bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cytopathological, Negative Staining and Serological Electron Microscopy of a Clostero‐like Virus Associated with Pear Vein Yellows Disease
Authors: Giunchedi L. , Pollini C. Poggi 
Published: May 2008

AbstractUltrastructural and immunocytochemical studies were made on thin sections of Nicotiana occidentalis leaves systemically infected with a clostero‐like virus associated with pear vein yellows. The virus particles were also studied in negative stain and by the decoration technique.Virus‐like particles were seen only in mesophyll parenchyma cells, usually arranged in long bundles. An antiserum to apple stem pitting virus gave positive gold labelling of the virion aggregates. Labelling intensity was higher using IgG‐gold than with protein A‐gold. Osmium tetroxide postfixation did not adversely affect the labelling. Virus particle morphology in negative stain resembled that of closteroviruses, although the cytopathic effects in many respects did not resemble those caused by closteroviruses; the cytoplasmic vesicles characteristic of closterovirus infections were not observed.Zusammenfassung Zytopathologische negative Färbung und serologische Elektronenmikroskopie eines clostero‐ähnlichen Virus, assoziiert mit der pear vein yellow Krankheit Ultrastrukturelle‐ und immunozytochemische Untersuchungen wurden an dünnen Schnitten von Nicotiana ocddentalis‐Blättern, die systemisch mit einem clostero‐ähnlichen Virus, assoziiert mit pear vein yellows, infiziert waren, durchgeführt. Die Viruspartikeln wurden auch bei der Negativfarbung und der Dekorations‐Technik untersucht.Virus‐ähnliche Partikeln wurden nur in Mesophyllparenchymzellen beobachtet, normalerweise in langen Bündeln orientiert. Ein gegen das apple stem pitting virus entwickeltes Antiserum verursachte eine positive Gold‐Markierung der Virionaggregate. Die Intensität der Markierung war mit IgG‐jGold höher als mit Protein‐A‐Gold. Eine Nachfixienmg mit Osmiumtetroxid beeinfiußte die Markierung nicht. Die Viruspartikelmorphologie in der Negativ‐Farbung war die der Closteroviren ähnlich, obwohl die zytopathologischen Einflüsse in vielen Hinsichten den durch Glosteroviren verursachten Einflüsse nicht ähnlich waren. Die zytoplasmatischen Vesikel, die bei Glosterovirusinfektionen charakteristisch sind, wurden nicht beobachtet.
Mode of Action of α, β Unsaturated Carbonyl Compounds
Authors: Larsen J. , Olson L. W. 
Published: May 2008

AbstractThe toxicity of the α, β unsaturated carbonyl compounds (α, β UCCs) (patulin, penicillic acid, parasorbic acid, tulipalin and plumbagin) towards Pythium sp. group F (Van Der Plaat‐Niterinks 1981) was neutralized by the addition of an excess of cysteine. This suggests that the mode of action of these compounds could be due to a binding of the α, βi UCCs to sulphydryl groups in enzymes or other macromolecules. Alcohol dehydrogenase (ADH), an enzyme with a sulphydryl group at the active site, was assayed spectrophotometrically and all the α, β UCCs inhibited ADH.
Symptom Severity, Yield, Seed Mottling and Seed Transmission of Soybean Mosaic Virus in Susceptible and Resistant Soybean: The Influence of Infection Stage and Growth Temperature
Authors: Tu J. C. 
Published: May 2008

AbstractThe effect of soybean mosaic virus (SMV) infection on symptom severity, yield, seed mottling and seed transmission in soybean in relation to the growth stage at infection and subsequent temperature was investigated using a susceptible (Harosoy), a moderately resistant (Evans) and a highly resistant (Merit) cultivar. Disease symptoms were more severe with early infection. A greater reduction in plant growth and seed yield, and higher percentages of mottled seeds and seed transmission of SMV also occurred with early infection. Virus titer was higher in younger plants than in older ones and also higher in plants infected at the ealier stage than at the later stage of growth. Merit (a highly resistant cultivar previously reported to be immune to seed mottling) inoculated at the early stage of plant growth resulted in infection and production of some mottled seeds.Temperature affected all parameters investigated. The effect of temperature was greater in the susceptible cultivar than in the resistant one. The optimal temperature for symptom severity, yield, seed mottling and seed transmission was 20 °C. Virus titer was highest at 30 °C in all three cultivars. Maturity of susceptible cultivar was delayed by infection.
Some Characteristics of Potyvirus Isolates from Vanilla tahitensis in French Polynesia and the Cook Islands
Authors: Wang Y.‐Y. , Pearson M. N. 
Published: May 2008

AbstractFurther characterization of vanilla mosaic potyvirus (VaMV) confirmed that it is quite distinct from vanilla necrosis potyvirus (VNV). In immuno‐blot ELISA, a polyclonal antiserum to vanilla mosaic virus from Vanilla tahitensis in French Polynesia did not react with vanilla necrosis potyvirus infected V. fragrans from Tonga. However, samples of V. tahitensis with leaf distortion and mosaic from the Cook Islands reacted strongly with the VaMV antiserum. Host range studies involving 20 plant species failed to find a host for VaMV outside the genus Vanilla, confirming that VaMV has a much more restricted host range than VNV. The mean particle length of VaMV from purified preparations was 763 nm (Std. Dev. 48) and SDS‐polyacrylamide electrophoresis indicates a single coat polypeptide of Mr 34 × lO3.
Use of Oospore Formulations of Pythium oligandrum for Biological Control of Pythium Damping‐off in Cress
Authors: McQuilken M. P. , Whipps J. M. , Cooke R. C. 
Published: May 2008

AbstracOospore preparations of Pythium oligandrum produced by liquid and solid‐substrate fermentations were evaluated for biocontrol activity against Pythium damping‐off in cress in artificially infested sand and naturally infested soil. Oospore biomass preparations from liquid fermentation of six isolates of P. oligandrum were equally effective in reducing damping‐off in sand when tested as seed‐coatings, whereas this type of preparation of a single isolate formulated as a kaolin dust, on Perlite and as alginate pellets incorporated into sand gave little or no control. None of the formulations containing oospores produced by solid‐substrate fermentation incorporated into sand had any effect. In soil, a formulation containing oospores produced in a barley‐Perlite solid‐substrate fermentation and all oospore‐biomass formulations which were prepared increased seedling survival, but none of these were as effective as a propamocarb HCl drench.
Endogenous Elicitor Present in Barley Seeds
Authors: Hiramoto T. , Tobimatsu R. , Shiraishi T. , Yamada T. , Ichinose Y. , Oku H. 
Published: May 2008

AbstractEndogenous elicitor(s) present in barley seeds induce the accumulation of antifungal substances effective against powdery mildew fungi. Antifungal substances induced by the treatment with barley seeds extract coincides with the one induced by the inoculation with compatible or incompatible races of powdery mildew fungi on thin‐layer chromatography analysis. The resistance induced by the treatment with barley seeds extract correlates to the accumulation of the antifungal substances in barley leaves. Furthermore, the activity of phenylalanine ammonia‐lyase was also induced by the treatment with barley seeds extract.
Protective Effect of Homologues of Host‐Specific AF‐Toxin I Produced by Alternaria alternata Strawberry Pathotype on Strawberry Cells
Authors: Lee S.‐S. , Tsuge T. , Doke N. , Nakatsuka S. , Nishimura S. 
Published: May 2008

AbstractThe protective effect of homologues of host‐specific AF‐toxin I from Alternaria alternata strawberry pathotype on susceptible strawberry cells was quantitatively examined by using the cultured cells. Among three AF‐toxin molecules, AF‐toxin II did not exhibit toxicity to strawberry cells, although AF‐toxin I and III were highly toxic to the cells. AF‐toxin II protected strawberry cells from AF‐toxin I action. The protection was remarkable when the cultured cells were exposed to excess amounts of AF‐toxin II both prior to and simultaneously with AF‐toxin I addition. The simultaneous treatment, however, was most effective at preventing AF‐toxin I action: it gave complete protection at a 50 : 1 (toxin II : toxin I) ratio on a molar basis. The epoxy‐decatrienoic acid moiety of the AF‐toxins also prevented the cell death caused by AF‐toxin I, but was less effective than AF‐toxin II. Protection was apparent when the cultured cells were exposed to AF‐toxin II for 3 h, rinsed to remove free AF‐toxin II and then exposed to AF‐toxin I. These results suggest that the toxoids of AF‐toxin I, such as AF‐toxin II and the decatrienoic acid, act as competitive inhibitors of AF‐toxin I.
Mycoplasma‐like Organisms Associated with Proliferation and Big Bud of Solanum lycocarpum St. Hil.
Authors: Chagas C. M. , Oliveira J. M. , Caner J. 
Published: May 2008

AbstractMycoplasma‐like organisms (MLOs) were found in sieve tubes of Solanum lycocarpum affected with prolferation and big bud. The MLOs were graft‐transmitted to tomato plants which developed similar symptoms. The association of MLOs with affected but not with symptomless S. lycocarpum and tomato suggests that the abnormality is induced by MLOs. The possible role of S. lycocarpum as a reservoir of a strain of the tomato big bud is discussed.
Zum Einfluß des bakteriellen Phytotoxins Coronatin auf pflanzliche Zellsuspensionskulturen
Authors: Perner Birgit , Schmauder Hans‐Peter 
Published: May 2008

Abstract Effect of the Bacterial Phytotoxin Coronatine on Plant Cell Cultures The influence of the bacterial phytotoxin coronatine on cell cultures of Lycopersicon peruvianum and Chenopodium album was studied. It was detectable that the cell culture L. peruvianum more related to the host plant of the phytopathogenic bacteria reacts more sensitive to coronatine. Concentrations of 3.5 ng coronatme/ml culture liquid mduce reductions in growth and the TTC‐activity. In the case of the other used cell culture the critical amount of coronatine was higher than 7 ng/ml culture liquid. In further experiments the concentrations of free amino acids and proteins within the cell were followed. After 6–7 days of culture a slightly recovery of the cultures treated with coronatine was detectable.
Biological Control of Fire Blight of Hawthorn (Crataegus monogyna) with Fluorescent Pseudomonas spp. under Protected Conditions
Authors: Wilson M. , Epton H. A. S. , Sigee D. C. 
Published: May 2008

AbstractNaturally‐occurring epiphytic fluorescent pseudomonads were isolated and characterized in terms of their potential to control fire blight infection of hawthorn, caused by Erwinia amylovora.Preliminary testing and selection of antagonists using an immature pear fruit assay gave some inconsistency in the amount of pathogen suppression on the pear tissue and also in the prediction of biocontrol effectiveness on the intact plant.Selected antagonists provided significant but variable control of fire blight under protected (polythene tunnel and glasshouse) conditions, with isolates HL83 and HL99 giving control of both blossom‐blight and shoot‐blight. In some cases the degree of control was equal to that of chemical treatments, including agrimycin 17 and experimental bactericides, and was achieved without any numerical advantage of applied control agent over pathogen. The timing of pseudomonad application in relation to pathogen inoculation was found to have a significant effect on the level of control of blossom‐blight.
Identification of Rhodococcus fscians (Tilford 1936) Goodfellow 1984
Authors: Hu F.‐P. , Fletcher M. J. , Watson D. R. W. , Clark R. G. , Young J. M. 
Published: May 2008

AbstractDeterminative laboratory tests which distinguish Rhodococcus fasdans from all other coryneform plant pathogenic bacteria were used to compare strains of this species with representative strains of Clavibacter spp. and Curtobacterium spp. The strains were also compared by colony hybridization using genomic DNA from R. fascians as a probe. Only strains of R. fascians authenticated with the determinative tests gave positive reactions to the probe.The pathogenicity of strains was tested in seedlings of Lathyrus odoratus L. (sweetpea) grown in soil, and asepticaily in agar in tubes. Fasciation was induced in sweetpea by 20 strains of R. fascisms from Begonia sp., Brodiaea laxa, Carica X heilbornii nm. pentagona, C. pubescens, Dahlia sp., Fragaria X ananassa, Lathyrus odoratus, and Verbascum nigrum. Strains of R. fasdans from Chrysanthemum sp., Gladiolus sp., and Justicia brandegeana did not induce fasciation in sweetpea.
Ultrastructural Visualization of Glucide Determinants in Membranes of Mycoplasma‐like Organisms
Authors: Poggi Pollini C. , Giunchedi L. 
Published: May 2008

AbstractPeriodic acid‐thiocarbohydrazide‐silver proteinate (PATAg) reaction for poiysaccharide localization was performed on ultrathin sections of Spurr resin‐embedded tissues of Physostegia virginina and Catharanthus roseusknown to be infected by mycoplasma‐like organisms (MLO). Electron microscopy of PATAg‐treated sections revealed heavy silver deposition on hmiting membranes of all MLO. It was not possible to detect differences m silver deposition within the multi stratified membrane structure because of masking by silver‐grain deposition. Silver deposition was not found in the cytoplasmic region of the MLO. The results indicate the presence of glucide determinants only in the limiting membrane of the MLO. The significance of this finding is discussed.
Effects of Seedbed Management on Blast Development in Susceptible and Partially Resistant Rice Cultivars
Authors: Sah D. N. , Bonman J. M. 
Published: May 2008

AbstractFour rice cultivars, susceptible or partially resistant to Pyricularia grisea were evaluated for their apparent infection rates (r) and for terminal severity values in seedlings grown in seedbeds. Susceptibility of partially resistant cultivars decreased when seeded in wet seedbed compared to those grown in raised or upland seedbed. The degree of blast reduction due to flooding varied with rice genotype, seeding rate, and environmental conditions. Flooding was effective in managing seedling blast of partially resistant cultivars but not of susceptible cultivar. Use of a lower seed rate in comparison to a higher seed rate also led to reductions in r‐values and terminal disease severities. However, in case of the susceptible cultivar IR50, effect of seed rate was more pronounced, when low amount and short duration of rainfall occurred. Flooding of wet beds with low seed rate further reduced the blast incidence. Results of this study suggest that with appropriate use of water, seed rate, and partial host resistance there are prospects for effective control of leaf blast in the tropics.
Host Effect on Cross Protection Between Two Strains of Tobacco Mosaic Virus
Authors: Rezende J. A. M. , Urban L. , Melgher U. , Sherwood J. L. 
Published: May 2008

AbstractThe expression of cross protection between two strains of tobacco mosaic virus (TMV‐C and TMV‐P) differed in Arabidopsis thaliana cv. Columbia and Nicotiana tabacum cvs Samsun and Xanthi. Protection in A. thaliana cv. Columbia was expressed as a prevention of systemic movement of the challenge strain, regardless of the protecting strain of TMV, Protection in N. tabacum cvs Samsun and Xanthi was expressed as an inhibition of an early event in the infection process. The results presented indicate that the host may influence the mechanism by which cross protection is expressed between the same virus strains.
Selection for Aggressiveness in Erysiphe graminis f. sp. Hordei Towards Partial Resistance in Barley
Authors: Newton A. C. 
Published: May 2008

AbstractIsolates of powdery mildew were subjected to recurrent selection on partially resistant barley cultivars for 76 inoculation cycles over three years. Previous intermediate tests on up to 32 cycles for adaptation to overcome the host resistance revealed a trend towards adaptation to the cv. 7204 recurrent host in infection frequency data but not towards cv. Golden Promise or 9319, Subsequent cycles demonstrated adaptation to these latter hosts also.
Suppression of Brown Spot Disease of Cultivated Chrysanthemum by Manipulating Phototropic Response of Conidium Germ Tubes of Septoria obesa
Authors: Honda Y. , Kashima T. , Kumagai T. 
Published: May 2008

AbstractAn antagonistic effect between the UV‐blue (shorter than 500 nm) and red (longer than 600 nm) wave regions on the induction of phototropic response in conidium germ tubes has been demonstrated in the fungus Septoria obesa, the causal organism of brown spot disease of cultivated chrysanthemum. Phototropic response of conidium germ tubes was dependent on the ratio of the fluence rates between negative phototropism‐inducing UV‐blue wave region and positive phototropism‐inducing red wave region. Elimination of the UV wave region shorter than 390 nm by an ultraviolet absorbing vinyl film significantly reduced the negative phototropic response of conidium germ tubes and suppressed the invasion of the fungus through the stomata. Thus, a manipulation of the phototropic response of conidium germ tubes by controlling light quality resulted in the suppression of brown spot disease of cultivated chrysanthemum.
Antibacterial and Antifungal Spectra of Antibiotics Produced by Different Strains of Erwinia herbicola (= Pantoea agglomerans)
Authors: El‐Goorani M. A. , Hassanein FerialM. , Shoeib AliaA. 
Published: May 2008

AbstractNine antibiotic producer strains of Erwinia herbicola (=Pantoea agglomerans), belonging to different groups, strongly inhibited growth of 21 streptomycin sensitive strains and 6 streptomycin resistant strains of E. amylovora.The antibacterial spectra of antibiotics produced by the tested strains of E. herbicola were mainly limited to E. amylovora and related tested species. The tested strains of E. amylovora that are resistant to streptomycin did not show cross‐resistance to the different types of antibiotics produced by the tested strains of E. herbicola.The antibiotics produced by the different tested strains of E. herbicola did not exert any activity on tested fungi with the exception that strains Eh 153 and Eh 351 slightly inhibited the growth of Verticillium dahliae.
Pepper Tree (Schinus terebenthifolius Radii), a New Host Plant for Xanthomonas campestris pv. mangiferaeindicae
Authors: Pruvost O. , Couteau A. , Luisetti J. 
Published: May 2008

AbstractApigmented bacterial colonies were obtained in Reunion Island from angular leaf lesions on Pepper tree (Schinus terebenthifoliusRadii), a member ofAnacardiaceae. All isolates were identified asXanthomonas campestris, using physiological and biochemical tests.These strains were reinoculated to Pepper tree leaves, and Koch postulates were verified. Furthermore, they were inoculated to mango leaves and produced lesions identical to those induced byXanthomonas campestrispv.mangiferaeindicae, the causal agent of bacterial black spot of mangoes. Apigmented and pigmented strains ofX. c.pv.mangiferaeindicaefrom Mango and Ambarella were pathogenic to Pepper tree.Strains isolated from Pepper tree were compared toX. c.pv.mangiferaeindicae, by means of phenotypic features (utilization of 147 carbon sources) and using a serological assay. A high homology among the strains was observed.Thus, It is concluded that strains isolated from Pepper tree belong to pv.mangiferaeindicae, and that Pepper tree is a host species forX. c.pv.mangiferaeindicae.
Pre–flowering Low Temperature Predisposition of Sorghum to Sugary Disease (Claviceps africana)
Authors: McLaren N. W. , Wehner F. C. 
Published: May 2008

AbstractThe relationship between pre–flowering climatic conditions and sugary disease incidence m sorghum was quantified over two seasons. In field trials with three male normal genotypes, low night temperatures 3—4 weeks prior to flowering increased susceptibility to the disease. Average night temperatures of <12 °C during the critical period resulted in male–normal genotypes being as susceptible as male–sterile genotypes. Seed set in uninoculated heads under pollination bags was also reduced, suggesting that increased susceptibility was the result of low temperature induced sterility. Genotypes differed in their ability to tolerate pre–flowering cold stress. Greenhouse and growth chamber trials confirmed that cold stress applied 7—8 weeks after planting reduced pollen viability and that this was the primary reason for increased susceptibility to sugary disease.
Observations on the Responses of Lentil Root Cells to Hyphae of Fusarium oxysporum
Authors: Bhalla Munjeet K. , Nozzolillo Constance , Schneider Edward F. 
Published: May 2008

AbstractThe infection of lentil roots by Fusarium oxysporum Schlecht and the responses of the host cells to invading hyphae were examined by light microscopy. Hyphae from inoculum placed on the zone of cell elongation entered the roots at the juncture of epidermal cells within 8 h after inoculation. Although swollen hyphal apices were observed on the epidermal cells, root penetration occurred without formation of these structures or appressoria. The sheath of material found on the surface of uninoculated roots was absent from inoculated roots penetrated by hyphae. Prior to penetration, the epidermal cells became irregular in shape and their cytoplasm appeared to be plasmolysed or granular. Hyphae were observed in the cortex 10—12 h after inoculation and non–penetrated cortical cells were distinctly lobate. Often these lobed cells had a broad, peripheral band of diffuse cytoplasm. When hyphae were first observed in the cortical cells, the walls were ruptured and only slightly stained or unstained by toluidine blue. The inability of such walls to bind the stain may have been the result of the removal of wall components by fungal enzymes.Although extensive proliferation of hyphae was evident throughout the cortex after 24 h of incubation, the endodermis and vascular cylinder were free of hyphae for at least 72 h. Hyphae from inoculum placed on the root hairs or the root apex failed to penetrate the roots during the first 24 h of incubation.The cytological results herein are discussed in relation to the infection of field plantings by this pathogen.
Induction of 6‐Methoxymellein and Resistance to Storage Pathogens in Carrot Slices by UV‐C
Authors: Mercier J. , Arul J. , Ponnampalam R. , Boulet M. 
Published: May 2008

AbstractBiotic (β‐glucan, fructosan and polygalacturonic acid fragments) and abiotic agents (ultraviolet‐C radiation, gamma radiation and heat) were screened for their potential to elicit the accumulation of the phytoalexin 6‐methoxymellein in carrot slices. Ultraviolet radiation was the only elicitor found effective, with an optimum dose of 2.20 × 105 erg cm−2. At 20 °C, the maximum level was reached in 72 hours and thereafter degradation was apparent. At lower temperatures (1° or 4 °C), 6‐methoxymellein accumulation was slower but reached higher levels which remained stable for up to 35 days after induction. Ultraviolet‐treated slices which were stored at 1° or 4 °C for two weeks to allow 6‐methoxymellein accumulation were significantly more resistant to infection when challenged with Botrytis cinerea or Sclerotinia sclerotiorum. Slices inoculated immediately after ultraviolet treatment did not show any resistance. The data showed that concentrations of 6‐methoxymellein above 30 μg g−1 of tissue were inhibitory to B. cinerea, with maximum inhibition observed around 60 μg g−1. Thus ultraviolet treatment could have potential to enhance the resistance of carrots to storage pathogens.