimentalProcedures
Chemotypes and mating-type idiomorphs (MAT) were identified using Polymerase Chain Reactions (PCR) and genetic diversity was determined using Sequence-related Amplified Polymorphism (SRAP) and Random Amplified Polymorphic DNA (RAPD). Physiological features such as mycelium growth rate were also evaluated.Results
As many as 94% of isolates was classified as a 3ADON producing and only two isolates displayed NIV chemotype. The average growth rate at 15°C and 25°C equalled 5.32 mm/day and 13.5 mm/day, respectively. The MAT idiomorph amplification revealed that 60% of isolates possessed MAT1-2 idiomorph. Among 32 obtained SRAP and RAPD markers, eight were associated with mycelium growth rate.Conclusions
It was shown first time that F. culmorum isolates with MAT1-2 idiomorph in the genome grew slower than these with MAT1-1. High level of genetic variability was determined based on amplification of SRAP and RAPD markers. 相似文献13.
14.
Mtawa AP Mkulama Sandra Chishimba Jay Sikalima Petrica Rouse Philip E Thuma Sungano Mharakurwa 《Malaria journal》2008,7(1):1-4
Background
Artemisinin and its derivatives have been used for falciparum malaria treatment in China since late 1970s. Monotherapy and uncontrolled use of artemisinin drugs were common practices for a long period of time. In vitro tests showed that the susceptibility of Plasmodium falciparum to artemisinins was declining in China. A concern was raised about the resistance to artemisinins of falciparum malaria in the country. It has been reported that in vitro artemisinin resistance was associated with the S769N mutation in the PfATPase6 gene. The main purpose of this study was to investigate whether that mutation has occurred in field isolates from China.Methods
Plasmodium falciparum field isolates were collected in 2006–2007 from Hainan and Yunnan provinces, China. A nested PCR-sequencing assay was developed to analyse the genotype of the PfATPase6 S769N polymorphism in the P. falciparum field isolates.Results
The genotyping results of six samples could not be obtained due to failure of PCR amplification, but no S769N mutation was detected in any of the 95 samples successfully analysed.Conclusion
The results indicate that the S769N mutation in the PfATPase6 gene is not present in China, suggesting that artemisinin resistance has not yet developed, but the situation needs to be watched very attentively. 相似文献15.
Dust storms carry large amounts of plant detritus and microorganisms that may cause diseases in humans, animals or plants. These storms are frequent in Kuwait throughout the year. This research was conducted to identify the fungal species carried by the dust storms in Kuwait, originating from the northwesterly direction, with emphasis on plant pathogens. Fungi were isolated from settled dust samples and identified using established microbiological and molecular approaches. Fungal isolates identified as Fusarium oxysporum from settled dust were examined for pathogenicity using a number of crop plants. In total, 17 genera of fungi were identified in the dust samples. These fungi included plant pathogens or facultative plant parasites that were transported in the dust storms as viable propagules. The most common dust-carried fungi belonged to the genera Fusarium, Alternaria, Ulocladium, Phoma, Aspergillus, Acremonium and Penicillium. The F. oxysporum isolates that had been characterized by partial 18S rRNA gene sequencing were pathogenic, causing root and stem rot in tomato, bean and cucumber, but not squash. 相似文献
16.
James M McMahon Malgorzata Simm Danielle Milano Michael Clatts 《Annals of clinical microbiology and antimicrobials》2004,3(1):1-4
Background
The Performance Standards for Antimicrobial Susceptibility Testing, Twelfth Informational Supplement, M100-S12, published by the National Committee for Clinical Laboratory Standards (NCCLS) in January 2002 introduced distinct minimum inhibitory concentration (MIC) interpretative breakpoints for ceftriaxone, cefotaxime, and cefepime for nonmeningeal isolates of Streptococcus pneumoniae. Previously, a single set of interpretative breakpoints was used for both meningeal and nonmeningeal isolates.Methods
To estimate the rate of adoption of the M100-S12 interpretive breakpoints by clinical laboratories, antimicrobial susceptibility test results for ceftriaxone and cefotaxime from nonmeningeal S. pneumoniae isolates were studied using data collected from January 2002 to June 2003 by The Surveillance Network® Database – USA (TSN®), an electronic surveillance database.Results
Of the 262 laboratories that provided data that could be evaluated, 67.6% had adopted the M100-S12 breakpoints one and one-half years after they were published.Conclusions
The NCCLS M100-S12 recommendation to interpret MICs to expanded-spectrum cephalosporins using two distinct sets of breakpoints for meningeal and nonmeningeal isolates of S. pneumoniae was steadily implemented by clinical microbiology laboratories in the United States following their initial publication in January 2002. The use of these new breakpoints more accurately reflects the clinical activities of expanded-spectrum cephalosporins than did the single set of interpretative breakpoints previously used for both meningeal and nonmeningeal isolates. 相似文献17.
Kátia Aparecida de Siqueira Elson Rudimar Brissow Jane Lima dos Santos James Francis White Fabrício Rios Santos Euziclei Gonzaga de Almeida Marcos Antônio Soares 《Symbiosis (Philadelphia, Pa.)》2017,71(3):211-222
We report the isolation and identification of endophytic fungi from Combretum lanceolatum Pohl ex Eichler. Further, we evaluated the relationships of fungi with the host plant and tested bioactivities of isolates. The fungi were isolated from disinfected root fragments and plated onto potato dextrose agar. Root pieces were also used to quantify fungal structures associated with the roots. Identification of fungi was carried out by characterization of morphological features and sequencing of the ITS region. Endophytism was confirmed by inoculation of endophyte-free seedlings followed by microscopic examination. The extract was obtained by maceration of the mycelium in ethyl acetate for antioxidant and antimicrobial evaluations. A total of 112 strains belonging to nine different species were isolated, the major classes were Dothideomycetes and Sordariomycetes. C. lanceolatum is colonized by dark septate endophytes (DSE), evidenced by the presence of microsclerotia and melanized hyphae. There is also co-colonization with mycorrhizal fungi in the same root fragments. Seedling inoculation experiments revealed that C. perangustum-95C and M. phaseolina-46C showed association with the seedlings of C. lanceolatum and differentiated microsclerotia and dark septate hyphae, indicating that these species are DSE. In the antimicrobial test, the D. phaseolorum-92C extract had the highest zones of inhibition against S. aureus and E. coli, respectively. The results showed that 100 % of the extracts have antioxidant activity ranging from low to moderate. All endophyte species had antioxidant and antimicrobial activities that were directly proportional to the dose-responses. Future research will involve chemical characterization and structural elucidation of bioactive compounds. 相似文献
18.
Aims
The objective of this study was to investigate the role of transpiration on accumulation and distribution of thallium (Tl) in young durum wheat (Triticum turgidum L. var ‘Kyle’) and spring canola (Brassica napus L. cv ‘Hyola 401’) plants.Methods
Seedlings were grown hydroponically and exposed to Tl(I) under different high relative humidity (RH) conditions which resulted in different rates of transpiration among treatments. Plants were harvested prior to exposure, after a dark period of 9 (wheat) or 10?h (canola), and after 24?h of exposure. Harvested plant material was digested and analyzed for Tl by GFAAS.Results
Our results indicated that accumulation and distribution of Tl by plants was dependent on plant species, Tl(I) dose, duration of exposure and RH, but that the effect of RH was influenced by plant species and Tl dose. Plants exposed to Tl(I) under different RH conditions did not accumulate more Tl overall. In wheat, shoots with higher transpiration rates contained a higher Tl concentration. In canola, the rate of transpiration did not consistently affect the concentration of Tl in shoots.Conclusions
Overall, our results suggest that accumulation and translocation of Tl by plants is influenced by environmental factors that affect transpiration, in addition to soil characteristics. 相似文献19.
The effect of transpiration on selenium uptake and mobility in durum wheat and spring canola 总被引:6,自引:0,他引:6
Heidi Renkema Amy Koopmans Leanne Kersbergen Julie Kikkert Beverley Hale Edward Berkelaar 《Plant and Soil》2012,354(1-2):239-250
Aims
The objective of this study was to determine the relative importance of transpirational pull, Se speciation, sulfate and species on Se accumulation by plants, in order to determine which of these factors must be considered in the future development of models to predict Se accumulation by plants.Methods
Seedlings of durum wheat (Triticum turgidum L. var durum cv ‘Kyle’) and spring canola (Brassica napus L. var Hyola 401) were grown hydroponically and exposed to SeO 4 2- (selenate) with or without SO 4 2- (sulfate), or to HSeO 3 - (biselenite) under different transpiration regimes altered through ‘low’ (~50%) or ‘high’ (~78%) relative humidity (RH). Plants were harvested after 0, 8, 16, or 24?h exposures, digested, and analyzed for Se by GFAAS.Results
Accumulation and distribution of Se by plants is dependent on plant species, Se speciation in the nutrient solution, SO 4 2- competition, and transpiration regimes. Canola accumulated and translocated more Se than wheat. In wheat and canola, the greatest accumulation and translocation of Se occurred when plants were exposed to SeO 4 2- without SO 4 2- compared to solutions of SeO 4 2- with SO 4 2- or HSeO 3 2- . Wheat plants exposed to SeO 4 2- and SO 4 2- had an increased Se accumulation and translocation under increased transpiration rates than when exposed to SeO 4 2- without SO 4 2- or HSeO 3 2- . On the other hand, increases in transpiration increased the translocation of Se to canola shoots when exposed to HSeO 3 - more than any other treatments.Conclusions
Overall, our results suggest that plant species is the most important factor influencing Se accumulation and translocation, but that these endpoints can be modified by climate and specific soil Se or S content. Models to predict accumulation of Se by plants must consider all of these factors to accurately calculate the mechanisms of uptake and translocation. 相似文献20.
Nadine R. Sousa Miguel A. Ramos Albina R. Franco Rui S. Oliveira Paula M. L. Castro 《Plant and Soil》2012,359(1-2):245-253