bluuebunny/crossref_metadata_2025 huggingface dataset:
Secretion of Extracellular Enzymes by Verticillium psalliotae Treschow and Verticillium lecanii (Zimm.) Viégas During Growth on Uredospores of the Soybean Rust Fungus (Phakopsora pachyrhizi Syd.) in Liquid Cultures
Authors: Saksirirat W. , Hoppe H.‐H.
Published: May 2008

Two isolates of the mycoparasite Verticillium psalliotae grew rapidly in liquid cultures on autoclaved uredospores of the soybean rust fungus (Phakopsora pachyrhizi Syd.) as sole carbon source and secreted β‐l,3‐glucanase, chitinase, and protease activities into the medium. One isolate of Verticillium lecanii grew slowly, failed to produce measurable chitinase activity and secreted lower specific activities of β‐l,3‐glucanase and protease, compared with V. psalliotae. The tested isolates of V. psalliotae and V. lecanii produced comparable levels of lipolytic activity. Amylolytic activity was secreted by V. lecanii but not by V. psalliotae. The isolates of V. psalliotae and V. lecanii used in our experiments differed clearly in protein and protease pattern, determined by electrophoresis on polyacrylamide gels. The results indicate that the rapid growth of V. psalliotae on autoclaved uredospores in liquid culture and on uredosori is probably based primarily on nutrients made available to the mycoparasite by activities of β‐1,3‐glucanases, chitinases and proteases.
The Discovery of Belladonna Mottle Virus in Czechoslovakia and its Comparison with a Hungarian Isolate of this Virus
Authors: Pelikánová J. , Petrzik K. , Honetšlegrová J.
Published: May 2008

Belladonna mottle virus (BMV) was found in Czechoslovakia in spontaneously infected deadly nightshade Atropa bella‐donna L. The Czechoslovakian isolate of BMV is serologically distinct from the Hungarian, but host range, symptomatology and particle morphology of both isolates are identical. Sinapis alba L. and Chenopodium murale L. are described as new host plants susceptible to BMV.

Die Entdeckung des belladonna mottle virus in der Tschechoslowakei und dessen Vergleich mit einem aus Ungarn stammenden Isolat

Das belladonna mottle virus (BMV) wurde in spontan infizierter Tollkirsche Atropa belladonna L. in der Tschechoslowakei gefunden. Das tschechoslowakische BMV‐Isolat unterscheidet sich serologisch von dem ungarischen Isolat, jedoch sind beide Isolate beim Wirtsspektrum, der Symptomologie und Partikelmorphologie identisch. Sinapis alba L. und Chenopodium murale L. sind als neue Wirtspflanzen des BMV beschrieben.
N Protein of Festuca Leaf Streak Virus (Rhabdoviridae) Detected in Cytoplasmic Viroplasms by Immunogold Labelling
Authors: Lundsgaard T.
Published: May 2008

Ultrathin sections of plant tissue infected with Festuca leaf streak virus (FLSV) were treated with polyclonal antisera against the three major structural proteins, G, N, or M, followed by protein A‐gold labelling. At the periphery of viroplasms, comprising groups of virions, all three major structural proteins were detected. In the granular matrix of the cytoplasmic viroplasms only N protein was detected.

N‐Proteine des Festuca leaf streak virus (Rhabdoviridae) festgestellt in cytoplasmatischen Viroplasmen durch Immunogoldmarkierung

Ultradiinne Schnitte von Pflanzengewebe, das mit Festuca leaf streak virus (FLSV) infiziert war, wurden mit polyklonalen Antisera gegen die drei Hauptstrukturproteine (G, N oder M) behandelt und anschließend einer Protein‐A‐Goldmarkierung unterzogen. Am Rand von Viroplasmen, die aus Viriongruppen bestanden, wurden alle drei Hauptstrukturproteine festgestellt. In der granulierten Matrix der cytoplasmatischen Viroplasmen wurde nur das N‐Protein ermittelt.
Relationship between Maize Stubble Placement in Soil and Survival of Stenocarpella maydis (Diplodia maydis)
Authors: Flett B. C. , Wehner F. C. , Smith Marie F.
Published: May 2008

Survival of and pycnidium production by Stenocarpella maydis in artificially infected maize stalk stubble placed on, half buried into, and buried in the soil were determined in field trials over a nine month period. Survival was higher in stubble which remained on the soil surface than in buried stubble. Pycnidial development increased on surface and buried stubble from September onwards, but subsequently decreased on buried stubble. Conidia retrieved from the variously positioned stubble segments did not vary in viability. More pycnidia were produced over an eleven month period on naturally infected stubble retrieved from the soil surface than from in soil. Reisolation and conidium viability of S. maydis from the surface stubble were higher than from buried stubble.

Der Zusammenhang zwischen der Lage des Maisstoppels im Boden und dem Überleben von Stenocarpella maydis (Diplodia maydis)

Über eìnen Zeitraum von 9 Monaten wurde das Überleben und die Pyknidienproduktion von Stenocarpella maydis in künstlich inokulierten Maisstoppeln unter Feldbedingungen beobachtet. Die inokulierten Stoppeln wurden auf dem Boden, zur Hälfte oder ganz im Boden plaziert. Die höchste Überlebensrate wurde in den Stoppeln, die auf der Bodenoberfläche lagen, festgestellt. Die Entwicklung von Pyknidien erhöhte sich an den Stoppeln ab September, unabhängig von der Lagerung, bei den begrabenen Stoppeln wurde jedoch ein Rückgang der Pykinidienentwicklung zu einem späteren Zeitpunkt beobachtet. Die Viabilität der Konidien alier Stoppeln war gleich. Mit natürlich befallenen Stoppeln wurde eine höhere Anzahl von Pyknidien über eine 11monatige Periode von den Stoppelstücken gewonnen, die von der Bodenoberfläche aufgelesen worden waren, als von denen, die in der Erde begraben waren. Außerdem war die Reisolierung und Konidienviabilität bei den von der Oberfläche stammenden Stoppelstücken höher als von den begrabenen.
An Extended Progeny/Parent Ratio Model II. Application to Experimental Data
Authors: Gessler C. , Blaise Ph.
Published: May 2008

A previously published model based on Vanderplank's progeny/parent ratio equation was tested using “Epiphyt”, its implementation on a microcomputer, with four sets of published epidemiological data and one set of data collected in a vineyard in Switzerland. The epidemics tested were of the diseases stripe rust and Septoria leaf blotch on wheat, apple scab, and downy and powdery mildew on grapes. The disease progress curves simulated by the model reflected the epidemics in their most important stages except for the termination phase of each epidemic. Advantages of such a model based solely on the parameters initial inoculum, daily progeny/parent ratio and length of latent period, are discussed.

Ein erweitertes Nachkommen‐/Eltern‐Modell: Anwendung an experimentelle Daten

Ein früher publiziertes Modell basierend auf Vanderplanks’ Nachkommen‐/Eltem‐Gleichung wurde getestet. Dazu wurde die Implementation des Modells auf Mikrocomputer, “Epiphyt”, sowie vier Datensets aus der Literatur und ein Datenset aus einem Rebberg in der Schweiz verwendet. Epidemien der folgenden Krankheiten wurden getestet: Gelbrost und Septoriose auf Weizen, Apfeischorf, falscher und echter Mehltau auf Reben. Die durch das Modell simidierten Epidemiekurven widerspiegelten die Epidemien in ihren wichtigsten Phasen außer der abfkchenden Endphase der Krankheitsausbreitung. Die Vorteile eines sokhea Modells, wekhes nur auf den drei Parametem Anfangsinokulum, tägliche Nachkommen‐/Eltem‐Rate und Länge der Latenzperiode berukt, werden diskutiert.
Changes in Xanthine Oxidase Activity in Bean Leaves Induced by Uromyces phaseoli Infection
Authors: Montalbini P.
Published: May 2008

A superoxide‐producing xanthine‐oxidizing enzyme characterized by NADH‐diaphorase activity, presumably a type O xanthine oxidase (EC 1.2.3.2), was isolated and quantified after polyacrylamide disc gel electrophoresis of crude leaf extract of Phaseolus vulgaris L. This enzyme was enhanced by Uromyces phaseoli (Pers.) Wint. infection in hypersensitive leaves (cvs K.W. 765, Olathe, CSW 643 and 51051) during the first phase of host‐pathogen interaction (values around 2 times the control at 1–2 days post‐inoculation) and necrotic lesion formation (values up to 5.5 times the control in cv. K.W. 765). In contrast, there were no early increases in xanthine oxidase in susceptible cvs Golden Gate Wax, Bountiful and Pinto HI, which instead showed a considerable drop in xanthine oxidase starting A–5 days post‐inoculation, the time when subepidermic fungal stroma structure (flecks) began to differentiate in the mesophyll.

This paper examines the possibility that xanthine oxidase of bean leaves, owing to its superoxide‐producing activity, may somehow be involved in the hypersensitive cell death associated to the incompatibility between Phaseolus vulgaris and Uromyces phaseoli.

Veränderungen in der Xanthinoxidase‐Aktivität in Bohnenblättern induziert durch eine Uromyces phaseoli‐lnfektion

Ein superoxidproduzierendes, xanthinoxidierendes Enzym, das durch eine NADH‐Diaphorase‐Aktivität charakterisiert war, vermutlich eine Typ O‐Xanthinoxidase (EC 1.2.3.2), wurde isoliert und quantifiziert nach der Polyacrylamidelektrophorese von ungereinigten Phaseolus vulgaris L.‐Blattextrakt. Dieses Enzym wurde durch eine Uromyces phaseoli‐lniektion von hypersensitiven Blättem (Sorten K.W. 765, Olathe, CSW 643 und 51051) während der ersten Phase der WirtPathogen‐Wechselwirkung (1–2 Tage nach der Inokulation lagen die Werte zirka doppeh so hoch wie die der Kontroiie) und der nekrotischen Läsionenbildung (Werte bis zu 5,5inal so hoch wie die der Kontrolle bei der Sone K.W. 765). Im Gegensatz dazu wurden frühe Steigerungen der Xanthin‐oxidase bei den anfälligen Sorten Golden Gate Wax, Bountiful und Pinto 111 nicht ermittelt, sondern eine erhebliche Abnahme der Xanthinoxidase 4–5 Tage nach der Inokulation festgestellt. Zur gleichen Zeit wurde eine weitere Entwicklung der subepidermalen pilzlichen Stromastruktur (als Flecken zu bezeichnen) im Mesophyll beobachtet.

Diese Arbeit untersuchte die Wahrscheinlichkeit, daß es einen Zusammenhang zwischen der Xanthinoxidase in Bohnenblättern durch ihre superoxidproduzierende Aktivität, und dem hypersensitiven Zellsterben, das mit der Unverträglichkeit zwischen P. vulgaris und U. phaseoli assoziiert ist, gibt.
Ozone Effects on Fungal Leaf Diseases of Wheat in Relation to Epidemiology
Authors: Tiedemann A. v.
Published: May 2008

Wheat plants at growth stages tillering, stem elongation, ear emergence and anthesis were exposed to 80, 160, 240 μg m−3 ozone for 5 days (7 h per day) and to charcoal‐filtered air. Post‐exposure inoculations with Septoria nodorum or Bipolaris sorokiniana revealed a faster growth of lesions on ozonated leaves. However, whereas maximum size of Septoria lesions was measured on leaves exposed to the highest concentration of O3, Bipolaris lesions developed best at 160 μg m−2 and were significantly reduced at 240 μg m−3 O3. These predisposing effects were largely independent of the four growth stages tested. The latent period of S. nodorum was inversely related to the lesion growth and particularly shortened by ozone at growth stages (GS) 37 and 55. The latent period of B. sorokiniana was most strongly shortened at GS 65 (anthesis). It is concluded that both diseases may be enhanced by ozone throughout the main growing season of wheat and that in particular S. nodorum epidemics may be accelerated by shortened latent periods at decisive stages of the early season.

Ozonwirkung auf pilzliche Blattkrankheiten an Weizen in bezug zur Epidemiologie I. Nekrotrophe Pathogene

Weizenpflanzen im Stadium Bestockung, Schossen, Ährenschieben und Blüte wurden mit 80, 160, 240 μg m−3 Ozon 5 Tage lang begast (7 Stunden täglich) bzw. aktivkohlegefilteiter Luft ausgesetzt. Nach anschließender Inokulation mit Septoria nodorum und Bipolaris sorokiniana, entstanden auf ozonbehandelten Blättern größere Läsionen. Während jedoch bei Septoria die größten Läsionen bei der höchsten Ozonkonzentration entstanden, war dies bei Bipolaris bei 160 μg m−3 der Fall, während sich bei 240 μg m−3 Ozon die Pilzläsionen deutlich schlechter entwickelten. Diese ozonbedingten Prädispositionseffekte konnten weitgehend in alien Entwicklungsstadien reproduziert werden. Die Latenzzeit von S. nodorum verhielt sich umgekehrt proportional zum Läsionenwachstum und war besonders stark bei EC 37 und EC 55 durch Ozon verkürzt. Bei B. sorokiniana war die Latenzzeit am stärksten bei EC 65 verkürzt. Es wird gefolgert, daß beide Krankheiten während der gesamten Hauptvegetationsperiode durch Ozon gefördert werden können, wobei der Epidemieaufbau insbesondere bei Septoria schon frühzeitig durch verkürzte Latenzzeiten beschleunigt werden kann.
Effects of Low Temperature on Stress Ethylene Biosynthesis in Soybean Hypersensitively Responding to Tobacco Necrosis Virus
Authors: Pennazio S. , Roggero P.
Published: May 2008

The hypersensitive reaction to tobacco necrosis virus in soybean plants grown at 10°C, when compared with that of non‐chilled plants (see Pennazio and Roggero, 1990 a, b), was characterized by (1) delayed appearance of necrotic local lesions, (2) smaller size of lesions, and (3) viability of the inoculated leaves. The content of virus antigen accumulated in the lesions was, however, unchanged. Chilling did not affect the biosynthetic pathway of stress ethylene, but did affect the kinetics of ethylene release. No burst of stress ethylene, followed by a rapid decline, was found, but ethylene production gradually increased up to moderate values, which were maintained for several days. This finding may explain the abolition, at 10°C, of the leaf fall occurring in non‐chilled conditions. Free ACC accumulation and stress ethylene release occurred 24 h before appearance of visible necrotic pin point lesions. EFE activity was, however, stimulated only in later stages of pathogenesis.

Stress ethylene release did not affect virus multiplication, nor was it considered a cause of the observed restriction of virus spread, which may have been an effect of the low temperature on the cell‐to‐cell virus transport mechanism.

Einfluß von niedrigen Temperaturen auf die Streß‐Äthylenbiosynthese in Sojabohnen bei einer hypersensitiven Reaktion gegen das tobacco necrosis virus

Die hypersensitive Reaktion gegen das tobacco necrosis virus in Sojabohnenpflanzen, die bei 10°C kultiviert worden waren, wurde mit der Reaktion bei nicht gekühlten Pflanzen verglichen (s. Pennazio and Roggero 1990 a, b). Die Reaktion der gekühlten Pflanzoa war charakterisiert durch: 1. die nekrotischea Läsionen erschienen spater, 2. die Läsionen waren kleiner, und 3. die unterschiedliche Viabilität der inokulierten Blätter. Der Gehalt an Virusantigen, das sich in den Läsionen akkumuliert, blieb jedoch unverändert. Eine Kühlung beeinflußt den biosynthetischen Weg des Streß‐Äthylens nicht, jedoch die Kinetik der Äthylenfreilassung. Es gab keinen plötzlichen Anstieg von Streß‐Äthylen, der von einer schnellen Abnahme verfolgt wurde, sondern es stieg die Äthylenproduktion allmählich an, bis maßige Werte erreicht wurden, die über einige Tage hinweg erhalten blieben. Diese Ergebnisse könnten eine Erklärung dafür sein, daß ein Abwerfen der Blätter unter nicht gekühlten Bedingungen bei den gekühlten Pflanzen nicht beobachtet wurde. Eine freie ACC‐Akkumulation und eine Streß‐Äthylenfreilassung konnte, 24 h bevor makroskopisch sichtbare, nadelpunktgroße nekrotische Läsionen zu erkennen waren, festgestellt werden. Die EFE‐Aktivität war jedoch erst zu einem späteren Zeitpunkt der Pathogenese angeregt.

Die Freilassung vom Streß‐Äthylen beeinflußt die Virusvermehrung nicht, dessen Beteiligung an der beobachteten Einschränkung der Virusverteilung wurde auch nicht vermutet. Diese Beobachtung könnte mit dem Einfluß der niedrigen Temperatur auf den Zelle zu Zelle Virustransportmechanismus gekoppelt sein.
Identification of Antagonists for Biological Control of the Post‐Harvest Pathogens Pezicula malicorticis and Nectria galligena on Apples
Authors: Schiewe A. , Mendgen K.
Published: May 2008

More than 700 isolates of microorganisms occurring naturally on apple trees and fruits during the growing season and on stored fruits were collected. The isolates were screened in vitro and in vivo for antagonistic activity against the post‐harvest pathogens Pezicula malicorticis Qacks.) Nannf. and Nectria galligena Bres. In agar cultures, 50 of these microorganisms were found to be antagonistic against one or both of the pathogens. On apple fruits, inoculated with the pathogens, four bacterial and three fungal isolates were able to reduce lesion development at 20 °C. At 4 °C, however, these isolates had little effect on lesion growth. Only culture filtrates from the fungal isolate 725 reduced lesion growth of both pathogens at 20 °C and of Pezicula malicorticis at 4 °C.

Identifizierung von Antagonisten zur biologischen Kontrolle der Lagerfäujniserreger Pezicula malicorticis (Jacks.) Nannf. und Nectria galligena Bres. auf Äpfeln

Über 700 natürlich vorkommende Mikroorganismen wurden während der Vegeutionsperiode von Apfelbäumen und Früchten und im Winter von gelagerten Äpfeln isoliert. Die Isolate wurden in vitro und in vivo auf antagonistische Aktivität gegenüber den Lagerfäulniserregern Pezicula malicorticis (Jacks.) Nannf. und Nectria galligena Bres. untersucht. 50 dieser Mikroorganismen waxen in Petrischalen‐Tests antagonistisch gegenüber einem der Pathogene oder gegenüber beiden. Auf Äpfeln reduzierten vier Bakterienisolate und drei Pilzisolate die Faulstellenentwicklung der Erreger bei 20°C. Der Einsatz der Isolate bei 4°C hatte jedoch keinen oder nur geringen Einfluß auf die Läsionsentwicklung. Nur das Kulturfiltrat des Pilzisolats 725 reduzierte die Fauistellenentwicklung beider Pathogene bei 20°C und die von Pezicula malicortkis auch bei 4°C.
Biological Seed Treatment of Corn with Mycopathogenic Fungi
Authors: Vakili Nader G.
Published: May 2008

Mycopathogenic fungi, Exobasidiellum sp., Gliocladium roseum, Gonatobotrys simplex, Sphaeronaemella helvellae, and Trichothedum roseum were tested and selected for their efficacy as biocontrol agents of seed‐ and soil‐borne fungi colonizing corn (Zea mays) kernels, and for their interaction with different corn genotypes. Kernels of inbred corn lines were coated with conidial suspension of mycopathogens and germinated in seed germinators and greenhouse bench sand. Treatment with mycopathogens increased germination and seedling dry weight, reduced colonization of germinated kernels by seed‐ and soil‐borne fungi, reduced infection of seedlings by pathogenic fungi and resulted in interaction with corn genotype. Gliocladium roseum was the most effective biocontrol agent of corn seed in this study.

Biologische Beizung von Maiskörnern mit mykopathogenen Pilzen

Die mykopathogenen Pilzarten Exobasidiellum sp., Gliocladium roseum, Gonatobotrys simplex, Sphaeronaemella helvellae und Trichothedum roseum wurden auf ihre Wirksamkeit als biologische Bekämpfungsagens gegen samen‐ und bodenbiirtige Pilzarten, die Mais‐(Zea mays)Körner besiedeln, untersucht und selektiert; außerdem wurde ihre Wechselwirkung mit unterschiedlichen Maisgenotypen geprüft. Die Samen von Inzuchtmaislinien wurden mit Suspensionen der Mykopathogenkonidien gebeizt und in Samenkeimungskammem bzw. in Sand zum Keimen gelegt. Eine Behandlung mit den Mykopathogenen erhohte die Keimuiigsrate und das Sämlingstrockengewicht, eine Besiedlung der gekeimten Körner durch samen‐ und bodenbürtige Pilzarten wurde vermindert, eine Infektion der Sälinge durch pathogene Pilze wurde reduziert, tuid hatte eine Wechselwirkung mit dem Maisgenotyp zur Folge. In dieser Untersuchung wurde G. roseum als wirksamstes sches Bekämpfungsagens von Maiskornern eingestuft.
Origin and Proportions of the Components of Composite Populations of Erysiphe graminis f. sp. hordei
Authors: Andrivon D. , Limpert E.
Published: May 2008

Comparisons of the pathotype composition in random samples of barley mildew populations collected in 1985 and 1986 in several European regions were made in an attempt to quantify the influence of migration on population structures. In each of the situations studied (northern France 1986 and eastern Lower Austria 1985 and 1986), evidence was obtained from influx of spores from at least two remote areas. Depending on year and location, 48 to 87 % of the resulting composite samples consisted of ‘foreign‐type’ isolates. Implication of long‐distance dispersal for studies on population dynamics and for control strategies relative to mildews and other wind‐spread pathogens are discussed.
In vitro Degradation of Cell Walls of Apple Leaves by Pectinolytic Enzymes of the Scab Fungus, Venturia inaequalis, and by Commercial Pectinolytic and Cellulolytic Enzyme Preparations
Authors: Valsangiacomo C. , Ruckstuhl M. , Gessler C.
Published: May 2008

A new method involving 14C‐labelled cell walls of apple leaves was developed in order to study the process of cell wall degradation in vitro and its role in pathogenesis and host‐resistance. 14C‐labelled cell walls were efficiently digested by commercial enzyme preparations and less efficiently by the polygalacturonase of Venturia inaequalis, the causal agent of apple scab. Further, degradability of cell walls from a susceptible and a resistant variety were compared, but there was no evidence for a correlation of reduced degradability with resistance. The method presented here can be regarded as a useful tool for investigations where enzymatic processes of polymerization or depolymerization of plant material is involved.
Etiology and Transmission of Sesame Phyllody in Iran
Authors: Salehi M. , Izadpanah K.
Published: May 2008

Phyllody is a destructive disease of sesame (Sesamum indicum L.) in Iran. The major symptoms of the disease are floral virescence, phyllody and proliferation. Other symptoms which sometimes accompany the disease are yellowing, cracking of seed capsules, germination of seeds in the capsules and formation of dark exudates on the foliage. Light microscopy of hand‐cut sections of sesame and colza (Brassica napus L. cv. Oro) stems treated with Dienes' stain showed blue areas in the phloem region of phyllody infected plants. Mycoplasma‐like bodies were found in the sieve cells of infected sesame stems when thin sections were examined m an electron microscope. Sesame phyllody was successfully transmitted from sesame to sesame by grafting. Among various leafhoppers collected in sesame fields only Neoaliturus haematoceps transmitted the disease. This is the first report on the identification of a Mycoplasma‐like organism (MLO) as the cause of sesame phyllody and N. haematoceps as an MLO vector in Iran. In host range studies using the leafhopper vector, only B. napus cv. Oro, Lepidium sativum, Catharanthus roseus, Lactuca sp. and Portulaca oleracea, but not 17 other species, developed symptoms. The species of vector and host range of MLO indicate that sesame phyllody in Iran is different from that reported in India and Upper Volta.
An Isolate of Brome Mosaic Virus Specifically Supports the Replication of a Defective Form of its RNA 3
Authors: Huth W. , AnDerong Dr. , Breyel E. , Koenig Renate
Published: May 2008

In one German isolate of brome mosaic virus, a defective form of RNA 3 was detected in addition to intact RNA 3. It was propagated only in barley, but was lost in Chenopodium quinoa and depended for its replication on the RNAs of the virus isolate from which it was derived. It did not induce any change of the symptoms produced in barley.
Mechanical Transmission of Barley Mild Mosaic Virus (BaMMV) to Rye (Secale cereale L.)
Authors: Ordon F. , Huth W. , Friedt W.
Published: May 2008

After mechanical spraygun inoculation barley mild mosaic virus (BaMMV) was detected in barley cv. ‘Gerbel’ (control) as well as in rye cv. ‘Somro’, but not in wheat cv. ‘Kanzler’ and oat cv. ‘Alfred’. ELISA values of infected barley and rye were similar. Furthermore, infected rye plants developed symptoms typical for barley yellow mosaic virus infection.
Resistance Against Drechslera teres (Sacc.) Shoem. in Progenies of in vitro Selected Callus Derived Plants of Barley (Hordeum vulgare L.)
Authors: Hunold R. , Hartleb H. , Afanasenko O. S.
Published: May 2008

Immature embryo derived callus cultures of barley were selected in vitro against a toxin (culture filtrate‐methanol supernatant) produced by Drechslera teres. Both S1 and S2 progenies of regenerated plants (selected by toxin application and non‐selected ones) were tested for their toxin tolerance and disease resistance. For this purpose, it was possible to use different culture filtrates and pathogen isolates, produced and maintained at two phytopathological institutes. Twelve out of 26 S2 progenies examined had a significantly reduced toxin sensitivity in comparison to the donor. Nine of these genotypes also expressed an isolate‐dependent improvement of their disease resistance. At the level of individual plants, 9 progenies showed a correlation between toxm tolerance and resistance against the pathogen. Somaclonal variation in reactions of non‐selected regenerated plants occurred. A mutagen treatment increased the number of toxin tolerant plants within s, progenies, and segregation took place for this trait.
Characterization of Peanut Stripe Virus Isolates from Soybean in Taiwan
Authors: Vetten H. J. , Green S. K. , Lesemann D.‐E.
Published: May 2008

Potyvirus isolates were obtained in Taiwan from soybean showing crinkle, mottle, mosaic or blistering. They were identified as peanut stripe virus (PStV) on the basis of host range, serology, molecular weight of the capsid proteins and morphology of cytoplasmic cylindrical inclusions. PStV was found to be closely related serologically to adzuki bean mosaic virus (AzMV), blackeye cowpea mosaic virus (BICMV), and the bean common mosaic virus (BCMV) strain NY 15. A clear differentiation of PStV from these related viruses was possible on the basis of the cylindrical inclusion morphology. Only the peanut isolate of PStV from the USA and the three soybean isolates of PStV from Taiwan produced pinwheels, scrolls and curved laminated aggregates whereas the other serologically related viruses produced scrolls only. Whilst the peanut isolate of PStV infected all nine peanut cvs tested, the soybean isolate PN of PStV infected two peanut cvs only. AzMV, BICMV and two strains of soybean mosaic virus did not infect any of the peanut cultivars tested. On the other hand, nineteen and three of the 27 soybean cvs were susceptible to the soybean isolate PN and the peanut isolate of PStV, respectively. The capsid proteins of the peanut and the three soybean isolates of PStV and of AzMV appeared to be proteolytically undegraded and to have nearly identical molecular weights of 35 kD. Based upon results of virus surveys in soybean plantings in Taiwan, the incidence of soybean isolates of PStV in soybean is similar to that of soybean mosaic virus, suggesting that these PStV strains might be economically significant to soybean production m Taiwan.
The Inhibition of Rust Fungus Growth in Allopurinol‐Treated Bean Plants: Indirect Evidence for the Involvement of Xanthine Oxidoreductase in the Biotrophism of Uromyces phaseoli
Authors: Montalbini P.
Published: May 2008

Allopurinol [4‐hydroxypyrazolo(3,4‐d)pyrimidine], a specific, potent inhibitor of xanthine oxidoreductase, effective in vitro and in vivo, was applied to bean plants as soil drench at a 400 μM concentration 8–10 days before inoculation and strongly reduced the development of Uromyces phaseoli in bean leaves. Allopurinol was ineffective on uredospore germination, presumably due to the absence of any xanthine oxidoreductase activity in the extract of germinated uredospores. The concentration of allopurinol used for the treatment did not significantly influence the level of ureides in leaves mainly because low concentration of these compounds were found in leaves and also probably because allopurinol‐insensitive biosynthetic route/s of these compounds are active in bean plants. This paper examines the possibility that host xanthine oxidase is in some way involved in the biotrophic nutritional process leading to the growth of bean rust fungus.
A New Phytotoxic Activity of the Cyclic Peptides Tentoxin and Dihydrotentoxin
Authors: Liebermann B. , Kölblin R.
Published: May 2008

Extracts of culture filtrate of the phytopathogenic fungus Alternaria alternata (Fries) Keissler cause distinct wilting of cuts of the problem weed Galium aparine L. We were able to demonstrate that the cyclic tetrapeptides tentoxin and dihydrotentoxin were reponsible for this effect. A tentoxin derivative, isolated from the culture filtrate, shows a similar, but stronger wilting activity.
Enzymes Associated with Defence against Toxic Oxygen Species in PCNB‐Tolerant and Sensitive Soil Fungi
Authors: Ephraim Cohen Prof. , Teomi Shoshana
Published: May 2008

The specific activities of enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPOX) and glutathione reductase (GR), which are involved in protection against toxic species of oxygen, were determined in mycelia extracts of pentachloronitrobenzene (PCNB)‐tolerant and susceptible soil fungi. The organisms assayed were the highly PCNB‐sensitive Rhizoctonia solani and Rhizopus arrhizus; Sclerotium rolfsii and Trichoderma harzianum, which are moderately susceptible to PCNB, and the fungicide‐tolerant Fusarium oxysporum f. sp. melonis and Pythium aphanidermatum. No GPOX activity was detected in the six examined fungi. Significant differences in the specific activities of the other enzyme systems among the fungi were evident. Remarkably low levels of CAT activities were measured in R. solani. Except for T. harzianum, no meaningful differences regarding SOD, CAT and GR activities with age of the fungi cultures were observed. The electrophoretic patterns of SOD and CAT displayed dissimilarities among the fungi under study. P. aphanidermatum is more polymorphic with respect to both SOD and CAT enzyme systems as compared to the other fungi. The SOD of F. oxysporum f. sp. melonis, R. arrhizus and T. harzianum is a cuprozinc enzyme, while the mangano‐SOD species was detected in S. rolfsii, R. solani and T. harzianum.
Antagonistic Activities of Trichoderma harzianum Against Pythium aphanidermatum and Pythium myriotylum on Tobacco
Authors: Devaki N. S. , Shankara Bhat S. , Bhat S. G. , Manjunatha K. R.
Published: May 2008

Trichoderma harzianum rendered Pythium aphanidermatum and P. myriotylum non‐viable in Petri dish dual culture. The Pythium mycelia from such cultures showed natural autofluorescence in the regions of interactions, indicating their death. Non‐volatile and volatile fungicidal activities were detected in T. harzianum culture. Lytic activity of β‐(l,3)‐glucanase was detected on the cell walls of the Pythium spp. There was a significant decrease in the disease incidence when T. harzianum was incorporated into sterile soil, whereas the effect was insignificant in natural soil.
Rapid Development of Resistance of Wounds on Immature Apricot Fruit to Infection with Monilinia fructicola
Authors: Wade G. C. , Cruickshank R. H.
Published: May 2008

Cleanly cut wounds on the surface of green apricot fruit are susceptible to infection with Monilinia fructicola when freshly made, but rapidly become resistant over 6 h. This was shown to be strongly correlated with the concentration of free nutrients, particularly sugars, which remain on the surface of the wound. Nutrients were rapidly removed by diffusion and absorption by underlying living cells. This is proposed as the basis of resistance which develops rapidly as the wounds age.

Structural and chemical barriers to infection, such as periderm, suberin and phenolic compounds, developed long after the wounds had become resistant.
Interspecific Hybrids between Fusarium oxysporum lycopersici and Fusarium graminearum by Mycelial Anastomoses
Authors: Madhosingh Clarence
Published: May 2008

Fusarium oxysporum lycopersici (FOL) and F. graminearum (FG) developed mycostatin (M) and cycloheximide (C) resistant mutants (FOL[M] and FG[C]) after treatment with nitrosoguanidine. Four hybrids, obtained from hyphal anastomoses between the mutants, were isolated from medium containing both mycostatin and cycloheximide at concentrations which did not permit growth of the mutants or the original parents. Both the mutants and the interspecies hybrids (ISH) derived from them expressed significant differences in pathogenicity to tomato and wheat from that expressed by the parents FOL and FG. Protein, esterase, pectinase and polyphenoloxidase electrophoretograms displayed unique patterns for the hybrids and the mutant parents. However, these patterns did not correlate with the pathogenicity expressions obtained. The study has demonstrated interspecies hybridizations between FOL(M) and FG(C) by hyphal anastomoses. Both the processes of mutation and hybridization altered the expression of pathogenicity in tomato and wheat The significance of these observations on the origin and development of new pathogenic forms is discussed.
A Detached Cotyledon Test for the Isolation of Mutants of Pyrenopeziza brassicae Defective in Pathogenicity Determinants
Authors: Ball A. M. , Ingram D. S. , Johnstone K.
Published: May 2008

A detached cotyledon pathogenicity test was devised for the isolation of UV‐induced mutants of the hemibiotrophie ascomycete pathogen of Brassica spp., Pyrenopeziza brassicae defective in pathogenicity determinants. At least 95 % of cotyledons of suitable susceptible cultivars of oilseed rape (Brassica napus L. ssp. oleifera cvs Shogun or Bolko) showed symptoms of disease (white spore pustules [conidiomata] on the surface of the cotyledon) within three weeks of inoculation of cotyledons with 104 conidia of P. brassicae. The test allowed rapid screening of UV‐induced mutants with a low frequency of false negatives. From 1,700 survivors of UV mutagenesis tested, 20 non‐pathogenic mutants were obtained.
Cell‐free Translation of Potyviral RNA Including Extracts from Disease Resistant Soybean
Authors: Mansky L. M. , Durand D. P. , Hill J. H.
Published: May 2008

Cell‐free translation of soybean mosaic virus (SMV), strain G2 or G7, RNAs in the presence of fractionated leaf extracts from the cultivars Davis or Williams‘82 revealed no differences that were associated with disease resistance of the cultivars to the virus strains. Extracts of leaf tissue from Davis (resistant to strain G2) and susceptible Williams‘82 were fractionated into three broad peaks. Apparent proteinase activity was detected in peak II of both soybean cultivars in the cell‐free translation of SMV‐G2 or ‐G7 RNAs. Inhibition of translation occurred in the presence of peak extracts from either of the soybean cultivars at levels of 500 μ/ml and/or 1000 μ/ml of protein. No inhibition of proteolytic processing was observed by extracts from either cultivar.
Antibacterial Activity of Tea and Coffee Wastes Against Some Plant Pathogenic Pseudomonas syringae Strains
Authors: Alström Sadhna
Published: May 2008

In vitro and greenhouse trials were conducted to elucidate the potential use of extracts of tea and coffee wastes to control plant diseases caused by the bacterial pathogens, Pseudomonas syringae pv. pisi (race 1 and 2) and P. s. pv. phaseolicola (race 1). The antibacterial activity was measured as the diameter of the inhibition zone in agar and also by periodical viable cell counts in laboratory tests. The effect on the hypersensitive reaction and the potential for disease control after leaf infiltration and seed treatment were studied on bean plants in the greenhouse. Results showed that both the tea and coffee extracts possessed antibacterial activity against the three pathogens, but that the effects varied depending on the strain and the test method. Strong reduction of halo blight disease and improvement in plant growth was obtained in presence of the coffee extract. For the halo blight pathogen, P. s. pv. phaseolicola, there was a good correlation between the results from the viable cell count method and the greenhouse tests, but the results from the in vitro studies did not agree with those from greenhouse as regards the P. s. pv. pisi strains. It is suggested that the component(s) in tea and coffee responsible for controlling the bean pathogen may not be the same as that for the pea pathogens.
Pathogenicity to Wheat of Isolates of Pseudocercosporella herpotrichoides (Fron) Deighton from Five Graminaceous Hosts
Authors: Kayser A. , Heitefuss R.
Published: May 2008

Eleven isolates of Pseudocercosporella herpotrichoides were obtained from field material of the Gramineae Agropyron repens, Alopecurus myosuroides, Apera spica‐venti, Hordeum vulgare and Triticum aestivum. Four of these isolates belonged to the variety acuformis and 7 isolates to the variety herpotrichoides of the fungus.

In a greenhouse experiment, winter wheat was inoculated with these isolates. All isolates were pathogenic on wheat. They differed in virulence, but these differences could not be related to the nature of their original hosts nor to their classification as variety acuformis or herpotrichoides.
Histopathology of Blackleg Development in Spring Rapeseed
Authors: Xi K. , Morrall R. A. A.
Published: May 2008

Hyphae of Leptosphaeria maculans were observed in all types of above‐ground tissue of two cultivars of Spring rapeseed plants exposed to natural infection. Large quantities of hyphae were distributed in the epidermis and cortex of the stem in symptomless plants at early growth stages, irrespective of resistance level of the cultivar. These results verified the extensive latent infection early in the season that had been detected by isolation in a previous study. Two types of hyphae occurred in plants: narrow hyphae (2.1 μm diam.) were usually found in symptomless plants at early growth stages, whereas thick hyphae (5.7 μm diam.) occurred in plants with symptoms as the late stages of growth. Resistance mechanisms were evidenced by the presence of heavily stained material and disintegration of the hyphae in cells of the resistant cultivar.
Purification and Some Properties of an Isolate of Beet Yellows Virus from Ukraine
Authors: Rogov V. V. , Karasev A. V. , Agranovsky A. A.
Published: May 2008

A purification procedure, which yielded up to 15–30 mg of beet yellows virus (BYV) per 100 g of infected Tetragonia expansa leaves, has been developed. The procedure included sap clarification with Triton X‐100, and two cycles of ultracentrifugation through sucrose cushion, which contained PEG‐6000 and NaCl. A specific antiserum was prepared, and BYV infection was successfully detected by the double‐antibody sandwich (DAS) ELISA in infected sugar beet leaves and roots diluted up to 1 × 105 and 1 × 104, respectively. The virus concentration was demonstrated to decrease in infected sugar beet roots slowly during 7 months, thus allowing successful diagnosis of planting material in winter storage. BYV presence in Myzus persicae aphids was also reliably detectable using the DAS‐ELISA. In a competitive DAS‐ELISA test, the Ukraine and the British BYV isolates were found serologically indistinguishable.
A Comparison of the Disease Reactions of Stems and Detached Leaves of Soil and in vitro Grown Plants and Regenerants of Oilseed Rape to Leptosphaeria maculans and Protocols for Selection for Novel Disease Resistance
Authors: Gretenkort Marie A. , Ingram D. S.
Published: May 2008

Protocols for selecting plant tissues of winter oilseed rape (Brassica napus subsp. oleifera) with resistance to Leptosphaeria maculans by either stem or leaf inoculation of both soil and in vitro grown plant material are described. The stem inoculation procedure gave good correlation (r = 0. 92) between the 50 day stem disease scores of eight out of nine cultivars of soil grown winter oilseed rape inoculated with isolate 41A4 of L. maculans and the N. A. B. esistance ratings or resistance data from field trials. The exception was the cultivar Liradonna. Inoculation of stems of five cultivars with isolates 41A4, 433 and 478 indicated a range of isolate virulence 478 > 41A4 > 433. This was the inverse of that observed in leaf inoculations. Application of the stem inoculation procedure to in vitro shoot cultures allowed differentiation of resistant and susceptible cultivars, including the cultivar Liradonna, after 20 days incubation at 20°C. The protocol was also applicable to plantlets regenerated from thin cell layer explants grown in vitro. Inoculations with isolate 433 allowed the differentiation of resistant, intermediately resistant and susceptible leaf material of soil grown plants, when leaf discs from young leaves were incubated on water agar supplemented with BAP (1 × 10−5 M) at 25°C for 10 days. Intermediately resistant leaves were resistant after 10 days and susceptible after 15 days of incubation. Leaves of shoot cultures grown in vitro were more susceptible than the corresponding soil grown material. However, inoculation of old leaves with isolate 41A4 (an isolate of less virulence on leaves than 433) distinguished the cultivars after 15 days of incubation. These protocols allow the accurate assessment of resistance to L. maculans at the stem or leaf level and are of use in traditional as well as in vitro selection programmes.
Incidence of White Mold and Yield of Upright Bean Grown in Different Planting Patterns
Authors: Saindon G. , Huang H. C. , Kozub G. C. , Mündel H. ‐H. , Kemp G. A.
Published: May 2008

The commercial dry bean (Phaseolus vulgaris L) production system in Alberta requires irrigation and the viny cultivars currently used in this production system are prone to outbreaks of white mold caused by Sclerotinia sderotiorum (Lib.) de Bary. The use of beans with an upright growth habit has potential for alleviating the disease problem, but the narrow profile of the upright beans may warrant a different planting pattern to achieve high yield. A study was undertaken to determine the effect of between‐ and within‐row spacings on the occurrence of white mold and seed yield of upright beans. An experimental navy bean composite with upright growth habit, and a susceptible control Red Mexican, UI 37, were evaluated using three between‐row (BR) and three within‐row (WR) spacings in presence or absence of white mold during a 2‐year period. The BR and WR spacings had no effect (P > 0. 05) on disease occurrence in the inoculated upright composite or in the viny control. Regardless of BR and WR spacings, the upright composite had less (P < 0. 01) disease than the control in both years. In general, large differences (P < 0. 05) were found between the upright composite and control spacing treatments in the presence or absence of white mold. BR spacing had a significant effect on seed yield, but WR spacing did not. In most cases, increasing plant density by reducing BR spacings resulted in higher seed yields. These findings suggest that producers may gain in seed yield without increasing risks for white mold occurrence by changing from viny to upright beans and planting in narrower rows.
Partial Resistance of Bell Pepper to Cucumber Mosaic Virus Movement within Plants: Field Evaluation of its Efficiency in Southern France
Authors: Nono‐Womdim R. , Palloix A. , Gébré‐Selassié K. , Marchoux G.
Published: May 2008

The spread of cucumber mosaic virus (CMV) was followed during three years in field plots of bell pepper varieties Yolo Wonder (susceptible) and Milord and Vania (partially resistant to CMV movement within plants). During the three test years, CMV spread was delayed 4 to 6 weeks in var. Milord and in var. Vania as compared to var. Yolo Wonder. Final CMV incidence and the apparent infection rate, the latter calculated from Van der Plank logistic analyses, were lower in var. Milord and in var. Vania than in var. Yolo Wonder. The resistance of var. Milord and var. Vania, expressed as a delay of spread and a reduced CMV incidence over the past three years, provides practical disease control.
Virus Resistance Induced with Mannan Sulphates in Hypersensitive Host Plants
Authors: Kovalenko A. G. , Grabina T. D. , Kolesnik L. V. , Didenko L. F. , Oleschenko L. T. , Olevinskaya Z. M. , Telegeeva T. A.
Published: May 2008

Mannan sulphates (MS), obtained by sulphatation of extracellular linear mannan (LM) from Rhodotorula rubra, induced resistance to tobacco mosaic virus (TMV) in hypersensitive plants, retained in isolated protoplasts. MS‐induced resistance in tobacco is accompanied by a marked increase of lytic processes in cells and a decrease of total (acidic and alkaline) protein content. In addition to this, new protein components, including PR‐proteins and antiviral substances, of the inhibitor of virus replication (IVR) type, appeared in treated plant tissues. MS‐induced resistance resembles localized resistance induced by TMV in hypersensitive tobacco plants and could serve as an experimental model for study of the latter.
The Natural Occurrence, Transmission, Properties and Possible Affinities of Cowpea Mild Mottle Virus
Authors: Jeyanandarajah Premala , Brunt Alan A.
Published: May 2008

Cowpea mild mottle virus (CMMV), although thought to be of only local importance when first found in 1973 infecting cowpeas (Vigna unguiculata) in Ghana, has since been shown to have a very extensive geographical distribution and a wide natural host range. It occurs in Africa, Asia, South America and Oceania in tomato (Lycopersicon esculenturri) and a range of leguminous crops including cowpeas, groundnuts (Arachis hypogaea, soybean (Glycine max) and French beans (Phaseolns vulgaris).

The virus has physico‐chemical properties resembling those of aphid‐borne carlaviruses; it has filamentous particles ca. 650 nm long which contain a single polypeptide of 31–33 KDa and single‐stranded RNA of 2. 5 × 106. Unlike carlaviruses, however, CMMV is transmitted in a non‐persistent manner by whiteflies (Bemisia tabaci) and the particles occur in vivo in characteristic brush‐like inclusions. It is also seed‐borne in some, but not all, cultivars of cowpea and soybean, but seed‐transmission is probably dependent upon the interaction of genotype, virus strain, time of infection and environmental factors.

CMMV is serologically closely related to, and thus probably synonymous with, viruses previously designated groundnut crinkle, Psophocarpus necrotic mosaic, Voandzeia mosaic and tomato pale chlorosis. It is, however, serologically unrelated to 18 recognized carlaviruses; because it is also transmitted by whiteflies and induces the formation of unusual brush‐like inclusions, it is probably best left unclassified or tentatively placed in a sub‐group of the carlavirus group until the taxonomic significance of these features has been fully evaluated.
Production of a Chlorosis‐Inducing, Host‐Specific, Low‐Molecular Weight Toxin by Isolates of Pyrenophora tritici‐repentis Cause of Tan Spot of Wheat
Authors: Brown D. A. , Hunger R. M.
Published: May 2008

An extraction procedure was developed to isolate toxin from cell‐free culture filtrates of Pyrenophora tritici‐repentis, cause of tan spot disease of wheat (Triticum aestivum). Designated Ptrtoxin, this low‐molecular weight toxin (MW 800–1800) induces the characteristic chlororis associated with tan spot disease when inoculated to healthy wheat leaves and differentially inhibits the elongation of wheat seedling coleoptiles. The sensitivity of seven wheat, one barley, and non‐host (corn) cultivars to Ptr‐toxin corresponds with reported field reactions to the pathogen. Seven isolates of P. triticirepentis from wheat in Oklahoma and four from smooth bromegrass Bromus inermis, an alternative host of P. tritici‐repentis), in North Dakota were evaluated for production of Ptr‐toxin in vitro.

Results indicate that Ptr‐toxin may be involved in the expression of disease symptoms in tan spot of wheat, but is not the sole determinant of P. tritici‐repentis pathogenicity. Instead, toxin production may contribute to the virulence of individual isolates of the pathogen. Isolates from the alternative host, smooth bromegrass, appear at least as toxigenic as those from wheat, with the exception of one which appeared more toxigenic than four of the wheat isolates tested. Possible relationships of Ptr‐toxin to high‐molecular weight toxins reported to be produced by P. triticirepentis in vitro (Ptr‐necrosis‐toxin) are not understood.