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1.
Collimonas sp. IS343, isolated from an organically-farmed arable soil and characterized as a broad-range oligotrophic bacterium, was shown to degrade chitin and to suppress R. solani mycelium growth under in vitro conditions at high and low carbon availabilities. In contrast to C. fungivorans Ter331, strain IS343 did not respond with an increase in growth rate to higher carbon levels in liquid medium, it reached higher cell numbers in carbon-poor media and it showed better survival in bulk soil. Therefore, it was concluded that strain IS343 cells are better adapted to circumstances of low carbon availability as present in bulk soils than strain Ter331 cells. Further, strain IS343 cells were more suppressive towards R. solani than strain Ter331 cells in vitro. When introduced into soil, strain IS343 cells delayed disease development caused by R. solani AG2-2IIIB in sugar beet plants. These results suggest that strain IS343 cells are able to tentatively suppress R. solani AG2-2IIIB mycelium growth in soil. Potential mechanisms behind the observed suppressive effects can be competition for available nutrients between strain IS343 cells and R. solani mycelium in soil or the production of chitinase as shown for this and other Collimonas species.  相似文献   

2.
Mazzola M 《Phytopathology》1999,89(10):920-927
ABSTRACT Changes in the composition of soil microbial communities and relative disease-suppressive ability of resident microflora in response to apple cultivation were assessed in orchard soils from a site possessing trees established for 1 to 5 years. The fungal community from roots of apple seedlings grown in noncultivated orchard soil was dominated by isolates from genera commonly considered saprophytic. Plant-pathogenic fungi in the genera Phytophthora, Pythium, and Rhizoctonia constituted an increasing proportion of the fungal community isolated from seedling roots with increasing orchard block age. Bacillus megaterium and Burkholderia cepacia dominated the bacterial communities recovered from noncultivated soil and the rhizosphere of apple seedlings grown in orchard soil, respectively. Populations of the two bacteria in their respective habitats declined dramatically with increasing orchard block age. Lesion nematode populations did not differ among soil and root samples from orchard blocks of different ages. Similar changes in microbial communities were observed in response to planting noncultivated orchard soil to five successive cycles of 'Gala' apple seedlings. Pasteurization of soil had no effect on apple growth in noncultivated soil but significantly enhanced apple growth in third-year orchard block soil. Seedlings grown in pasteurized soil from the third-year orchard block were equal in size to those grown in noncultivated soil, demonstrating that suppression of plant growth resulted from changes in the composition of the soil microbial community. Rhizoctonia solani anastomosis group 5 (AG 5) had no effect on growth of apple trees in noncultivated soil but significantly reduced the growth of apple trees in soil from third-year orchard soil. Changes in the ability of the resident soil microflora to suppress R. solani AG 5 were associated with reductions in the relative populations of Burkholderia cepacia and Pseudomonas putida in the rhizosphere of apple.  相似文献   

3.
A real-time PCR assay specific for Sclerotium cepivorum, the causal agent of white rot in onions, was developed for use with a new DNA extraction method capable of processing up to 1?kg of soil in weight. The assay was specific for S. cepivorum when tested against 24 isolates representative of 14 closely related species and other pathogens of onion. The assay was highly sensitive when used with soil DNA extracted using the new DNA extraction procedure. In three different field soils tested, a good relationship between cycle threshold (Ct) and number of sclerotia was observed (R2?=?0.89). Twenty-nine soil samples from onion and leek crops were obtained and the pathogen was detected in four samples. All four positive samples were associated with current or past outbreaks of white rot of onion. Additional assays were also used on the 29 field soil samples, Botrytis aclada and Rhizoctonia solani AG8 were also detected, in one soil sample each. Rhizoctonia solani AG2-1 was more widespread and was detected in eight different soil samples. The method is therefore suitable to quantify levels of S. cepivorum in soil samples, with the added advantage that the technique allows other soil pathogens of interest to be assayed from the same DNA sample. The bulk soil DNA extraction method described here has the potential to be used to detect soil-borne pests and pathogens for other crops in a wide range of soil types.  相似文献   

4.
Alternatives to soil fumigation are needed for soilborne disease control. The aim of this study was to test anaerobic soil disinfestation (ASD) as an alternative to soil fumigation for control of critical soilborne pathogens in Californian strawberry production. Controlled environment experiments were conducted at 25 and 15 °C to test different materials as carbon sources for ASD using soil inoculated with Verticillium dahliae. Field trials were conducted in three locations comparing ASD with 20 Mg ha?1 rice bran (RB) against fumigated and untreated controls, steam, mustard seed meal and fish emulsion. In ASD‐treated soils, temperature and extent of anaerobic conditions were critical for control of V. dahliae, but multiple carbon inputs reduced inoculum by 80–100%. In field trials, ASD with RB provided control of a number of pathogens, and in three of four trials produced marketable fruit yields equivalent to fumigation. Little weed control benefit from ASD was found. ASD with RB also induced changes in the soil microbiome that persisted through the growing season. When equivalent yields were obtained, net returns above harvest and treatment costs with ASD RB were 92–96% of those with bed fumigation based on average prices over the previous 5 years. ASD can be a viable alternative for control of some soilborne pathogens. Growers are adopting ASD in California strawberry production, but research to determine optimal soil temperatures, anaerobicity thresholds and carbon sources for effective control of specific pathogens is needed.  相似文献   

5.
The soilborne fungi Sclerotinia sclerotiorum, Rhizoctonia solani and the oomycete Pythium ultimum are among the most destructive pathogens for lettuce production. The application of the biocontrol agent Paenibacillus alvei K165 to the transplant soil plug of lettuce resulted in reduced S. sclerotiorum, R. solani and P. ultimum foliar symptoms and incidence compared to untreated controls, despite the suppressive effect of the pathogens on the rhizosphere population of K165. In vitro, K165 inhibited the growth of S. sclerotiorum and R. solani but not P. ultimum. Furthermore, the expression of the pathogenesis‐related (PR) gene PR1, a marker gene of salicylic acid (SA)‐dependent plant defence, and of the Lipoxygenase (LOX) and Ethylene response factor 1 (ERF1) genes, markers of ethylene/jasmonate (ET/JA)‐dependent plant defence was recorded. K165‐treated plants challenged with P. ultimum showed up‐regulation of PR1, whereas challenge with R. solani resulted in up‐regulation of LOX and ERF1, and challenge with S. sclerotiorum resulted in up‐regulation of PR1, LOX and ERF1. This suggests that K165 triggers the SA‐ and the ET/JA‐mediated induced systemic resistance against P. ultimum and R. solani, respectively, while the simultaneous activation of the SA and ET/JA signalling pathways is proposed for S. sclerotiorum.  相似文献   

6.
为明确荧光假单胞菌SS101对苹果再植病害的生防效果,采用平板对峙法和孢子萌发法研究了SS101菌株对9株来自不同苹果产区病原菌的抑制作用以及对盆栽海棠实生苗、海棠大苗和苹果树生长的影响,并测定了连续处理4年苹果树的产量。结果显示,SS101菌株对9株病原菌的菌丝生长抑制率为39.39%~72.00%,对孢子萌发抑制率为19.86%~51.77%;经SS101菌株处理后,海棠实生苗叶绿素含量、株高和鲜重均显著高于再植土处理,分别提高13.38%、19.39%和48.26%;经SS101菌株处理后,海棠大苗定植9个月后,茎粗净增长量为2.97 mm,增长率为214.05%,而再植土处理仅为114.02%;连续处理4年的苹果树平均单株产量比再植土处理提高139.46%,且消除了再植病害症状。研究表明,SS101菌株对苹果再植病害病原菌具有显著抑制作用,在田间对再植病害具有良好的防控效果。  相似文献   

7.
Isolates of R. solani AG 2–1, AG 8, AG 10 and binucleate Rhizoctonia (Ceratobasidium spp.) were tested for virulence on Brassica crops in growth chamber experiments. Isolate virulence and genotype resistance were determined based on percent of seedling survival, shoot length reduction, and shoot fresh weight. Isolates had significant effects on all tested measurements, compared to the non-inoculated controls. Rhizoctonia solani AG 2–1 appears to be the most aggressive pathogen on all tested genotypes followed by R. solani AG 8, binucleate Rhizoctonia and R. solani AG 10, respectively. Genotype by isolate interaction effects were found to be significant for percent of seedling survival and shoot length reduction. None of the tested genotypes exhibited any level of resistance to R. solani AG 2–1, but three promising genotypes with moderate levels of resistance to R. solani AG 10, R. solani AG 8 and binucleate Rhizoctonia were identified. Moderate heritability (0.57) was observed for the percent of seedling survival in the resistant genotype KS4022.  相似文献   

8.
Biotic and abiotic factors from soils have been implicated in the disease suppression of Rhizoctonia solani. This study included a Eucalyptus twig baiting assay, disease index and qPCR quantification of R. solani, and physicochemical analysis of 10 tobacco soils from five different locations (V: Vaqueros, C: Cerrillos, R: Rosario de Lerma, SA: San Agustín, CH: Chicoana) in the northwest of Argentina. Levels of Rhizoctonia soil inoculum quantified by baiting assay and qPCR were positively correlated. However, there was no correlation with root rot disease index in tobacco fields. Soils from V1, SA2 and CH2 fields, which reduced root rot disease on tobacco plants, were suppressive to R. solani infection. High clay, pH, organic matter content and physical stability in tobacco soils were the main physicochemical properties that limited Rhizoctonia development. Interestingly, growth of R. solani subgroups AG4-HGI and AG4-HGIII was highly suppressed in V1 and CH2 fields, and in SA2 fields, respectively. Undisturbed soil from a local forested mountain also resulted in reduction of growth of AG4-HGIII and AG4-HGI, while AG2-1 was less affected, suggesting that high soil organic matter contributed to suppression of R. solani. Soils highly suppressive of R. solani had significantly different populations of culturable bacteria, Pseudomonas and fungi, but populations of actinobacteria and Trichoderma spp. did not differ. These different populations may be involved in the inhibition of fungal growth. The results demonstrated that physicochemical and biological properties of soil suppressive to R. solani could act as an alternative for controlling Rhizoctonia diseases on tobacco.  相似文献   

9.
Stages of oat–vetch cover crop decomposition were characterized over time in terms of carbon and nitrogen cycling, microbial activity and damping-off pathogen dynamics in organically and conventionally managed soils in a field and a controlled incubation experiment. A measurement of relative growth consisting of radial growth of a fungal colony over non-sterilized soil divided by that over sterilized soil was used as an assay of suppressiveness. No differences in relative growth of Pythium aphanidermatum and Rhizoctonia solani were detected between organic and conventionally managed soils amended with cover crop residue. Significant effects of cover crop decomposition stage on the relative growth of both pathogens were obtained. Relative growth of P. aphanidermatum was highest just after incorporation and decreased 3 weeks after incorporation. Relative growth of R. solani was highest about 20 days after incorporation, and decreased 2 weeks later in the organic system, but continued to increase in the conventional system. In both experiments, the N or C content, C:N ratio or dry weight of retrieved debris were significantly correlated with relative growth of P. aphanidermatum. Relative growth of R. solani was significantly correlated with the C:N ratio of soil or the C or N content of debris. Microbial activity was not consistently associated with relative growth of either pathogen.  相似文献   

10.
Tare soil is soil attached to harvested products like potato tubers. Tare soil becomes a considerable waste stream after storage, washing and processing of harvested products. There is a high risk on contamination of tare soils with (quarantine) phytopathogens, because of import of harvested products from different regions of the world. Disinfestation is necessary to make tare soils applicable for agricultural production. Anaerobic (non-chemical) soil disinfestation (ASD) and inundation are suitable methods to disinfest tare soils. Two different soils (marine loam and glacial sand) were either treated with five (2011) or four (2012) treatments and these were: (i) no treatment (control), (ii) freshly cut grass, (iii) Herbie 7025, (iv) inundation (five cm water on top of the soil surface), and (v) combination of Herbie 7025 and inundation (2011 only). Containers with treated and untreated soils were inoculated with two quarantine phytopathogens, Ralstonia solanacearum biovar 2 and Globodera pallida. After soil inoculation, the containers were airtight closed and only opened for destructive sampling after 84 days. Then, soils were analysed for the presence of R. solanacearum biovar 2, using immunofluorescence colony staining, and for the presence of viable G. pallida eggs, determined by the number of juveniles hatched from eggs and lured to potato root exudate. Strong (> 99.4 %) declines of both pathogens in treated versus the appropriate control soils were observed. Repetition of the experiment revealed the same pattern and therefore it was concluded that ASD and inundation, as separate treatments, have promise for remediation of tare soils from contaminating quarantine pathogens.  相似文献   

11.
A polynucleate Rhizoctonia isolate (R3) was analysed for virulence, growth characteristics, enzyme production and presence of dsRNAs. Taxonomic position was assessed morphologically and by anastomosis group (AG) testing and ITS sequence analysis. Results indicated that R3 is a hypovirulent R. solani AG 4. Mechanisms underlying biocontrol towards virulent R. solani and Botrytis cinerea were investigated and plant-mediated resistance was followed using biochemical markers of defence (PR1, laminarinase, chitinase). Control apparently relies on spatial and nutrient competition in soil, and on systemic induced resistance. This is the first report on induction of systemic resistance and of defence markers by a hypovirulent strain of R. solani.  相似文献   

12.
Mazzola M  Gu YH 《Phytopathology》2000,90(2):114-119
ABSTRACT Studies were conducted to assess the impact of short-term rotations of wheat on microbial community composition and growth of apple in soils from replant orchard sites. Soils from two orchards were cultivated with three successive 28-day growth cycles of 'Eltan', 'Penewawa', or 'Rely' wheat in the greenhouse and subsequently planted to 'Gala' apple seedlings. Cultivation of orchard replant soils with any of the three wheat cultivars enhanced growth of apple relative to that achieved in untreated soils. Improved growth was associated with a marked reduction in apple root infection by species of Rhizoctonia and Pythium. Populations of plant-parasitic nematodes were below damage threshold levels in these orchard soils; however, apple seedlings grown in wheat-cultivated soils had significantly lower root populations of Pratylenchus spp. than did seedlings grown in untreated soils. Growth of apple in 'Penewawa'-cultivated soils often was superior to that observed in soils planted with 'Eltan' or 'Rely'. In untreated orchard soils, fluorescent pseudomonad populations isolated from soil and the apple rhizosphere were dominated by Pseudomonas fluorescens biotype C and Pseudomonas syringae. Cultivation of replant soils with wheat induced a characteristic transformation of the fluorescent pseudomonad population, and Pseudomonas putida dominated the population of this bacterial group recovered from wheat-cultivated replant orchard soils. Results from this study suggest that use of short-term wheat cropping sequences during orchard renovation could be useful in management of replant disease and that this disease-control option may operate, in part, through modification of the fluorescent pseudomonad community.  相似文献   

13.
In 1983, seed dressing of peas with fosetyl-Al (Aliette) compared favourably with all other treatments on a field heavily contaminated with foot and root rot pathogens. Experiments carried out in 1983 and 1984 could not establish the reason for this phenomenon. Artificial inoculation with the most frequently isolated pathogens (Fusarium oxysporum, Phoma medicaginis var.pinodella, Pythium ultimum andFusarium solani f.sp.pisi) of sterilized soil before planting treated seeds did not reproduce the field observations, but glasshouse experiments using soil from the experimental field did. Glasshouse experiments in 1989, afterAphanomyces euteiches had been identified as a frequently occurring pea pathogen in the Netherlands, confirmed the favourable effect of fosetyl-Al as a seed treatment whenA. euteiches was in the pathogen flora.Samenvatting In 1983 bleek op een zwaar met voetrotpathogenen besmet veld zaaizaadbehandeling van erwten met fosetyl-Al (Aliette) gunstig af te steken bij alle andere behandelingen. De oorzaak kon toen niet worden gevonden. Kunstmatige besmetting van gesterilisserde grond vóór het planten van behandelde zaden met de meest geïsoleerde pathogenen (Fusarium oxysporum, Phoma medicaginis var.pinodella, Pythium ultimum enFusarium solani f.sp.pisi) gaf resultaten die niet overeenstemden met die van het proefveld, maar kasproeven met grond van het proefveld deden dat wel. Nadat was aangetoond dat het erwtepathogeenAphanomyces euteiches in Nederland veel voorkomt, bevestigden nieuwe kasproeven in 1989 het gunstige effect van fosetyl-Al als zaaizaadbehandeling wanneerA. euteiches deel uitmaakt van de pathogene bodemflora.  相似文献   

14.
The impact of soil type, long-term soil management, and short-term fertility input strategies on the suppressiveness of soils against soil-borne (Ocimum basilicum – Rhizoctonia solani, Lepidium sativum – Pythium ultimum) as well as air-borne (Lycopersicon esculentum – Phytophthora infestans, Arabidopsis thaliana – Hyaloperonospora parasitica) diseases was studied. Soils from field trials established in five European sites with contrasting pedo-climatic conditions were examined. Sites included (i) a long-term management field trial comparing organic and conventional farming systems (DOK-trial, Therwil, Switzerland) (ii) a short-term fertility input field trial comparing mineral and organic matter fertilisation regimes (Bonn (BON), Germany) (iii) two short-term fertility input field trials (Stockbridge (STC) and Tadcaster (TAD), UK) comparing the impact of farmyard manure, composted farmyard manure, and chicken manure pellet amendements and (iv) soil from a site used as a reference (Reckenholz (REC), Switzerland). Soil type affected disease suppressiveness of the four pathosystems signficantly, indicating that soils can not only affect the development of soil-borne, but also the resistance of plants to air-borne diseases at relevant levels. Suppressiveness to soil- and air-borne diseases was shown to be affected by soil type, but also by long-term management as well as short-term fertility inputs.  相似文献   

15.
Rhizoctonia solani is an important pathogen of potatoes causing stem canker and black scurf. The fungus is a species complex comprised of 13 known anastomosis groups (AGs). AG3-PT is the anastomosis group frequently associated with disease in potatoes. A real-time PCR assay was designed to the rDNA ITS region of AG3-PT isolates to enable the pathogen to be detected directly in tuber and soil samples. The resulting assay was highly specific for AG3-PT, and did not amplify DNA from isolates from other AGs or subgroups of AG3. Using a bulk DNA extraction method capable of extracting from up to 250 g of soil, the assay could detect one individual sclerotium of AG3-PT (weighing 200 μg) in 250 g of soil. The AG3-PT assay was used, with assays for AG2-1, AG5 and AG8 to determine the prevalence of those AGs in UK potato soils and tubers. AG2-1 and AG3-PT were the predominant groups in tubers and soils, although AG3-PT was more frequently isolated from tubers, highlighting its importance as a potato pathogen. AG3-PT was also detected in more than half of the tuber samples tested suggesting the importance of seed borne inoculum.  相似文献   

16.
Delayed sprouting and white rot of leaf tips were found on Chinese chives in a greenhouse in Hokkaido, Japan, in the spring of 2006 and 2007. The causal fungus was identified as Rhizoctonia solani anastomosis group (AG)-2-1 and discriminated from the leaf rot pathogen R. solani AG-4 HG-I in terms of pathogenicity. Symptoms and the time of year that the disease occurs also apparently differ for the two pathogens. This is the first report of white leaf rot on Chinese chive caused by R. solani AG-2-1.  相似文献   

17.
The herbicides fluchloralin and alachlor applied to soil altered the effectiveness of fungicide treatments to seed and soil for controlling cowpea damping-off. These herbicides also modified the in-vitro toxicity of the fungicides to the mycelial growth of Pythium butleri and Rhizoctonia solani in a nutrient medium. Both herbicides reduced the toxicity of 2-methoxyethylmercury chloride (MEMC) and propamocarb to the growth of P. butleri, and of carbendazim to the growth of R. solani, but enhanced the toxicity of captafol and quintozene to P. butleri and R. solani, respectively. In pot tests, quintozene gave better control of R. solani damping-off in soil treated with fluchloralin or alachlor than in untreated soil, whereas disease control by carbendazim was decreased in similarly treated soils. Both herbicides attenuated the effectiveness of MEMC and captafol to control the damping-off caused by P. butleri; the efficacy of propamocarb was increased by alachlor but was decreased by fluchloralin. The implications of herbicide-fungicide interactions are discussed in the context of fungicidal control of root diseases in herbicide-treated soil.  相似文献   

18.
Biofumigation potential of Brassicaceae cultivars to Verticillium dahliae   总被引：1，自引：0，他引：1  
The biofumigation potential of brassicaceous green manures to Verticillium dahliae was systematically assessed. In a toxicological study, five different isothiocyanates (ITCs) were tested using a bioassay with sterile quartz sand artificially infested with microsclerotia. For 2-propenyl ITC, a LD90 value of 88.7 nmol g?1 was determined. Furthermore, 2-propenyl ITC with a dose of 150 nmol g?1 soil was tested in 22 naturally infested soils. The efficiency varied from 9 % to 92 % and was negatively correlated with the organic carbon content of the soils, indicating that in many soils much higher concentrations will be necessary to achieve sufficient control. To evaluate the biofumigation potential of different Brassicaceae, 19 cultivars of Brassica juncea, Rhaphanus sativus and Sinapis alba were grown in the field. Biomass production was measured and glucosinolate concentrations were analyzed. Simulating the field situation, the biofumigation effect of cultivars was assessed in a standardized laboratory bioassay with microsclerotia-infested sterile quartz sand amended with freeze-dried ground plant tissues. Amendments of B. juncea shoot tissue reduced the number of viable microsclerotia significantly with efficiencies from 69.3 to 81.3 %. Total potentially released amounts of 2-propenyl ITC ranged between 50.6–78.1 nmol g?1sand and indicate a clear ITC-related suppression. However these are considered too low for effective control in practice as low release efficiencies mean that effective levels fall well short of the estimated 150 nmol g?1 of soil required. In comparison with B. juncea, the R. sativus and S. alba were less effective due to lower concentrations and/or toxicity of the ITC released. In summary, the biofumigation potential of the cultivars tested appears insufficient alone for effective control, especially on soils with higher (>1.0 %) organic carbon content.  相似文献   

19.
ABSTRACT Apple replant disease typically is managed through pre-plant application of broad-spectrum soil fumigants including methyl bromide. The impending loss or restricted use of soil fumigants and the needs of an expanding organic tree fruit industry necessitate the development of alternative control measures. The microbial community resident in a wheat field soil was shown to suppress components of the microbial complex that incites apple replant disease. Pseudomonas putida was the primary fluorescent pseudomonad recovered from suppressive soil, whereas Pseudomonas fluorescens bv. III was dominant in a conducive soil; the latter developed within 3 years of orchard establishment at the same site. In greenhouse studies, cultivation of wheat in replant orchard soils prior to planting apple suppressed disease development. Disease suppression was induced in a wheat cultivar-specific manner. Wheat cultivars that enhanced apple seedling growth altered the dominant fluorescent pseudo-monad from Pseudomonas fluorescens bv. III to Pseudomonas putida. The microbial community resident in replant orchard soils after growing wheat also was suppressive to an introduced isolate of Rhizoctonia solani anastomosis group 5, which causes root rot of apple. Incorporation of high glucosinolate containing rapeseed ('Dwarf Essex') meal also enhanced growth of apple in replant soils through suppression of Rhizoc-tonia spp., Cylindrocarpon spp., and Pratylenchus penetrans. Integration of these methods will require knowledge of the impact of the biofumigant component on the wheat-induced disease-suppressive microbial community. Implementation of these control strategies for management of apple replant disease awaits confirmation from ongoing field validation trials.  相似文献   

20.
建立了简单、灵敏的土壤及苹果中草甘膦残留量的气相色谱检测方法。土壤样品用2 mol/L 的氨水提取,经三氟乙酸酐(TFAA)和三氟乙醇(TFE)衍生化后,由配有氮磷检测器的气 相色谱(GC-NPD)进行检测。土壤中草甘膦的最小检出量为9×10-12 g,最低检出浓度为0.02 mg/kg, 平均回收率及变异系数分别为84.4% ~94.0% 和7.46% ~10.40%。苹果样品则采用去离子水提取,经二氯甲烷液液分配和BIO-RAD AG 50W-X8阳离子交换柱净化后,再用TEAA和TFE衍生化,最后用GC-NPD检测,其中草甘膦的最小检出量(LOD)和最低检出浓度(LOQ)与土壤样品中的相同,平均回收率及变异系数分别为80.7% ~98.6%和9.3% ~11.8%。草甘膦的衍生化产物通过气相色谱-质谱联用仪(GC-MS)进行了确证。在北京昌平地区进行的消解动态和最终残留试验结果表明,以推荐高剂量(有效浓度)的1.5倍(2 025 g/hm2)施药,草甘膦在土壤中的半衰期为 9.2 d。两年的最终残留试验结果表明,无论是高浓度区(2 025 g/hm2)还是低浓度区(1 350 g/hm2),苹果收获时(距施药75 d),土壤和苹果样品中均未检出草甘膦。  相似文献   

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