bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in Cell Size and Flagellation in the Phytopathogen Pseudomonas syringae pv. tabaci Cultured in vitro and in planta: A Comparative Electron Microscope Study
Authors: Sigee D. C. , El‐Masry M. H.
Published: May 2008

In parallel experiments, cells of Pseudomonas syringae pv. tabaci were infiltrated into tobacco leaves (to determine bacterial changes occurring in planta) and inoculated into nutrient broth (to make comparative observations on cells cultured in vitro). In each case, details of surface structure, bacterial size and flagellation were determined in a sequence of samples by transmission electron microscopy of whole mount stained and unstained preparations.

In both in planta and in vitro environments, bacterial population showed a clear phase of exponential increase. In each case, bacterial size was highest during the early part of the multiplication phase, then decreased during the rest of the multiplication period. In each case also, the proportion of cells with flagella showed a similar trend ‐ with an initial decrease after infiltration, followed by a major increase during the phase of bacterial multiplication. These results suggest that changes in bacterial size and flagellation in planta relate directly to the growth phase of the population, and are therefore determined primarily by internal cellular (endogenous) factors ‐ rather than by external factors within the leaf environment.
Occurrence and Identification of Eggplant Mottled Crinkle Virus in India
Authors: Raj S. K. , Aslam M. , Srivastava K. M. , Singh B. P.
Published: May 2008

A virus isolated in India from eggplant (Solanum melongena) showing chlorotic rings, line pattern and mosaic on leaves accompanied with stunted growth was identified as a strain of eggplant mottled crinkle virus on the basis of host range, in vitro properties, particle morphology, molecular weight of capsid protein and serological relationship. The sodium dodecyl sulfate‐polyacrylamide gel electrophoresis of virus coat protein revealed the presence of a single polypeptide with a molecular weight of 41,000. An antiserum to the virus produced in rabbit had a titre of 1: 2048 in double diffusion tests.
Characterization of a Latent Elongated Virus from Globe Artichoke (Cynara scolymus L.) in Italy
Authors: Rana G. L. , Piazzolla P. , Lafortezza R. , Greco N.
Published: May 2008

A virus with filamentous particles was isolated from symptomless plants of Cynara scolymus cvs Romanesco and Terom obtained by in vitro meristem culture in northern Italy. The virus was characterized biologically, physico‐chemically and serologically. The cytopathology induced by its infection in two artificial hosts (Chenopodium quinoa and Nicotiana benthamiana) was also investigated. The virus has slightly flexuous elongated particles measuring 12 ± 664 nm; its sedimentation coefficient, RNA content, mol. wts. of RNA and coat protein subunits are 150 S, 6 %, 2.2 × 106 and 2.9 × 104, respectively. In microprecipitation tests, it resulted serologically related to poplar mosaic virus (PopMV) (SDI = 4–5). Cellular inclusions and cytopathology observed in both the artificial hosts conform to those of the carlavirus group.
Phytophthora and Pythium in Pot Plant Cultures Grown on Ebb and Flow Bench with Recirculating Nutrient Solution
Authors: Thinggaard K. , Middelboe A. L.
Published: May 2008

The occurrence of pythiaceous fungi in pot plant cultures grown in ebb and flow bench systems was investigated monthly from May to December, Phytophthora, Pythium and Saprolegnia (in all 351) were isolated from water samples and identified. Nearly all the isolates of Pythium produced zoospores in water.

A pathogenicity test involving 15 isolates of Pythium“group P”, and 7 of Pythium“group F” showed that 73 % were pathogenic on cucumber, 66 % on Gerbera, 59 % on lettuce, 50 % on tomato, and 32 % on cress. Control of Pythium and Phytophthora is important in order to improve the health of plants grown in ebb and flow systems.
Ultrastructural Studies of Zoosporangium and Resting Sporangium of Synchytrium desmodii
Authors: Lange Lene , Lenné Jillian M. , Olson Lauritz W.
Published: May 2008

The development of the zoosporangium and resting sporangium of Synchytrium desmodii, the causal agent of the wart disease of Desmodium is described. During zoosporangium development synaptonemal complexes are formed. (The presence of synaptonemal complexes is characteristic for pachytene of the first meiotic nuclear division.) Zoospore differentiation and maturation in zoo‐sporangia within the same sorus is asynchronous. Prosorus formation was not observed and it is suggested that previous descriptions of a prosorus in S. desmodii may have been based on observations of an empty collapsed zoosporangium. The resting sporangium of S. desmodii is ultrastructurally similar to that observed for S. endobioticum, S. mercuralis and S. anemones. The mature resting sporangium contains a single centrally located nucleus, a large amount of reserve material (lipid) and is surrounded by an extremely thick multilaminate wall which may be up to 15 μm in thickness.

Germination studies of surface sterilized seeds of Desmodium and seeds contaminated with resting sporangia of S. desmodii did not lead to plants infected with S. desmodii and thus no conclusion can be made about whether the wart disease of Desmodium can be seed transmitted but only that resting sporangia of S. desmodii may be found on the surface of seeds harvested from naturally infected fields.
Purification and Serology of the Iranian Maize Mosaic Rhabdovirus1)
Authors: Izadpanah K.
Published: May 2008

Leaves of maize infected with the Iranian maize mosaic rhabdovirus (IMMRV) were homogenized in 0.1 M citrate‐0.04 M Na2SO3 buffer, pH 5.4, containing 10 % sucrose and the extract was subjected to low speed and high speed centrifugation followed by resuspension in 0.05 M potassium phosphate buffer, pH 7.2, containing 10 % sucrose. Partially purified preparation was obtained by density‐gradient centrifugation, removal of the virus zones and their concentration by high speed centrifugation. Two virus specific bands were observed in density‐gradient columns. An antiserum with a titer of 128 was prepared by injecting partially purified virus into rabbits. In agar‐gel‐diffusion tests, the antiserum produced one or two precipitin lines against diseased maize extract but none against healthy maize extract. IMMRV was not related to barley yellow striate mosaic (BYSMV), cereal chlorotic mottle (CCMV), Cynodon chlorotic streak (CCSV), Festuca leaf streak, and maize mosaic (MMV) viruses as well as to two unidentified rhabdoviruses occurring in wheat and Bermuda grass in the vicinity of Shiraz, when these viruses were tested against IMMRV antiserum in agar‐gel‐diffusion and enzyme‐linked immunosorbent assay. Likewise, IMMRV did not react with antisera to BYSMV, CCMV, CCSV and MMV in agar‐gel‐diffusion tests. IMMRV appears to be different from most reported rhabdoviruses of cereals.
Developpement de Leveillula taurica en Fonction des Facteurs Climatiques et Sensibilité de Capsicum annuumà Differents Stades Végétatifs
Authors: Diop‐Bruckler Marguerite
Published: May 2008

Influence of environmental factors on the development of L. taurica on pepper genotypes To our knowledge, the effects of certain environmental factors, as well as those of host genotype on the development of Leveillula taurica on pepper have not been extensively investigated. To study effects of the above factors on the development of this parasite, two Capsicum genotypes (‘Yolo Wonder' and ‘line 815’) have been tested and compared under different light and relative humidity conditions.

In vitro, optimal light intensity for spore germination was situated between 20 and 80 μE/m2/s, and for the growth of germ tubes it was 20 μE/m2/s.

In vivo, under continous darkness during 20 days, the different organs of the hosts were only slightly affected. Under light conditions, during 20 days after inoculation, the highest infection level on leaves was observed at 20 μE/m2/s, (60 % of leaves) while with the cotyledons it was observed between 20–80 μE/m2/s.

Effects of relative humidity on the development of this parasite were also studied on ‘Yolo Wonder’ and ‘line 815′. With relative humidity below 50 %, 60 % of ‘Yolo Wonder’ plants and 33 % of ‘line 815’ were infected. Under conditions of saturated relative humidity, the level of infection was the inverse, i. e. 13 and 55 %, respectively.

Moreover, ‘Yolo Wonder’ plants were found more or less susceptible to infection with L. taurica during their different development stages. At the cotyledon stage all plants were infected. After this stage, up to flowering, susceptibility depended on the physiological age of the leaves. First leaves (older leaves) were not infected, while young ones near the apex became progressively susceptible.
Der Einfluβ von Sauerstoff und UV‐Licht auf die Konidienproduktion von Pseudocercospordh herpotrichoides (Fron) Deighton, Merkmale zur Morphologie des Erregers und dessen Nachweis an Dikotyledonen
Authors: Gieffers W. , Paul V. H. , Ritter E.
Published: May 2008

The influence of oxygen and U.V.‐light for the conidia production of Pseudocercosporella herpotrichoides (Fron) Deighton, morphological characters of the pathogen and its evidence on dicotyledons The particular importance of oxygen was detected for sporulation of Pseudocercosporella herpotrichoides. Four methods have been elaborated for different sporulation requirements of P. herpotrichoides. Only for a few populations three methods were necessary for rapid conidia production. The best method for maximum conidia production consisted of the following conditions: a constant temperature of 10 °C, permanent moistening with liquid water for inoculated materials, oxygen and U. V.‐light. Infected stalks and leaves from cereals were sporulating after 3 days and inoculated materials after 3 to 6 days. Maximum conidia production was reached after 7 to 21 days. Good sporulation was obtained also under cool temperatures, permanent moisture and air and light conditions in the open. But the conidia production was stronger under controlled conditions.

Different isolates of P. herpotrichoides were compared with respect to morphological characteristics of hyphae, mycelia and conidia.

Thus far observed only on cereals and grasses. P. herpotrichoides was found also on dicotyledons by the sporulation method described. This evidence has been obtained on an isolate of 00‐winter rape (Brassica napus, ssp. Oleifera). Moreover P. herpotrichoides has been found on chlorotic and necrotic leaves of rape, flesh‐coloured trefoil (Trifolium incarnatum), madia‐oil plant (Linum usitatissimum L.) and lady's‐thistle (Silyhum marianum [L.] Gaertn.) in high frequency. P. capsellae was found on necrotic leaves of chickweed (Stellaria media).
Bacillus thuringiensis ‐ A New Perspective for an Induced Protection to Coffee Leaf Rust*
Authors: Roveratni Dagmar S. , Teixeira Ana Regina R. , Moraes Walkyria B. C.
Published: May 2008

Susceptible coffee plants (Coffea arabica cv. ‘Mundo Novo’) treated with a suspension of Bacillus thuringiensis or with three of commercial products (Thuricide HD, Bactimos and Bactospeine PM) of B. thurngiensis were protected against a later inoculation with Hemileia vastatrix, the causal agent of coffee leaf rust. Thuricide HD was effective at concentrations from 5 to 20 mg/ml; at this concentration, protection reached 90 %, lasted for at least 5 weeks, and was systemic. Induced resistance was determined by the reduction of the average number of lesions per leaf in treated leaves when compared with non‐treated controls. A decrease in lesion size as well as a delay in sporulation time were also observed in protected plants treated with Thuricide HD.
ELISA Detection of Odontoglossum Ringspot Virus in Mature Plants and Protocorms of Cymbidium Orchids: Potential Solutions to Problems of Sample Preparation Time and Low Virus Concentration
Authors: Arunasalam G. , Pearson M. N.
Published: May 2008

The ability to detect Odontoglossum ringspot virus (ORSV) released from the cut surfaces of leaf discs by ELISA was examined. Results indicate that ORSV from leaf discs can be detected but that multiple discs are necessary to obtain reliable detection of low virus concentrations, ELISA of Cymbidium protocorms, known from immunosorbent electron microscopy to be infected with ORSV, frequently produced A435 values which would be considered either negative or marginally positive on the basis of commonly accepted statistical limits (i, e. 2 x mean, or mean + 3 x standard deviation). The comparison of paired samples, one of which had been pretteated with ORSV antiserum, improved the sensitivity of the test from 10 ng ml ‘’ of virus to 2 ng ml’.
Chlorate Sensitivity of Sclerotium bataticola Isolates from Different Hosts
Authors: Zazzerini A. , Tosi L.
Published: May 2008

Our results indicate that it is impossible to characterize Isolates of Sclerotium bataticola Taub. [=Macrophamina phaseolina (Tassi) Goid.; Tiarosporella phaseolina (Tassi) Van der Aa] obtained from different plants (sunflower, sorghum, soybean and safflower) by using the chlorate sensitivity test. Indeed, strains isolated from the same species and from the same location reacted differently towards chlorate. The pathogenicity test proved the non‐existence of host specialization by the parasite.
Vector and Host‐Plant Relationships of the Leafhopper‐Borne Maize Yellow Stripe Virus
Authors: Ammar E. D. , Elnagar S. , Abul‐Ata A. E. , Sewify G. H.
Published: May 2008

Maize yellow stripe virus (MYSV), associated with tenuivirus‐like filaments, is transmitted in a persistent manner by the leafhopper Cicadulina chinai. In this vector, MYSV acquisition and inoculation threshold times were 30 min each, latent period ranged from 4.5 to 8 days depending on temperature (14‐25 °C), and retention periods were as long as 27 days. Up to 26 % of C, chinai collected from maize fields in Giza, Egypt, during September and October 1985 were naturally infective with MYSV. Two symptom‐types (fine and coarse stripe) appeared on experimentally infected plants, usually on separate leaves of the same plant. However, these two symptom‐types could not be isolated on separate plants through transmission by single C. chinai leafhoppers. MYSV was transmitted by nymphs and adults of C. chinai from maize to maize, wheat and barley, and from wheat to maize plants. Up to 6 % of the wheat plants examined in Naga Hamadi (Southern Egypt) in February 1986, were naturally infected. It is suggested that wheat, barley and possibly graminaceous weeds may serve as winter hosts or reservoirs for MYSV and its leafhopper vector in Egypt.
Pathotypes of Peronospora viciae in Britain
Authors: Taylor P. N. , Lewis B. G. , Matthews P.
Published: May 2008

Fifty‐five isolates of Peronospora viciae from a wide range of locations in Britain were tested on 10 inbred lines of Pisum sativum. Reactions ranged from extreme resistance, where the pathogen failed to spread in the tissues and caused no macroscopic symptoms, to extreme susceptibility, where the pathogen spread extensively and sporulated abundantly. Based on two differential reactions, namely, symptomless resistance and all other more susceptible reactions, 22 groups of isolates were distinguishable. On the four most discriminating differential lines, eleven groups of isolates were distinguished; these are designated UK Pathotypes, (UKP) 1–11, and the four lines nominated as standard differential hosts.
Methods of Inoculation of Faba Bean Plants with Sclerotinia sclerotiorum
Authors: Lithourgidis A. S. , Tzavella‐Klonari K. , Roupakias D. G.
Published: May 2008

Different organic materials colonized by the fungus were applied, as an energy‐rich inoculum, on faba bean plants cv. Polycarpe in growth chamber experiments. The organic materials used were colonized pieces of celery stems, faba bean petioles, and carrot root, blocks of cultures on potato dextrose agar and pieces of sclerotia. The inoculum was left attached to the plant stems for 48 h. After removal of the inoculum the plants were scored for disease incidence and severity. It was found that colonized pieces of carrot root produced the most uniform disease incidence and severity.
Effect of Growth Stage and Initial Inoculum Level on Leaf Rust Development and Yield Loss Caused by Puccinia recondita f. sp. tritici
Authors: Subba Rao K. V. , Snow J. P. , Berggren G. T.
Published: May 2008

The effects of the combinations of leaf rust inoculation at different growth stages and initial inoculum levels on leaf rust development and yield of winter wheat cultivars, McNair 1003 and Coker 762 were evaluated. Disease onset stage and initial inoculum level affected the rate of leaf rust development and shape of the disease progress curves in both cultivars. Epidemics with common onset stages and different initial inoculum levels differed in area under the disease progress curve (AUDPC). Leaf rust epidemics initiated at Feeke's growth stages 5, 7, and 10 reduced yield in both cultivars. Leaf rust epidemics initiated early with high inoculum levels had the greatest deleterious effect on yield. Maximum losses due to leaf rust were 30–40 %. Yield loss was directly related to AUDPC when the AUDPC varied from 500 to 1700 in McNair 1003 and from 250 to 1700 in Coker 762. Yield reduction was mainly due to reduction in grain weight.
Suppression of Root Rot on Peas, Beans and Beetroots Caused by Pythium ultimum and Rhizoctonia solani through the Amendment of Growing Media with Composted Organic Household Waste
Authors: Schüler C. , Biala J. , Bruns C. , Gottschall R. , Ahlers S. , Vogtmann H.
Published: May 2008

In pot experiments under controlled environmental conditions, composted organic household waste showed a suppression of soilborne plant pathogens. The addition of 8 %, 10 % and 30 % compost to the potting material which was artificially infested with Pythium ultimum or Rhizoctonia solani considerably reduced the incidence of disease in different varieties of host plants. It became evident that the degree of protection provided by compost depends upon the amount of compost added and upon the vulnerability of the host plant to infection. In an experiment using increasing levels of inoculum, the compost proved suppressive to the pathogen even under extreme disease conditions. This suppressive effect was still evident in compost which had been stored for prolonged periods.
The Occurrence of Cell Wall Appositions in Flag Leaves of Spring Wheats, Susceptible and Partially Resistant to Wheat Leaf Rust
Authors: Jacobs Th.
Published: May 2008

In two experiments, the presence of cell wall appositions in flag leaves of spring wheat genotypes susceptible and partially resistant to wheat leaf rust was studied. More cell wall appositions were observed near aborted infection structures than in estabhshed colonies. There was not a marked difference in the number of cell wall appositions per colony between susceptible and partially resistant genotypes. More cell wall appositions per unit area colony were present in partially resistant genotypes. It was concluded that the low number of cell wall appositions could not be responsible for the observed difference in colony size between susceptible and partially resistant genotypes. Partial resistance in wheat to wheat leaf rust can be divided into two phases. The first phase is pre‐haustorial and results in a reduction of the number of colonizing infection structures. In the second phase a post‐haustorial retardation of fungal growth rate occurs. The latter appears to be the more important phase.
Isolation of Proteins Related to the β‐Lectin from Potato which Bind to Hyphal Wall Components of Phytophthora infestans
Authors: Furuichi N. , Suzuki J.
Published: May 2008

Proteins from potato cells which recognize fungal cell wall components of Phytophthora infestans were isolated after passage of a potato homogenate through an affinity column which contained bound fungal cell wall components. Bound potato proteins were eluted with NN′‐diacetylchitobiose, and fractionated by SDS‐polyaciylamide gel electrophoresis. Eluted proteins from cv. Yukijiro (R1‐gene) and cv. Irish Cobbler (r‐gene) had similar profiles and the same apparent Mr, 66, 58 and 41.5 kD and other proteins with lower molecular weight.

Only the 41.5 kD and lower molecular weight proteins reaeted with polyclonal antibodies against the β‐lectin from the R1 cultivar, Rishiri.

The surfaces of protoplasts from cvs Yukijiro and Irish Cobbler also reacted with the antibodies to the lectin. Treatment of potato protoplasts with hyphal cell wall components of P. infestans caused cytoplasmic aggregation, a response characteristic of the hypersensitive reaction. Oligomers of N‐acetyl glucosamine reduced the ability of fungal cell wall components to cause this cytoplasmic aggregation. These results suggest that binding between fungal cell wall eomponents and certain potato proteins is sensitive to N‐acetylglucosamine, and may play a role in the hypersensitive reaction.
Ultrastructure at the Host‐Parasite Interface of Phytophthora capsici in Roots and Stems of Capsicum annuum
Authors: Hwang ByungKook , Kim WoonBong , Kim WooKap
Published: May 2008

The infecting hyphae of Phytophthora capsici grew intercellularly in infected tissues of roots and stems of pepper (Capsicum annuum). The vascular tissues were not markedly disorganized even when heavily infected. Intercellularly growing hyphae penetrated the host cells by forming haustorium‐like bodies. The consistent features of ultrastructural changes in infected tissues of pepper roots and stems were degeneration of cell organelles and dissolution of host cell walls. The cytoplasm detached from the cell wall aggregated abundantly around some haustorium‐like bodies or the penetration sites of fungal hyphae. The host cell walls were palely stained, thinned and swollen, possibly being biochemically altered by the action of fungal macerating enzymes. Electron‐dense, wall‐like material was apposed on the outer wall of xylem vessel contacted by fungal hyphae. The infecting hyphae were also surrounded by granular, dark‐staining cytoplasm. Characteristics of host cell responses to the invading P. capsici were the deposition of papilla‐like material on host cell walls next to hyphae and the encasement of haustorium‐like bodies with wall appositions.
Correlations between Accumulation of Dianthramides, Dianthalexin and Unknown Compounds, and Partial Resistance to Fusarium oxysporum f. sp. dianthi in Eleven Carnation Cultivars
Authors: Baayen R. P. , Niemann G. J.
Published: May 2008

The accumulation of dianthramides, dianthalexin and other phenolic compounds in carnation cells at different times before and after inoculation of plants with Fusarium oxysporum f. sp. dianthi, and the development of wilt symptoms were compared for eleven carnation cultivars. Untreated and water‐treated controls contained only a little acetone‐extractable phenolics. Upon inoculation with F. oxysporum f. sp dianthi, all cultivars accumulated the same range of phenolic compounds, including several dianthramides and dianthalexin, but in different proportions. The total amount of accumulated phenolic compounds per fresh material weight of the extracted stem segments could not be related to the disease resistance level of the different cultivars. However, the accumulation of dianthramides and dianthalexin in the cultivars was positively correlated to resistance, while the accumulation of two other, as yet unidentified, compounds was inversely related to resistance.
Cell Wall Monosaccharide Composition and Muskmelon Resistance to Myrothecium roridum1
Authors: Kuti Joseph O. , Ng T. J , Gross K. C. , Moline H. E.
Published: May 2008

In vitro growth of Myrothecium roridum, a pathogen of muskmelon (Cucumis melo L.), on media supplemented with eight cell wall‐related monosaccharides revealed that germination and germ tube elongation were enhanced in the presence of arabinose, galactose and glucose. Colony expansion of established mycelia of M. roridum was also enhanced by arabinose and glucose but inhibited by galactose, Non‐cellulosic neutral sugar analysis of fruit cell walls from muskmelon cultivars resistant or susceptible to M. roridum revealed that susceptible cultivars had consistently higher arabinosyl, galactosyl and glucosyl residue content than resistant cultivars, while a net loss of galaciosyl and arabinosyl residues occurred in cell walls of fruits between 20‐ and 27‐days post‐anthesis. M. roridum germinated more rapidly on isolated fruit cell walls from susceptible than resistant cultivars, but no correlation was found between cultivar resistance to M. roridum and inhibitin of fungal colony expansion on cell walls. Although factors affecting spore germination and mycelial growth of M. roridum, in vitro and in vivo, may differ, any factor that increases cell wall polysaccharide hydrolysis may contribute to ability of M. roridum to become established in immature fruit of muskmelon.
Effects of Nitrogen, Plant Density, Moisture Stress and Artificial Inoculation with Macrophomina phaseolina on Charcoal Rot Incidence in Grain Sorghum
Authors: Pande S. , Mughogho L. K. , Seetharama N. , Karunakar R. I.
Published: May 2008

Effects of different levels of nitrogen, plant density, soil moisture stress and of anificial inoculation with Macrophomina phaseolina on charcoal rot incidence in grain sorghum were studied in a split‐split‐split field plot design. Nitrogen levels were applied to main plots; plant densities, moisture stresses and inoculations were replicated in sub, sub‐sub and sub‐sub‐sub plots. A gradient of soil moisture stress was created during grain filling by line‐source sprinkler irrigation. Analysis of variance indicated significant effects of moisture stress, plant density and their interactions on charcoal rot disease incidence as measured by piant lodging. Lodging increased linearly along the gradient of water supply suggesting a positive relationship between moisture stress and disease development. Lodging was also significantly (P < 0.01) and highly correlated with other charcoal rot disease parameters (soft stalk, number of nodes crossed, root infection and plant senescence). There were no significant differences (P < 0.05) in charcoal rot incidence among inoculation treatments. Lodging increased in both high nitrogen and high plant population treatments under moisture stress conditions.
African Cassava Mosaic Virus (ACMV): Stability of Purified Virus and Improved Conditions for its Detection in Cassava Leaves by ELISA
Authors: Kounounguissa Basfle R. , Givord Louise , Walter Bernard
Published: May 2008

African Cassava Mosaic Virus (ACMV) was purified by a method which allowed the separation of monomer from dimcr virus particles.

Optimal conditions for storing purified virus to be used for immunization were determined by ELISA and inoculation on Nicotiana benthamiana. Purified virus could be stored without loss of infectivity and serological activity for more than 145 days at 4 °C or frozen at –20 °C, but not longer than 40 days in the presence of 50 % redistilled glycerol.

Rabbit and chicken immunoglobulins were used to detect ACMV in cassava leaves by direct and indirect ELISA. To obtain the same absorbance values, it was necessary to use longer incubation times with the indirect method, but the virus detection end‐point m sap from infected plants was the same for the two methods (1/512).

Conditions for improving virus detection tn cassava samples were determined. The virus was better detected when leaves from diseased plants were ground in 100 mM Tris‐HCl containing 1 % polyvinylpyrrolidone at pH 8.5 than in phosphate buffer. Plant inhibitors were the restricting factor in the detection of virus by ELISA, but this difficulty was avoided when leaves to be tested were harvested from the top of the cassava plants.
Evolution of Ethylene Production, ACC and Conjugated ACC Levels Accompanying Symptom Development in Tomato and Gynura aurantiaca DC Leaves Infected with Citrus Exocortis Viroid (CEV)
Authors: Bellés J. M. , Conejero V.
Published: May 2008

Ethylene production, ACC and Conjugated ACC levels as related to symptom development in leaves of tomato and Gynura aurantiaca infected with citrus exocortis viroid (CEV) were studied. In both hosts, the infection induced an increase in ethylene production and ACC levels and a strong accumulation of Conjugated ACC, Contrary to what happens with the stimulation of ethylene production and the enhancing of ACC content which maintain a steady level as leaves and their symptoms develop, conjugated ACC accumulation increased with the intensification of symptoms.
Relation Between the Chemical Structure and the Biological Activity of Hydroxystilbenes Against Botrytis cinerea
Authors: Pont V. , Pezet R.
Published: May 2008

Some substituted trans‐hydroxystilbenes derived from pterostilbene and resveratrol were tested on germination, lethal effect and respiration of the conidia of Botrytis cinerea. These biological effects were related to the electronic character, to the lipophility of the substances and to their molecular volume. The products destroy the cellular membranes and could interfere with proteins of the electron transport systems.
Acrocalymma medicaginis and Phomopsis sp. as Causal Agents of Crown Rot of Lucerne in Australia
Authors: Nikandrow A.
Published: May 2008

Fungi associated with crown rotting were isolated from 3 year‐old lucerne plants growing in sandy and loam soils in an irrigated stand, declining in productivity, at Langhorne Creek, South Australia. The method of isolation markedly affected the range of species recovered. Fusarium spp. and Phomopsis sp. were isolated from washed and surface sterilized crowns, whereas a larger range of fungi, especially Acrocalymma medicaginis, was isolated from unwashed crowns. A. medicaginis was most frequently isolated from rotted tissue flecked with red, while a species of Phomopsis was the dominant fungus in whitish tissue containing zone lines, especially in crown branches. A. medicaginis and Phomopsis sp. caused crown rotting of mature, wounded lucerne plants at temperatures equivalent to summer conditions at Langhorne Creek. There was no evidence that Fusarium oxysporum or F. solani, two of the most frequently isolated species, were pathogens of mature lucerne plants.
Ultrastructural Study of Cytoplasmic Inclusions in Plants Infected with Potyviruses
Authors: Pisi A. , Bellardi M. G.
Published: May 2008

The ultrastructure of cell inclusions of different ornamental plants infected with several filamentous viruses of the potyviruses was studied at the transmission electron microscope. The plants examined were: Crocus sativus, Hyacinthus sp., Gladiolus sp., rhizomatous Iris, Muscari sp., Nerine bowdenii and Sparaxis sp. Differences in morphology of cylindrical inclusions have been used to separte the potyviruses in several subdivisions.
In vitro Analysis of Defence Mechanism in the System Solanum tuberosum‐Alternaria alternata
Authors: Pellegrini M. G. , Garbuglia A. R. , Guerrazzi S. , Bogani P. , Bettini P. , Storti E. , Simeti C. , Buiatti M. , Broggio M. , Nascari G.
Published: May 2008

In a preliminary study on the interaction between an Alternaria alternata pathotype and Solanum tuberosum a series of parameters, indicative of active and passive defence processes, was investigated in vitro using tolerant (Chiquita) and susceptible (Superior) cultivars. Ion leakage experiments along with growth of suspension cultures and plating efficiencies in the presence of fungal culture filtrates suggest that toxin tolerance is a valuable character in distinguishing between resistant and susceptible genotypes. As far as active defence was concerned, although TLC patterns suggested the synthesis of different fluorescent compounds, probably phenolic acid, when fungal elicitors were applied to Chiquita or susceptible tissue,cultures, no consistent pattern suggesting a relationship with defence could be observed. On the other hand, peroxidase isozyme analysis after different dual culture periods showed the activation of ionically and covalently bound peroxidases in the prese,nce of the pathogen only in cv. Chiquita.
An Inflorescence Disease of Amaranthus spp. in Nigeria Associated with Choanephora cucurbitarum
Authors: Adebanjo A.
Published: May 2008

Abstract Symptoms of a devastating inflorescence disease of Amaranthus spp. associated with Choanephora cucurbitarum are described. It is characterized by extensive blighting of the inflorescence head and is often accompanied by inflorescence dieback and severe breaking of the floral head. In fields with severe infestation and under favourable conditions the inflorescence heads may be completely cut off. Such a plant will not produce any seeds or the yield may be reduced to half or less.

Laboratory experiments confirm observations made in the field that the fungus is aggressively pathogenic on the apical region of the inflorescence. Usually, the green young inflorescences are more susceptible.
Characterization of Pseudomonas syringae pv. tomato by Numerical Analysis of Phenotypic Features and Total Soluble Proteins11)
Authors: Serfontein J. J. , Hattingh M. J.
Published: May 2008

Abstract The homogeneity of South African and other strains of Pseudomonas syringae pv. tomato was determined by numerical analysis of differential phenotypic features and computer‐assisted comparison of gel electropherograms of soluble proteins. Two closely‐related groups, that could only be separated by their reaction in litmus milk, were distinguished in a phenotypic dendrogram. Three non‐South African reference strains fell outside these groups, indicating the possible existence of more groups, worldwide. No clear‐cut correlation was found between clustering of strains and their geographical origin. Forty‐seven strains examined had similar protein patterns, reflecting their close genetic resemblance. All strains were pathogenic on tomatoplants.
In vivo Role of Indole‐3‐acetic Acid, Gibberellic Acid, Zeatin, Abscisic Acid and Ethylene in Floral Malformation of Mangifera indica L.*
Authors: Singh Zora , Dhillon B. S.
Published: May 2008

Abstract The endogenous levels of indole‐3‐acetic acid (IAA), gibberellic acid (GA3), zeatin, abscisic acid (ABA) and ethylene were studied in panicles/shoots of Dusheri mango at four stages viz., (I) fully swollen buds; (II) bud inception; (III) fully grown panicles prior to full bloom and (IV) fully grown panicles at full bloom, for three consecutive years. The malformed panicles and the shoots bearing malformed panicles (SBMP) possessed lower levels of IAA in relation to healthy panicles and shoots bearing healthy panicles (SBHP) at stage I, II, III and IV. The malformed panicles and SBMP maintained lower levels of GA3 than healthy panicles and SBHP at stage I. However, the converse was true for stages II, III and IV. The malformed panicles and SBMP exhibited higher levels of zeatin compared with their healthy counterparts at the four developmental stages. Likewise, the contents of ABA and ethylene were also higher in malformed panicles and SBMP than healthy panicles and SBHP at all the stages. It is concluded that floral malformation is associated with malformin stimulated ethylene production and higher levels of ABA, gibberellic acid, zeatin and lower levels of IAA.
Effect of Fumigants and Agrobacterium radiobacter Strain 84 in Controlling Crown Gall of Apple Seedlings
Authors: UTNIQUE R. S. , SMITH E. M.
Published: May 2008

Abstract Field trials at Summerland and Creston in 1984 and 1985 on loam soils naturally intested with Agrobadonum nonfactures showed that A radiobacter Strain 84 K‐S4, did not control crown gall on Antonovka apple seedlingy when applied as a root‐dip. K‐84 controiled crown gall at Sidney on sandy loam soil m 1984 and 1985, but tailed in 1986. At Creston, higher than standard concentrations of K‐84 did not control crown gall of seedlings, whether the seedlings were grown in unsterililzed soil 1986) or in sterile soil, 1987 before transplanting them into A nonfactures naturally intested soil. It a field trial in 1986 at Summerland, root‐dip treatment with K‐84 alone or in combination with broadeast treatments of melam‐sodium of formalin tailed to control crown gall on Antonovka seedlings. However, crown gall intection was significantly reduced with metam‐sodium or K‐84 treatment alone when seedlings were raised in sterile soil before transplanting in naturally instead safe at Summerland in 1987.
Occurrence of Eggplant Mottled Dwarf Virus in Jordan
Authors: Al‐Musa A. M. , Lockhart B.
Published: May 2008

Abstract A virus isolated from stunted eggplant (Solanum melanogena L.) with severe vein yellowing, was identified as a strain of eggplant mottled dwarf rhabdovirus (EMDV‐J) on the basis of host range, transmissibility and serology.

The isolate is seemingly a unique strain of eggplant mottled dwarf virus that differs from the reported strains in the host range.

The virus was recovered from Withania somnifera, a perennial plant, which suggests the availability of a virus reservoir at times when the Jordan valley is practically free from cultivated eggplants.
Beziehungen zwischen dem Wirkungsgrad antiphytoviraler Substanzen und dem Niveau der quantitativen Sortenresistenz sowie der Virulenz von Virusisolaten an Virus/Wirt‐Systemen der Kartoffel
Authors: Bittner Heide , Schenk G.
Published: May 2008

Relationship between the efficiency of antiphytoviral substances, the degree of quantitative resistance of cultivars, and the virulence of virus isolates on virus/host‐systems of potato.

In vitro systematically infected with potato virus S, potato virus M or potato virus X stem cuttings of different potato varieties were treated with 2,4‐dioxohexahydro‐1,3,5‐triazine and Ribavirin. The reduction of virus replication by chemotherapy differed between varieties depending on their level of quantitative resistance and the virulence of virus isolates.

An increasing resistance level of cultivars and a decreasing virulence of the virus isolates resulted in a relative enhancement of the inhibitory of the antiphytoviral substances.
Utilization of Carbon, Nitrogen and Sulphur Compounds by Kabatiella zeae Narita et Hiratsuka
Authors: Levic J. , Pencic V.
Published: May 2008

Abstract Morphogenesis of two K. zeae isolates (V7486 and ZP24986) on carbon, nitrogen and sulphur solid nutritive media after 2, 10, 18 and 28 days of incubation were studied. Highly significant differences were found between the isolates in regard to the use of compounds containing these elements. On carbon sources the fungus generally developed smaller colonies of branchy, loose, creamy‐brown appearance, with abundant sporulation and abnormal conidia. Sucrose and D‐glucose were the best carbon sources for K. zeae because both isolates had the maximum growth, abundant to medium abundant sporulation and mostly typical conidia. K. zeae colonies on organic and inorganic nitrogen and on sulphur sources too were leathery, creased, predominantly pink. Organic nitrogen sources lead to maximum growth and abundant sporulation, whereas ammonium and nitrate compounds caused intermediary growth and medium to very poor fungus sporulation. Addition of different sulphur sources, except sodium thiosulphate and thiocarbamide, did not affect the growth and sporulation of V7486. The growth of ZP 24986 depended on potassium and ammonium sulphate and sodium bisulphate.
Light‐ and Scanning Electron Microscopic Studies on the Development of the Mycoparasite Verticillium psalliotae Treschow on Uredospores of the Soybean Rust (Phakopsora pachyrhizi Syd.)
Authors: Saksirirat W. , Hoppe H.‐H.
Published: May 2008

Abstract By light and scanning electron microscopy it is shown that a strain of Verticillium psalliotae, originally isolated from pustules of the soybean rust in Thailand, is able to infect uredospores of this rust fungus. In most cases appressoria‐like structures were formed at the infection sites. However, only a part of the spores were infected. Most spores appeared heavily damaged without any visible mycelium inside. This indicates that growth of Verticillium psalliotae on uredospores of the soybean rust is probably mainly based on the production of lytic enzymes.
Effect of Some Factors on Detectability of Virulence Genes in Phytophthora infestans (Mont.) de Bary
Authors: Sujkowski LudwikS.
Published: May 2008

Abstract Inoculum concentration, length of incubation period and passages on leaves of potato R–genotypes were found to influence the detectability of virulence genes in Phytophthora infestans.

At lower inoculum concentrations, only a few virulence genes were detected, these were usually 1 and 4. Coupled with an increase of the inoculum dose a gradual increase was found in the number of detected genes and their multiple combinations. An increased incubation time also resulted in the detection of additional virulence genes and their combinations. Two successive passages on respective potato R‐genotypes produced a 2‐‐3 fold rise in the number of detected genes.

To explain this phenomenon, a hypothesis has been proposed which suggests that for a virulence gene to be detected, certain infection thresholds have to be reached, which may be different for particular differential host genotypes or virulence genes.
Histology of Disease Development in Resistant and Susceptible Cultivars of Chickpea (Cicer arietinum L.) Inoculated with Spores of Ascochyta rabiei
Authors: Höhl B. , Pfautsch M. , Barz W.
Published: May 2008

Abstract Histological studies were performed on a compatible and an incompatible interaction between chickpea (Cicer arietinum L.) plants and the fungus Ascochyta rabiei (Pass.) Labr. The time course of infection, development on leaflets and stems of susceptible (ILC 1929) and resistant (ILC 3279) plants was monitored by light or scanning electron microscopy with the aim to compare histological changes as the basis for further work on biochemical changes in this plant‐pathogen interaction.

Spores of A. rabiei began to germinate from 12 hpi on and developed a polar germ tube; fungal colonization, secretion of a mucilaginous exudate and appressoria formation (1–3 dpi) were identical on both cultivars. Leaves of susceptible plants were invaded by the fungus directly through the cuticle, the fungus then spread subepidermally followed by a rapid collapse of the leaf tissue (4–6 dpi). Development of leaf spots and fungal pycnidia could be observed 6–8 dpi. The resistant cultivarrapidly responded (24–48 hpi) to fungal infection and cells of the palisade parenchyma exhibited autofluorescence. In later stages of the infection (4–5 dpi) fluorescent areas developed to small necrotic spots all over the leaflet. These necrotic areas, were the result of cell death and a subsequent change in the leaf structure and were characterized by the accumulation of phenolic compounds. Leaves of the resistant cultivar were invaded by the fungus to less than 5%.
Effects of Self‐sown Wheat on Levels of the Take‐all Disease on Seedlings of Winter Wheat Grown in a Model System
Authors: Brassett P. R. , Gilligan C. A.
Published: May 2008

Abstract The mechanisms of build‐up of inoculum of the take‐all fungus, Gaeumannomyces graminis var. tritici. and infection of crop plants from self‐sown (volunteer) wheat were analysed in a factorial experiment in a glasshouse. Treatments comprised sowing‐date, inoculum density, soil aeration and texture, volunteer density and control of volunteers. Timing of treatments was related to field practice by the use of cumulative day‐degrees and by consideration of sowing date and the geometry of seed placement. Prior sowing of volunteers, which were exposed to soil inoculum. resulted in significant increases in the incidence and severity of disease on subsequently sown seedlings. Increasing the density of volunteer seedlings increased the levels of subsequent infection. This effect, however, was significantly influenced by sowing date and density of the initial inoculum. The use of glyphosate to kill volunteers did not markedly affect the carry‐over of disease.
Some Etiological Characteristics of Xanthomonas campestris pv. sesami and Disease Reaction of Different Sesame Cultivars
Authors: Abdel‐Rahim A. M. , Adam F. S.
Published: May 2008

Abstract Isolates of X. campestris pv. sesami used in the present work behaved almost similarly on the basis of their morphological, biochemical and physiological characterization. The studies failed to differentiate any strains within the isolates.

Pathogenicity of the isolates to sesame plants was proved by inoculation experiments. When other plant species were inoculated infection did not occur.

The levels of resistance of some naturally selected sesame cultivars were investigated following artificial infection with the pathogen. Seven cultivars proved resistant, three (cvs Tozi 3, S‐76F2‐22 and K 112) were highly resistant.
Improved Dot‐Blot Hybridization Assay for Large‐Scale Detection of Potato Viruses in Crude Potato Tuber Extracts
Authors: Nikolaeva O. V. , Yu. Morozov S. , Zakhariev V. M. , Skryabin K. G.
Published: May 2008

Abstract A rapid and simple technique has been developed to enhance the sensitivity of virus detection in dot‐blot hybridization assay by up to 1000 fold. The procedure generally follows that of Baulcombeet al. (1984) but includes moderate heating of the nitrocellulose filter in 10XSSC, 0.5% SDS solution at 55°C after sample application. Using this procedure, four potato viruses (PVX, PVS, PVM and PVY) were detected with cloned virus‐specific 32P‐cDNA probes in 2 μl spots containing 0.2–2 pg of purufied virus (0.1–1 ng/ml). The procedure was also successfully applied for the detection of PVX, PVS, PVM and PVY in crude potato tuber extracts.
Isolates of Phytophthora cryptogea Pathogenic to Wheat and Some Other Crop Plants
Authors: Larsson Mariann , Gerhardson Berndt
Published: May 2008

Abstract A fungus of the genus Phytophthora, frequently isolated from diseased spinach roots and also from field‐grown wheat plants in an area in the south of Sweden, was identified as P. cryptogea on the basis of morphology, growth characters and cardinal temperatures. Mycelium or zoospores applied as inoculum in a series of pathogenicity tests induced symptoms in spinach, sugarbeet, wheat, cucumber, oil‐seed rape, pea and oats. These ranged from death of all (spinach) or some inoculated plants (sugarbeet and wheat), to only slight root symptoms (oats). Successful re‐isolations from all plants tested, confirmed infectivity in all cases. This is the first report of the occurrence of P. cryptogea in Sweden and, as far as we know, of pathogenicity of this fungus to wheat, oil‐seed rape and oats.
Specificity of Antisera Against Rhodococcus fascians (Tilford) Goodfellow in Indirect Immunofluorescence
Authors: Scortichini M. , Todisco C. , Varvaro L.
Published: May 2008

Abstract The possibility to obtain specific antisera to detect Rhodococcus fascians in imported lily bulbs is taken into consideration for not allowing the admission of this pathogen in Italy. For the production of specific antisera and in order to avoid the occurtence of cross‐reactions between R. fascians and some of the most widespread soilborne, plant decay bacteria and with Erwinia carotovora subsp. carotovora a preliminary work for singling out the best immunogens, scheduleof immunization and antisera dilution for using in indirect immunofluorescence has been carried out. Living cells and heattreated cells were proved to be good immunogens and long‐term immunization provided higher titers than short‐term immunization. Toobtain a satisfactory specificity the dilution of the antisera is required. The 1: 800 dilution is quite effective in overcoming cross‐reactions whereas undiluted antisera and antisera used at 1: 100 and 1: 200 dilution did not provide specificity.
A Rapid Assay for Monitoring Peroxidase Activity in Melon as a Marker for Resistance to Pseudoperonospora cubensis
Authors: Reuveni R. , Shimoni M. , Karchi Z.
Published: May 2008

Abstract A rapid assay for monitoring peroxidase activity in melon as a marker for resistance to Pseudoperonospora cubensis was developed. A high correlation was demonstrated between peroxidase activity and resistance in test wells containing leaf disks of melon plants with known levels of susceptibility or resistance to P. cubensis. The possibility of using such an assay for a preliminary selection of melons resistant to P. cubensis is suggested.