bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructural Studies on the Microconidia of Botrytis cinerea Pers. and their Phialoconidial Development
Authors: Urbasch I. 
Published: May 2008

AbstractThe genesis and ultrastructure of microconidia of Botrytis cinerea Pers. were studied, using TEM and SEM.Microconidia are produced in flask‐shaped, terminal or lateral phialides. The first microconidium develops holoblastically, subsequent microconidia are formed enteroblastically, in basipetal succession from a fixed conidiogenous locus.Mature microconidia are characterized by a two‐layered spore wall covered by mucilage, a single, sickle‐shaped nucleus, one or two large lipid bodies, a few mitochondria of the cristae‐type, ribosomes, sparse endoplasmatic reticulum close to the plasmalemma and a small amount of cytoplasma. The basal septum which is surrounded by a collar‐like rim is perforated by a simple central pore with a pore plug.Differences in genesis and ultrastructure of microconidia compared with macroconidia are discussed in relation to the function of these two spore types.
Untersuchungen zur Anfälligkeit und Resistenz von Kopfsalat (Lactuca sativa) gegen falschen Mehltau (Bremia lactucae): II. Licht‐ und elektronenmikroskopische Untersuchungen zur Morphologie des Wirt‐Parasit‐Verhältnisses
Authors: Zinkernagel V. 
Published: May 2008

Abstract Investigations on the susceptibility and resistance of head lettuce (Lactuca sativa) to downy mildew (Bremia lactucae) II. Light and electron microscopic examinations of the host‐parasite interface Infected leaves of lettuce varieties susceptible and incompletely resistant to Bremia lactucae were observed by light and electron microscopy. Primary infection structures in the epidermal cells as well as intercellular hyphae with the adjacent haustoria could be seen by differential interference contrast microscopy. The haustoria in host cells of susceptible varieties collapsed before degeneration of the invaded host cell. On the contrary, host cells of incompletely resistant varieties died before the haustoria in these cells showed any sign of degeneration. Electron microscopic investigations confirmed the observations with light microscopy. In incompletely resistant varieties, an electron transparent sheath enveloped the haustorium. In the sheath fragments of membranes are localized. These membrane particles as seen by using the goniometer in electron microscopic work were flat faced. The sheath material consists of transformed host cell wall material and involves fragments of the host plasmalemma as well as fragments of the unit membrane separating the sheath from extrahaustorial matrix. The sheath has an important role as a special filter to prevent the passage of nutrients from the host cell into the haustorium. Thus the incomplete resistance is based not only on an impeded penetration of the parasite into the epidermal cells and their hypersensitive reactions in case of a successful penetration but also on hypersensitivity of mesophyll cells which does not necessarily lead to death of the parasite but does impede the absorption of nutrients.
Dispersal of Septoria nodorum Pycnidiospores by Simulated Rain and Wind
Authors: Brennan R. M. , Fitt B. D. L. , Taylor G. S. , Colhoun J. 
Published: May 2008

AbstractThe influence of wind on the splash dispersal of Septoria nodorum pycnidiospores was studied in a raintower/wind tunnel complex with single drops or simulated rain falling on spore suspensions or infected stubble with windspeeds of 1.5 to 4 m/sec. When single drops fell on spore suspensions (depth 0.5 mm, concentration 7.8 × 105 spores/ml) most of the spore‐carrying droplets collected on fixed photographic film between 0–4 m downwind (windspeed 3 m/sec) were >200 μm in diameter. However, most spores were carried in droplets with diameter > 1000 μm, 70 % of which carried more than 100 spores. When simulated rain fell on infected stubble most of the spore‐carrying droplets collected beyond 1 m downwind (windspeeds 1.4 and 4 m/sec) were <200 μm in diameter and none were >600 μm; most of these droplets carried only one spore.The distribution of splash droplets (with diameter >100 μm) deposited on chromatography paper showed a maximum at 40–50 cm upwind of the target but many more droplets were deposited 20–30 cm downwind, when single drops fell on a spore suspension (concentration 1.2 × 105 spores/ ml) containing fluorescein dye with a windspeed of 2 m/sec; droplets were collected up to 3 m downwind but not more than 70 cm upwind. With a windspeed of 3 m/sec, numbers of sporecarrying droplets and spores collected on film decreased with increasing distance downwind; most were collected within 2 m of the target but some were found up to 4 m. When simulated rain fell on infected stubble, increasing the windspeed from 1.5 to 4 m/sec greatly increased the number of spores deposited more than 1 m downwind. At 1.5 m/sec none were collected beyond 2 m downwind, whereas at 4 m/sec some were collected at 4 m. A few air‐borne S. nodorum spores were collected by suction samplers at a height of 40 cm at distances up to 10 m downwind of a target spore suspension on which simulated rain fell.
Pathogenicity of Fusarium avenaceum Isolates from Cereals and their Ability to Produce Substance with Yellow Fluorescence
Authors: Chelkowski J. , Mańka M. , Goliński P. , Visconti A. 
Published: May 2008

Abstract Fusarium avenaceum isolates from wheat, rye, barley, triticale, corn and potato formed substance with yellow fluorescence with properties similar to citrinin. Pathogenicity of 17 isolates tested against cereals seedlings was weaker than F. culmorum isolates; one isolate only was strong, two medium and the remaining 82 % were very weak or non pathogenic.
Manifestation et Mode de Conservation de Leveillula taurica, Agent de l'Oïdium de la Tomate au Maroc
Authors: Besri M. , Hormattallah A. 
Published: May 2008

Abstract Manifestation and conservation of Leveillula taurica on tomatoes in Morocco Powdery mildew of tomato, caused by Leveillula taurica, was considered a minor disease until 1978 when serious outbreaks occurred. These outbreaks coincided with periods of a draught and the introduction of new hybrids from Europe.The pathogen infects a variety of plants, including eleven cultivated and five wild species. Infections of tomato plants were obtained by isolates collected from cultivated plants (Cynara cardunculus, Cicerarietinum, Medicago sativa, Capsicum annuum, Tropaeolum majus) and wild species (Chenopodium ambrosioides, Sonchus asper, Oxalis cemua, Urtica urens).
The Influence of Ustilago maydis on Free Radicals Concentration in Zea mays Tissues
Authors: Michalov J. 
Published: May 2008

AbstractIn the plant Ustilago maydis causes: 1. A lowering of free radical concentrations in tissues of nodal roots and in internodial tissues close to the fungus. 2. Conversely, in tissues of the primary root, of aerial roots, of leaves and nodes 1–5, 13, 15 and 16 it causes a rise of free radicals concentration. Ustilago maydis has a similar effect upon free radicals concentration in maize leaves as Erysiphe graminis in barley leaves.
Role of Sugars and Phenols in Charcoalrot Resistance of Sorghum
Authors: Patil S. H. , Hedge R. K. , Anahosur K. H. 
Published: May 2008

AbstractTotal sugars, reducing sugars, and phenols were estimated in internodes of tolerant and highly susceptible sovhum genotypes to charcoal, ln tolerant genotypes the sugar level was 2 to 3 times higher than in susceptible ones; phenol concentration also was higher in tolerant genotypes. In tolerant genotypes, sugar and phenol concentration was high in the lower most and in the upper most mternode. This may be used to identify sources of resistance.
Effect of Fusarium moniliforme var. subglutinans Infection on Mangiferin Production in the Twigs of Mangifera indica
Authors: Chakrabarti D. K. , Ghosal S. 
Published: May 2008

AbstractThe effect of Fusarium moniliforme var. subglutinans on the concentration of mangiferin (1,3,6,7‐tetrahydroxyxanthone‐C2‐beta‐D‐Glucoside) was studied. The role of the temperature gradient on the severity of infection and mangiferin production was examined in the light of the proliferation of the fungus. The infection prevented the transportation of mangiferin from the site of its synthesis to the storage site (bark). The variation in the concentration of mangiferin was attributed to its conversion to a polymeric quinone.
Physico‐Chemical Properties of Linseed Oil as Affected by Various Seed‐Borne Fungi
Authors: Dubey G. L. , Vayas K. M. , Dubey Onkar 
Published: May 2008

AbstractThe effect of six seed‐borne fungi on linseed oil was studied. Alternaria alternate, Aspergillus flavus, Aspergillus repens, Fusarium culmorum and Torula allii reduced oil content while Cladosporum herbarum slightly increased it. All fungi increased the free fatty acid content and saponification number linseed oil. Iodine number was decreased except in Cladosporium herbarum and Fusarium culmorum. Aspergillus flavus was the most destructive parasite in altering quantity and quality of linseed oil.
Uredospore Germination and Development of Some Cereal Rusts from South‐central Chile at Constant Temperatures
Authors: Tollenaar H. 
Published: May 2008

AbstractThe minimum and maximum temperatures for germination of uredospores of Puccinia striiformis, P. recondite, P. coronata and P.gramnis isolates from south‐central Chile were 0°C and 26°C, 0°C and 32°C, 8°C and 30°C, and 4°C and 34°C, respectively, whereas the shortest latent period was 8.5 days for P. struformis at 20°C, 5 days for P. recondite at 26°C, 5.5 days for P. coronata at temperatures, reaching the minimum and maximum threshold temperatures at 0.006°C and 23°C for P. strüformis, 0.31°C for P. recondita, 2.87°C and 30°C for P. coronata, and 1.72°C and 32°C for P. graminis. rspectively.The cardinal temperatures give no explanation as to the observed sequential appearance of these rusts during the growing season. Other phenomena like the systemic mycelial growth of P.striiformis might be involved here.At temperatures between 19°C and 22°C, the average daily increase of the area of sporulation of P.striiformis in wheat leaves varied between 9.05 and 22.48 mm2/infection site. This variation was due to substrate (plant) history and environmental factors.
Relationship between Field Levels and Light and Darkness on the Development of Phytophthora Blight of Pigeon Pea (Cajanus cajan (L.) Millsp.)
Authors: Singh U. P. , Chauhan V. B. 
Published: May 2008

AbstractThe incidence of Phytophthora blight of pigeon pea (Cajanus cajan (L.) Millsp.) caused by Phytophthora drechsleri f. sp. cajani was observed in the whole area of an experimental field plot where the topography varied. There was a positive correlation between low level of the field and maximum disease incidence. The incidence of disease was lowest at high field levels. This may be due to high or low moisture contents in both the levels. Leaf blight developed more rapidly under conditions of night darkness in the field and this was confirmed under conditions of artificial darkness in the glasshouse.
Obtaining a High Percentage of Explants with Negative Serological Reactions against viruses by Combining Potato Meristem Culture with Antiphytoviral Chemotherapy
Authors: Borissenko S. , Schuster G. , Schmygla W. 
Published: May 2008

AbstractA high percentage of plantlets, in which PVX, PVM, and PVS were no longer detectable by precipitin tests was obtained from 100% virus‐infected stocks of the potato varieties Rosa and Priobskij rannija by combining meristem (tip) culture with antiphytoviral chemotherapy. When 2,4 ‐ dioxohexahydro 1,3,5‐triazinc (DHT) was added to the nutrient media, no virus was detectable serologically in 72% of the corresponding explants of the variety Rosa and in 66% of that of the variety Priobskij rannija, respectively. Contrary to this, all untreated control explants proved virusinfected. Treatment with 2‐thiouracil resulted in 46.6%, with cyanoguanidine in 28.6% of plantlets, in which no virus was detectable serologically.
Freeing Sweet and Sour Chery Trees from Prunus Necrotic Ringspot Virus by Injections of 2,4‐Dioxohexahydro‐1,3,5,‐triazine (DHT)
Authors: Bogusch L. J. , Verderevskaja T. D. , Schuster G. 
Published: May 2008

AbstractAfter three injections of 1 ml of 0.01% DHT solutions under the cortex of the stems of 100% artificially or naturally with prunus necrotic ringspot virus infected sweet and sour cherry plants of 4 varieties axillary buds were grafted onto the indicator plant Shirofugen. 99% of these buds proved virus free. Contrary to this, only 28 to 32% of the buds from solvent injected control plants proved free of viruses. About 65% of the fruit‐trees grown up from buds of DHT treated plants were still virus free, when the test procedures were performed again two years later. Treatments of the sour cherry variety Podbelskaja with DHT were by far less effective.
Pathogenicity of Fusarium oxysporum Isolates from Malaysia and F. oxysporuin f. sp. elaeidis from Africa to Seedlings of Oil Palms (Elaeis guineensis)
Authors: Ho Y. W. , Varghese G. , Aylor G. S. T. 
Published: May 2008

AbstractPathogenicity tests with Fusarium oxysporum isolated form Malaysian oil palm were made with oil palms seedlings raised form Malaysian seed as well s with wilt‐susceptible seedlings gown from African seed. Oil palm seedlings grown form Malaysian seed were also inoculated with African isolates of F. oxysporum f. sp. elaeidis and F. oxysporum var. redolens. The experiments were made under normal soil moisture conditions and under water stress. F. oxysporum f. sp. elaeidis isolates form Africa were pathogenic to oil palm seedlings from Malaysian seeds but the Malaysian F oxysporum isolates were non‐pathogenic to plams grown from Malaysian seed or the wilt‐susceptible palms from African seed. Seedlings from Malaysian seed proved to be highly susceptible to the vascular wilt disease caused by F. oxysporum f. sp. elaeidis as 75–90% of the palms were infected. The susceptibility of the palms from Malaysian seed varied with different African isolates tested. The Yaligimba isolate from Zaire which was found to be F. oxysporum var. redolens was the most virulent.Disease was more severe when oil palm seedlings were subjected to a period of water stress. The incidence of death in the seedlings under stress conditions was 45% as compared with only 15% for palms grown under normal conditions.
Survival of Phytophthora cinnamomi in Buried Eucalyptus Roots
Authors: Mackay A. , Weste G. , Sharpe K. 
Published: May 2008

AbstractColonization and survival of Phytophthora cinnamomi in roots was tested in 3 months old, axenically grown seedlings of Eucalyptus maculata (field resistant) and E. sieberi (susceptible). The roots were inoculated, then one week later were excised and buried in three non‐sterile, conducive soils; a lateritic gravel, an infertile duplex soil, a loamy sand as well as in a fertile, suppressive krasnozem. Pathogen viability, percentage root colonization and chlamydospore numbers were examined at matric potentials of −1/3, −5 and −10 bar after periods of 10, 100 and 200 days at 21°C.At 10 days, survival was 100% in the form of mycelium and the only significant difference was between the two Eucalyptus species. At 100 days survival was solely due to chlamydospores, but the pathogen was viable in all inoculated roots and at each matric potential. At 200 days soils had dried to less than −10 bars and the pathogen failed to survive. No significant differences were found between the two pathogen isolates but significant differences were obtained between the susceptible and field resistant Eucalyptus species.Pathogen viability, percentage root colonization and chlamydospore number were highly correlated with soil types and matric potential. These components declined with decreasing soil matric potential. The Krasnozem was only suppressive at relatively high soil matric potentials (−1/3 bar). At lower values (−5, −10 bar) survival of the pathogen, chlamydospore numbers and percentage colonization of the roots in the Krasnozem were comparable with that of the 3 conducive soils tested.Chlamydospores were present, but in low numbers in roots buried in the suppressive soil at −1/3 bar.
The Action of Polygalacturonase and Cellulase Enzymes of Botryodiplodia theobromae Pat. on Yam (Dioscorea spp.) and Sweet Potato (Ipomoea batatas) Tissues
Authors: Arinse A. E. 
Published: May 2008

AbstractThe action of an endo‐polygalacturonase PG3 and cellulase of Botryodiplodia theobromae, in the crude and pure forms, on sweet potato and yam slices was investigated. The purified isoenzyme PG3 and the crude pectic enzyme preparations macerated and killed the cells of both tissues although the former did so at a faster rate. Purified cellulase neither macerated nor killed cells from either plant. Although the action was delayed, the crude preparation of cellulase slightly macerated and killed the cells of sweet potato. Yam tissue was, however, not macerated by crude cellulase.Plasmolysis of the cells of both tissues delayed the toxicity and macerating action of the pure PG3 on the tissues. This delay in cell death was, however, not observed when the plasmolysed cells were treated with the crude cellulase preparation.
Fusarium oxysporum f. sp. psidii as a Pathogen Causing Wilt of Guava in Varanasi District, India
Authors: Pandey R. R. , Dwivedi R. S. 
Published: May 2008

AbstractA serious wilt disease of guava has been observed in the Varanasi district of eastern Uttar Pradesh of India. The causal organism has been identified as Fusarium oxysporum f. sp. psidii. Pathogenicity tests were performed in pot experiments to confirm the causal agent of the disease. Infected plants developed chlorosis followed by wilting of entire seedlings and leaf abscission. Histopathological studies showed the presence of hyphae in xylem vessels of roots of the wilted seedlings and when sections of such roots were transferred to potato dextrose agar medium, this pathogen grew in culture.
World Wide Distribution of a Bacterial Stripe Pathogen of Rice Identified as Pseudomonas avenae
Authors: Shakya D.D. , Vinther F. , Mathur S.B. 
Published: May 2008

AbstractSixty‐two sample of rice from 29 countries were tested for presence of Pseudomonas avenae and 55 from 28 countries proved to be infected. The presence of the bacterial stripe pathogen constitutes the first report from these countries. Infection ranged from 1 to 75%. P avenae was identified by symptoms in the seedings and its identity confirmed serologically. The bacterium was found even in 8‐year‐old seed samples which had been stored at 5°C.
Induction of Susceptibility and Resistance of Wheat Leaves by Preinoculation with High and Low Virulence Races of Puccinia recondita f. sp. Tritici
Authors: Bahamish H. S. , Wood R. K. S. 
Published: May 2008

AbstractIsolates R1 and R2 of Puccinia recondita f. sp. tritici of low or high virulence on leaves of a series of cultivars of wheat behaved very similarly up to the formation of appressoria above stomata and sub‐stomatal vesicles. Differences in growth of hyphae and in responses of host cells became clearly apparent only 24 h after infection; they then increased so that 10 days after inoculation high virulence isolates had produced freely sporulating sori (infection type 4) whereas low virulence isolates produced small colonies which did not erupt and sporulate and were associated with large numbers of dead host cells.The cultivar Timmo was selected for experiments on induced susceptibility and induced resistance. It was highly susceptible (infection type 4) to isolate Rl and to a mutant RlM, similar in pathogenicity on many cultivars but with uredospores different in colour from those of R1 and those of isolate R2 to which Timmo was highly resistant (infection type 0). This difference facilitated interpretation of results of experiments in which leaves were inoculated with more than one isolate.Inoculation with R1 (or with RUM which always behaved similarly) made leaves susceptible to R2 inoculated 4 days later. R2 sori were about 70 % the area of and about 70 % as frequent as Rl sori when inoculated on the same area on the same surface or on an area on the lower surface below a similar area on the upper surface inoculated with Rl. There also developed in the same area small, non‐erumpent colonies associated with large numbers of dead host cells; these necrotic lesions were very similar to those produced in leaves inoculated only with R2. There were significantly fewer sori and more necrotic lesions when Rl was inoculated 1 or 2 days before R2. Totals of sori and necrotic lesions were about the same when the interval between inoculations was 1, 2 or 4 days; they were also similar with an interval of 3 days when numbers of sori were substantially less than after 4 days.Inoculation with Rl had some but much less effect in making tissues susceptible to R2 when again it was inoculated later but about 2 mm away.Although inoculation with R1 sufficiently in advance had the striking effect of making tissue almost as susceptible to normally low virulence R2 as it was to R1, colonies and sori of R1 which developed in association with those of R2 were substantially smaller than those which developed when R1 was inoculated alone. But there were similar differences in sizes of colonies and sori when R1 and RIM were inoculated together or separately. They probably depended on competition for nutrients. Possible mechanisms of induced susceptibility and induced resistance and implications for disease in the field are discussed briefly.
Sporenkeimung von Phoma lingam (Tode ex. Fr.) Desm. und Resistenzprüfung bei Raps im Gewächshaus
Authors: Wittern I. , Krüger W. 
Published: May 2008

Abstract Spore germination of Phoma lingam (Tode ex. Fr.) Desm. and methods to determine resistance of oil seed rape in the greenhouse It was the aim of this investigation to obtain more insight into the epidemiology of Phoma lingam (Tode ex. Fr.) Desm. (stat. gen. Leptosphaeria maculans (Desm.) Ces. et de Not.) and to improve the existing methods for resistance testing.In laboratory experiments the differing demands on temperature of both, the sexual as well as the non sexual phase were observed. Many ascospores developed germ tubes after eight hours at 4‐8°C whilst pycnidiospores needed 24 hours at 16°C to have similar development.In greenhouse experiments young plants were infected by spraying or by placing a droplet of spore suspension onto cotyledons or leaves. Generally, ascospores were more virulent than pycnidiospores. The ascospores were obtained from old rape stalks which could be stored at ‐18°C without losing virulence. The most severe attack was observed after incorporating infested oat kernels (3 % w/ w) into soil, but the difference between cultivars vanished which was already low with the other methods, and which did not always correspond with results obtained in the field at stage 85, so that all these methods are not as suitable as those in the field.The distribution of pycnidiospores is also possible by adhering to the seed after threshing. The infection of the seedlings from this source was more pronounced in steamed than in unsteamed soil. The re‐isolation of P. lingam increased as well from plants grown in steamed soil. Furthermore, pycnidiospores are distributed by wind during combining to neighbouring fields, already prepared at that time for rape sowing.