bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Wheat Streak Mosaic Virus Infection on Total DNA and Chloroplast Ribosomal RNA in Wheat Leaves
Authors: Brakke Myron K. , White J. L. , Samson R. G. , Joshi J.
Published: May 2008

The amount of chloroplast 23s rRNA relative to either DNA or to cytoplasmic 28s rRNA was reduced in young wheat leaves infected with wheat streak mosaic virus.

Chlorophyll was reduced in infected leaves. Fresh weight per leaf and DNA content per leaf were reduced in infected leaves, but DNA per g was increased.

Cytoplasmic ribosomal RNA appeared to degrade more slowly during senescence in infected leaves than in uninfected. Virus was undetectable by density gradient centrifugation in systemically infected leaves less than 6 cm long and reached its highest concentration when young leaves reached their maximum size. Mosaic developed in leaves that became infected when 5 cm long or less. Since the entire leaf eventually developed mosaic, the events leading to mosaic occur after cell division, which is limited, to the basal cm of young leaves.
Induction of Pathogenesis‐related Proteins in Barley during the Resistance Reaction to Mildew
Authors: Bryngelsson T. , Gustafsson M. , Leal M. Ramos , Bartonek E.
Published: May 2008

Changes in the soluble protein pattern of leaves of eight lines of barley, carrying different resistance genes to mildew, were analysed by SDS‐polyacrylamide gel electrophoresis and isoelectric focusing. Apparently new host proteins were induced by Erysiphe graminis f. sp. hordei in the incompatible reaction which were not present in the immune or susceptible response. These proteins are of low molecular weight, 13,500–27,500 d, and have either very low or very high isoelectric points. Thus, they resemble the pathogenesis‐related proteins found in many dicotyledonous species.
Resistance to Leptosphaeria maculans in Hybrids of Brassica oleracea and Brassica insularis
Authors: Mithen R. F. , Lewis B. G.
Published: May 2008

The inheritance of hypersensitive resistance to Leptosphaeria maculans in a cross between B. oleracea var. alboglabra and B. insularis was studied. Analyses of F1 and F2 progeny suggested that resistance is determined by two dominant, independently‐segregating genes. F1 hybrids were semifertile but normal levels of fertility were restored in a proportion of the F2 progeny.
Phyllody Disease of Crotalaria saltiana in the Sudan: Transmission to Catharanthus roseus and Detection of MLOs by Fluorescence and Electron Microscopy
Authors: Dafalla G. A. , Cousin M. T.
Published: May 2008

Phyllody disease of Crotalaria saltiana Andr. first noted in the Sudan in 1962, was recently observed in many localities in the Gezira province in the central region of the country. Diseased plants generally exhibited stunting and excessive proliteration of lateral shoots (witches' broom growth) with small and chlorotic leaves. Morphological transformations of flowers were the most striking symptoms. Floral segments showed various stages of virescence and phyllody as a part of a complete transformation of floral buds into leafy branches. The Crotalaria phyllody agent was transmitted by grafting to faba bean (Vicia faba L.) and with dodder from the latter to periwinkle (Catharanthus roseus). The symptoms reproduced in C. roseus resembled those induced in it by the faba bean phyllody MLO (mycoplasma‐like organism), suggesting a close relationship between the two agents. Fluorescence and electron microscopy were used to detect and characterize MLO in diseased plants. Fluorescence reactions in sieve tube elements were observed in sections stained with the DNA‐binding fluorochrome Bisbenzimid H 33258. Electron microscope observations in corresponding zones permitted the visualization of wall‐less pleiomorphic MLOs confined to sieve tube elements of the phloem tissues of diseased plants.
Pathogenicity of Race‐1 and Race‐2 Tomato Wilt Isolates of Verticillium dahliae from Different Geographical Origins
Authors: O'Garro L. W. , Clarkson J. M.
Published: May 2008

Fourteen race‐1 and race‐2 isolates of Verticillium dahliae from North America, Europe and Australia were screened against the near isogenic pair of tomato cultivars Roma and Roma VF. The foliar symptoms, extent of stunting and vascular colonization were assessed. Race‐1 isolates were significantly more pathogenic on Roma which lacks the Ve resistance gene. Race‐2 isolates from N. America were more pathogenic than those from Australia. All isolates tested colonized both cultivars to some extent although the level of colonization by race‐1 isolates was significantly higher in Roma than in Roma VF. All race‐1, and the majority of race‐2, isolates caused stunting of Roma. No isolates stunted Roma VF.
Dependence of the Effectiveness of Induced Resistance on Environmental Conditions
Authors: Falkhof A.‐G. , Dehne H.‐W. , Schönbeck F.
Published: May 2008

Resistance induced by microbial metabolites against powdery mildew on barley always proved to be highly effective particularly under practical conditions in field. The results obtained in the present study demonstrate that the successful induction of resistance requires a conditioning of plants by the environmental conditions acting prior to the application of the inducer. If plants were grown in the greenhouse or outdoors, the infection densities were efficiently reduced after the treatment with the inducer. In contrast to this the disease intensities were not reduced on plants grown at constant temperature, light and humidity conditions. Frequently changing temperatures and the daily courses of temperature, normally occurring in greenhouse or outdoors, were substantiated as the most important factors for a successful induction of resistance. The conditioning of the plants under these temperature conditions depended on light energy, especially in just developing leaves. The dependence of the induced resistance on the environmental conditions was proved with other host‐pathogen‐relationships as well as with barley and powdery mildew.
Characterization of Isolates of Bacterial Blight of Cotton (Xanthomonas campestris pv. malvacearum) from Nicaragua
Authors: Zachowski A. , Rudolph K.
Published: May 2008

Seeds from cotton plants infected with Xanthomonas campestris pv. malvacearum were collected in different parts of Nicaragua in 1986. When the seeds were homogenized the pathogen could not always be identified by dilution plating. Therefore, an enrichment of bacteria on the natural host was induced before isolation. The cotton seeds were shaken with water and sand for 2 days and then sown in sand for germination. Rather often the developing cotyledons showed typical water‐soaked spots, from which the pathogen could be isolated easily. This new method needed more time but made it possible to detect a low level of bacterial infestation. Altogether, 42 bacterial isolates were obtained.

For inoculation experiments suspensions with 5x105 CFU ‐ ml−1 were infiltrated into cotton leaves. Incubations of inoculated plants in growth chambers, but not in greenhouses, resulted in typical and uniform disease symptoms (water‐soaked leaf spots). Nine of the ten cotton differentials tested were highly susceptible to all the 42 bacterial isolates. Since only line 101‐102B proved to be resistant, the Nicaraguan isolates of bacterial blight of cotton were characterized as race 18, of the pathogen. The main cotton cultivars grown in Nicaragua (H‐373 and G‐286) were strongly affected by the isolated bacterial strains. In order to reduce the disease incidence in Nicaragua, the cultivation of resistant cotton varieties is suggested.
Stimulation of Fruit Ethylene Production by Wounding and by Botrytis cinerea and Geotrichum candidum Infection in Normal and Non‐Ripening Tomatoes
Authors: Barkai‐Golan Rivka , Lavy‐Meir Gila , Kopeliovitch E.
Published: May 2008

Inoculations with both Botrytis cinerea and Geotrichum candidum stimulated ethylene evolution in the pre‐climacteric normal tomato fruit and the non‐ripening nor mutant which did not show any rise in ethylene when uninfected. In the post‐climacteric normal fruits, new peaks in ethylene production were formed. The rise in ethylene evolution in all types of infected fruits has already been detected during the incubation period of the disease. Ethylene peaks were detected earlier and were higher in fruits infected with B. cinerea than with G. candidum, coinciding with the faster rate of growth of the former. Mechanical wounding also stimulated ethylene synthesis by the non‐ripening fruits, production being directly proportional to wound dimension. Considerably higher rates of ethylene were recorded for infected fruits than for mechanically‐injured fruits in which wound dimensions were similar to those of lesion development.

Applying aminoxyacetic acid at the site of inoculation inhibited ethylene production by 55–60 % in the normal fruits and by about 80 % in the nor mutant fruits. A similar pathway of ethylene synthesis was suggested for normally ripening tomato fruit and non‐ripening infected tissues.
Transmission of a New Mycoplasma‐Like Organism (MLO) from Cuscuta odorata (Ruiz et Pav.) to Herbaceous Plants and Attempts to its Elimination in the Vector
Authors: Heintz W.
Published: May 2008

A new MLO‐type, originating from a holoparasite plant Cuscuta odorata (Ruiz et Pav.) causing stunting and reduction of flower‐ and leaf size on Catharanthus roseus (L.) G. Don. (HEINTZ 1986) was transmitted to Apium graveolens L., Plantago major L., Bellis perennis L. and Cirsium japonicum hybrid. The observed symptoms on the test plants probably caused by the MLO have not yet been described in the literature. The symptomatology on these herbaceous plants gives further data in order to classify the MLO as a new one which is named Guscuta latent MLO (Cl‐MLO). Attempts to transmit the pathogens by the leafboppers Euscelidius variegates (Kirschbaum) and Euscelis lineolatus (Brullé) failed. It also was impossible to elimmate the MLO completely from Cuscuta odorata by heat treatment and antibiotic application. However, we succeeded in eliminating the pathogens from Catharanthus roseus by heat treatment.
Influence of Plant Growth Regulators on Growth and Virulence of Rhizoctonia solani (Kühn) Pathogenic to Groundnut Seedlings (Arachis hypogaea L. var. TMV 2)
Authors: Reddy M. N. , Strzelczyk E.
Published: May 2008

Growth of R. solani was markedly influenced by GA3, kinetin but not by lAA. The mycelium used for inoculation of groundnut hypocotyls was obtained from cultures grown on solid media supplemented with various concentrations of GA3, kinetin and IAA. The virulence was evaluated by measuring the lesion size 48 h after inoculation. Gibberellic acid followed by kinetin caused enhanced lesion size at 0.5 μg/ml in the medium. A correlation was observed between the infection cushions produced and the virulence of the pathogen.
Occurrence in Soil and Primary Infections of Pseudomonas corrugata Roberts and Scarlett
Authors: Scortichini Marco
Published: May 2008

The occurrence of Pseudomonas corrugata in soil has been checked. Semiselective medium TNR (a modified SNR) permitted to isolate the causal agent of “tomato pith necrosis” from that source. The average soil population of the bacteria was 3.1 × 104 CFU × g of soil. P. corrugata was also isolated from plants sowed in the naturally infected soil. It was supposed that primary infections came from here.
Direct Introduction of Fluorescein Isothiocyanate‐conjugated Albumin into Intact Macroconidia of Fusarium oxysporum f. sp. lycopersici by Electroporation
Authors: Matsuda Y. , Toyoda H. , Nishiguchi T. , Ouchi S.
Published: May 2008

An electroporation procedure for the introduction of fluorescein isothiocyanate‐conjugated albumin into intact macroconidia of Fusarium oxysporum f. sp. lycopersici was performed in this paper. FITC‐albumin was used to establish an efficient electroporation procedure because its presence in spores could be easily detected by fluorescence microscopy. The uptake of fluorescein isothiocyanate‐conjugated albumin into spores was successfully mediated by high voltage electrical pulses at field strength of 10 KV/cm. In electroporation of 106 macroconidia per ml with the present system, 1.2 × 105 spores incorporated the protein, and then 3.1 × 104 normally germinated, elongated vegetative hyphae, and produced spores.
Roditis Leaf Discoloration ‐ A New Virus Disease of Grapevine: Symptomatology and Transmission to Indicator Plants
Authors: Rumbos I. C. , Avgelis A. D.
Published: May 2008

The symptoms and some characteristics of an unreported disease of grapevine, which was observed during the last years on the cv. ‘Roditis’ in central Greece, are described. The disease is transmissible to V. vinifera‘Mission’ and to some herbaceous test plants. The constant association of a virus to naturally infected plants cv. ‘Roditis’ and chip‐budding infected indicator plants cv. ‘Mission’ supports the evidence that the disease is caused by a virus.
Epidemics of Diseases and Pests of Winter Wheat at Different Levels of Agrochemical Input
Authors: Daamen R. A. , Wijnands F. G. , Vliet G. vander
Published: May 2008

The cropping system with winter wheat has changed considerably during the past fifteen years in the Netherlands. Crop biomass has been increased by use of new cultivars and higher levels of fertilizers and pesticides. The question which arises is to what extend the level of fertilization affects epidemics of pests and diseases, compared to the well‐known effects of pesticides and cultivars. Epidemics observed in the winter wheat fields of the Development Farming System project (DFS) at Nagele, in 1984 and 1985 provided data for this analysis. Higher levels of fertilization stimulated epidemics of yellow rust, mildew, snow mould, leaf miners and cereal leaf beetles in the fields. The magnitude of the effect was comparable to those of the pesticides used and the cultivars sown. The level of fertilization showed no effect on five other species. How these interrelations between cropping practices and the associated development of pests and diseases can be used to design an integrated approach towards cereal cropping and breeding is discussed.
Dracaena Leaf Proliferosis, a Newly Recorded Disease Affecting Dracaena sanderiana in Egypt
Authors: Wagih E. E. , Shehata M. R. A. , Farag Samia A. , Dawood M. K.
Published: May 2008

Dracaena leaf proliferosis is a newly reported disease affecting Dracaena sanderiana in Egypt. A cause and effect relationship between this disease and the fungus,Fusarium proliferatum var. minus has been established. In addition to D. sanderiana the fungus was found to be pathogenic, when tested in the laboratory, to several other members of the family Liliaceae. While the in vitro growth of the fungus is optimum at 25 °C, symptom expression is best at 30°C. Twelve fungicides were tested for their in vitro effect on fungal growth. Benlate, Rubigan, Saprol, Cercobin and Vitavax‐200 came first on the list and inhibited growth at 2.5, 12.0, 55.0, 75.0, and 94.0 μg/ml, respectively. Although, Benlate was the most effective fungicide in this respect it failed to demonstrate similar effect on disease development when applied to plants artificially inoculated with the fungus. Fungal growth was completely inhibited on PDA medium by a bacterium belonging to Bacillus sp. but when the bacterium at a concentration of 1 × 1011 cell/ml was applied 24 h before, at the same time with, or 24 h after inoculation no control of the disease was achieved. Naturally‐infected plants could, however, be freed from infection when subjected to a hot air treatment at 35 ± 5 °C during day time and 25 ± 5° C at night for 3 months.
The Development of Infection Structures of Sderotium cepivorum on Onion
Authors: Stewart A. , Backhouse D. , Sutherland P. W. , Fullerton R. A.
Published: May 2008

Growth of Sderotium cepivorum mycelium on root tissue differed from that on stem tissue. Hyphae grew along the lines of the longitudinal epidermal cell walls often producing side branches which resulted in a distinctive pattern of growth. Penetration occurred mainly between anticlinal wall junctions with occasional direct penetration through the periclinal wall. Growth on the surface of the stem resulted in the formatíon of donne shaped infection cushions, arising from repeated dichotomous branching of hyphal tips. Penetration of the stem tissue occurred solely from these structures.

The results of experiments using artificial membranes and surface replicas indicated that the stimulus for attempted penetration was chemical in nature but that the nature of the infection structure produced was determined by the relative strength of the tissue under attack.
Epirus Cherry Virus, an Unusual Virus Isolated from Cherry with Rasp‐Leaf Symptoms in Greece
Authors: Avgelis A. , Barba Marina , Rumbos I.
Published: May 2008

Severe rasp‐leaf symptoms were observed on a cherry tree in an orchard in northwestern Greece. A virus, given the proposed name Epirus Cherry Virus (EpCV), was mechanícally isolated, which on the basis of biological, morphological and serological properties, appeared different from all known viruses associated with or causing rasp‐leaf symptoms on cherry. The virus has at least three types of particles sedimenting as three components in a sucrose density gradient. No serological relations were found with other similar viruses.
Use of Monoclonal Antibodies for Differentiation of Different Isolates of Phytomonas (Plant Trypanosomatids)
Authors: Petry K. , Gargani D. , Baltz Th. , Kastelein P. , Dollet M.
Published: May 2008

The Phytomonas genus was created arbitrarily to designate plant trypanosomes. A serological study with polyclonal and monoclonal antibodies was carried out to situate these trypanosomatids with respect to other trypanosomatids ‐ Herpetomonas, Crithidia, Trypanosoma ‐ and to compare different plant trypanosome strains with each other. The use of monoclonal antibodies directed against two different isolates makes it possible to distinguish plant trypanosomatids according to their geographical origin and to separate clearly the plant trypanosomatids from the South of France from other lower trypanosomatids, which seems to justify creating the Phytomonas genus.
Elimination of Mycoplasma‐like Organisms from Witches' Broom Infected Sweet Potato
Authors: Green S. K. , Luo C. Y. , Lee D. R.
Published: May 2008

The witches' broom disease of sweet potato has so far been reported only from Asia and the South Pacific. To insure safe distribution of germplasm it is important that vegetative material introduced from regions in which this disease is present has to be free of this pathogen. Meristem tip culture was found to be effective in eliminating MLO from infected sweet potato tissue. On the other hand, all plantlets originating from 1 cm long stem tips immediately below the meristems developed typical witches' broom symptoms as early as 5 weeks after excision of the stem tips. A high percentage of stem tips originating from cuttings previou.sly treated with 25, 50 and 100 mg tetracycline for 3 days developed into healthy plants. Similarly, more than 90 % of plants derived from stem tips excised from cuttings which had received a one‐month heat treatment at 37°C remained without symptoms for 9 months.
Induction of Disease Resistance by Nɛ‐Trimethyl‐L‐Lysine in Bean Plants Against Uromyces phaseoli
Authors: Tyihák E , Steiner U , Schönbeck F
Published: May 2008

The endogenous primary amino acid derivative N‐Trimethyl‐L‐lysine (TML) induces resistance in bean plants against the biotrophic fungi Uromyces phaseoli The effectiveness of protection depends on the interval between treatment and inoculation of the plants and on the dosage of applicated TML It acts as resistance inducer within two concentration ranges of 103–10‐3 and 103–1010 mol/l, respectively, if applied 6 or 8 days after inoculation
Detection of Petunia Asteroid Mosaic, Carnation Ringspot and Tobacco Necrosis Viruses in Ditches and Drainage Canals in a Grapevine‐Growing Area in West Germany
Authors: Koenig Renate , Rüdel Maria , Lesemann D.‐E.
Published: May 2008

A number of virus isolates were obtained from ditches and drainage canals in the Palatinate grapevine‐growing area (‘Rheinpfalz’) in West Germany. By means of the immunoelectron microscopical decoration and the agar gel double diffusion tests these isolates were identified as petunia asteroid mosaic virus, carnation ringspot virus and tobacco necrosis virus strain D, respectively.
Pod Spot and Seed Blight: A New Disease of Mesquite Caused by Macrophomina phaseoVma
Authors: Muchovej J. J. , Campelo C. R. , Dos Santos J. M. , da Cruz Filho J.
Published: May 2008

A new disease of pods and seeds of mequite caused by Macrophomina phaseolina is described from Northeastern Brazil. Affected pods showed a brown discolouration which often included pycnidia of the fungus. Infected seeds did not germmate.
UDP‐N‐Acetylglucosamine and Uridine Pools in Puccinia striiformis Infected Wheat
Authors: Backer A. , Wagner K. G.
Published: May 2008

The uridine diphosphate sugar pools were analyzed in young wheat plants at the three leaf stage in which the distal half of the second leaf was uniformly infected with Puccinia striiformis. Whereas UDP‐glucose did not change significantly, UDP‐N‐acetylglucosamine, the precursor of fungal chitin synthesis, was very low in the control and the healthy proximal part of the infected second leaf but increased markedly (250 nmol per g dry weight) in the infected distal half. Of the nucleosides only uridine increased in the infected distal half which was interpreted to indicate a recycling of the UDP moiety of the chitin precursor. Inorganic phosphate determinations showed a strong accumulation not only in the infected distal half but also in the healthy proximal part of the infected second leaf.
Protection Induced by Protein‐Lipopolysaccharide Complexes in Tobacco Leaves: Role of Protected Tissue Free‐space Solutes*
Authors: Minardi Paola , Fede Alessandro , Mazzucchi Umberto
Published: May 2008

Hypersensitive confluent necrosis in tobacco leaves, caused by Pseudomonas syringae pv. aptata, is prevented by an intercellular injection of protein‐lipopolysaccharide (pr‐LPS) complexes 48 h earlier. An increase (48 %) in the peroxidase activity and a new low molecular weight protein (ε 17.5 kD) were found in the intercellular fluid of protected tissue (treated fluid) 48 h after pr‐LPS infiltration. Up to 24 h after pr‐LPS infiltration the treated fluid did not inhibit the in vitro growth of heterologous bacteria. Injected into tobacco leaves 30 min before the bacteria, the treated fluid retarded the rate of intercellular bacterial growth between 8 and 12 h after infiltration of the bacteria compared with the control fluid. Up to 4 h after injection, the attachment of live and dead bacteria to the cell walls occurred in both the protected tissue and in the control; 4 h after injection, however, the dead bacteria were only weakly attached in the protected tissue. Within 20 min after the intercellular infiltration, there was a decrease in the heterologous bacterial number in the protected tissue, 33 % less than that in the control tissue.

Protected tissue free‐space solutes did not have a direct antibacterial effect but activated an antibacterial response in the leaf tissue. Attachment of bacteria to the cell walls did not in itself trigger hypersensitive confluent necrosis. The protected tissue was initially more favourable for the survival of heterologous bacteria.
Assessment of the Effect of Oil on the Potyvirus Aphid Transmission Process
Authors: Qiu Ji Yan , Pirone ThomasP.
Published: May 2008

Mineral oil sprays applied to plants or to artificial membranes were assessed for their effect on virus and helper component (HC), both of which are required for aphid transmission. Probing oil‐treated surfaces prior to or after probing a virus‐HC mixture, HC, or virus, reduced or abolished transmission. Oil also inhibited transmission when contacted after aphids had penetrated membranes which contained a virus + HC mixture. Oil had no apparent effect on aphid probing behaviour. The data support the hypothesis that oil affects the interaction of virus and HC with aphid mouthparts or alimentary tract.
Haustorium Formation and Cell Wall Appositions in Susceptible and Partially Resistant Wheat and Barley Seedlings Infected with Wheat Leaf Rust
Authors: Jacobs Th.
Published: May 2008

Phase contrast light microscopy observations of wheat and barley seedlings infected with wheat leaf rust spores suggested that cell wall appositions are structural barriers against haustorium formation leading to abortion of infection structures. Nearly equal numbers of cell wall appositions per infection structure were detected in seedlings of susceptible and partially resistant wheat genotypes. Differences between susceptible and partially resistant genotypes became evident after the first haustorium had been formed. This again indicates the presence of a post‐haustorial effect of partial resistance. Some factors influencing nutrient uptake are discussed.

Wheat leaf rust colonies hardly formed haustoria in barley seedlings, the few not aborted infection structures were accompanied by cell collapse. The mechanisms of partial resistance in wheat and barley to their respective leaf rust fungi seem different, but their non‐host reactions appear similar.
Infectivity Studies on Cucumber Mosaic Virus Treated with a Clay Material
Authors: Piazzolla P. , Palmieri F. , Nuzzaci M.
Published: May 2008

Montmorillonite, an expansible layer silicate, proved to be the main component of the sediments present in river waters in which cucutnber mosaic virus (CMV), a widespread plant virus, was found. Infectivity assays carried out after treatment of a virus suspension with this clay material, revealed that montmorillonite adsorbed most of the virus‐associated infectivity and saved the infectivity of a CMV suspension even after exposure at high ionic strength (lM LiCl).
Extracellular Enzymes of Colletotrichum nicotianae Causing Tobacco Leaf Anthracnose in Nigeria
Authors: Oke O. A.
Published: May 2008

Bioassays for extracellular enzyme production were carried out in cultures of Colletotrichum nicotianae and in tobacco leaves infected with the same organism. Pectinolytic and cellulolytic enzymes were produced abundantly in culture and in diseased leaves. The activity of pectinesterase was highest at 40 °C and about pH 6. The greatest activity of carboxylcellulase was between 40° and 50 °C and at pH 6. These findings are discussed in relation to the probable roles of these enzymes in pathogenicity.
Analysis of Cross‐Reactive Antigens of Phytophthora fragariae and Strawberry and their Relation to Resistance and Susceptibility
Authors: Mohan Sudesh B.
Published: May 2008

The presence of cross‐reactive antigens between five isolates of P, fragariae (Pf 1, Pf 2, Pf 3, Pf 10 and Pf 11) belonging to five physiological races of the fungus and five strawberry cultivars (Cambridge Favourite, Hapil, Red Gauntlet, Siletz and 52AC18) exhibiting different disease responses to the five isolates was demonstrated by Western blotting. Antiserum anti‐H, raised against extracts of healthy Cambridge Favourite roots, detected two antigens which were common to all isolates. Concentration of one of these antigens might be related to the pathogenicity of P. fragariae isolates. Antiserum anti‐PfM, raised against mycelial suspensions from the five isolates, detected a doublet of 64 and 61 kDa in the soluble extracts of healthy roots from the five cultivars tested. The corresponding root suspensions revealed numerous other antigens which reacted with anti‐PfM.

In susceptible interactions, the doublet described above and two additional polypeptides of 38 and 31 kda were detected in large concentrations in both the soluble extracts and root suspensions. These four polypeptides were shown to be present in the healthy roots as well as in the mycelial extracts. In resistant interactions, a 116 kDa polypeptide, present in the root suspensions of the healthy host, was detected in the soluble extracts of the infected roots. It is suggested that these antigens might have a role in resistance and susceptibility.
A New Leaf Spot of Ginger in Southern Africa and its Control
Authors: Grech N. M. , Wtllers P. , Frean R. T. , Marx D. H.
Published: May 2008

Khuskia oryzae Hudson was consistently isolated from ginger plants with a severe leaf spot disease, and its pathogenicity confirmed experimentally. All available commercial ginger selections were found to be susceptible to the disease in field and glasshouse trials, selection Gl being the most susceptible. In chemical control trials in the field, iprodione and a mixture of benomyl, mancozeb and soluble boron gave the best control. Soil fumigation with hot methyl bromide also reduced disease.
Efficacy of Certain Nonfumigant Nematicides on the Control of Pigeonpea Wilt Involving Heterodera cajani and Fusarium udum
Authors: Hasan A.
Published: May 2008

The efficacy of aldicarb, carboturan and phorate nematicides on the control of wilt disease complex involving Fnsarium udum was studied in pot culture. The two pathogens interacted synergistically. The severity of the disease complex was significantly reduced at all the dosages of these nematicides but the greatest reduction occurred at the highest dosage (20 mg a. i. Kg soil). The final total population of H. cajani was significantly reduced by F. udum as well as by these nematicides. These nematicides adversely affected not only the developmental stages of nematode resulting in a significant increase in 3rd—4th stage juveniles and decrease in 2nd stage juveniles, adults and cysts, even impeded the fecundity of the nematode.
Oversummering Hosts For Some Cucurbit Viruses in the Jordan Valley
Authors: Al‐Musa A. M.
Published: May 2008

Variable mosaic and yellow symptoms were often encountered in weeds growing during the summer of 1987 and 1988 in the Jordan Valley. Cucumber mosaic virus was recovered in the summer only from Dolicus lablab or from Solatium nigrum. In addition to the cucurbit weeds watermelon mosaic virus‐2 occurred in Malva parviflora. Zucchini yellow mosaic virus was found in all tested cucurbit weeds except for Ecballium elaterium. Moreover this virus was isolated from Sysimbirium irio and Crepis aspera. Cucumber vein yellowing virus was recovered from some cucurbits with vein yellowing.
Systemic Invasion of Plum Seed and Fruit by Xanthomonas campestris pv. pruni through Stalks
Authors: Plessis H. J. du
Published: May 2008

Many fruits on Golden King plum trees inoculated through the stalks with Xanthomonas campestris pv. pruni developed unusual lesions extending from the exocarp to the endocarp. A few uninoculated, diseased fruits had similar lesions. The pathogen was isolated from both inoculated and uninoculated stalks and from seeds inside fruits. Scanning electron microscopy of inoculated stalks and mature fruits with unusual lesions revealed that vascular channels of the stalk, seed coat, stony endo, carp, and mesocarp were filled with masses of X. campestris pv. pruni. Bacterial colonies also occurred in other tissues of these fruit parts but were apparently absent from the starchy endosperm or surface of the diseased exocarp. This is the first full report of systemic movement of X. campestris pv. pruni to seed and fruit through stalks.
A Rapid Viability Test for Sclerotia with Fluorescein Diacetate
Authors: Dittmer U. , Weltzien H. C.
Published: May 2008

Four different fluorescent dyes Acridine Orange (AO), Fluorescein Diacetate (FDA), Calcofluor White M2R (CW), and Europium (III) Thenoyltrifluoroacetonate, 3‐Hydrate (Eu(TTA)3) were tested to distinguish rapidly between dead and living sclerotia from Sclerotinia trifoliorum. FDA, 0.01% diluted in phosphate buffer, had the shortest staining period and was easy to handle. It is especially suitable to test large numbers of sclerotia for viability. Furthermore the preparation of the samples for the staining procedure is described in this paper.
Nachweis des Teleomorph Mycosphaerella graminicola (Fuckel) Schroeter (Anamorph: Septoria tritici Rob. apud Desm.) in der Bundesrepublik Deutschland
Authors: Verreet J. A. , Hoffmann G. M. , Portner J.
Published: May 2008

Evidence of the teleomorph Mycosphaerella graminicola (Fuckel) Schroeter. (anamorph: Septoria tritici Rob. apud Desm.) in the Federal Republic of Germany

Due to the fullfillment of certain biological requirements, the dominant occurrence of Septoria tritici is restricted mainly to the milder climate of maritime regions. However, following mild winters in continental climatic zones, an increased and yield damaging appearance, which is additionally influenced by early sowing dates, can be observed. Previous proofs of the teleomorph Mycosphaerella graminicola (Fuckel) Schroeter were found in Australia, Brazil, Great Britain, Chile and the USA., With the first proof of teleomorph in Bavaria and herewith the complete life cycle, the optimum mechanism for an early and widespread primary infection of young wheat plants has been confirmed.
Assessment of Anthracnose Disease in Some Cultivars of Cowpea (Vigna unguiculata) Caused by Colletotrichum lindemuthianum
Authors: Latunde‐Dada A. O.
Published: May 2008

Anthracnose disease was assessed in populations of five cowpea cultivars: Farin Juda‐C, Ife Brown, Market Brown, IT82E‐60 and TVX 3236. Disease progress was estimated by weekly measurements of the length of necrotic lesions on stems as well as by a visual symptom assessment key. Direct significant correlations were obtained between visual assessment scores and the lengths of peduncle lesions in three comparisons using cultivars of varying susceptibility. In addition, the response of hypocotyls excised from the seedlings of these cultivars corresponded with adult plant reactions to Colletotrichum lindemuthianum. The significance of these results is discussed in relation to currently available information on other anthracnose diseases.
Analysis of Pectic Enzyme Zymograms of Fusarium Species.
Authors: Szécsi Á.
Published: May 2008

Zymograms of the extracellular polygalacturonase (PG), produced by isolates of F. culmorum and F. graminearum originating from different geographic locations and different sources, were compared. PG patterns were prepared by polyacrylamide gel electrophoresis (PAGE) and isoelectric focusing (IEF) of untreated fluid from liquid pectin salts cultures.

There was no intraspecific variability between isolates of both Fusarium species. Electrophoretic and isofocusing PG patterns were species specific. On the basis of IEF patterns, F. culmorum (4 isozymes, estimated pI's 6.4, 6.6, 6.9, 7.1) and F. graminearum (5 isozymes, estimated pI's 6.4, 6.6, 6.9, 7.1, 7.5) could be separated from one another by the pH 7.5 PG isozyme.
Pathogenicity of Fusarium graminearum Chemotypes Towards Corn, Wheat, Triticale and Rye
Authors: Logrieco A. , Manka M. , Altomare C. , Bottalico A.
Published: May 2008

The pathogenicity of nine Fusarium graminearum isolates belonging to three different trichothecene‐producing chemotypes, i.e. NIV + FUS, DON + 3‐AcDON, and DON + 15‐AcDON was tested on corn, wheat, triticale and rye. Although these compounds are known to have different toxicity, no difference in pathogenicity was observed among the mean values for chemotypes. However, within each chemotype there were isolates with different pathogenicity which was not correlated with the ability to produce trichothecenes in vitro. The pathogenicity of each isolate was almost the same for all tested cereals. The involvement of trichothecenes in pathogenesis was investigated in infected corn stalk tissues. All the expected trichothecenes were detected with the exception of NIV and FUS.
Characterization and Serological Detection of Four Closterovirus‐like Particles Associated with Leafroll Disease on Grapevine
Authors: Zimmermann D. , Bass P. , Legin R. , Walter B.
Published: May 2008

Four serologically unrelated closterovirus‐like particles (GLRV‐1, GLRV‐2, GLRV‐3 and GLRV‐4) were isolated in our laboratory from leafroll diseased grapevines. Polyclonal antibodies raised against these particles were useful for their characterization and their detection in infected plants.

The coat proteins of these four serotypes were characterized by a SDS‐PAGE after denaturation, followed by a transfer on nitrocellulose sheet and immunoprinting using the specific polyclonal antibodies. The capsid of GLRV‐1, GLRV‐2, GLRV‐3 and GLRV‐4 contains a single protein species with molecular weight of about 39 Kd, 26 Kd, 43 Kd and 36 Kd respectively. No serological relation was found between these four filamentous particles either by ELISA, immuno electron microscopy or immunoblotting experiments.

Serological analysis of many grapevines originating from the Middle East and Europe showed a very close association between the presence of GLRV‐1, GLRV‐2, GLRV‐3 and GLRV‐4 antigens, and leafroll symptoms on Vitis vinifera Pinot Noir. This association was confirmed by testing symptomless and diseased grapevines collected in the field, and by serological analysis of heat treated plants originally infected by GLRV‐1 and GLRV‐3, which are the most widespread antigens detected in leafroll infected grapevines.
Features of Resistance to Take‐all Disease in Cereal Species Evaluated by Laboratory Assays
Authors: Solel Z. , Ben‐Ze'ev I. S. , Dori S.
Published: May 2008

Development of take‐all disease, caused by Gaeumannomyces graminis var. tritici, on wheat, barley and rye, respectively, susceptible, moderately susceptible and resistant under field conditions, was evaluated by laboratory assays. The root system, which grew either in vermiculite in plastic tubes or polyethylene sleeves, or in a sand mix in plastic pots, was inculated, and lesion frequency and extension, both considered as resistance factors, were monitored. In assays in tubes and pots, both enabling multiple infection points, the infection scores of wheat, barley and rye on a scale of 0–5 were in decreasing order. In assays in sleeves, with a single point inoculation, lesion length on barley and rye was similar and less than thaton, wheat, but percentage of infected roots was markedly lower on rye than on barley. For large‐scale screening programs we suggest to employ both the Tube Assay, which is reliable and easy to perform and the Slanted Sleeve Assay, which is more sensitive allowing detection of even a small degree of resistance. Selected accessions could be subsequently evaluated by the Pot Assay, under more natural conditions, and the resistance to take‐all must eventually be verified under field conditions.
In vitro Translation Studies with cDNA Clones Corresponding to the RNA's of Barley Yellow Mosaic and Barley Mild Mosaic Viruses
Authors: Pröls Markus , Davidson Andrew , Schell Jeff , Steinbiss Hans‐Henning
Published: May 2008

RNAs isolated from a mixture of barley yellow mosaic virus (Ba YMV‐NM) and barley mild mosaic virus (BaMMV previously BaYMV‐M) were used as templates for cDNA synthesis. Southern blot hybridization analysis revealed that the cDNA library contained 4classes of non‐cross hybridizing cDNA clones. The largest cDNA clone of each class was used for hybridization to the viral RNAs of BaMMV and BaYMV. This resulted in the identification of 4 individual cDNA clones which cover approximately 80% of RNA 1 and 90% of RNA 2 for each virus. The cDNA clones plM7 (6.3 kb) and psM18 (3.5 kb) correspond respectively to RNA 1 and RNA 2 of BaMMV whilst plY29 (6.4 kb) and psY35 (3.7 kb) correspond to BaYMV RNA 1 and RNA 2. Restriction enzyme analysis suggested that th,e two viruses have genomes with a substantially different nucleotide sequence. In vitro transcripts were prepared from the cDNA clones and used for in vitro translation. Only one strand of each of the cDNA clones was found to code for protein products. The in vitro translation assays support the view that BaYMV and BaMMV are different viruses.
Symptomatological and Morphological Study of the Resistance of Wild Beet Species of the Patellares Section to Cercospora beticola Sacc.
Authors: Carels Mr. N. , Dekegel D. , Van Heule Mrs. G. , Lepoivre P.
Published: May 2008

The reactions of Beta procumbens C. Sm. and Beta webbiana Moq. were compared to those of Beta vulgaris L. with regard to an infection by Cercospora beticola Sacc. The fleck reaction obsrved in B. webbiana may be interpreted as hypersensitivity based on symptomatological, light microscopical, fluorescent microscopical and electron microscopical data. The B. procumbens clone was found to show resistance characteristics similar to those of B. webbiana and B. vulgaris, as it reacted both by flecks (B. webbiana) and leaf spots (B. vulgaris) to a C. beticola infection.
Evaluation of the Single Tillers Method for Yield Loss Assessment in Wheat Under Israeli Conditions
Authors: Shtienberg D. , Dinoor Amos , Marani Avishalom
Published: May 2008

A method for estimating disease induced yield losses by using single wheat tillers as experimental units was evaluated under commercial field conditions. Natural epidemics of Septoria tritici blotch, yellow rust and leaf rust which developed late in the season had no effect on the vegetative growth of the host, but caused only reduced kernels weight. The optimal sample size was determined experimentally to be 300 tillers. Losses were also estimated in the same experiments using field plots as experimental units. Yield loss estimates derved from using single tillers were significantly correlated with those derived from using field plots. The relationship between disease and yield varied significantly among fields, even in a given year, region and cultivar. Thus, it was concluded that this relationship has to be established empirically wherever yield losses are to be estimated, and that under Israeli conditions it may be done by using the single tillers method.
The Loss of Structural Integrity in Damaged Spruce Needles from Locations Exposed to Air Pollution I. Mesophyll and Central Cylinder
Authors: Hasemann Gudrun , Wild Aloysius
Published: May 2008

Abstract In connection with the new type of forest damage, the individual disease situation of two‐year‐old spruce (Picea abies) needles was analyzed histopathologically in forest areas exposed to different levels of O3‐, SO2‐ and NO3‐ pollution.

Early damage results from losses of chlorophyll in the mesophyll cells. The bleaching is more intensive towards the apex in severely damaged needles. The cytoplasm is aggregated at the cell wall and the chloroplasts show definite structural damage as well.

The mesophyll cells below the epidermis, or the cells adjacent to the vascular bundle sheath, appear to be particularly susceptible. Collapsed cells (bone cells), which increase in number with damage, can lead to tissue death in certain needle areas, (brown tips, transverse bands).

Necrotic spots are manifested as groups of dissociated cells in which hypertrophic and collapsed cells as well as abnormal proliferations can be observed.

Hypertrophy and cell collapse appear in the central cylinder in addition to severe phenol deposits.

Bone cells and chlorophyll losses can already be detected in the green needles of damaged trees, indicating latent damage, which becomes macroscopically visible only after more extensive damage.

Our results indicate that no biotic stress factors take part in the damage of the spruce needles investigated here. Anthropogenic air pollutants in addition to abiotic stress factors must be regarded as a main cause of damage.
Elicitor–like Substances Present in Barley and Wheat Seeds
Authors: Yamada T. , Hiramoto T. , Tobimatsu R. , Shiraishi T. , Oku H.
Published: May 2008

Abstract Barley and wheat seeds contain elicitor–like substances which induce the production of antifungal substances in the host plants effective against powdery mildew fungi. Seed extract per se does not exhibit direct antimicrobial activity but induces the resistance response on the host. It also induces the systemic resistance in juvenile leaves. Host resistance induced by the treatment with seed extract shows some degree of cultivar specificity.
Ethylene Stimulation During the Hypersensitive Reaction of Soybean to Tobacco Necrosis Virus under Different Photoperiods
Authors: Pennazio S. , Roggero P.
Published: May 2008

Abstract The production of stress ethylene was increased in soybean leaves hypersensitively responding to tobacco necrosis virus, independently of photoperiod. However, only little increase occurred under continuous darkness, whereas most occurred under continuous darkness, whereas most occurred under continuous light. Ethylene stimulation paralleled accumulation of 1‐aminocyclopropane‐1‐carboxylic (ACC) and its conversion to ethylene. Continuous darkness substantially inhibited viral antigen accumulation but not lesion area in comparison to continuous light. Ethylene release, viral lesion area and antigen accumulation were substantially increased when darkened leaf tissues were fed with glucose, this suggesting that dark inhibition was due to energy and/or, metabolic depletion. Co2+ and aminoethoxyvinylglycine, which completely inhibited stress ethylene, and ACC, which conspicuously increased it, had no effect on both viral lesion and antigen accumulation.

These results indicate that stress ethylene developing during a HR to virus does not affect the localizing mechanism operating during it.
Production of Monoclonal Antibodies Against Banana Bunchy Top Virus and Their Use in Enzyme‐Linked Immunosorbent Assay
Authors: Wu R. Y. , Su H. J.
Published: May 2008

When purified banana bunchy top virus (BBTV) was used to immunize Balbc mice, all 480 wells from one fusion contained hybridomas and culture fluid from 92% of them showed a positive reaction to BBTV using plate trapped antigen (PTA) ELISA (also known as indirect ELISA). After a third screening, 84 hybridoma cell lines retained their ability to produce BBTV‐specific antibodies. Fitry‐eight monoclonal cell lines with the ability to produce BBTV‐specific antibodies. were obtained when these hybridomas were cloned by limiting dilution to single cells. The antibodies produced by these monoclonal hybridomas were mostly isotype IgG2a. The titres of antibody in culture supernatant and ascitie fluid of one clone were 104 and 104, respectively, while those of another clone were as high as 104 and 104. Hybridomas produced 40 to 62 times more anti‐BBTV specific antibodies in mouse ascites than in culture. The minimum active concentration of purified immunoglobulin produced by three hybridomas ranged from 0.03 to 0.06 μg/ml, while the minimum detectable concentration of BBTV antigen was 0.26 μg/ml with PTA ELISA. Antibody trapped antigen (ATA) ELISA (also known as direct ELISA) was 16 times more sensitive than PTA ELISA in detecting BBTV. Although PTA ELISA could not detect BBTV in crude extract of diseased tissues, ATA ELISA was able to detect the virus even when the extract was diluted 1/512.
Investigations on Alternaria solani Infections: Detection of Alternaric Acid and a Susceptibility‐Inducing Factor in the Spore‐germination Fluid of A. solani
Authors: Langsdorf G. , Furuichi N. , Doke N. , Nishimura S.
Published: May 2008

Abstract The spore‐germination fluid of Alternaria solani was examined for factors which are important in the early stages of infection and probably explain the selectivity of A. solani to tomato and potato as host plants. The following activities of the spore‐germination fluid were found: 1. Host‐selective toxicity at low concentrations. 2. Infection promotion and enhancement of A. solani infections on host plants when spore‐germination fluid was added to the inoculum. 3. An induction of susceptibility which enabled a non‐pathogenic A. alternata isolate to cause necrotic spots on the leaves of the host plants of A. solani when its inoculum contained spore‐germination fluid of A. solani. Properties 1 and 2 seemed to, be attributed to alternaric acid. This phytotoxin was detectable in effective concentrations in the spore‐germination fluid. A factor, responsible for the susceptibility‐induction for A. alternata on the host plants of A. solani was characterized as a water‐soluble fraction of the spore‐germination fluid which was free of alternaric acid and not toxic.