bluuebunny/crossref_metadata_2025 huggingface dataset:
Antifungal Effects of Bacilysin and Fengymycin from Bacillus subtilis F‐29‐3 A Comparison with Activities of Other Bacillus Antibiotics
Authors: Loeffler Wolfgang , Tschen Johannes S.‐M. , Vanittanakom Nongnuch , Kugler Martin , Knorpp Elisabeth , Hsieh Ting‐Fang , S. M. , Wu Tene‐Gene
Published: May 2008

Of the two antifungal antibiotics produced by Bacillus subtilis F‐29‐3, the dipeptide compound bacilysin inhibits yeasts (and bacteria), whereas the formerly unknown fengymycin, a complex of closely related lipopeptide components, shows antibiotic activity against filamentous fungi.

Bacilysin production, formerly known for a few strains only, could be demonstrated for all 12 wild‐type cultures of Bacillus subtilis tested during this study. The antibiotic also occurs in some strains of three other Bacillus species considered as closely realted to B. subtilis.

Members of the lipopeptide class of antifungal Bacillus metabolites were formed by 8 of 12 Bacillus subtilis‐isolates and several other Bacillus strains.

The antibiotics of F‐29‐3 were compared with antifungal metabolites of other Bacillus isolates using TLC, agar‐diffusion techniques and tests demonstrating the capacity of six lipopeptide and peptide preparations to protect rice seedlings from phytomycosis due to Rhizoctonia solani.

Fengymycin proved to be different from the other compounds tested. It was less toxic to the test plants and protected them better from Rhizoctonia disease than the other antibiotics of the study did.
Zum Auftreten von Phoma nigrificans (P. Karst.) comb. nov. (Teleomorph Didymella macropodii Petrak) an Winterraps (Brassica napus L. var. oleifera Metzger)
Authors: Boerema G. H. , Loerakker W. M. , Wittern I.
Published: May 2008

On the occurrence of Phoma nigrificans (P. Karst.) comb. nov. (teleomorph Didymella macropodii Petrak) on winterrape (Brassica napus L. var. oleifera Metzger)

With a screening for resistence of winterrape to Phoma lingam (teleomorph Leptosphaeria maculans), in various places in North Germany, another species of Phoma was repeatedly isolated from plants with blackleg symptoms. This Phoma species could easily be distinguished from P. lingam by its larger conidia and its lower optimal temperature. Comparative study with isolates in the Phoma‐collection of the “Plantenziektenkundige Dienst” (Wageningen) showed that it, represents the anamorph of Didymella macropodii, an Eurasian Ascomycete occurring on different wild crucifers and originally described from Macropodium nivale in Siberia. The Phoma‐anamorph of this fungus was first described in Finl, and from Armoracia rusticana as Sphaeronaema nigrificans. This binomial is now transferred to Phoma (“section Sclerophomella”). Inoculation of rape seedlings with Phoma nigrificans (Didymella macropodii) resulted, in dark discolorations and constrictions of the hypocotyls of the seedlings.
Affinity Purification of Specific Antibodies from Plant Virus Capsid Protein Immobilised on Nitrocellulose
Authors: Rybicki E. P.
Published: May 2008

The application of a small‐scale method for the preparation of antibodies specific for coat proteins of simple plant viruses is described. The method entails the preparative electrophoresis of crude virion extracts, electrophoretic transfer of the resolved proteins onto nitrocellulose paper, excision of a specific protein band, and the attachment and subsequent elution of antibodies specific for the excised protein. The method was tested with brome mosaic virus (BMV) and low molecular weight plantproteins. It was possible to produce antibodies from multiply‐reactive sera that reacted only with the proteins used to purify them. Antibodies eluted from BMV coat protein monomer reacted strongly with intact virus in indirect ELISA. Other possible applications of the technique to plant virology are discussed.
Transmission of Pseudomonas avenae, the Cause of Bacterial Stripe of Rice
Authors: Shakya D. D. , Chung H. S. , Vinther F.
Published: May 2008

Transmission of Pseudomonas avenae from rice seed to seedling and from plant to seed was shown. Based on experiments with unhulled and hulled seeds and on histopathological studies the location of the pathogen in seeds and the possible pathway of the pathogen from seed to seedling is suggested. Infected seeds were harvested from plants on which no symptoms were observed after the seedling stage. The experimental conditions indicated that the bacterium can be transmitted internally from plantto seed in latently infected plants.
Enzyme Changes Associated with Host‐Parasite Interactions between Pearl Millet and Downy Mildew Fungus
Authors: Arora Y. K. , Mehta N. , Thakur D. P. , Wagle D. S.
Published: May 2008

During the pathogenesis of pearl millet by the downy mildew (Sclerospora graminicola [Sacc.] Schroet.), the activities of peroxidase (PO) and indoleacetic acid oxidase (IAAO) and their isozyme pattern determined by isoelectric focusing on polyacrylamide gels, were observed in extracts of leaves and ears at different stages of development. The PO activity in extracts from infected plants of a susceptible cultivar was found to be higher than in healthy plants. The higher activity was most probably due to the acceleration of host senescence by the pathogen. Quantitative differences in the isozyme patterns of PO and IAAO were found. In inoculated plants of the resistant cultivar, no symptoms developed under the conditions used for infection of the susceptible cultivar and the changes in enzyme activities after inoculation were not significant. The results indicated that different proteins are synthesized in the two cultivars.
Fungal Antagonists of Gerlachia nivalis
Authors: Al‐Hashimi Mediha H. , Perry D. A.
Published: May 2008

Trichoderma viride was strongly antagonistic to Gerlachia nivalis in agar plate culture and it controlled infection of barley seedlings from seed‐borne inoculum when incorporated in soil as straw culture and from soil‐borne inoculum when conidia were applied to the seed coat. Penicillium expansum and Papulaspora byssina were inhibitory towards G. nivalis in culture, although not as strongly as T. viride, and they did not control seedling infection as effectively.
A Bark Necrosis of Grapevine Caused by Pseudomonas syringae V. Hall, in Sardinia
Authors: Cugusi M. , Garau R. , Prota U. , Dore M.
Published: May 2008

An unusual disorder occurred on ‘Vernaccia’ vine, particularly in the typical cultivation area of the variety, in the province of Oristano. Main symptom is the decaying of wood and bark. This causes the loss of the bark on the circumference of the trunk and causes the plants to die. Degradation can develop very deep in the wood rings. Affected rings can detach from the new formed ones.

The infectious process is very serious in the younger plants and can slow their evolution in the years. Furthermore it does not allow the recovery of the affected plants. In some vineyards 4 % of affected plants occur. Mortality can reach up to 20%, of the affected plants and is very high during the early years after infection.

A bacterium has been constantly isolated from decaying tissues; for its morphological and physiological characters and the response to serological tests it has been included in the Pseudomonas syringae Van Hall group. Pathogenicity tests carried out on ‘Vernaccia’ vines and other varieties resulted always positive; the bacterium has always been reisolated from artificially affected areas. The latter were much diffused and, sometimes, reproduced the typical symptomatology of the disease observed in nature.
Control of Downy Mildew, Plasmopara viticola (de Bary) Berlese et de Toni, on Grapevine Leaves through Water Extracts from Composted Organic Wastes
Authors: Weltzien H. C. , Ketterer N.
Published: May 2008

Watery extracts of composted manure‐straw‐soil mixtures induced increased resistance of grapevine leaves against downy mildew, Plasmopara viticola, if applied by dipping or spraying. The extracts had no direct fungicidal or fungitoxic effects.
Serological and Lysotypical Variability of Xanthomonas albilineans (Ashby) Dowson, Causal Agent of Sugarcane Leaf Scald Disease
Authors: Rott P. , Arnaud M. , Baudin P.
Published: May 2008

The serological and lysotypical properties of 28 strains of X. albilineans originating from different geographic zones were analysed. Using the indirect immunofluorescence technique with 3 anti X. albilineans immunsera, the existence of three serovars was shown. The isolation of lytic bacteriophages from the soil enabled us to classify the bacterial strains into 6 lysovars. A correspondance between serovars and lysovars was revealed. These results show a variability of the X. albilineans species, and enable an analysis of the structure of its populations to be proposed, especially that of Tropical Africa.
Investigation of a Great Number of Actinomycete Isolates on Their Antagonistic Effects Against Soil‐Borne Fungal Plant Pathogens by an Improved Method
Authors: Turhan Gülay , Grossmann F.
Published: May 2008

By means of a modified agar‐ring method, the antibiotic efficacy of 300 isolates of actinomycetes, obtained from soil samples from Turkey, against six different test fungi was investigated. A wide range in their degree of sensitivity was evident. Whereas Sclerotinia sclerotiorum was completely inhibited by more than 90 % of the tested isolates, Rhizoctonia solani and Alternaria alternata were suppressed by only 17 and 14 %, respectively; Pythium debaryanum, Cochliobulus sativ, us and Macrophomina phaseolina held an intermediate position. Isolates which completely prevented the growth of Rhizoctonia solani and Alternaria alternata, were usually also highly effective against the other test fungi. Possible conclusions which may be drawn from these results are discussed.
Carpogenic Germination of Sclerotia of Sclerotinia sclerotiorum after Periods of Conditioning in Soil
Authors: Phillips A. J. L.
Published: May 2008

Periods of conditioning in soil reduced the length of the resting period needed before sclerotia of Sclerotinia sclerotiorum could germinate to form apothecia. Curves for germination of sclerotia were fitted by a form of the log‐logistic equation and from this equation the time taken for 50% germination (x50) was calculated. These x50 values were used as the basis for comparing germinability of sclerotia collected from infected sunflower plants and others conditioned in soil, or moist vermiculite for various times. Sclerotia from sunflower roots germinated sooner than those from the stem cavities. Germinability increased with the length of the conditioning period. Conditioning in soil was more effective than in moist vermiculite.
The Search for a Specific Antigen for Erwinia amylovora
Authors: Laroche M. , Verhoyen M.
Published: May 2008

A specific reaction has been observed in immunodiffusion, using the supernatant obtained after centrifugation of E. amylovora phenol treated cells. This reaction occurred for all the E. amylovora strains examined and could be distinguished from all other reactions occurring with different species of Erwinia. We called the product inducing the specific reaction: Specific Antigenic Fraction or SAF.

The immunological and chemical characteristics of SAF have been compared with other extractable products from the bacteria (LPS, ‘O'Ag), from the culture media (EPSc) and from the ooze (EPSo). This revealed that SAF is lipopolysaccharide in nature and that the specific antigen(s) involved would be on a polysaccharidic fraction.
A Comparison of the Effects of Temperature on the Growth of Fusarium oxysporum f. sp. narcissi in Solid and Liquid Media
Authors: Linfield Christine A.
Published: May 2008

The effect of different temperatures on mycelial growth of Fusarium oxysporum f. sp. narcissi in liquid and on solid medium was compared. Differences between optimum and maximum temperatures using these substrates were considerable and, could lead to different interpretations of the parasitic growth of the pathogen in vascular tissues, for example, in liquid culture Fusarium grew at 45°C whereas it did not on solid media. Initially F. oxysporum f. sp. narcissi may, be encouraged to grow faster in warm air drying systems than those using lower temperatures. The rates of diffusion between 17°C and 35°C are not markedly different. The speed with which moisture is removed from the internal tissues of the remaining roots is governed more by air flow over the bulbs than by temperature.
Production of Cutin Hydrolyzing Enzymes by Botrytis cinerea in vitro
Authors: Salinas J. , Warnaar F. , Verhoeff K.
Published: May 2008

The production in vitro of cutin hydrolyzing enzymes by five isolates of B. cinerea was studied, using cutin of tomato fruits as a carbon source. Chemical depolymerisation of the cutin yielded 10,16‐dihydroxyhexadecanoic acid as the main component. The same fatty acid was found after incubation of cutin with a crude enzyme preparation from a culture filtrate of B. cinerea. Hydrolysis was optimal at pH 5.5–6.0. In cultures with glucose as the only carbon source no cutinase activity was detected. Crude enzyme preparations which hydrolyzed cutin, also hydrolyzed para‐nitrophenylbutyrate, with an optimum activity at pH 8. All five isolates showed para‐nitrophenylbutyrate hydrolyzing activity when grown on tomato cutin, but the activity varied with the isolate used. No correlation was found between para‐nitrophenylbutyrate‐hydrolyzing activity of an isolate and its production of small lesions on young tomato fruits.
Biological Control of Fireblight (Erwinia amylovora [Burr.] Winslow et al.) on Ornamentals
Authors: Isenbeck M. , Schulz F. A.
Published: May 2008

Several yellow pigmented, rod‐shaped bacterial strains with antagonistic activity against E. amylovora had been isolated from blighted ornamental shrubs. Criteria of the mode of action have been investigated under in‐vitro conditions and in inoculation experiments. In contrast to the noninhibitory isolates of the same host origin the active forms obviously produce a substantial principle. This is active only under acid conditions, it is heat‐stabile, it can be dialyzed and is solublein water and methanol. It is not a phenolic compound.

In disease control experiments using culture filtrates of the antagonistic bacterial isolates fireblight could be reduced to a limited extend following shoot tip inoculation of Cotoneaster bullatus under controlled conditions. Compared to application of the living antagonists in the control experiments disease reduction, however, was considerably less expressed.
Interaction between Venturia inaequalis and Apple Callus Tissue Cultures: an Electron Microscopic Study
Authors: Beech I. , Gessler C.
Published: May 2008

Untrastructural interactions between Venturia inaequalis and callus cultures from scab susceptible and resistant apple varieties, were similar. Host cell wall changes, appositions, and invagination of host plasmamembrane at sites of close contact with fungal hyphae were regularly observed. The ultrastructural observations are described and discussed. The host cell alterations as well as many fungal structures corresponded to those known in young leaves of susceptible apple varieties.
Induced Systemic Resistance in Tomato Plants against Phytophthora infestans
Authors: Heller Werner E. , Gessler Cesare
Published: May 2008

Infection of lower leaves of tomato plants with Phytophthora infestans followed by a period unfavourable to disease development increased the general resistance of the plants against the pathogen. Induced resistance to a second infection of upper leaves was expressed in the development of necrotic lesions that were sharply defined and reduced in size. Sporulation of the pathogen was suppressed. Lesions on unprotected plants expanded with a sporulating zone passing gradually to the healthy tissue under the same conditions. Induced resistance delayed and reduced penetration of the pathogen into the epidermis and subsequent colonisation of the mesophyll by formation of papillae in epidermal cells and hypersensitive‐like reactions of penetrated, mesophyll cells.
Ultrastructural and Histochemical Studies on Mildew of Barley (Erysiphe graminis DC. f. sp. hordei Marchal)
Authors: Heitefuss R. , Ebrahim‐Nesbat F.
Published: May 2008

Plants of the mildew susceptible barley cultivar Peruvian and the adult plant resistant cultivar Osiris were inoculated with Erysiphe graminis f. sp. hordei at the first and fifth leaf stages. Samples taken at 32 hr after inoculation were examined by electron microscopy to compare papillae associated either with penetration failure or with successful penetration of the fungus into the epidermal cell and haustorium formation. Four types of papillae with ultrastructural differences could, be classified. Although their definite association with fungal ingress or failure is not possible, our data suggest that papillae with larger, more compacted and amorphous or globular structures may be more effective as penetration barriers than others, with more or less uniform distribution of irregular, smaller electrondense structures.
Cross Protection Between Strains of Fusarium oxysporum f. sp. vasinfectum and its Effect on Vascular Resistance Mechanisms
Authors: Hillocks R. J.
Published: May 2008

The severity of symptoms induced in cotton plants by stem inoculation with Fusarium oxysporum f. sp. vasinfectum was reduced by inoculation with a non‐pathogenic strain (NPS) of the fungus 3 days previously. Symptom reduction was associated with reduced populations of the pathogen in the stele tissue of the stem. This cross‐protective response became effective within 24 h of inoculation with the NPS. Although both vascular occlusion and terpenoid aldehyde synthesis were induced by theNPS, the short time required for cross protection to become effective and the duration of the effect, indicated that vascular occlusion rather than fungitoxicity of the terpenoid aldehyde compounds was the mechanism of protection.
Effect of Herbicides and Oat Amendment on Soybean Disease Development and Seed Quality
Authors: Bowman J. E. , Sinclair J. B.
Published: May 2008

The effects of four herbicides and hand weeding and no weeding on soybean disease development and seed quality were studied in the field. Chloramben, dinoseb, fluchloralin, and trifluralin were preplant incorporated at recommended rates. In addition, the effect of an in‐furrow oat (Avena sativa L.) amendment used as an inoculum carrier was studied in all treatments. Compared with the hand‐weeded control, yield, incidence of Septoria leafspot (Septoria glycines), and the recovery of Phomopsis spp. from pod and stem tissues were reduced in the week‐infested control and dinosebtreated plots. Recovery of Alternaria spp. was greater from crown tissues of plants grown in chloramben‐ and fluchloralin‐treated plots compared with, either the weed‐infested or hand‐weeded control. Septoria leafspot ratings and recovery of Phomopsis spp. from various plant tissues were higher in plants from hand‐weeded plots compared with weed‐infested plots, whereas the opposite was truefor, the recovery of Fusarium spp. Chloramben‐treated plots were high‐yielding and had the best weed control of all herbicide treatments. Seed quality was not affected by herbicide treatment. Plants from furrows with autoclaved oats had a lower incidence of Septoria glycines, a greater recovery of Fusarium spp. from pod and stem pieces, and produced seed with lower quality than plants from rows with no oat amendment.
The Nature of Systemic Invasion of Stem and Leaves of Sunflowers by Plasmopara helianthi Novot. var. helianthi Novot. with Mechanism of Sporulation and Zoospore Release
Authors: Döken M. Timur
Published: May 2008

During the systemic development of Plasmopara helianthi Novot. var. helianthi Novot. the hyphae in the stem advance especially through the intercellular spaces of loose parenchyma forming haustoria in adjacent cells. The hyphae which reach leaf blades through petioles continue their growth along the main veins intercellularly in non‐vascular tissues enclosing the vascular bundles. At the same time, the hyphae spread to intercellular spaces of spongy parenchyma where the growth is limited by the veinlets resulting in angular chlorotic lesions.

Under humid conditions the sporangiophores arising from the aggregated hyphae in a substomatal cavity emerge through the stomatal pore on the lower side of the leaf and zoosporangia are borne terminally on sporangiophores. Soon after biflagellated zoospores are liberated into distilled water from the zoosporangia, they retract their flagellae and then lyse.
Phialophora parasitica, Causal Agent of Cherry Dieback
Authors: Rumbos I. C.
Published: May 2008

A serious fungal disease causing dieback symptoms on cherry tree was observed in the period 1982–86 in different locations of Greece. Isolations from affected branches yielded consistently the fungus Phialophora parasitica. Pathogenicity tests carried out on cherry, apricot, olive and peach trees showed that the pathogen was capable to induce disease symptoms on all these fruit trees.
Variability in Sensitivity to Polyoxin B of Isolates of Alternaria mali and Decreased Fitness of Polyoxin resistant Isolates
Authors: Hwang Byung Kook , Yun Ju Ho
Published: May 2008

The 540 monoconidial isolates of Altemaria mali were obtained in 1983 from apple orchards at Seoul, Suweon, Cheongju, Kochang, Daegu, and Jinju in Korea. The sensitivity of A. mali to polyoxin B greatly varied among isolates and locations. Most of isolates were sensitive to polyoxin B, but 11 isolates showed a high level of resistance, particularly from Kochang and Daegu where polyoxin B had been applied frequently. Conidial germination and mycelial growth of resistant isolates were not inhibited at higher concentrations of polyoxin B compared to the sensitive ones. The polyoxin‐resistant isolates were not resistant to the fungicides iprodione and polydong and showed a reduced activity for conidial formation and mycelial growth. The isolates of A. mali with resistance to polyoxin B appear to have decreased fitness in nature.
The Effect of Glumes on Fungal Infection of Germinating Seed of Spelt (Triticum spelta L.) in Comparison to Wheat (Triticum aestivum L.)
Authors: Riesen Th. , Winzeler H. , Rüegger A. , Fried P. M.
Published: May 2008

The influence of fungi on seedling emergence of naked and hulled spelt (Triticum spelta L.) and winter wheat (Triticum aestivum L.) was investigated. Seeds were sown in flat trays and placed in a growth chamber under stress conditions (low temperature and water logging) for four weeks, followed by favourable growth conditions. At weekly intervals, 150 seeds were removed, surface sterilized, and investigated for fungi. Pythium aristosporum Vanterpool, a causal agent of damping‐off, was found to be best adapted to the unfavourable conditions and to be a major cause of pre‐emergence damping‐off. The frequency of seed‐borne fungi decreased during the stress period, whereas soil‐borne fungi survived and could be isolated from seeds and glumes in the following period with more favourable growth conditions. Seedlings from hulled seeds of spelt emerged more frequently than from naked kernels of spelt and both emerged at a higher rate than from seeds of winter wheat. This is good evidence that glumes protect seeds against fungal colonization and therefore increase the fitness of spelt under unfavourable germinating conditions.
Pathogenic Potential of Soil Fusaria from Malaysian Oil Palm Habitats
Authors: Ho Y. W. , Varghese G.
Published: May 2008

A total of 353 Fusarium isolates consisting of 8 species and 2 varieties obtained from the soils of 22 sampling sites in oil palm habitats in Peninsular Malaysia was tested on 2‐leaf stage oil palm seedlings. None of the isolates tested produced any symptoms of vascular wilt or other diseases. However, some of the isolates did have an adverse effect on the growth and vigour of the palms. They were found to cause significant reduction in palm growth. Isolates causing a reduction in the growth of the oil palm seedlings were not confined to a certain type of soil or a particular location.
Isolation and Characterization of a Virus Inhibitor from Spinach (Spinacia oleracea L.)
Authors: Straub Petra , Adam G. , Mundry K.‐W.
Published: May 2008

A virus inhibiting protein (VI) was isolated from spinach (Spinacia oleracea L.). The VI inhibited infections of test plants with plus‐ and minus‐strand RNA viruses. Inoculation of both local lesion and systemic hosts with TMV in the presence of varying amounts of the VI resulted in typical dose response curves for the number of local lesions or the amount of virus respectively. The lowest concentration of VI leading to a significant reduction in the number of local lesions was 0.06 μg/ml. The VI was found to inhibit local lesion formation only when applied within 2–3 h p.i. but still reduced the number of local lesions when applied up to 9 h prior to virus inoculation.

The antiviral activity could be attributed to a protein of molecular weight 29,000 dalton with an isoelectric point of 10.3. Its activity was destroyed by heating for 30 min to 70°C. These characteristics resemble those of other virus inhibiting proteins described for members of the order Caryophyllales such as the Phytolacca inhibitor against which a serological relationship was obtained.
Factors Affecting the Production of Antifungal Compounds by Enterobacter aerogenes and Bacillus subtilis, Antagonists of Phytophthora cactorum1
Authors: Gupta V. K. , Utkhede R. S.
Published: May 2008

The effects of temperature and pH on the production of antifungal compounds and growth in sterilized soil of Enterobacter aerogenes and Bacillus subtilis, antagonists of Phytophthora cactorum, the cause of crown rot of apple trees, were studied. With E. aerogenes maximum amounts of antifungal compounds were produced between 14 and 21°C and at pH levels between 3.5 and 5.0. Bacillus subtilis produced maximum amounts of antifungal compounds between 21 and 28°C andwith pH levels between 5.0 and 8.0. P. cactorum inoculum, produced in the presence of E. aerogenes or B. subtilis at optimum temperature and pH levels, was significantly less virulent compared with controls. The optimum temperature of maximum population growth in sterilized soil for E. aerogenes was 18°C and for B. subtilis 25°C. The population growth of B. subtilis was much slower than that of E. aerogenes. Fosetyl Al stimulated the multiplication of bacteria at lower temperatures while metalaxyl had the same effect at higher temperatures. These results indicate that populations of these antagonistic bacteria increase in sterile soil up to the 33rd day from inoculation and that the fungicides fosetyl, Al and metalaxyl did not limit their multiplication and production of antifungal compounds.
Hyperparasitism of Streptomyces albus on a Destructive Mycoparasite Nectria inventa
Authors: Tu J. C.
Published: May 2008

Using scanning electron microscopy, Streptomyces albus was proved to be a hyperparasite of Nectria inventa, itself a well‐known mycoparasite on many fungi. The hyperparasite had no apparent antagonistic activity against N. inventa, but did have intense tropic response toward it. Upon contact with the host, the hyperparasite grew along, and formed appressorium‐like structures on the host hyphae. The parasitism that led to the eventual collapse of the host cells was not necessarily accompanied by actual hyphal penetration. The hyperparasite could, however, readily penetrate the host hyphae, and its hyphae were frequently found inside the host hyphae.
Zum Einfluß von Pythium ultimum und Cochliobolus sativus auf Wachstum und Wurzelleistung der Wintergerste in Abhängigkeit vom Düngungsniveau
Authors: Brinkmann R. , Schönbeck F.
Published: May 2008

Influence of Pythium ultimum and Cochliobolus sativus on growth and root efficiency of winter barley dependent on fertilizer level

The colonization of barley roots by Pythium ultimum and Cochliobolus sativus can be symptomless or cause root rot. Disease severity of the root systems was increased at higher fertilizer level. Since root length growth was much more affected than shoot growth, the undamaged roots of an infected root systems had an increased efficiency per unit root length. Nevertheless the total root systems, when infected, were positively inferior to the healthy ones. Their utilization of additionaln, utrients was less efficient. This indicates the importance of root health in economical and ecological respect.
Ultrastructural and Histochemical Studies on Mildew of Barley (Erysiphe graminis DC. f. sp. hordei Marchal)
Authors: Ebrahim‐Nesbat F. , Heitefuss R. , Rohringer R.
Published: May 2008

Fifth leaves of the barley cultivar ‘Osiris’ with adult plant resistance against powdery mildew were inoculated with Erysiphe graminis f. sp. hordei. Samples were taken at 32 hours after inoculation for cytochemical treatments and electron microscopy. Deposition of gold‐labelled wheat germ lectin was detected in the wall of the haustorial neck of the fungus and in an outer layer of a papilla, indicating the presence of oligomers of N‐acetylglucosamine. Con A binding was detected mainly, in a middle layer of a papilla, demonstrating the presence of α‐bound glucose and/or mannose. Treatment with PA‐TSH‐SP revealed glycosubstances with vicinal hydroxyl groups present mainly in an outer layer of another type of papilla. Pretreatment with, protease before PA‐TSH‐SP staining resulted in a positive Thiery reaction in spherical structures of a papilla, indicating that vicinal hydroxyl groups were exposed to staining after removal of protein from these structures.
Nutzung von In‐vitro‐Pflanzen der Kartoffel zur Prüfung der antiphytoviralen Wirkung von 2,4‐Dioxohexahydro‐1,3,5‐triazin (DHT) in Kombination mit N‐Cyanoguanidin
Authors: Bittner H. , Schenk G. , Schuster G.
Published: May 2008

Suitability of in vitro potato plantlets for testing of antiphytoviral effect of a combination of 2,4‐dioxo‐hexahydro‐1,3,5‐triazine (DHT) and N‐cyano guanidine

The suitability of a semiquantitative determination of virus content for the detection of antiphytoviral effects of chemicals was demonstrated by ELISA directly applying at in vitro potato cultures systemically infected and chemotherapeutically treated. The combination of 2, 4‐dioxohexahydro‐1,3,5‐triazine (DHT) and N‐cyanoguanidine both applied at a concentration of 0.03% to the culture medium resulted in a high significant reduction of the relative concentration of the potato virus S in the, potato genotype ‘M‐812820’ of 44–73 %. A phytotoxic influence of the substances was not observed. The combination of the two antiphytoviral substances had no effect against potato virus Y in explants of the variety ‘Ackersegen’. Differences in the susc, eptibility of various genotypes against biologically active substances were indicated.
Identification of Scopoletin as a Phytoalexin of the Rubber Tree Hevea brasiliensis1
Authors: Giesemann A. , Biehl B. , Lieberei R.
Published: May 2008

In leaves of Hevea sp. the production of a blue fluorescing phytoalexin is induced by various fungi. This compound is shown by chromatographic and spectrophotometric means to be scopoletin.
Factors Affecting Race Prevalence of Melampsora lini1
Authors: Saharan G. S. , Singh B. M.
Published: May 2008

No correlation was found between virulence of races and their prevalence, although races which attacked one or two genes for resistence only constituted more than 71% of the isolates studied. Differences in race prevalence were not associated with their incubation or latent period. Uredospore germination of races differing in virulence indicated that a race of narrow virulence and wide prevalence germinated better over a wider range of temperature than races of higher virulence and showed better germ tube elongation at extreme temperatures. These factors may be in part responsible for the wider prevalence of some races.
Stalk Rot of Maize: Host‐pathogen Interaction
Authors: Chambers K. R.
Published: May 2008

Four maize cultivars were each separately inoculated with 10 different isolates of Diplodia zeae, Fusarium moniliforme, F. graminearum and Macrophomina phaseolina. D. zeae consistently caused most stalk rot, followed in decreasing order by M. phaseolina, F. graminearum and F. moniliforme. Significant intraspecific differences in stalk rot were recorded. No significant stalk rot x cultivar interaction occurred. Stalk rot correlated non‐significantly with yield loss but significantly with cellulase production in vitro.
Fusarium lateritium Nees ex Link as a Parasite and Host in Interfungal Hyphal Interactions
Authors: Vajna L.
Published: May 2008

In dual cultures Fusarium lateritium Nees ex Link coiled, penetrated and destroyed young actively growing hyphae of Botrytis cinerea Pers., Cytospora rubescens Fr., Eutypa armeniacae Hansf. et Carter, Sphaeropsis malorum Peck, Rhizoctonia solani Kühn, Trichoderma koningii Oud. (Tk‐1) and Trichoderma hamatum (Bon.) Bain. (Tha‐2), and conidiophores and conidia of Botrytis cinerea Pers. The isolates of Trichoderma koningii Oud. (Tk‐3) and Trichoderma pseudokoningii Rifai (Tp‐1) parasited and destroyed the hyphae of Fusarium lateritium. There was no hyphal interaction between Fusarium lateritium and an isolate of Trichoderma longibrachiatum Rifai. Hyphal, interactions occurred mostly on the aerial hyphae of test fungi which grew over the inhibition zone formed between the colonies of Fusarium lateritium and the test fungus, and contacted the hyphae of Fusarium lateritium.

Details of dual culture studies are given.
Induced Resistance in Hypersensitive Tobacco Against Tobacco Mosaic Virus by Injection of Intercellular Fluid from Tobacco Plants with Systemic Acquired Resistance
Authors: Wieringa‐Brants D. H. , Dekker W. C.
Published: May 2008

Acquired resistance in hypersensitive tobacco plants against tobacco mosaic virus (TMV) was induced by components occurring in the intercellular fluid (IV) obtained from virus‐infected plants or by plant cell wall components. Induced resistance could be transmitted through seed to the progeny. Lesion size and number were reduced significantly when the progeny was tested by TMV‐inoculation.

IV was extracted from the upper uninoculated leaves of four times TMV‐inoculated Nicotiana tabacum cv. ‘Xanthi’ nc plants. Injection of IV from induction‐inoculated plants (SAR‐IV) into leaves of healthy plants followed by TMV‐infection reduced lesion size significantly. A concentration of 5 × 10−7 g SAR‐IV/ml was still active. IV from healthy plants was inactive. The IV's were partly purified by gel filtration on a Sephadex G‐50 column. Some fractions were active in inducing resistance as expressed in reduction of lesion size. Fractions of control‐IV were inactive.

It is still unknown whether the active substances in SAR‐IV are in fact cell wall fragments acting as regulatory molecules in disease resistance.
The Role of Calcium Nutrition on Fusarium‐Wilt Syndrome in Muskmelon
Authors: Spiegel Y. , Netzer D. , Kafkafi U.
Published: May 2008

The influence of various calcium salts was evaluated on non‐inoculated muskmelon plants and on plants inoculated with the Fusarium‐wilt pathogen, and maintained in silica sand or vermiculite. Disease severity of inoculated seedlings maintained in vermiculite was markedly higher than that of seedlings grown in silica sand, and onset of wilt was recorded earlier in the former. These trends were more conspicuous in seedlings treated with Ca2+, especially when this cation was accompanied, by nitrate. In vermiculite–compared with silica sand, Mg and K contents in the shoot were higher while Ca values were lower. Irrespective of the form of calcium salt or the plant's growth medium, the Ca concentration was higher in Fusarium‐inoculated shoots while K content was depleted, compared with non‐inoculated plants.
Deposition of Erysiphe graminis Conidia on a Barley Crop
Authors: McCartney H. A. , Bainbridge A.
Published: May 2008

Naturally released Erysiphe graminis conidia were trapped (on horizontal slides, on vertical sticky cylinders and in suction traps) in a barley crop infected with powdery mildew and the numbers of single spores and of clumps of different sizes deposited on the traps were counted. The efficiencies of impaction calculated from deposits and wind speed measurements were higher than expected from mean wind speed measurements. The values were consistent with the hypothesis that spores were removedpredominantly in gusts. More than half the conidia were removed in clumps of two or more spores. The measurements suggest that clumps were more effectively deposited than single spores. The measurements demonstrate that spore release mechanisms can influence spore deposition significantly, especially close to the source.
Studies on the Extracellular Polysaccharides (EPS) Produced in vitro by Pseudomonas phaseolicola I. Indications for a Polysaccharide Resembling Alginic Acid in Seven P. syringae Pathovars
Authors: Gross M. , Rudolph K.
Published: May 2008

Extracellular polysaccharides (EPS) produced by Pseudomonas syringae pv. phaseolicola are obviously composed of two main components: the long known levan consisting of fructose, and a mannuronan consisting mainly of mannuronic acid (manA), thus resembling alginic acid (alginate). The identification of manA was established by TLC utilizing different developing systems, and by cellulose acetate electrophoresis in different buffers. References were authentic uronic acids and hydrolyzed authentic alginate. A rough quantification of the “alginate” present in crude EPS was achieved with a selective colour reaction which largely excluded compounds other than uronic acids.

Levan was only synthesized with sucrose as primary carbon source. When grown on several other sugars and related compounds “alginate” was the predominant component of the EPS. Additionally, rhamnose, fucose, glucose and amino sugars were found in some instances in hydrolysates of crude EPS, suggesting the release of lipopolysaccharides (LPS) from the bacterial cell walls during culture. Growth on carbon sources not related to sugars resulted in these “LPS” as the main constituent of EPS. After cultivation with sucrose, the “alginate” was restricted to the “slime” fraction of the EPS. In the “capsular” fraction, levan was predominating.

A screening program revealed the capacity to synthesize the “alginate” in six additional P. syringae pathovars: pisi, lachrymans, aptata, tomato, syringae, and glycinea.

All of the strains tested so far produced levan from sucrose, however, the “alginate” was formed not by all of them. There was a tendency that fresh isolates produced more “alginate” than strains subcultured for an extended time in vitro. This was also true for the total amount of EPS.
Demonstration of the Specific Involvement of Coat Protein in Tobacco Mosaic Virus (TMV) Cross Protection using a TMV Coat Protein Mutant
Authors: Sherwood J. L.
Published: May 2008

The DT‐1G mutant of tobacco mosaic virus (TMV) which has no coat protein was used to study the specific involvement of coat protein in TMV cross protection in N. sylvestris. Leaves of N. sylvestris previously inoculated with the mutantor the common strain of TMV were challenged with either turnip mosaic virus (TuMV) or a strain of TMV (TMV‐N). Both TuMV and TMV‐N produce necrotic lesions on N. sylvestris. About one‐half as many lesions were produced by TuMV and TMV‐N on leaves, inoculated with the DT‐1G mutant compared with lesions produced by the same inoculum on control leaves. When leaves of N. sylvestris previously inoculated with the common strain of TMV were challenged with either TuMV or TMV‐N, TuMV produced about one‐half as many lesions as on control leaves whereas TMV‐N produced about one‐tenth as many lesions as on control leaves. A high level of non‐specific resistance was induced by the mutant without coat protein, but it did not specifically protect against TMV.
Virulence Frequencies Influenced by Host Resistance in the Host‐Pathogen System Wheat‐Powdery Mildew
Authors: Heun M.
Published: May 2008

The virulence spectrum for different regions in Germany in 1986 shows that only virulences for resistance genes Pm1, 4a, 7, 8 and Ml‐i are common in Northern Germany; in the Southern part only Pm3b and 9 (+Pm1+ 2) remain effective; the combination Pm2 + 6 is effective within the whole country. The selection pressure of resistance genes on virulences is complex, but was relatively stable under different environmental conditions in 1985 and 1986.
Electron Microscopy of an Isometric Caulimo‐Like Virus from Sweet Potato (Ipomoea batatas)
Authors: Atkey P. T. , Brunt A. A.
Published: May 2008

A newly recognised virus with isometric particles 50 nm in diameter was detected in Ipomoea batatas (sweet potato) by graft‐transmission to I. setosa. Virus particles and intracellular inclusions, although not seen in infected I. batatus, were found in the cytoplasm of most cell types of I. setosa. The caulimo‐like particles were most abundant with vesicles immediately adjacent to inclusions. The ovoid or spherical inclusions, which differ markedly from those of caulimovi, ruses, have a large central lacuna and usually several smaller peripheral lacunae. Infected vascular parenchyma cells sometimes protrude into, and occasionally completely occlude, adjacent xylem vessels, observations possibly explaining the sudden wilting and premature senescence of infected leaves.
Some Properties of Moroccan Pepper Virus and Tombusvirus Neckar
Authors: Gallitelli D. , Russo M.
Published: May 2008

Some unreported characteristics of moroccan pepper virus (MPV) and tombusvirus Neckar (TVN) are given in this paper. Virus particles have a sedimentation coefficient of 140 S (MPV) and 133 S (TVN) and a buoyant density of 1.357 (TVN) and 1.355 (MPV), g/cm3 in CsCl. They are constituted by a single protein species with a molecular weight of 43,000 (MPV) and 45,000 (TVN) which encapsidate a single species of nucleic acid with the apparent size of 4,700 nucleotides. The estimated percentage sequence homology of this genomic RNA with that of the type member of the group was 10% (MPV) and 15% (TVN). All these characteristics strongly suggest to consider both MPV and TVN as true tombusviruses.
Observations on a Mixed Soil‐Borne Wheat Mosaic Virus and Wheat Spindle Streak Mosaic Virus Infection in Durum Wheat (Triticum durum Desf.)
Authors: Rubies‐Autonell C. , Vallega V.
Published: May 2008

Both Wheat Spindle Streak Mosaic Virus (WSSMV) and Soil‐borne Wheat Mosaic Virus (SBWMV) were found on durum wheat plants (Triticum durum Desf.) grown in a field near Rome (Italy). The simultaneous occurrence of these pathogens was demonstrated by host‐symptomatology, pattern of disease occurrence in the field, mechanical transmission tests, as well as by the morphology of viral particles and of ultrastructural modifications. Negatively stained preparates of diseased leaves collected in early, spring showed WSSMV particles and cytoplasmic cylindrical inclusions. SBWMV particles were found only in samples collected later in the season. Ultrathin sections of infected leaves collected in early spring showed characteristic WSSMV modifications such as pinwheels and membranous bodies, whereas samples collected later in the season contained also SBWMV‐like crystalline aggregates. WSSMV infection appeared to develop and decline earlier than SBWMV in the leaves of durum wheat plants infected by both, viruses. WSSMV had not been reported in Italy before.
Application of Cluster Analysis for Establishment of Genetic Similarity in Gene‐For‐Gene Host‐Parasite Relationships
Authors: Lebeda A. , Jendrulek T.
Published: May 2008

Genetic similarity and/or dissimilarity among virulence phenotypes of phytopathogenic organisms and generally in gene‐for‐gene relationships can be exactly expressed by cluster analysis. The present paper deals with the application of a definite hierarchical agglomerative clustering method based on μ‐connected clusters as a means for describing genetic structure of virulence in a set of 48 physiological races (isolates) of Bremia lactucae (lettuce downy mildew). A dendrogram and a minimums, panning tree were used to distinguish between virulence phenotypes of B. lactucae. Further application of the methods of numerical taxonomy to phytopathology is briefly discussed.
Transmission of Bacterium Corynebacterium michiganense pv. michiganense by Seeds
Authors: Tsiantos J.
Published: May 2008

The results of experiments on transmission of Corynebacterium michiganense pv. michiganense showed that the spread of the bacterium by artificially infested seeds varies, but it was confirmed that from artificially infested seeds few diseased plants can be grown. The results depend on the environmental conditions during experimentation and the method of assaying the seedlings. High relative humidity favours the spread of the pathogen. The use of selective media helped the detection ofthe pathogen in seemingly healthy plants. It was proved that host can have population of C. michiganense pv. michiganense in a resident phase. It is assumed that when conditions are favorable the pathogen multiplies and cause disease.
Occurrence of Mycoplasma‐like Organisms in Parenchyma Cells of Cuscuta odorata (Ruiz et Pav.)
Authors: Siller W. , Kuhbandner B. , Marwitz R. , Petzold H. , Seemüller E.
Published: May 2008

In shoots of the dodder Cuscuta odorata mycoplasma‐like organisms (MLO) were observed to occur in nearly all mature sieve elements. Their frequency within the sieve elements varied from a few organisms to high concentrations. In addition, MLO, were found in other cell types. By identifying these cells and investigating the location in the vascular tissue three different types of cells infected with MLO could be distinguished: (1) phloem parenchyma cells, (2) parenchyma cells separating the five vascular bundles of C. odorata and (3) cells in the outer region of the vascular system next to the cells looking like an endodermis. Within the cells of the types 2 and 3, MLO occurred in large numbers and at different morphological structures., Therefore, we assume that the MLO multiply in these cells.
Non‐Reciprocity of the Serological Relationship Between the Italian III Strain and Other Strains of Tobacco Mild Green Mosaic Virus
Authors: Wetter C. , Altschuh D.
Published: May 2008

The Italian III strain (It III) of tobacco mild green mosaic virus (TMGMV) could not be distinguished from other strains of TMGMV using three antisera to this strain in precipitin, immunodiffusion gel tests, and ELISA. Antisera to the strains U2, PTMV, G‐TAMV, and type TMGMV, however, were able to differentiate these strains from It III strain. The non‐reciprocity of the serological relationship may be explained by assuming that It III lacks a specific epitope that the other strains have or that the, corresponding region in It III is not immunogenic.
Arachidonic and Linoleic Acids Elicit Isoflavonoid Phytoalexin Accumulation in Phaseolus vulgaris (French bean)
Authors: Longland Annette C. , Slusarenko A. J. , Friend J.
Published: May 2008

Arachidonic and linoleic, but not α‐linolenic or γ‐linolenic acids, induced necrosis and the accumulation of isoflavonoid phytoalexins in leaves of French bean (Phaseolus vulgaris L.) cv. ‘Red Mexican'. The levels of phytoalexins which accumulated were similar to those found in an incompatible interaction between cv. ‘Red Mexican’and an avirulent race 1 isolate of Pseudomonas syringae pv. phaseolicola. Maximum amounts of phytoalexins accumulated in response to 1.6 mM fattyacids, as opposed to 3.3 or 0.6 mM. The most severe tissue necrosis was not accompanied by the highest levels of phytoalexin accumulation. In contrast to leaves, only trace amounts of phytoalexins were elicited in hypocotyls. The possible significance of, these results is discussed in terms of mechanisms leading to plant cell death and phytoalexin accumulation.