bluuebunny/crossref_metadata_2025 huggingface dataset:
Activity of Glucanases of Zygorrhynchus moelleri in Relation to Antagonism Against some Soil‐Borne Plant Pathogenic Fungi
Authors: Brown Averil E.
Published: May 2008

Zygorrhynchus moelleri antagonized some soil‐borne fungi on agar and in composts. Filtrates of Z. moelleri cultures contained high levels of β‐1,3‐glucanase (exoglucanase) and β‐1,3(4)‐glucanase (endoglucanase) when the fungus was grown on hyphal wall material from Rhizoctonia solani or Pythium intermedium as sole carbon source. Lower exo‐ and endoglucanase activities were produced on Fusarium oxysporum f. sp. lini (F.o.l.) hyphal walls while insignificant levels were produced on Z. moelleri hyphal walls. Protease was also produced when Z. moelleri was grown on hyphal wall material, but chitinase or cellulase were not detected. Optimum production of both glucanases occurred in media at pH,6 to 7 and activity was optimal at pH 5. The enzymes were active over a temperature range in excess of 20–50 °C but optimum activity occurred at 40 °C.

Cell free culture filtrates containing exo‐ and endoglucanase activity lysed living hyphal walls of R. solani, P. intermedium, Verticillium albo‐atrum and F.o.l. although walls of the latter were least sensitive to lytic activity. The culture filtrates did not lyse living mycelium of Z. moelleri. Z. moelleri also produced substances inhibitory to growth of colonies of test fungi on agar.

In glasshouse experiments disease severity in flax induced by R. solani and P. intermedium, in parsley by P. paroecandrum and in radish and Zinnia by P. intermedium was suppressed in composts inoculated with sporangiospore suspensions of Z. moelleri.
Detection by ELISA of Two Tobamoviruses in Orchids Using Monoclonal Antibodies
Authors: Dore I. , Dekker E. L. , Porta C. , Van Regenmortel M. H. V.
Published: May 2008

Five monoclonal antibodies (McAbs) were raised to the tobamovirus, odontoglossum ringspot virus (ORSV). All five McAbs reacted with the virus in double antibody sandwich (DAS) ELISA but not in an ELISA using virus‐coated plates. All the McAbs recognized a panel of ORSV strains and isolates, although one of the antibodies reacted better with some isolates and another reacted less with certain isolates than with type ORSV. It was possible to use the same McAbs both as coating and as biotinylated antibody in DAS‐ELISA.

None of the five McAbs was able to bind to orchid strains of tobacco mosaic virus (TMV). In order to detect strains of both viruses, ORSV and TMV, in infected orchids it was necessary to include also McAbs raised against TMV in the immunoassays. The use of a mixed polyclonal‐monoclonal antibody DAS‐ELISA system is advocated for detecting both tobamoviruses in orchids.
Corn Stunt Spiroplasma in the Leafhopper Euscelidius variegatus
Authors: Alivizatos A. S.
Published: May 2008

Corn stunt spiroplasma (CSS) multiplied in all leafhoppers Euscelidius variegatus injected with a culture of CSS, reaching titres of over 1x106 colony forming units (cfu) per insect and 2x104 cfu per salivary gland of each insect. CSS could be isolated from the haemolymph and the salivary glands at any time after injection. The growth of CSS in culture was inhibited by insect extract at concentrations greater than the equivalent of 0.1 insect/ml.

Transmission of CSS to sterile feeding solution and to broad beans were compared using 24 h feeding periods. A porportion of 1.7 % of injected leafhoppers began to transmit to sterile feeding solution through membranes by the 4th day after injection, and reached a maximum of 30 % by day 14. Similar insects started transmitting to broad bean plants on day 12 (2 %), reaching a maximum of 7.5 % by day 14. The number of spiroplasmas transmitted by each insect to sterile feeding solution increased from 3, cfu on day 4 to a maximum of 80 cfu by day 14.

Helices were seen in the haemolymph at any time after injection. However, partially deformed cells were not present until the 1st week and clumps of 3–4 cells and small aggregates until the 3rd week after injection. The salivary glands of injected insects contained membrane‐bound “pockets” or “colonies” packed with pleomorphic, filamentous (helical and non‐helical) cells and aggregates. Intracellular colonies were always at the periphery of the acini and were easily detectable by fluorescence microscopy after staining with a DNA‐binding fluorescent stain. Pleomorphic and filamentous cells were also seen intercellularly in the salivary glands.
Isolation of Sordaria fimicola from Maize Stalks
Authors: Chambers K. R. , De Wet D. C.
Published: May 2008

Sordaria fimicola, which does not appear to have been isolated from maize before, was isolated from stalks in the field throughout the growing season. The fungus occurred at low frequencies and was confined largely to the nodes. Although it was repeatedly isolated from maize stalks it appears to be an opportunistic inhabitant. In a greenhouse study it could not be re‐isolated from maize seedling roots although a reduction in dry weight accumulation, root length and plant height was recorded.
Presence of a Root Malformation Factor in Culture Filtrates of Fusarium moniliforme var. subglutinans1
Authors: Kumar J. , Singh U. S. , Beniwal S. P. S.
Published: May 2008

The presence of a root malformation factor, different from plant growth substances viz. NAA, GA3, Kinetin and reduced Glutathion was demonstrated in culture filtrates of Fusarium moniliforme var. subglutinans, a fungus commonly associated with malformed mango tissues. Culture filtrate extracts of the fungus caused curling and stunting of maize and pea roots and formation of flap like growth at the tip of wheat roots, but failed to induce malformation in bean plants as reported, for malformin.
Sclerotia of Botrytis as a Source of Primary Inoculum for Bunch Rot of Grapes in New South Wales, Australia
Authors: Nair N. G. , Nadtotchei A.
Published: May 2008

Sclerotia of Botrytis cinerea were found to be a source of primary inoculum for bunch rot of grapes in the Hunter Valley of New South Wales. Conidia‐bearing sclerotia were found on canes on grapevines. Resporulation of sclerotia was observed and sporogenic germination led to infection of flowers and berries. Sclerotia survived for eight months in untreated soil in the laboratory. Application of dicarboximides (procymidone, iprodione and vinclozolin) reduced infection of flowers and bunch rotcaused by the sporogenic germination of sclerotia.
Mode of Infection of Ascochyta Blight of Chickpea Caused by Ascochyta rabiei
Authors: Pandey B. K. , Singh U. S. , Chaube H. S.
Published: May 2008

Process of infection and histological changes with Ascochyta blight of chickpea caused by A. rabiei (Pass.) Labr. were studied by light microscopy. Germ tubes from conidia of the fungus penetrate the stem tissue at the juncture of two epidermal cells and form subepidermal aggregates until the fourth day. On the sixth day, yellowing and necrotisation of host tissue coincides with formation of mature pycnidia. Fungus causes extensive damage to cellulosic cell walls of parenchymatous cortical and pith tissues in advance of invading hyphae indicating involvement of cell wall degrading enzymes. Lignified tissues, particularly xylem tracheary elements, remain intact.
Ultrastructure of Inclusions Formed by Ribgrass Mosaic Virus in Leaf Cells
Authors: Ernwein Cornelia , Wetter Carl
Published: May 2008

Diffrent types of cytoplasmic inclusions were observed in ultrathin sections of plants systemically infected with three different strains of ribgrass mosaic virus (RMV) (tobamovirus group). Tissue from uninoculated plants did not contain such inclusions. Most common were “rounded plates” consisting of layers of aligned virus particles 300 nm long. RMV also induced angled layer aggregates in Capsicum annuum plants. A novel type of inclusion for the tobamovirus group were the abundant spiral aggregates found in Digitalis purpurea, systemically infected with strain D of RMV. In these aggregates the virions become circularly arranged around a center. The orientation of the particles changes in such a way that virions being 300 nm apartare cut in the longitudinal and in the transverse direction respectively.
The Pattern of Bacterial Leaf Blight Disease Development and spread in Rice
Authors: Nayak P. , Reddy P. Ranga
Published: May 2008

The pattern of occurrence and spread of bacterial leaf blight among rice plants in the field was studied through the test of randomness of infected plants by fitting negative binomial distribution, ordinary runs and doublets analyses. The low k value obtained through negative binomial distribution indicated the clustering of infected plants. The high negative values of standardized Z in ordinary runs test at higher levels of incidence indicated non‐random pattern of occurrence and spread of the disease by alloinfection. Negative binomial distribution and ordinary runs test were preferred over doublets test to study the pattern of spread of bacterial leaf blight disease of rice because they revealed realistically the field situation.
Bell Pepper Mottle Virus, a Distinct Tobamovirus Infecting Pepper
Authors: Wetter Carl , Dore Isabelle , Bernard Monika
Published: May 2008

Bell pepper mottle virus (BPeMV) can be distinguished by symptomatology and host range from other tobamoviruses but a reliable identification needs serological tests. The relationships of BPeMV to tobacco mosaic virus (TMV), Odontoglossum ringspot virus (ORSV), tobacco mild green mosaic virus (TMGMV), and pepper mild mottle virus (PMMV) were investigated using precipitin drop tests on slides, immunodiffusion gel tests, double antibody sandwich enzyme‐linked immunosorbent assay (ELISA), and indirectELISA using enzyme‐linked goat anti‐rabbit globulins for the determination of antiserum titers and serological differentiation indices (SDI). Comparisons of SDIs and amino acid composition data demonstrated that BPeMV is a new species of the tobamovirusgroup. BPeMV, ORSV, PMMV, and TMGMV form a cluster within the genus (group) and could be considered as a subgenus of tobamoviruses.
Electron Microscopical and Serological Detection of Virus‐like Particles Associated with Lettuce Big Vein Disease
Authors: Vetten H. J. , Lesemann D.‐E. , Dalchow J.
Published: May 2008

Very labile rod‐shaped particles measuring 324 and 152 nm × 18 nm were isolated only from lettuce plants affected with lettuce big vein (LBV) but not from healthy ones. An antiserum to these particles was prepared which enabled us to diagnose LBV‐affected plants, using immunosorbent electron microscopy (ISEM) and enzyme‐linked immunosorbent assay (ELISA). Clearly positive reactions were obtained in ISEM and ELISA even when symptoms of LBV‐affected plants raised in soil from various locations were indistinct. Higher ELISA values were obtained with extracts from leaves than with those from roots. In ISEM high numbers of particles were trapped from extracts of LBV‐affected plants with antiserum to tobacco stunt virus.
Alternative Gramineous Hosts of Leptosphaeria nodorum Including Two New Records for the U. S. A.
Authors: Khokhar L. K. , Pacumbaba R. P.
Published: May 2008

Leptosphaeria nodorum was isolated from various wheat sources (seeds, seedling, straw, and volunteers) and from triticale, little wild barley, ryegrass, smooth bromegrass, aegilops, quackgrass, Bermuda grass, and air. The level of seed contamination in wheat cultivars varied from 3–63%. Initial detection of the pathogen from field samples of plant material varied from 5–58%. Four out of the 12 plates exposed to the air showed growth of the pathogen. The presence of spores from aerial sporetrapping decreases to zero by 30 December. The pathogen was undetected from the leaf samples of wheat and triticale from 15 January to 15 February. Spore size and cultural growth differed among the various isolates. Isolates from wheat straw, Bermuda grass, little wild barley, and triticale were fluorescent variable while the other isolates fluoresced under NUV light. Symptoms were induced when wheat cv.‘Callahan 513’ and four other grasses were inoculated with isolates of L. nodorum from various gramineous sources. The infection by the pathogen on ‘Callahan 513’ was greater than the infection of the same isolates in their gramineous weed hosts. Ryegrass and Bermuda grass were demonstrated as additional alternative gramineous hosts of L.nodorum in the United States.
Chemotherapeutical Elimination of Potato Virus X from Potato Stem Cuttings
Authors: Bittner Heide , Schenk G. , Schuster G.
Published: May 2008

Potato virus X was completely eliminated from all infected potato stem cuttings grown in nutrient media containing 0.02 or 0.03 % 2,4‐dioxohexahydro‐1,3,5‐triazine (DHT). When DHT was added to the media in concentrations of 0.01 and 0.005% the efficiency by which the virus was eliminated differed between the varieties tested.

The method is less time‐consuming than the generally used meristem (axillary‐) tip culture in combination with chemo‐ or thermotherapy.
The Influence of pH and Temperature on Cellulolytic and Pectolytic Activity ofCylindrocarpon destructans(Zins.) Scholt.
Authors: Strzelczyk E. , Dahm H. , Kowalski S.
Published: May 2008

In studies on the effect of pH and temperature on cellulolytic and pectolytic activity of C.destructans, it was found that the isolates used produced only endoglucanases. The temperature and pH affected the synthesis of these enzymes. Fungi cultured at 26°C produced more of these enzymes than those grown at the two other temperatures. At 10°C, only one isolate produced minute amounts of endoglucanases. None of fungi studied exhibited cellulolytic activity in cultures grown at 20°C. Cellulolytic activity was found only in acidic media (pH 5.0). The fungi studied exhibited higher pectolytic than cellulolytic activity. In the post culture liquids of these organisms, both types of pectolytic enzymes (exo‐ and endo‐PMG) were detected. Different temperature and pH values affected the production of these enzymes differently in various isolates.
Differential Influence of Ectomycorrhizae on Plant Growth and Disease Resistance in Pinus sylvestris Seedlings
Authors: Chakravarty P. , Unestam T.
Published: May 2008

The influence of Laccaria laccata, Hebeloma crustuliniforme, and Pisolithus tinctorius mycorrhizae and a mixture of naturally occurring mycorrhizae on the resistance of Pinus sylvestris seedlings to attack by Fusarium moniliforme and Rhizoctonia solani was investigated periodically during an entire year under greenhouse conditions following inoculation with both mycobiont and pathogen. Using artificial root substrate the seedlings were provided with a balanced butlow nutrient supply. Seedling growth (dry weight) as well as short‐root formation was stimulated to different extents depending on the mycobiont species; in addition, the degree of stimulation varied over the year. Parasitized plants were more stimulated, than nonparasitized ones. Disease severity and plant mortality caused by either pathogen were drastically reduced in the presence of the mycorrhizal fungi, even before mycorrhiza formation. All mycorrhizae, except the association with Hebeloma, remained highly protective throughout the year; with Hebeloma it remained protective for only about 3 months. Growth stimulation or mycorrhiza frequency was not always correlated with the level of protection; e.g. Hebeloma protected withoutstimulating growth. Two types of protection apparently exist, one related to and another unrelated to growth stimulation. Mycorrhizal fungi had little or no antagonistic effects on fungal pathogens in vitro.
Experimental Transmission of Plum Pox Virus (PPV) to Prunus Mahaleb and Prunus avium
Authors: Dosba F. , Maison P. , Lansac M. , Massonie G.
Published: May 2008

Sharka caused by plum pox virus (PPV) is a disease spread in France since 1970, and causing severe damages essentially on apricot but also on plums and peach.

Cherry is generally considered as not infected by PPV. Experimental transmissions by chip budding or aphids allowed to show that 3 isolates of PPV can multiply inside three cherry rootstocks (P. Mahaleb cv.‘SL 64′, P. avium cv.‘F 12‐1′, and P. avium*P. pseudocerasus cv. ‘Colt') (Tables 1 and 2).

But generally, the virus remained localized to the infection site and disappeared quickly (Table 3). Typical symptoms of chlorotic ringspot or vein clearing are also limited to the leaves probed by the aphids.

The fact that no translocation was detected is discussed.
The Influence of Temperature on Phytophthora infestans (Mont.) de Bary
Authors: Sujkowski L. S.
Published: May 2008

The influence of temperature on the growth rate, sporulation density and zoospore release of Phytophthora infestans, cultivated on rye agar, has been studied.

Temperature significantly influenced all the features of the fungus mentioned above. The highest yield of sporangia per 1 cm2 of aerial mycelium occurred at 24°C while the highest percentage of sporangia releasing zoospores was observed when the fungus was grown at 15 °C. When considering the size of the fungal colony the highest production of sporangia was obtained at 20°C.

It was concluded that the temperature at which the fungus was cultured predetermined the way it germinated.
Lectins Specificity to Pathogenesis of Fusarium oxysporum f. sp. vasinfectum
Authors: Abd‐El‐Rehim M. A. , Abou‐Taleb E. M. , Tohamy A.
Published: May 2008

Lectins of cotton were isolated from either resistant or susceptible seed cultivars. In agar‐gel double diffusion tests, positive reactions took place between lectins of cotton cultivars and the antisera of their corresponding wilt Fusaria. The number of precipitin bands correlated with the degree of susceptibility of the tested cultivars. On the other hand, no visible reaction was detected when these antisera were subjected to react with either the resistant host or nonhost lectins.
Viruses Associated with a Mosaic Disease of Crotalaria juncea in Nigeria
Authors: Ladipo J. L.
Published: May 2008

Cowpea mosaic virus was one of the viruses isolated from Crotalaria juncea showing mosaic, distortion and puckering symptoms. The virus induced local necrotic lesions in Canavalia ensiformis, Cassia occidentalis, Nicotiana debneyi, N. occidentalis, N. repanda and N. sylvestris and some cultivars of Phaseolus vulgaris 4–6 days after inoculation. It induced local chlorotic spots, which later became necrotic, as well as systemic chlorotic spots, vein chlorosis, distortionand puckering in Chenopodium amaranticolor.

Sap from systemically infected cowpea cv. ‘C20‐55’was infective after dilution to 10−5 but not 10−6, after 10 min at 65°C but not 70°C, or after 4 days, but not 5 days, at a room temperature of 15–25°C. Infectious virus was recovered from fresh reproductive tissues of infected cowpea cvs ‘C20‐55’and ‘Ife Brown’ plants but not after dehydration.
Systemic Invasion of Immature Sweet Cherry Fruit by Pseudomonas syringae pv. morsprunorum Through Blossoms1
Authors: Roos Isabel M. M. , Hattingh M. J.
Published: May 2008

Cherry blossoms inoculated with a rifampicin‐resistant strain of Pseudomonas syringae pv. morsprunorum died or gave rise to fruits containing necrotic spots at or near the blossom ends. Scanning electron microscopy of developing fruits indicated that the pathogen had invaded the entire pericarp, including the endocarp. Bacteria also spread to the fruit stalk and, to a lesser extent, to the spurs. Mesocarp cells below the lesion collapsed. Infected fruit, stalks, and spurs contained, respectively, ca. 109, 107, and 102 colony forming units of P. syringae pv. morsprunorum as determined by a dilution plate method on an agar medium supplemented with 50 μg/ml rifampicin. This is the first report of systemic spread of P. syringae from blossoms to developing fruit of a deciduous crop.
MLO‐Associated Decline of Alnus glutinosa, Populus tremula and Crataegus monogyna
Authors: Seemüller E. , Lederer W.
Published: May 2008

In the Heidelberg area of southwestern Germany declining trees of Alnus glutinosa (L.) Gaertn. and Populus tremula L. as well as stunting shrubs of Crataegus monogyna Jacq. were observed. In all 3 species mycoplasmalike organisms, which appear to be the causal agents of the disorders, were detected by fluorescence and electron microscopy. The diseases of alder and aspen seem to be lethal while the hawthorn apparently is less affected.
Transmission of Three Viroids Through Seed and Pollen of Tomato Plants
Authors: Kryczyński S. , Paduch‐Cichal E. , Skrzeczkowski L. J.
Published: May 2008

The severe strain of potato spindle tuber viroid (s‐PSTV) as well as chrysanthemum stunt (CSV) and cucumber pale fruit (CPFV) viroids were found to be transmitted through seed and pollen of the tomato cvs. Rutgers and Najwcześniejszy. Plants pollinated with a pollen infected with any of these three viroids became systematically infected. Plant, fruit and seed symptoms of viroid infection were noted on sap‐ and pollen‐inoculated plants and the yield of these plants was reduced.

Tomato cv. Rutgers plants grown from infected seeds were symptomless although all three viroids were detected in these plants by bioassay and by electrophoresis on 5% polyacrylamide gel.

When DNA complementary to s‐PSTV RNA was used for a direct viroid detection in seed samples by spot hybridization technique it hybridized not only with s‐PSTV RNA but also with CSV RNA as well as with CPFV RNA.
Hypersensitive Reaction in Petunia
Authors: Nicoud S. , Dumas E. , Cornu A. , Gianinazzi S.
Published: May 2008

Intercellular fluid (IF) extracted from the apoplastic leaf spaces of Petunia contained up to 6 new soluble proteins, called d proteins (d0 to d5). Characterisation of the d proteins has shown that they can be divided into groups and show a genetic variability similar to the PR(b) proteins from Nicotiana. d protein patterns from Petunia interspecific hybrids clearly show that the determinant for the d proteins in sexually transmitted as is the case for b proteins in Nicotiana. d‐protein induction in TMV‐SM1 infected Petunia leaves is discussed in relation to the resistance to infection shown by cultivars and hybrids of Petunia.
Antibiosis of Streptomyces griseus Against Colletotrichum lindemuthianum
Authors: Tu J. C.
Published: May 2008

Streptomyces griseus produces an antibiotic substance against Colletotrichum lindemuthianum because, in dual culture on potato dextrose agar (PDA), a large inhibitory zone was formed between the colonies of S. griseus and C.lindemuthianum. When S. griseus was placed adjacent to a colony of C. lindemuthianum in PDA, S.griseus grew poorly in PDA but it thrived and sporulated profusely when it came in contact with a colony of C. lindemuthianum indicating that S.griseus might require some essential nutrients from C.lindemuthianum. Scanning electron microscopy showed that hyphae of S.griseus in contact with C.lindemuthianum produced appressorium‐like swellings or simply grew on the hyphal surface of C.lindemuthianum. Internal parasitism was evidenced by the presence of hyphae and conidia of the mycoparasite inside the host hyphae. Internal parasitism resulted in formation of several blebs. Cell walls of the parasitized hyphae degenerated having a sponge‐like texture. The blebs broke off and left rounded holes on the hyphae.
Further Studies on a Virus Causing a Green Mosaic Disease of Eggplant in Nigeria
Authors: Ladipo J. L. , Lesemann D.‐E. , Koenig R.
Published: May 2008

A virus reported earlier to cause a green mosaic disease of eggplant in Nigeria was studied in more detail. Its filamentous particles with a normal length of 820 nm reacted in immunoelectron microscopical tests strongly with the homologous antiserum and less strongly with antisera to dioscorea green banding mosaic, groundnut eyespot, zucchini yellow mosaic viruses and to a tomato potyvirus isolate from Taiwan. No reactions were seen with antisera to 25 other potyviruses. Several new host plants were identified. Infected cells contained cylindrical inclusions with scrolls and short curved laminated aggregates and clusters of small vesicles with electron‐dense content. Host range and serological reactivities differentiate the virus for which the name eggplant green mosaic virus is suggested from all potyviruses so far known.
Enzyme‐Linked Immunosorbent Assay (ELISA) of a Coryneform Isolated from Ratoon Stunted Sugarcane
Authors: Pillay D. , Oellermann R. A.
Published: May 2008

An enzyme‐linked immunosorbent assay (ELISA) was developed for the coryneform bacterium isolated from ratoon stunted surgarcane. Parameters governing the ELISA were optimized. These included antibody coating concentration, conjugate concentration and diluent, antigen diluent, the washing procedure, incubation temperature for sample and conjugate, pH and time. The level of detectability of the cultured bacterium by the ELISA was ≥ 1 × 104 Zellen · ml‐1.
Small RNAs Originating from Symptomless and Damaged Spruces (Picea spp.)
Authors: Beuther E. , Köster S. , Loss P. , Schumacher J. , Riesner D.
Published: May 2008

Ribonucleic acids were extracted from needles of symptomless and damaged spruces (Picea spp.). Trees from three locations of different altitudes in Nordrhein‐Westfalen were taken for sampling. The samples were collected from the same individual trees at different times during the growing seasons of the years 1984–1986.

Small RNAs (Mr <300 000) were analyzed by a two‐dimensional gelelectrophoresis. The aim was to detect “disease associated” RNAs by a comparison of the RNA‐patterns of symptomless and damaged spruces. A RNA of about 450 nucleotides was a strong candidate, though it was found in needles of both damaged and symptomless trees. The concentration of the RNA450 is dependent on the season, the needle age, and the location of the tree. In damaged trees the level of the RNA450 ishigher than in symptomless trees. The RNA450 was found to be an endogeneous RNA, which indicates both the developmental state of the needle, and an interference with the development by the damage already at the early level of RNA metabolism.
The Effect of Gentisic Acid on Activity of Peroxidase from Citrus aurantifolia Swing
Authors: van Lelyveld L. J. , van Vuuren S. P.
Published: May 2008

The present study indicates that the peroxidase activity can be partly inhibited by gentisic acid and possibly thereby interferes with the mechanism of resistance to greening diseases of citrus.
RNA/cDNA Hybridization and Infectivity Tests Suggest that Barley Yellow Mosaic Virus Isolate M has a Bipartite Genome
Authors: Koenig R. , Huth W.
Published: May 2008

Northern blot analysis with random‐primed cDNAs revealed that RNAs 1 and 2 of barley yellow mosaic virus (Ba YMV) isolate M have no extensive base sequence homologies. Both RNAs are needed for infection. RNA 2 is therefore neither a subgenomic nor a, satellite RNA, but rather an essential part of the viral genome. Ba YMV isolate M has thus a bipartite genome.
Electron Microscopic Studies of Spruce Needles in Connection with the Occurrence of Novel Forest Decline
Authors: Jung Georg , Wild Aloysius
Published: May 2008

Needles of four spruce trees showing different degrees of novel kinds of forest decline were investigated by electron microscopy. Green needles appearing at least superficially still intact were selected for the present investigation. Most of the mesophyll appeared to be undamaged. However, groups of atypical mesophyll cells were found close to the endodermis or the hypodermis. The chloroplasts of the apparently damaged cells were particularly affected. Changes in the matrix of the chloroplasts, i.e,. increased affinity to osmium, occurrence of extensive nests of plastoglobuli, as well as damage to the membranes, i.e. lesions in the envelope and abnormal thylakoid membranes, were observed. Signs of decomposition of other cellular structures including mitochondria were also detectable. There appeared to be a close correlation between the degree of damage at the whole tree level and the degree of damage occurring at the cellular level. It is concluded that particularly the lipids and the proteinsof, the membranes are affected by anthropogenic air pollutants and natural stressors. The altered membrane structure may for instance cause abnormal osmotic conditions for the cellular compartments and may impair transport processes and thus lead to lossof function not only of the cells but also of the whole needle.
Intracellular Localization of the Systemic Fungicide Triadimenol in Phytopathogenic Fungi
Authors: Hippe Sigrun , Hermanns Monika
Published: May 2008

The intracellular localization of the radioactively labelled fungicide (3H)triadimenol A in the in vitro grown sporidia of Ustilago avenae and in the in vivo cultured powdery mildew (Erysiphe graminis f. sp. hordet) on barley (Hordeum vulgare) is described. The specimens were prepared by low temperature techniques: shock freezing, freeze substitution and embedding in Spurr's low viscosity resin. The localization of the fungicide was achieved by means of conventional electron microscopic autoradiography. The available experimental data allow a first qualitative analysis of the distribution of silver grains on freeze substituted sporidia of U. avenae and the infection structures of Erysiphe graminis f. sp. hordei. Concerning U. avenae the fungicide is detected preferentially over the vacuoles, the cytoplasm, and the cell walls after a six month exposure. The host pathogen system powdery mildew on barley exhibits an accumulation of silver grains in the host cell wall adjacent to the infection site and the papillae whereas decisively fewer grains occur inside the haustoria. Apart from this general localization pattern the haustoria show ultrastructural changes caused by the fungicide treatment: vesiculation and collapse of the sheath membrane as well as a diffuse appearance of the haustorial cytoplasm. Around the haustoria an aggregation of host cytoplasm material is observed.
Fluorescence and Electron Microscopy of Cynodon dactylon Affected with a White Leaf Disease in the Sudan
Authors: Dafalla G. A. , Cousin M. T.
Published: May 2008

A disease characterized by complete chlorosis of plant foliage was recently observed in Cynodon dactylon L. naturally growing in central Sudan. Severely affected plants were stunted with short internodes and small inward folded leaves. Examination of sections from paraffin embedded leaf and rhizome fractions, stained with a DNA‐binding fluorochrome Bisbenzimid H 33258, and observed in a fluorescent microscope revealed abnormal amounts of DNA material in the phloem sieve tubes of diseased plants. More intense fluorescence was also observed in the xylem region and was shown to be due to the presence of a rod‐shaped bacterium. No such anomalies were observed in healthy plants. Electron microscopy of ultrathin sections prepared from phloem zones, reacting with fluorescence in light microscopy revealed the presence of pleomorphic prokaryotes in the sieve tube elements of such zones. No helical forms were observed in semi‐thin sections from the same plant material, suggesting the MLO nature of these prokaryotes.
In vitro Selection of Strains of Phytophthora cactorum Resistant to Metalaxyl
Authors: Utkhede R. S. , Gupta V. K.
Published: May 2008

Isolates of Phytophthora cactorum resistant to the systemic fungicide metalaxyl were obtained by exposing them to sequentially increased concentrations of metalaxyl. A linear relationship was observed between the concentrations of metalaxyl and percentage inhibition of mycelial growth of P. cactorum. The stability of metalaxyl‐resistant isolates 150R and 250R was confirmed after six serial transfers on corn meal agar without fungicide. The in vitro metalaxyl‐resistant isolate (Ph10) was less aggressive on apple rootstocks compared with the Ph07 isolated from metalaxyl‐treated trees and the Ph03 isolated from untreated trees. Metalaxyl‐resistant and sensitive isolates remained sensitive to the chemically unrelated fungicide fosetyl‐Al at high concentration (600 μg/ml), to mancozeb, and to a mixture of metalaxyl + mancozeb. Significant differences in resistance to metalaxyl existed among P. cactorum field isolates.
Preliminary Investigations about the Mode of Transmission and Spread of Xanthomonas campestris pv. graminis on Forage Grasses
Authors: Leyns F. , De Cleene M. , Van Bogaert G. , Van de Wiele A. , De Ley J.
Published: May 2008

Extensive studies showed that no disease was caused when seeds of different forage grasses were inoculated with Xanthomonas campestris pv. graminis. The disease could easily be induced by infecting the plants in the root system, leaves or flower. The inoculation site in the leaf proved to be of vital importance for the development of the disease. Wilting symptoms were quickly induced when the pathogen was inoculated near the leaf base. Plants in root‐contact with diseased plants showed disease symptoms. It is not known whether these symptoms were caused by the bacteria or by toxins released by nearby diseased plants. Cross inoculation trials on different grass varieties revealed that different pathovars exist in the group of xanthomonads, pathogenic to forage grasses. Some have a broad host range whereas others are more limited to a single plant genus. Field trials suggest that in Belgian climatic conditions, the losses caused by bacterial wilt are rather limited.
A Simple Procedure for the Purification and Antiserum Production of Bean Yellow Mosaic Virus
Authors: Makkouk K. M. , Katul L. , Rizkallah A.
Published: May 2008

A simple procedure was developed to purify bean yellow mosaic virus from infected faba bean. The procedure included clarification of tissue homogenate by 25% chloroform followed by low‐speed centrifugation, virus concentration by polyethylene glycolprecipitation and further purification by agarose‐acrylamide gel electrophoresis. The partially purified virus preparation was electrophoresed in 0.5% agarose‐2% acrylamide gel for 4 h. Gel bands containing the virus were collected, homogenized, and mixed (1:1) with Freunds adjuvant. Four weekly intramuscular injections and a booster injection four weeks after the fourth injection were given to a rabbit. Antisera collected from the first five bleedings produced high A405 readings in ELISA (0.47,5–0.790) with virus‐infected faba bean leaves and low readings (0.030–0.065) with healthy tissue. Plates were coated with 5μg/ml of gammaglobulins (IgG) fractionated from the different bleedings of the antiserum prepared and a 1: 1000 dilution ofthe IgG from the third bleeding conjugated to alkaline phosphatase was used.
Peroxidase Activity in Leaves of Wheat Cultivars Differing in Resistance to Erysiphe graminis DC.
Authors: Patykowski J. , Urbanek H. , Kaczorowska T.
Published: May 2008

The peroxidase activities in leaves from resistant and susceptible cultivars of wheat infected and non‐infected by Erysiphe graminis DC were studied. In non‐infected wheat, soluble and ionic bound peroxidase activity level was found to be higher in the resistant cultivar than that in the one susceptible to Erysiphe graminis DC. After infecting wheat leaves with Erysiphe graminis DC a remarkable increase in the activity of soluble and ionic bound peroxidases was detected 5 days after inoculation only in the resistant cultivar. In the susceptible cultivar a high increase in the activity of the soluble and ionic bound peroxidases occurred only 15 days after inoculation.

Using ion exchange chromatography four peroxidase fractions were obtained from infected susceptible and resistant cultivars as from non‐infected ones. The fraction II in non‐inoculated resistant cultivars was much higher than that in the susceptible one. This fraction increased after inoculation in both cases reaching a higher level in resistant cultivars. Fraction I was higher in the susceptible cultivar.

Electrofocusing profiles of peroxidase from the susceptible and resistant cultivar differed from one another. New peroxidase bands after inoculation appeared only in the resistant cultivar.
Conditions for Efficient Isolation and Regeneration of Protoplasts from Fulvia fulva
Authors: Harling R. , Kenyon L. , Lewis B. G. , Oliver R. P. , Turner J. G. , Coddington A.
Published: May 2008

A procedure for producing high yields and high regeneration frequencies of protoplasts from Fulvia fulva is described. This procedure was devised by systematic trials of various parameters, such as culture age and osmotic support, which are known to affect protoplast yield and regeneration. Mycelium from liquid cultures of 24–48 h, incubated with Novozym 234 in buffered 1.0 M MgSO4, gave the best conditions for protoplast release. Regeneration frequencies up to 50% were obtained with a complete medium containing 0.8 M sucrose for osmotic support.
Untersuchungen über endophytische Pilze der Rebe unter besonderer Berücksichtigung des Gefäßsystems der Unterlage
Authors: von Tiedemann Sabine , Brendel Günter , Fehrmann Hartmut
Published: May 2008

Investigations on endophytic fungi of grapevine with special emphasis on the vascular system of rootstocks

In three vegetation periods endophytic fungi from rootstocks of grafted grapevines were isolated, and their influence on the host‐plant was determined. Before grafting (pre‐nursery) about 40 to 50% of grapevines were colonized by endophytic fungi; in grafted material after growing in a nursery this rate increased up to 50 to 90% (post‐nursery). Most of these fungi areDeuteromycetes, especiallyMonilialesandCoelomycetes.Only a fewAscomyceteswere found. The spectrumof fungi differs, mainly depending on the season (pre‐ and post‐nursery), but less on the variety and year of sampling. Contradictory results from investigations of the relationship between the isolated fungi and the vitality of grafted grapevines were found, however the endophytes clearly showed no pathogenic character. On the contrary in some cases a higher vitality of the grapevines correlated with presence of endophytes.
Isolation of Eutypa lata from Juglans regia, and Pathogenicity Studies on Different Wood Plants
Authors: Rumbos IoannisC.
Published: May 2008

The fungus Eutypa lata was isolated from diseased walnut trees (Juglans regia) exhibiting small cankers. The morphological characteristics of the culture and the pathogenicity were compared with those of known isolates of the fungus from other hosts. Inoculation tests with walnut isolates on grape, walnut, almond and apricot yielded characteristic cankers. Furthermore, pathogenicity tests on walnut with isolates from other different hosts resulted in differences in virulence. Similar differences in virulence were observed between 13 single ascospore isolates of the fungus ex apricot inoculated on walnut.
Use of Horseradish‐Peroxidase Labelled Antibodies in ELISA for Plant Virus Detection
Authors: Polák J. , K&rcarístek J.
Published: May 2008

Detection of plant viruses by ELISA using horseradish peroxidase for antibody labelling (ELISA‐peroxidase) has been standardized by evaluating variants of the procedure, regarding composition and concentration of buffers and additives. Immunoglobulins (IgG) are isolated from antisera by precipitation with ammonium‐sulphate and by purification with DEAE‐52 (Whatman) cellulose. IgG are conjugated with horseradish peroxidase by a modified oxidation‐periodate method.

In ELISA‐peroxidase 0.05 M carbonate‐bicarbonate coating buffer pH 9.6 has been substituted by 0.01 M carbonate buffer pH 9.2. Extraction buffer is used with 0.5% bovine serum albumin (BSA), without polyvinylpyrrolidone (PVP). Samples are diluted in, phosphate buffered saline (PBS) pH 7.2 with 0.05% Tween 20 and 0.5% BSA. IgG are conjugated with horseradish peroxidase, diluted in 0.1 M Tris‐HCl, pH 7.4 with 0.05% Tween 20 and 1% BSA. The substrate is incubated in the darkness for 20 min at room temperature. ELISA‐peroxidase proved to be equivalent in sensitivity and specificity with ELISA using alkaline phosphatase for antibody labelling. Its advantage is a lower cost of chemicals used in the test.
Molecular Cloning of DNA Complementary to the RNA‐Genome of Plum Pox Virus (PPV)
Authors: Maiss E. , Breyel E. , Brisske A. , Casper R.
Published: May 2008

Genomic RNA of plum pox virus (PPV) was used as a template for the synthesis of complementary DNA (cDNA). The generated cDNA molecules were subsequently cloned into pBR 322. A physical map covering 9700 bases of the PPV genome was constructed from 8, clones by hybridization and restriction endonuclease digestion. Clone pPPV‐NAT 309, starting at the 3′‐end, with an 866 bp insert was used in Northern‐ and Dot‐hybridizations for the detection of single‐stranded viral RNA in total nucleic acid as well as in sap preparations of PPV infected Nicotiana clevelandii. The nucleotide sequence of this clone was determined, the amino acid sequence of the coat protein C‐terminal part was deduced and compared with four other coat proteins of potyviruses.
Endophytic Fungi in Four Winter Wheat Cultivars (Triticum aestivum L.) Differing in Resistance Against Stagonospora nodorum (Berk.) Cast. & Germ. =Septoria nodorum (Berk.) Berk.
Authors: Sieber T. , Riesen T. K. , Müller E. , Fried P. M.
Published: May 2008

Four winter wheat cultivars with different levels of resistance to Septoria nodorum were investigated at four locations during two vegetation periods. Forty plants per cultivar and site were collected at random at seven defined growth stages from crop emergence to harvest. Samples from roots, culms, leaves, glumes and kernels were examined for the occurrence of endophytic fungi after surface sterilization. 83% of the 26944 isolates sporulated and were assigned to 213 species. The most frequent were: Septoria nodorum (20.1%), Alternaria tenuissima (9.8%), Epicoccum purpurascens (9.1%), Idriella bolleyi (6.9%), Fusarium graminearum (5.3%), Fusarium culmorum (4.0%), Cladosporium oxysporum (3.7%), Didymella exitialis (3.1%), Fusarium nivale (2.8%) and Rhizoctonia solani (2.1%). Each species occurred preferentially in one or more plant organs. A factorial analysis of variance showed that plant organ, sampling site, vegetation, period and cultivar in decreasing order of importance influenced the quantitative and qualitative composition of the fungal populations. No relationship between endophytic fungi was found to be constantly antagonistic or mutualistic. Septoria nodorum was isolated mainly from culms. The number of S. nodorum isolates differed significantly between cultivars in culms and glumes but not in flag leaves. The results are discussed in relation to resistance breeding and the effect endophytic fungi, might have on yield.
Production of Conidia by Botrytis fabae grown in vitro
Authors: Harrison J. G. , Heilbronn Jacqueline
Published: May 2008

Conidiation in Botrytis fabae was stimulated by irradiating 1 to 3 day old, but not 4 to 5 day old mycelium. Three cycles of 12 h irradiation + 12 h darkness stimulated the production of about twice as many spores compared with only 12 h irradiation. At 18°C all the spores had been produced within 3 days but not within 2 days from the start of irradiation. Near‐u.v. irradiation at wavelengths of 375–400 nm induced most sporulation. Red light at 600–650 nm also stimulated conidiation but irradiation at other wavelengths from 300 to 700 nm was ineffective. Fewer conidia were produced when the fungus was kept in darkness at 4°C between periods of irradiaton at 18°C compared with continuous 18°C. The optimum osmotic potential of the culture, medium for conidiation was about‐27 bar although more mycelium grew at even lower osmotic potentials. Abundant spore production occurred when the fungus was grown in media with a wide range of pH values.
Induced Resistance in Tomato Against Corynebacterium michiganense pv. michiganense by Prior Inoculation with Pseudomonas syringae Pathovars
Authors: SüLE S.
Published: May 2008

Prior inoculation of wounded tomato petioles with a minimum concentration of 5 × 104 cells per wound of various Pseudomonas syringae pathovars completely protected plants against subsequent infection with Corynebacterium michiganense pv. michiganense inoculated on the same site. Only living cells induced effective protection. In protected tissue, cells of Corynebacterium michiganense pv. michiganense remained localized at the inoculation site and their multiplication was restricted. Irrespective of the cell number introduced, initial population decreased slowly and then levelled off below the initial inoculum level. This level remained constant throughout the experimental period (15 days). Similarly, the, cell number of the inducer Pseudomonas syringae pv. phaseolicola levelled off at ca. 106 cells per plant. The protection was not systemic and could be eliminated by removing the upper 5 mm of the inoculated wound tissues containing, the inducer.
Side‐Effects of Field Applications of ‘Propiconazol’ and ‘Captafol’ on the Composition of Non‐target Soil Fungi in Spring Barley
Authors: Elmholt S. , Smedegaard‐Petersen V.
Published: May 2008

The results show great seasonal variation in number and composition of the fungi isolated from the upper soil layer, especially owing to an increased isolation of primary saprophytic fungi during the late growing season. Before fungicide treatment no statistically significant difference was measured between the number of isolated fungi from the examined soils. During the treatment period significantly fewer fungi were isolated from plots treated with ‘captafol’ or ‘propiconazol’ than from the untreated plots. The differences between untreated and treated plots were not statistically significant 30 days after the last treatment. The ecotoxicological effect on the total isolated fungal flora thus seems negligible. However the fungi responded differen, tly to treatment with ‘captafol’ and ‘propiconazol’. None of the fungi were significantly affected for more than a month when treated with ‘propiconazol’. The number of primary saprophytic fungi (Cladosporium spp., Alternaria spp., Epicoccum purpurascens, and Stemphylium sp.) and Sphaeropsidales, however, was significantly reduced for more than a month when treated with ‘captafol’.
Common Antigen(s) in Cotton to Fusarium oxysporum f. sp. vasinfectum
Authors: Abd‐El‐Rehim M. A. , Abou‐Taleb E. M. , Tohamy A.
Published: May 2008

Antigen‐antibody reactions in agar gel, as demonstrated by the double diffusion technique, between cotton seed globulins and the antisera specific to each of the tested Fusarium oxysporum f. sp. vasinfectum isolates as well as the antiserum of F. moniliforme revealed that all the tested antisera of F. oxysporum f. sp. vasinfectum reacted with seed globulins except the Menoufi cultivar globulins. No precipitin lines were detected in the reaction between the antigenof the cotton cultivar Acala SJ2 versus the antiserum of P10 isolate. The 5 cultivars behaved differently with each fungal antiserum to the extent that they could be distinguished accordingly. When the seed globulins of the susceptible cultivars (Giza 74, and Bahtim 110) reacted with antiserum of the tested F. oxysporum f. sp. vasinfectum isolates, more precipitin lines were formed than the resistant cultivars. On the other hand, no obvious reaction was detected in case of F. moniliforme antiserum.
Ethylene as a Mediator of Rubigan Biological Action in Cowpea Plants
Authors: Madkour M. A. , Shehata M. R. A. , Farag Samia A. , Wagih E. E.
Published: May 2008

Rubigan (a systemic fungicide) inhibited the growth of Rhizoctonia solani in vitro when used at concentrations of 6, 12 and 24 μg/ml respectively. Application of Rubigan as a soil drench significantly reduced the damping‐off incidence on cowpea (Vigna sinensis) plants.

Symptoms of growth retardation appearing on cowpea plants treated with Rubigan could be mimiced using an ethylene releasing compound (Ethrel). Ethrel at 10 and 20 μl/ml added to the soil around the seeds induced severe dwarfing as evidenced from measurements of plant length, dry weight and leaf area. Gas chromatographic analysis revealed that ethylene was released either from Rubigan mixed or not with the soil. Rates of ethylene production from soils drenched with Rubigan were relatively inferiorto those produced by authentic Rubigan solutions not added to the soil. Moreover, in all cases ethylene was released at rates proportional to the Rubigan concentrations applied.

Factors involved in growth retardation of Rubigan‐treated cowpea plants were discussed in the light of the possible interaction between ethylene and endogenous gibberellin levels.