bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oospore Formation in Phytophthora drechsleri f. sp. cajani
Authors: Singh U. P. , Chauhan V. B. 
Published: May 2008

Abstract Phytophthora drechsleri f. sp. cajani (Pal et al.) Kannaiyan et al. causes stem and leaf blight in pigeon pea (Cajanus cajan [L.] Millsp.) in India. The asexual phase occurs in artificial culture as well as on the host tissue. Sparse oospore formation has been observed in old cultures. A technique has been evolved in which abundant mature oospores are formed on the leaflets of pigeon pea and also on glass slides using zoospores and mycelial discs on the former butonly mycelial discs on the glass slides. The largest number of oospores was formed after incubation for 36 h at 25°C.
Johnsongrass Chlorotic Stripe Mosaic and its Associated Viruslike Particles in Iran1
Authors: Izadpanah K. 
Published: May 2008

AbstractA mosaic disease of Johnsongrass characterized by the presence of short and long chlorotic stripes in leaves and stunting of plants was found in two locations about 300 km apart in the Fars Province of Iran. The disease occurred in patches or along the irrigation ditches. The disease agent could not be transmitted mechanically or by certain insects and mites. About 0.5% of the seedlings, grown in soil from the root zone of diseased plants, developed the disease after 1–8 months. Electron microscopy, of leaf‐dip preparations showed presence of isometric viruslike particles (VLPs) of about 35 nm diameter in unusually high concentrations in diseased plants but not in healthy plants. VLPs from diseased leaves were purified by low‐pH clarification followed by differential and densitygradient centrifugation. Purified VLP preparations showed UV absorption spectrum typical of nucleoproteins. A260/A280 was 1.48. High titered antisera obtained by injecting rabbits with purified VLPs reacted with sap from diseased plants but not healthy plants. Purified VLP preparations and sap from diseased plants did not react with antisera to Bermuda grass etched line, Brachypodium sylvaticum, brome mosaic, maize chlorotic dwarf, maize rayado fino, maize white line mosaic and tobacco necrosis viruses.
Fatty Acid Profiles of Erwinia amylovora as Influenced by Growth Medium, Physiological Age and Experimental Conditions
Authors: Casano F. , Wells J. , van der Zwet T. 
Published: May 2008

AbstractTotal cellular fatty acids for 20 strains of Erwinia amylovora grown on trypticase soy agar (TSA) for 3 days at 27°C, and for 3 strains grown on nutrient agar (NA), King's B (KB), glucoseyeast extract carbonate (GYCA) and TSA for 1, 3 and 6 days were analyzed by gas‐liquid chromatography. Forty one percent of total fatty acids were saturated even‐carbon straight chains, 6 % were saturated odd‐carbon chains, 34 % unsaturated acids, 6 % hydroxy‐substituted acids, 1 % branched chains, 7 % cyclic acids, and 4 % unidentified components. Composition was affected by growth medium, physiological age of cells, and chromatograph sensitivity. On TSA and NA saturated odd‐carbon and cyclic acids of the 3 strains (combining 1, 3 and 6‐day data) were higher than on KB and GYCA. Cyclic acids increased with physiological age on GYCA and KB medium. Even‐carbon straight chain and unsaturated fatty acids (major components) constituted a significantly lower percentage of total fatty acids in chromatograms of high sensitivity (30–50 components) than of low instrument sensitivity (15–20 components).
A Potential Defense Mechanism of Tomato Against the Late Blight Disease is Suppressed by Germinating Sporangia‐derived Substances from Phytophthora infestans
Authors: Storti E. , Pelucchini D. , Tegli S. , Scala A. 
Published: May 2008

AbstractHypersensitive browning, host cell death and phytoalexins (rishitin) synthesis in both callus cultures and cotyledons have been observed in a susceptible tomato cultivar following treatment with high molecular weight cell wall components from Phytophthora infestans race 1B. The growth of the pathogen was restricted on both elicited differentiated and undifferentiated tomato tissues. Subtance(s) released by germinating sporangia, but not by the mycelium, suppressed the hypersensitive reaction.
Production and Dispersal of Conidia of Peronospora pisi on Pea Leaves
Authors: Singh U. P. , Reddy D. H. K. B. , Gupta Sushma 
Published: May 2008

AbstractThe number of crops of conidiophores and conidia of Peronospora pisi produced on a single lesion on leaflets of pea (Pisum sativum L.) was determined both in vitro and in vivo by artificial inoculation. Only two crops were produced in vitro whereas five crops were discerned under in vivo conditions. There was a marked difference in the size of conidiophores and conidia formed under the above two conditions.Temperature had a marked effect on the penetration of pea leaflets by conidial germ tubes of P. pisi. The pathogen penetrated the leaf tissues at 12‐14°C in 8.0‐8.5 h whereas more time (9.5‐16.5 h) was required for penetration at higher temperatures (15‐18°C).Use of systemic fungicides has been suggested to control downy mildew of pea because of its capacity to produce more than one crop of propagules on the same lesion.Maximum spore discharge in P. pisi was observed from 9.00 to 15.00 hours. However, presence of light, high temperature, lack of moisture on leaf surface and wind velocity affected spore discharge.
Scopolin, a Biochemical Marker for Resistance to Thielaviopsis basicola in Callus and Crown‐Gall Tissue Cultures of Tobacco
Authors: Gasser R. , Kern H. , Défago G. 
Published: May 2008

AbstractScopolin concentration increased in tissue cultures where Thielaviopsis basicola growth ceased (primary and established callus cultures of the resistant tobacco cultivar Ky 170) while it decreased in tissue cultures where fungal growth persisted (primary and established callus cultures of the susceptible tobacco cultivar Ky 151 and crown‐gall cultures of Ky 170 and Ky 151). The concentration of chlorogenic acid, scopoletin, and two other unknown soluble phenols varied after inoculation and no, correlation with tissue culture resistance could be established. Incorporation of Agrobacterium tumefaciens T‐DNA in the genome of both cultivars induced a drastic reduction of scopolin in inoculated tissue cultures. T‐DNA incorporation had less, influence on uninoculated tissues. Scopolin at concentrations found in tissue cultures was not toxic to the fungus.
Préparation des Antigenes des Mycoplasmes (MLO) Pathogènes de la Flavescence Dorée, à Partir de Tissus Végétaux
Authors: Caudwell A. , Kuszala Catherine , Fleury A. 
Published: May 2008

Abstract Antigen preparation from plant tissues of pathogenic mycoplasms (MLO) causing flavescence doree disease Extraction and purification of plant yellow's pathogen mycoplasms (MLO) from plant tissues is a difficult problem. It concerns indeed non cultivable, heterogeneous and fragile organisms which are localized in the fibrous and resistant phloem tissue. In a work directed by an infectivity test by leafhopper injection, our laboratory investigated the best host plant and the best extraction method for this type of pathogen.Broad bean, Vicia faba gave better extracts than Vitis vinifera. Stems are better than petioles or lamina. The best results were obtained with the top region of the stem, at the level where symptoms are apparent on young plants.The most efficient mincing method is achieved with razorblades moved alternatively by the rapid vertical movement of an electric knife.The extraction medium already published (Caudwell and Kuszala 1986) has to be modified for plants by various additional components, histidine buffer, antioxidizers (glutathion 0.2 mg per ml) and polymers 0.5 to 1 p 100 PVP or Polyclar, 1–2 p 100 PEG). 1 g of plant infected tissue is minced in 4 ml of medium. The extracts are filtered through a 100 mesh nylon cloth. After this stage the purification method goes parallel to that used for leafhopper extracts (Caudwell and Kuszala 1986). It is possible to obtain 4 × 106 infectious units from 1 g of broad bean stem (for calculation, see C 1986). It is possible to obtain 4 × 106 infectious units from 1 g of broad bean stem (for calculation, see Caudwell 1977).The possibility to extract MLO, either from infectious leafhoppers or from diseased plants enabled cross immunological assays involving antigens from one host and antibodies directed towards the other host antigens. The first step was the successful ISEM visualization of ttie MLOs (Caudwell et al. 1982), the second is the immunoenzymatic MLO‐detection (Boudon et al. 1986).
Antagonistic Activity of Neocosmospora vasinfecta var. africana (von Arx) Cannon & Hawksworth against Soil‐borne Fungi
Authors: Turhan Gülay , Grossmann F. 
Published: May 2008

AbstractAn isolate of Neocosmospora vasinfecta var. africana (F‐2) was assayed for its antagonistic activity against 15 soil‐borne fungi; 14 of them were important plant pathogens. The fungus exhibited a strong antibiotic effect against most of the fungi under test. While Pythium debaryanum, Macrophomina phaseolina, Phytophthora capsici, Sclerotinia sclerotiorum, Cochliobolus sativus and Alternaria alternata showed a very high degree of sensitivity as evidenced by the respectivezones of inhibition caused by the antagonist, Phoma betae, Rhizoctonia solani and Verticillium dahliae proved to be the most resistant. A mutual antibiosis existed between N. vasinfecta var. africana and five of the test fungi.The culture filtrate of the antagonist, diluted ten times with PDA, suppressed the mycelial growth of P. debaryanum and P. capsici completely. Whereas in this test R. solani proved to be the least sensitive, the remaining test fungi showed some differences in their susceptibility, but in any case their growth was inhibited significantly as compared to the controls.
Effects of Salicylate on Systemic Invasion of Tobacco Plants by Various Viruses
Authors: Roggero P. , Pennazio S. 
Published: May 2008

AbstractSalicylate watered onto soil in which White Burley tobacco plants were grown represents a reversible stress characterized by stomatal closure, slight slackening of plant growth and low chlorophyll loss. Salicylate affected viral pathogenesis in opposite ways. It had no effect against local and systemic infections by potato virus X (PVX), potato virus Y0 (PVY0) or tobacco mosaic virus (TMV), whereas it completely prevented systemic infection by alfalfa mosaic virus (AIMV) or tobacco, rattle virus (TRV) in a high proportion of treated plants. When infection moved from leaves inoculated with AIMV or TRV, the tendency to limit systemic spread was shown by the restriction of systemic infection to very limited areas erratically distributed in some uninoculated leaves.The salicylate‐induced restriction of AIMV or TRV infectivity to inoculated leaves did not appear due to inhibition of virus multiplication because the inoculation of potentially resistant leaves of salicylate‐reated plants resulted in virus antigen accumulation comparable to that of untreated controls. Salicylate may therefore inhibit some long distance virus transport function.Salicylate appears able to evoke true hypersensitivity only against systemic viruses able to induce local necrotic lesions, probably by activating some genetic information for resistance that is normally not expressed.
The Seed‐borne Inoculum of Peronospora manshurica, Causal Agent of Soybean Downy Mildew
Authors: Roongruangsree U‐Tai , Olson L. W. , Lange L. 
Published: May 2008

AbstractThe seed‐borne inoculum of P. manshurica is described using various microscopic techniques and staining reactions. The inoculum, in addition to the oospores, consists of a thin walled mycelium under the hourglass cell layer of the seed coat and a thick walled resting mycelium in the oospore crust on the seed surface. By a modified Feulgen staining technique it was possible to demonstrate that the thin walled and the thick walled resting mycelium as well as thin and thick walled oogonia contain nuclei which are Feulgen positive suggesting that portions of the mycelium of P. manshurica may survive even on the surface of dry, mature seeds.
The Differentiation of Infection Structures as a Result of Recognition Events between some Biotrophic Parasites and their Hosts
Authors: Mendgen K. , Schneider A. , Sterk M. , Fink W. 
Published: May 2008

AbstractMost uredospores of rust fungi develop infection structures in a typical pattern so that they can infect the host plant. The function of these infection structures is divided into the following three phases:

In the recognition phase, the germ tube recognizes the cuticle and the stoma. This process may occur independently from the host plant since copies of the cuticle induce similar reactions of the fungus. During fungal growth on the epidermis, unspecific stress responses of the plant are triggered.
In the signal phase, the fungal substomatal vesicle and infection hypha(e) contact the host cells within the leaf parenchyma. A signal from the host induces further development of the fungus. Haustorium mother cell differentiation is effected and haustorium formation is initiated. At the same time, the fungus suppresses the synthesis of stress metabolites by the plant.
In the parasitic phase, the fungus penetrates the host cell and complex interactions between host and parasite begin. A highly specialized interface around the haustorium develops presumably in order to allow a more efficient nutrient transfer from host to parasite. Eventual defence reactions of the plant, generally on the race‐cultivar level, fail to be evoked or are suppressed in compatible combinations.
Expression of Resistance of Wheat to Fusarium graminearum and F. culmorum Under Various Experimental Conditions
Authors: Mesterházy Á. 
Published: May 2008

AbstractThe resistance ranking was very similar under different periods of incubation except the 17 and 24 h variants under plastic bags and with the presence or absence of Bayleton treatment. Very similar ranking was recorded also in the tests where four plot replicates were used, e.g. the reaction severity was so close in different plot replicates that one plot per genotype seemed to be enough for serial resistance tests. The significant plot × genotype interaction shows that relative resistance ranking may vary to some extent, but basic changes do not occur. Also similar cultivar reactions were observed at different levels of disease severity resulting from inoculation with isolates differing in pathogenicity. An average reaction to these levels is closer to the genetically determined resistance. Analysis of the behaviour of a cultivar at different disease severity levels helps to predict the field behaviour of a given genotype. The Bayleton treatment was ineffective against scab, although there was some interaction with cultivars.
Effect of Salicylic Acid and Phenylserine on the Hypersensitive Reaction of Tobacco to Tobacco Mosaic Virus
Authors: Wieringa‐Brants D. H. , Schets F. M. 
Published: May 2008

AbstractInjection of leaves of tobacco (Nicotiana tahacum cv. ‘Xanthi’ nc) with salicylic acid (SA) or phenylsene (PS) had an effect on the local lesion development caused by tobacco mosaic virus (TMV), depending upon the concentration used and the time interval between injection and challenge inoculation. Maximum reduction in lesion size was obtained with 0.75 mM SA or with 8 mM PS. Concentrations higher than 1 mM SA or 25 mM PS damaged the leaf tissue, PS being far less toxic than SA. The leaves responded rapidly to injection with SA or PS. A time interval of only 1 h between injection and TMV inoculation reduced the lesion size significantly.Isolated tobacco cell walls incubated with SA yielded carbohydrate fractions capable of reducing lesion size significantly after injection. Cell walls incubated without SA or with PS did not yield active carbohydrate fractions.
Health Status (Virus) of Native North American Humulus lupulus in the Natural Habitat
Authors: Hampton R. O. 
Published: May 2008

AbstractNinety‐one native North American Humulus lupulus plants from natural habitats in seven western and mid‐western states of the U.S.A. were tested by ELISA serology for presence of two ilarviruses and three carlaviruses common to cultivated hops. All plants in natural habitats were free of detectable viruses. Propagations of 14 such plants from earlier collections had become infected, particularly with two carlaviruses (hop latent virus, American hop latent virus) after exposure for 22 years tobreeding nurseries. ELISA tests of some 284 hop plants primarily from breeding nurseries in Oregon indicated the following infection rates: Prunus necrotic ringspot virus, 85/284, 30%; apple mosaic virus, 88/234, 38%; hop mosaic virus, 59/158, 37 %; hoplatent virus, 104/158, 66 %; and American hop latent virus, 79/158, 50 %. Inoculum reservoirs of AHLV were sought among 53 principally perennial non‐Humulus plant species surrounding AHLV‐infected hop yards and nurseries. AHLV was neither indigenous to native North American H. lupulus nor detectable in these selected non‐Humulus plant species. Breeding nurseries and commercial hop yards, thus, were the only detectable inoculum reservoir for AHLV.
Penetration of the Periderm of Red Raspberry Canes by Leptosphaeria coniothyrium
Authors: Seemüller E. , Kartte Sylvia , Erdel M. 
Published: May 2008

AbstractUmwounded raspberry canes were inoculated with Leptosphaeria coniothyrium. After penetration of the epidermis the fungus invaded the cortex readily. The accumulation of mycelium in this tissue lead to a partial digestion of the middle lamellae of the outermost cork layer within the polyderm. The fungus penetrated this single cell barrier through the openings between the separated cells and colonized the phelloid tissue between the first and second cork layer. After vigorous growth in this non‐suberized tissue the fungus penetrated the second cork barrier in the same way as the first layer. This mode of penetration was repeated until the fungus had spread beyond the periderm and into the vascular tissues. The invasion process occurred rather slowly and was enhanced by weakening of the canes by defoliation at the time of inoculation.
Latency of Infection in Unripe Avocados by Colletotrichum gloeosporioides is Not Due to Inadequate Enzyme Potential
Authors: Sivanathan S. , Adikaram N. K. B. 
Published: May 2008

Abstract Colletotrichum gloeosporioides produced exo‐pectin lyase and protease in a) liquid cultures with incorporated washed cell wall material from unripe or ripe avocado and b) autoclaved immature fruit. The activity of exo‐pectin lyase and protease produced in liquid cultures incorporating washed cell walls from immature fruits was almost the same as when washed cell walls from ripe fruits were incorporated. Ripe fruit tissue rotted by the fungus contained exo‐pectin lyase, endo‐polygalacturonase (endo‐PG) and protease. The endo‐PG was found to be endogenous to avocado fruit, and had a pH optimum of 5.5. The pH optima of exo‐pectin lyase and protease were 8.5 and 7.5 respectively in all three enzyme preparations. All these enzyme preparations completely macerated avocado fruit tissue discs in vitro in less than 3 h of incubation but not potato tuber discs. Neither immature nor ripe fruit contained substances, proteinaceous or otherwise, which could inhibit the exo‐pectin lyase or protease activity of these preparations. The results indicated that C. gloeosporioides possesses sufficient enzyme potential to invade cell walls of unripe fruit and that the fruit tissue does not have a mechanism to inactivate such enzymes.
Bis‐thiourea Metal Complexes with Enhanced Antiphytoviral Activity
Authors: Davarski K. A. , Schuster G. , Vassilev G. N. 
Published: May 2008

AbstractThe activity of bis‐thiourea, diallyl‐bis‐thiourea and in part of diphenyl‐bis‐thiourea against potato virus X (PVX) can be augmented considerably by complexation of the mentioned compounds with Cu±±, Ni±±, and Co±±. Contrary to this, complexation with Fe±± and Cd±± does not augment or reduce the antiphytoviral activity. Most antiphytoviral active are the diallyl‐bis‐thiourea complexes with Cu±±, Ni±± and Co±±. The antiphytoviral activity of the Cu±± and Cd±± complexes with bisthiourea can be additionally augmented by combined treatment with small amounts of 2,4‐dioxohexahydro‐l,3,5‐triazine (DHT).
Tomato Yellow Leaf Curl Virus DNA Forms in the Viral Capside, in Infected Plants and in the Insect Vector
Authors: Czosnek H. , Ber R. , Navot N. , Antignus Y. , Cohen S. , Zamir D. 
Published: May 2008

AbstractTomato yellow leaf curl virus (TYLCV) DNA was used as a probe to identify and analyze virus‐related DNAs in the viral capside, in infected tomato plants and in the virus vector, the whitefly. In addition to the single‐stranded viral genomic DNA, double‐stranded virus‐related DNA molecules were detected in infected plants. Not all of the virus‐related DNA forms are present simultaneously in the infected plant. The double‐stranded molecules, which are probably the replicative form of the viral genome, have been purified from an infected tomato plant. In the viruliferous whitefly, only the single‐stranded unit‐size viral genome was detected.
Alteration of Bark Proteins Associated with Citrus Tristeza Virus (CTV) Infection on Susceptible Citrus Species and Scion‐Rootstock Combinations
Authors: Moreno P. , Guerri J. , Ortiz J. 
Published: May 2008

AbstractThe effect of citrus tristeza virus (CTV) on bark protems of susceptible citrus species and scion‐rootstock combinations was studied by polyaerylamide gel electrophoresis (PAGE). Protein pattern of sour orange bark from CTV‐infected trees on this rootstock showed reduced intensity in a protein band, about 20,000 daltons molecular weight, as compared with similar CTV‐free trees. This protein modification appears specifically associated with decline induced by tristeza since it was observed on trees of different ages and scion‐rootstock combinations, grown in various locations and infected with several CTV isolates, but not on trees exhibiting decline from other causes. The observed protein alteration was localized in the ribosomic fraction.No protein alteration, associated with CTV infection could be found on lemon bark, although this citrus species also behaves as a CTV‐susceptible rootstock.Electrophoretic profiles obtained from CTV infected Mexican lime and Etrog citron seedlings also showed reduced intensity in a protein band with the same electrophoretic mobility as the tnodified band of sour orange.
A Tobamovirus Causing Heavy Losses in Protected Pepper Crops in Spain
Authors: Alonso E. , García Luque I. , Avila‐Rincón M. J. , Wicke B. , Serra M. T. , Díaz‐Ruiz J. R. 
Published: May 2008

AbstractDuring a four‐year (1982–1985) survey of plant viruses infecting pepper cultivars grown under plastic in the Southeastern region of Spain, a tobamovirus was found to be the major disease agent of this crop. The virus produces slight or no symptoms on the leaves, but causes chlorotic mottling, malformation and reduction in size with occasional necrosis on the fruits and was able to infect all commercial pepper cultivars tested, including those resistant to other tobamoviruses, causing a catastrophic disease. The biological and serological characterization of the virus showed that it is very similar to pepper mild mottle virus (PMMV) (Wetteret al. 1984) and therefore we have termed it as Spanish strain of PMMV (PMMV‐S). The need of grouping all the so‐called “pepper strains” of tobacco mosaic virus (TMV) as a new distinct member of the tobamovirus group with the name of PMMV is emphasized.