bluuebunny/crossref_metadata_2025_split huggingface dataset:
Occurrence of Melon Necrotic Spot Virus in Crete (Greece)
Authors: Avgelis A. 
Published: May 2008

AbstractSince 1982 melon plants cv. Galia grown in plastic houses showed severe leaf and stem necrosis. A virus isolated from affected plants infected only Cucurbitaceae. Systemic infections were only developed in melon and Luffa acutangula, while a severe hypocotyl necrosis was observed in watermelon. Purified virus sedimented in sucrose gradients as a single component and reacted only with antisera to melon necrotic spot virus (MNSV). Seed transmission (22.5%) of the virus was observed m melon plants grown from seed of naturally infected melons, but the virus could not be detected in triturated seeds. The virus could be isolated from leachate of contaminated soil and melon plants became infected when grown in contaminated soil or when watered with suspensions of virus. These properties suggest that the virus is an isolate of MNSV.
Relative Heterothallism and Production of Hybrid Perithecia by Auxotrophic Mutants of Glomerella cingulata from Apple
Authors: Beraha L. , Garber E. D. 
Published: May 2008

Abstract Glomerella cmgulata is a homothallic species but produces a ridge of fertile perithecia at a frontier between certain wild‐type strains on agar. To account for the presence or absence of perithecia earlier workers suggested that alleles at A and B loci control the formation of perithecia at mycelial frontiers in + and – strains. We propose that G. cingulata actually demonstrates “relative heterothallism”. Of 7 induced nutritionally deficient mutants (auxotrophs) in 2 wild‐type strains from apple, only one methionine (met‐1) and one arginine (arg) mutant in only one wild‐type strain gave a heavy ridge of perithecia at their junctures. Neither the met‐l nor arg mutations have been identified as those in the A or B locus. The perithecia were either homozygous (selfs) for met‐1 or arg, or heterozygous (hybrids). Paired met‐1 and arg segregants from hybrid perirhecia as well as diauxotrophic strains from met‐l or arg mutants also gave hybrids of selfs. Specific nutritional deficiencies in certain wild‐type strains which can direct sexuality are not yet known. Genetic studies are now feasible in G. cingulata to define enzymatic factors responsible for pathogenicity.
The Role of Ethylene in Growth and Endopolygalacturonase Production by Sclerotium rolfsii
Authors: Madkour M. A. 
Published: May 2008

AbstractGrowth of and endopolygalacturonase production by Sclerotium rolfsii was better on a defined mineral medium than on a medium containing segments of tomato leaf petioles. The effect of treatment with ethylene (10μl/l) upon endopolygalacturonase activity with investigated at various stages of growth, in a mineral defined medium. Addition of ethylene to a 10 days‐old culture of S. rolfsii resulted in a decrease in activity by day 14, whereas the addition of ethylene to a 4, 6 and 8 days old cultures resulted in an increase in endopolygalacturonase activity. Ethylene seems to have little or no stimulating effect upon growth of S. rolfsii when applied after 8 days. However, inhibited fungal growth, after the addition of ethylene at earlier stages of growth, was obtained due to the depletion of oxygen from sealed culture flasks. Endopolygalacturonase was extracted and purified from control cultures after 14 days of growth. Fractionation of this enzyme protein on Sephadex G‐100 gel filtration columns resulted in two peaks of activity measured by the release of reducing sugars from polygalacturonic acid (PGA).
Effect of Potassium Chloride vs. Potassium Sulphate Fertilization at Different Soil Moisture on Take‐All of Wheat
Authors: Trolldenier G. 
Published: May 2008

AbstractA pot experiment was conducted with two moisture levels to study the influence of KC1vs. K2SO4 fertilization on the growth of healthy and take‐all infected spring wheat.Transpiration and diffusive resistance were measured in the flag leaves. The flag leaves of healthy plants had the highest rate of transpiration.Transpiration declined with higher incidence of Gaeumannomyces grminis var. trutici (Ggt).With low soil moisture and also with sulphate fertilization transpiration tended to be lower.The difference between sulphate and chloride fertilization was relatively greater in more severely affected than in healthy plants, in particular with lower soil moisture. The flag leaves of plants were maintained in a green state for a longer period of time by chloride fertilization. This indicates a higher and prolonged metabolic activity which is reflected in the grains yields. Yield depressions as a consequence of Ggt infection were smaller with KC1 than with K2SO4 fertilization and more marked under water stress than with optimal water supply.
Studies on the Diagnosis of Bacterial Ring Rot of Potatoes
Authors: Zeller W. , Xie Y. 
Published: May 2008

AbstractThe eggplant test, described by Olsson (1976) and Lelliott and Sellar (1976) as a means of detecting Corynebacterium sepedonicum, the causal agent of bacterial ring rot, has been tested for its reliability. Eggplants inoculated with a pure suspension of bacterial cells developed typical chlorotic symptoms at a minimum concentration of 2 × 103 cells/ml inoculum. Whereas with an inoculum which consisted of potato tissue equally mixed with the bacterial suspension, the first symptoms developed at a concentration of 104 cells/ml. Reisolation of the pathogen by the IFAS‐test or on YDC‐medium was possible following innculation at a concentration of 2 × 103 cells/ml. It was mostly possible to isolate the bacteria in pure culture. Further solanaceous host species tested in comparison with the eggplant did not develop typical symptoms following inoculation with C. sepedonicum. On this account, the eggplant test should currently be considered as the most suitable biological assay to detect C.sepedonicum.
On the Enhanced Callose Deposition in Barley with ml‐o Powdery Mildew Resistance Genes
Authors: Skou J. P. 
Published: May 2008

AbstractCarborundum treatment of barley leaves induced a callose deposition which was detected as diffuse blotches in the epidermal cells of susceptible barleys and as deeply stained tracks along the scratches in barleys with the ml‐o powdery mildew resistance gene. Subsequent inoculation with powdery mildew resulted in appositions that enlarged inversely to their size in the respective varieties when inoculated without carborundum treatment.Aphids sucking the leaves resulted in rows of callose containing spots along the anticlinal cell walls. The spots were larger in the ml‐o mutant than in the mother variety.Callose was deposited in connection with the pleiotropic necrotic spotting in barleys with the ml‐o gene. Modification of the necrotic spotting by crossing the ml‐o gene into other gene backgrounds did not result in any change in the size of appositions upon inoculation with powdery mildew.Callose deposition was never observed in cells subsidiary to the guard cells, and the absence of callose in such cells is suggested to be the reason for the sporadic occurrence of powdery mildew colonies on barleys with the ml‐o gene.
Water Stress‐Induced Changes in the Morphology of the Powdery Mildew, Leveillula taurica (Lèv.) Arn.
Authors: Caesar J. Cartey , Clerk G. C. 
Published: May 2008

AbstractWater stress in Capsiucm annuum L., induced by means of polyethylene glycol influenced the length and branching frequency of conidiophores and conidial dimensions of the powdery mildew, Leveillula taurica (Lèv.) Arn. Conidiophore branching frequency and length as well as conidial length and width decreased with decreasing relative water content. The availability of water to host plants seems to have a direct effect on the growth vigour and development of the powdery mildew possibly is suggested that water stress may be imposed on host plants by the dry harmattan season resulting in reduced growth vigour of the powdery mildew. Morphology of powdery mildew developing under low water potential may be altered.
Einfluß von Tricyclazol auf die Entwicklung und Melaningehalte der Sklerotien von Botrytis cinerea
Authors: Zeun R. , Buchenauer H. 
Published: May 2008

Abstract Effect of tricyclazole on production and melanin contents of sclerotia of Botrytis cinerea Tricyclazole retarded production of sclerotia of Botrytis cinerea on agar medium more severely than mycelium growth. At a concentration range (50–200 mg/l) that did not control Botrytis on grape leaves, sclerotia production was significantly reduced. There was a negative relation between the bleaching duration of sclerotia and the tricyclazole concentrations in the medium on which they were formed. Light microscopical studies showed that sclerotia from tricyclazole‐containing medium contained a significantly poorer developed outer melanin layer than that from the control medium. Ultrastructural studies with 5 days old untreated sclerotia revealed intense electron impermeable deposits in the intercellular spaces and a small electron dense layer in the outer cell walls, on the other hand treated sclerotia of the same age showed only sporadic small pigmented deposits between the cells and the pigmentation of the outer cell wall was absent.
Rôle de L'éthylène dans L'Accumulation de Capsidiol et la Sensibilité a Phytophthora capsici chez le Piment Traite par un Eliciteur
Authors: Molot P. M. , Toppan A. , Mas P. 
Published: May 2008

Abstract Role of ethylene in both the synthesis of capsidiol and the susceptibility to Phytophthora capsici of pepper treated with an elicitor With inoculated plants, there is a strong increase of ethylene, specially with Phyo 636. But, with plants inoculated and treated with G5 15 the quantities of ethylene are less important than with those ones inoculated and untreated with G5 15.After contamination (and only in this case), there is capsidiol synthesis as well wit h treated plants as with untreated ones, and the quantities are not significantly different.Generally, the level of induced resistance is higher wit h Phyo 636 (genetically resistant) than with Yolo Wonder (genetically susceptible).The adjunction of ethylene precursor (ACC) to G5 15 elicitor increases induced resistance with Yolo Wonder but decreases with Phyo 636: the inverse effect is observed when using ethylene inhibitor (AVG).It is suggested that, in the interaction Pepper—Phytophthora capsia, neither ethylene production nor capsidiol synthesis can be considered as biochemical tracers of induced resistance.
Dispersal of Septoria nodorum Pycnidiospores by Simulated Raindrops in Still Air
Authors: Brennan R. M. , Fitt B. D. L. , Taylor G. S. , Colhoun J. 
Published: May 2008

AbstractSimulated raindrops, diameter c. 3 or 4 mm, fell 13 m down a raintower onto suspensions of Septoria nodorum pycnidiospores, depth 0.5 mm, or infected straw pieces. Splash droplets were collected on pieces of fixed photographic film. It was estimated that one drop generated c. 300 spore carrying splash droplets, containing c. 6000 spores, from a concentrated spore suspension (6.5 × 105 spores/ml) and c. 25 spore‐carrying droplets, containing c. 30 spores, from infected straw pieces (11 × 106 spores/g dry wt).When the target was a spore suspension in water without surfactant, most spore‐carrying droplets were in the 200—400 μm size category and most spores were carried in droplets with diameter >1000 μm. When surfactant was added to spore suspensions, most spore‐carrying droplets were in the 0–200 μm category and most spores were carried in droplets with diameter 200–400 μm and none in droplets >1000 μm. Regression analyses showed a significant (p < 0.001) relationship between square root (number of spores per droplet) and droplet diameter; the slope of the regression line was greatest when surfactant was added to the spore suspensions.The distribution of splash droplets with distance travelled from the target was better fitted by an exponential model than by power law or Gaussian models. The distributions of spore‐carrying droplets and spores with distance were fitted better by an exponential model than by a power law model. Thus regressions of log, (number collected) against distance were all significant (p < 0.01); the slopes of the regression lines were steepest when surfactant was added to the spore suspension. At a distance of 10 cm from target spore suspensions most splash droplets and spore‐carrying droplets were collected at height 10–20 cm, with none above 40 cm; at a distance of 20 cm there were most at heights 0–10 cm and 40–50 cm.
Modulation des Réactions de Défense du Palmier a Huile Contre le Fusarium oxysporum f. sp. elaeidis (Schlecht) Toovey: Applications: Prémunition et Stimulation Chimique
Authors: Taquet B. , Ravisé A. , Renard J. L. , Kunesch G. 
Published: May 2008

Abstract Defence reactions of palm trees to Fusarium oxysporum f. sp. elaeidis (Schlecht) Toovey Cross protection and stimulation of inhibitory substances In palm tree genetic characters of tolerance to Fusarium oxysporum f. sp. elaeidis are correlated with synthesis of fungal inhibitors in infected tissues. Individual variation of synthesis level is also observed among plants of a same line. Defence reactions are triggered by pre‐inoculation of an avirulent strain of Fusarium oxysporum. Similar results are obtained by application of analogs of fungal elicitors like arachidonic acid. Quite the contrary, treatment of plants with a competitive inhibitor of PAL downs natural barriers and in a same way the effects of cross protection and arachidonic treatment. Seven phenolic compounds, mainly benzoic acid derivatives, inhibit in vitro the growth of pathogen like spores germination. The variability of the host reaction and its stimulation by elicitors could be used to improve the resistance.
Mise en Évidence d'une Induction de Résistance chez le Piment et la tomate Après Absorption par les Racines d'une Fraction Élicitrice Hydrosoluble
Authors: Molt P.M. , Mas P. 
Published: May 2008

Abstract Resistance induction on pepper and tomato after dipping roots into watersoluble elicitor Fractions issued from Phytophthora casici culture filtrate are generally tested for the elicitor activity on detached cotyledons, Another technic is proposed: young plants (pepper or tomato) are uprooted and their roots dipped into elicitor; after detaching the foliar organs, resistance induction is controlled against Phytophthora capsici or Phytophthora infestans.With pepper, dipping time optimum is about 48 hours; the leaves are better protected than the cotyledons.After elicitation and transplanting, resistance induction remains at the level of the leaves during about one month (50% protection) and decreases progressively beyond.Systemicity of induction is discussed and several hypothesis proposed.
Host‐Parasite Relationship in a Susceptible and a Resistant Rose Cultivar Inoculated with Sphaerotheca pannosa: I. Fungal Growth, Mechanical Barriers and Hypersensitive Reaction
Authors: Conti G. G. , Bassi M. , Maffi D. , Bonecchi R. 
Published: May 2008

AbstractConidial germination and development of Sphaerotheca pannosa were studied on a susceptible and a resistant cultivar (rose Cardinal and rose Queen Elisabeth, respectively) in relation to the morphology of the leaf surface which was examined by scanning and transmission electron microscopy.Conidial germination was completed within 24 h in both cultivars and seemed to be higher in the resistant cultivar; fungal development, however, was stopped when the haustoria containing cells became necrotic.The only morphological difference between the leaves of the two cultivars is a thinner cuticle in rose Cardinal. Wax deposits on the leaf surface are similar; a layer of substances reacting to rhutenium red, most likely glycoproteins or protein‐polysaccharide complexes, also are similar.
The Susceptibility of Monocotyledons to Agrobacterium tumefaciens
Authors: De Cleene M. 
Published: May 2008

AbstractThe susceptibility of 257 monocotyledon species belonging to 139 genera and 27 families, has been tested and the literature on this subject reviewed. In contrast with dicotyledons and gymnosperms, monocotyledons are much less susceptible to Agrobacterium tumefaciens: only 3 % of the species of monocotyledons tested were host plants, whereas 60 % of the dicotyledons and gymnosperms were susceptible. Only the closely related monocotyledon orders Liliales (6 families) and Arales (1 family) contained species that were susceptible. These results are consistent with a proposed taxonomic relationship between the Liliales and the dicotyledons. A correlation between host biochemical capabilities and susceptibility to crown gall is suggested.
Spore Deposition Velocities Measured Over a Barley Crop
Authors: McCartney H. A. , Bainbridge A. , Stedman O. J. 
Published: May 2008

AbstractDeposition velocities, vg, to horizontal slides were measured over a barley crop for a range of air spora. Slides were either freely exposed, placed on a 60 cm2 table or placed in a large beaker. Deposition velocities calculated from the spore catch on freely exposed slides were 2–3 times the sedimentation velocity for all spore classes. While exposure of slides in protected enclosure reduced turbulent deposition, the values of vg were still almost twice the sedimentation velocity. Thus caution must be advised when interpreting such deposition measurements in terms of spore concentration.
Monitoring of Virulence in Populations of Pbytophthora infestans Using a Schwarzbach Spore Trap
Authors: Skidmore D. I. , Shattock R. C. 
Published: May 2008

AbstractA modified Sehwarzbach jet spore trap was used to sample Phytophthora infestans populations in small crops of potato within polyethylene tunnels and in the field. Airborne sporangia were eaptured in the trap and deposited upon potato leaf discs, of a cultivar lacking race‐specific resistance genes, contained within the trap. Virulence characters of isolates captured in the spore trap were determined by subculturing the isolates on leaf discs of a range of potato genotypes with race‐specific resistance (R‐genes), incubating them and then recording compatible and mcompatible reactions, reactions. For four isolates of P. infestans the levels of sporulation on the differential leaf discs were noted and although cultivar × isolate interactions were inconsistent, variable light and temperature conditions had no significant effect on the reactions of the cultivars.
A Possible Role for Ferrous Complexes in Fungal Disease Suppression: Glume Blotch and Net Blotch of Cereals
Authors: Brown A. E. , Sharma H. S. S. 
Published: May 2008

AbstractGermination of spores of Septoria nodorum and Pyrenophora teres was inhibited and germ‐tube growth in germinated spores was reduced b y ferrous ions complexed with a number of cheiating agents. No such inhibition was observed with ferric complexes and none of the chelating agents in the desferri form was toxic to the fungi. The germination mechanism in spores suspended in ferrous‐2,3‐dihydroxybenzoic acid (Fe11‐DHBA) for 24 h could not subsequently be released to any great extent by incubation with ethylenediamjne‐di (o‐hydroxyphenyl‐acetic acid) (EDDHA).Lesion development by the fungi in the presence of ferrous complexes on detached leaves of host plants was almost totally suppressed, but compounds which preferentially chelate ferric ions, used in the desferri form significantly stimulated lesion development by S. nodorum on wheat leaves. Cermination, appressorium formation and lesion development on leaves of host plants were also significantly reduced by Fe11‐DHBA when plants were sprayed to run‐off up to 5 days prior to inoculation.Disease development and subsequent 1000 grain weight loss were reduced by approximately 50 percent in wheat and barley plants when the flag leaves were treated with Fe11‐DHBA (5 × 10−4 M) prior to inoculation with S. nodorum and P. teres respectively, compared with inoculated, untreated plants.
Effect of Cuticle Treatments on Infection of Phaseolus vulgaris by Rhizoctonia solani
Authors: Stockwell Virginia , Hanchey Penelope 
Published: May 2008

Abstract Rhizoctonia solani, the causal agent of stem canker of beans, does not commonly infect beans more than two weeks old. Treatment of the cuticular layer by abrasion or chloroform rinsing results in decreased cuticular autofluorescence and the ability of stains to penetrate the hypocotyl surface. Infection cushions preferentially formed near these treated areas on both young and old plants. The morphology of infection cushions on older plants is simpler than those found on young, susceptible plants, but they are fully competent to form lesions.
The Adsorption of a Polygalacturonase Isoenzyme of Botryodiplodia theobromae on Plant Tissues and the Implication on the Pathogenicity of the Fungus
Authors: Arinze A. E. 
Published: May 2008

AbstractThe polygalacturonase isoeazyme (PG 3) of Botryodiplodia theobromae extracted from rotted sweet potato was adsorbed by sweet potato, potato, carrot, bean stem and tomato fruit to various degrees. Adsorption was greater with sweet potato and tomato fruit tissues. Carrots, bean stem and potato absorbed the enzyme to more or less the same degree. The enzyme was not adsorbed on tomato stem. A spore/mycelial suspension of B. theobromae infected the test tissues to various degrees. The enzyme completely macerated sweet potato roots, potato tubers and tomato fruits within 5 h while the bean stem and onion tissues were little affected by the enzyme. The tomato stem was neither infected by the fungus nor macerated by the enzyme.
Interactions between the vesicular‐arbuscular mycorrhizal fungus Glomus fascicuhtum and Aphanomyces euteiches root rot of peas
Authors: Rosendahl S. 
Published: May 2008

AbstractInteractions between Glomus fasciculatum and Aphanomyces euteiches root rot of peas (Pisum sativum), were studied in pot experiments using irradiated soil.Infections with the pathogen were suppressed by VAM when plants were challenge inoculated after two weeks. No reduction of the pathogen was detected when the plants were inoculated with both fungi at the same time.The suppression of the pathogen, obtained by preinoculation with G. fasciculatum, was not reduced when the inoculum level of the pathogen was increased thirty times.The induced resistance to A. euteiches in VAM plants was partially a systemic effect. When root systems were split into two halves, one with mycorrhiza and one with A. euteiches, the oospore production was reduced in both root systems. The infection with the pathogen was only suppressed when both fungi were present in the same pot. The background for the induced resistance is discussed.