bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differentiation of Yam Virus Isolates Using Symptomatology, Western Blot Assay, and Monoclonal Antibodies
Authors: Goudou‐Urbino C. , Givord L. , Quiot J. B. , Boeglin M. , Konate G. , Dubern J. 
Published: May 2008

AbstractMonoclonal antibodies (mAbs) were prepared against a yam mosaic virus (YMV) isolate from the Côte d'Ivoire. Symptomatology, Western immunoblotting, and ELISA were used to discriminate 69 isolates of YMV originating from different Dioscorea species and from various yam producing areas. These isolates induced two types of symptoms, were of four different electrophoretic mobilities and formed two serogroups. These results suggest that at least six differetit groups of isolates exist, three of which infect the main cultivated species in various geographical areas while two others were from unusual samples in our collection. An isolate from ‘Pilimpikou Yam’ from Central Burkina Faso was serologically distinct. It is concluded that there is a significant variability among yam virus isolates which is unrelated to the origin of the isolate (geographic or host species). It is suggested that precautions should be taken in order to avoid international exchange of infected material.
Infection of Adventitious Roots of Agrostis palustris by Idriella bolleyi1
Authors: Hodges C. F. , Campbell D. A. 
Published: May 2008

AbstractSeven isolates of Idriella bolleyi obtained from adventitious roots of Agrostis palustris displaying symptoms of thinning, low vigor, and death of turf in a random, nondescript pattern were evaluated for their ability to infect adventitious roots of A. palustris under high and low temperature regimes and to affect plant growth and symptom expression. All isolates of I. bolleyi infected roots under high and low temperature regimes and all but one isolate decreased shoot and root dry weight. Isolate IB‐2 decreased dry weight under low temperatures, but not under high temperatures. Stolon growth of root‐inoculated plants increased or remained unchanged among plants subjected to high temperature; stolon growth decreased on plants subjected to low temperature. Most isolates of I. bolleyi decreased the chlorophyll content of leaves of plants subjected to high temperature; chlorophyll content of leaves of inoculated plants subjected to low temperature remained unchanged. Hyphal growth was observed on inoculated adventitious roots and was accompanied by dark clusters of fungal cells and chlamydospores on the epidermis and cessation structures within the cortex. Vascular tissues were not penetrated by I. bolleyi. It was concluded that I. bolleyi can infect adventitious roots of A. palustris as a minor root pathogen and alter root and shoot growth.
Barley Yellow Dwarf Luteovirus (BYDV) Infectivity of Alate Aphid Vectors in Northeast Spain
Authors: Comas J. , Pons X. , Albajes R. , Plumb R. T. 
Published: May 2008

Abstract Rhopalosiphum padi and Sitobion avenae alates were collected from colonised winter cereals and maize in N.E. Spain and fed on young wheat plants for 7–10 days in the glasshouse. Then, aphids were killed and the plants on which aphids reproduced were kept in the glasshouse for 30–40 days. ELISA of infested plants was made using polyclonal and monoclonal antisera against PAV‐, RPV‐ and MAV‐like isolates. In autumn and spring, MAV serotypes were transmitted by S. avenae and R. padi, mainly in mixed infections with PAV serotypes. This possibly explains the high frequency of MAV‐like isolates and their previously recorded year‐to‐year stability in maize, grain and forage winter cereals and cereal volunteers. PAV‐like isolates were rarely transmitted by S. avenae and its spread thus depends almost exclusively on R. padi. These results confirm the importance of forage cereals and cereal volunteers as virus sources for winter cereal infection in the autumn, and the latter as a source of BYDV for maize in spring.
Root Colonization by Bipolaris sorokiniana in Different Cereals and Relations to Lesion Development and Natural Root Cortical Cell Death
Authors: LIUEROTH E. , Franzon‐Almgren I. , Gunnarsson T. 
Published: May 2008

AbstractA GUS‐transformed strain of B. sorokiniana was used to study the relationship between fungal growth, lesion development and natural root cortical cell death (RCD) in roots of different cereals. Roots of 10‐day‐old seedlings, grown on filter paper, were inoculated with the fungus and at different time intervals lesion size and GUS‐activity in the roots were determined. A significant, positive correlation was found between GUS‐activity and ergosterol content in barley roots infected with this transformed strain and these results indicate that GUS can be used as a marker to study fungal growth in plant tissue. The fungus had a slower growth rate in resistant barley varieties, i.e., those producing smaller lesions, than in more susceptible varieties.In wheat and triticale, the fungal growth was faster than in barley, despite the smaller and lighter coloured lesions in these species. This may be explained by the fact that wheat and triticale have a faster rate of root cortical senescence than barley. Presumably, dying cortex cells cannot respond to the fungal invasion by producing phenolic compounds that cause browning of the tissue. Among seven investigated cereal species, there was a positive correlation between the degree of RCD and fungal biomass increase in roots after inoculation.
Interaction Of Barley Yellow Dwarf Virus and Fusarium culmorum (W. G. Sm.) Sacc. in Winter Wheat
Authors: Koch N. , Huth W. 
Published: May 2008

AbstractThe barley yellow dwarf virus (BYDV) epidemics, which occurred predominantly in northern Germany in 1988–90 and caused unusual yield losses of wheat, prompted our study on interactions of BYDV and Fusarium culmorum. At the late stages of plant development (EC 55/65) infections with BYDV resulted in a lower yield reduction of wheat plants than infections with F. culmorum. Combined infections at flowering resulted in severer yield reduction, indicating additive effects of the two pathogens. However, if wheat infected by BYDV at stage EC 25/35 was secondarily inoculated with the fungus at EC 55/65 the yield was less reduced than in combined infections at EC 55/65. Our results proved that the susceptibility of wheat plants to F. culmorum is increased when infection by BYDV takes place during the late stages of growth. These results correspond to observations during 3 years of the epidemic in Germany. In these years BYDV was spread mainly during the late spring, resulting in a severe secondary infection by the fungus. From the results of these investigations it may be concluded that during the years of BYDV epidemic the yield of wheat was reduced to an economically important extent because of the fungal infection, which was favoured by the virus infection.
Effect of Toxic Compounds of Exserohilum turcicum on Chlorophyll Content, Callus Growth and Cell Viability of Susceptible and Resistant Inbred Lines of Maize
Authors: Chauhan R. S. , Singh B. M. , Develash R. K. 
Published: May 2008

AbstractToxicity of toxic compounds in the culture filtrates of Exserohilum turcicum towards seed germination, inhibition of shoot and root growth, callus growth and on reduction in chlorophyll content and cell viability of maize was studied. There was no germination in unautoclaved extracts at 100% (undiluted) and 50% concentrations, whereas germination was normal at all the concentrations of autoclaved toxic compounds. Inhibition of root growth was higher compared with that of shoot growth in all the test preparations of toxic compounds. Reduction in total chlorophyll and also chlorophyll a and b contents of disease resistant (KWTC‐17) and susceptible (DK‐4) inbreds occurred at 50, 25 and 10% concentrations of toxic compounds, with maximum reduction in the susceptible compared with the resistant inbred. Chlorophyll a was found to be more sensitive, showing 7.2% reduction in content in susceptible inbred even at 5% toxin concentration. Callus cultures/cell suspensions derived from coleotible nodes of DK‐4 were more sensitive compared with that of KWTC‐17 in all the test concentrations of toxic compounds. Callus growth of susceptible inbred DK‐4 was inhibited by 32.7% compared with 15.31% of resistant inbred KWTC‐17 at 5% concentration of toxic compounds. Cell viability of resistant and susceptible inbreds was 62.0% and 20.2% at 10% toxic concentration, respectively. Spore germination assay with four fungal species or leaf puncture assay were not found useful.
PAL Activity and Differential Ozone Sensitivity in Tobacco, Bean and Poplar
Authors: Biagioni M. , Nali C. , Heimler D. , Lorenzini G. 
Published: May 2008

AbstractTwo cultivars of tobacco and bean and two clones of poplar differing in their phenomenological response to ozone were exposed to a single ozone pulse. The first visible foliar injury appeared after 24–48 h in the sensitive material only. The constitutive levels of PAL activity of ozone resistant and sensitive cultivars/clones were similar. In sensitive material, ozone induced a marked, but transient, increase in PAL activity, which in tobacco cv. Bel‐W3 and Pinto bean was associated with necrosis development. In the resistant material ozone stimulated PAL activity, but the levels remained lower than those observed in the sensitive material. Quantitative and qualitative determinations of phenolic compounds were carried out in the poplar clones. In the sensitive clone only the behaviour of caffeic acid was different, an increase being observed a week after the treatment. The resistant clone exhibited marked increase of all compounds assayed. The results are discussed in relation to the possible role of PAL and secondary metabolites to ozone toxicity mechanisms.
Temperature and Effects of Seed‐borneBotrytis cinereaorAlternaria linicolaon Emergence of Linseed (Linum usitatissimum) Seedlings
Authors: Harold J. F. S. , Fitt B. D. L. , Landau S. 
Published: May 2008

AbstractExperiments were done at temperatures from 5 to 20 C to investigate the effects of infection of linseed seed (cv. Antares) byBotrytis cinereaorAlternaria linicolaon seedling emergence and to study transmission of the pathogens from seed to seedlings. In one experiment with freshly harvested seed, the maximum percentage emergence decreased linearly as the incidence ofB. cinereain seed increased from 0 to 83% at 18 C day/12 C night temperatures. In another experiment, the decrease in percentage emergence of seed associated with infection byB. cinerea.the transmission of the pathogen to seedlings to produce disease symptoms on their hypocotyls and the incidence of post‐emergence death all increased as temperature decreased from 20 to 5 C. However, the decrease in percentage emergence of seed associated with infection byA. linicolaand the transmission of the pathogen to seedlings to produce cotyledon lesions both increased as temperature increased from 5 to 20 C. There was little effect of either pathogen on the time from sowing to 36% of maximum emergence, which decreased with increasing temperature. In a subsequent experiment at 10 C comparing seed infected withB.cinereaorA. linicola.using the same seed sources as in the previous experiments, infection byA. linicoladecreased emergence more than infection byB. cinerea, even though the incidence ofA. linicolain the seed was smaller. Analyses of position and parallelism suggested that regressions of maximum percentage emergence (logitransformed) against temperature were fitted best by non‐parallel lines for seed infected byB. cinereaorA. linicola.
Influence of Pathogenic and Non‐pathogenic Bacteria on Soybean Suspension Cells
Authors: Müller J. , Vöulksch B. , Fritsche W. 
Published: May 2008

AbstractCo‐cultivations of plant suspension cultures of soybean (Glycine max) with compatible phytopathogenic (Pseudomonas syringae pv. glycinea), incompatible phytopathogenic (Pseudomonas syringae pv. tomato), and different non‐pathogenic (Erwinia herbicola, Escherichia coli) bacteria were carried out. Growth and viability (triphenyltetrazolium chloride activity) of plant cells and bacteria as well as enzyme activities of peroxidase (PO), polyphenoloxidase (PPO), and phenylalanine ammonialyase (PAL) within the plant cells were investigated over an incubation period of 7 days. The compatible pathogen inhibited growth and viability of the plant cells after 1 day and led to the death of the majority of the plant cells by the seventh day. In contrast, the incompatible pathogen directly reduced growth and viability of the soybean cells and caused a strong induction of enzyme activities of PO and PAL to more than 4 times of the untreated control by the seventh day. The epiphytic bacterium Erwinia herbicola caused a slight inhibition of growth and viability of the plant cells after the second day of co‐cultivation. The PO activity increased in the same manner as in the incompatible interaction. The saprophytic Escherichia coli strain had a negligible influence on soybean suspension cells. All the bacteria tested except for Escherichia coli multiplied rapidly during co‐cultivation and reached populations of 108‐109 colonyfoming units/ml in the stationary phase. The results from this study demonstrate that the soybean suspension cells react differently to compatible, incompatible and saprophytic bacteria.
Pre‐harvest Fungal Colonization Affects Storage Life of Bing Cherry Fruit
Authors: Dugan F. M. , Roberts R. G. 
Published: May 2008

AbstractTreatment of sweet cherry (Prunus avium cv. Bing) trees with either two mildewcide cover sprays or multiple (18) applications of topical and systemic fungicides produced cherry fruit that were either highly colonized or relatively uncolonized by fungi, respectively. Fruit from the multiple application treatment had a storage life of up to 8 weeks (7 weeks at 1‐4°C plus 1 week at simulated retail temperatures of 20–21°C), whereas the commerciallymanaged fruits (two mildewcides) were extensively colonized by fungi and extensively decayed when stored under the same conditions. Stringent post‐harvest disinfection did not significantly reduce postharvest decay, and only slightly reduced isolation frequency of fungi. The data obtained in this study suggest that the degree of preharvest fungal colonization is a primary determinant of the percentage of post‐harvest decay, and that pre‐harvest colonization can potentially be addressed by pre and post‐harvest management practices.
Changes in Pollen Viability and Concomitant Increase in the Incidence of Sorghum Ergot with Flowering Date and Implications in Selection for Escape Resistance
Authors: McLaren N. W. 
Published: May 2008

AbstractPollen viability and ergot severity were monitored in a line evaluation nursery at Potchefstroom and Bethlehem (South Africa). Percentage grain fill was also evaluated at the latter locality. Changes in pollen viability with flowering date were closely correlated with changes in ergot severity (r = 0.91 and r = 0.81 at Potchefstroom and Bethlehem, respectively). Pollen viability was significantly reduced by pre‐flowering daily minimum temperatures < 16°C at both localities during the period 23–27 days before flowering. The concomitant increase in ergot severity closely mirrored changes in pollen viability. Lines differed in their ability to tolerate low pre‐flowering minimum temperature. Lines with pollen viabilities > 60% despite pre‐flowering minimum temperature <14°C were observed. A number of lines with inherent low pollen viability, despite minimum temperatures >17°C were also found. Avoiding these in favour of vigourous pollen producers may contribute towards enhancing escape resistance in sorghum to ergot.
Rapid and Sensitive Detection of Xanthomonas fragariae by Simple Alkaline DNA Extraction and the Polymerase Chain Reaction
Authors: Zhang S. , Goodwin P. H. 
Published: May 2008

AbstractMethods for DNA preparation from Xanthomonas fragariae in infected or artificially contaminated strawberry plants were compared in diagnostic assays using the polymerase chain reaction (PCR). The bacterium was detected using PCR with primers specific to a region of its hrp gene. Sensitivity of detection was 1.25 ×l 103 CFU ml‐1 using DNA from bacterial suspensions prepared by an alkali extraction method. This was 10‐fold more sensitive than DNA extraction by boiling, and was equal to that in which DNA was prepared by a more involved cetyltrimethylammonium bromide (CTAB) procedure. Sensitivity of detection from artificially contaminated strawberry tissues was 10‐fold less than that from cell suspensions. The results indicated that a rapid and simple method of alkali DNA sample preparation is applicable for the sensitive and reliable detection of X. fragariae and possibly other plant pathogenic bacteria.
Quantitative Assessment of Lesion Characteristics and Disease Severity Using Digital Image Processing
Authors: Tucker C. C. , Chakraborty S. 
Published: May 2008

AbstractThis work describes a dedicated software which detects and characterizes disease lesions on leaves to provide data on the number and type of lesions and the percentage of leaf area diseased (severity). The software, written in C2+, can be used with a standard computer in combination with a colour CCD camera and a frame grabber for image acquisition. The usefulness and adaptability of the software was evaluated using two foliar diseases, Alternaria blight of sunflower and oat leaf rust (Puccinia coronata f.sp. avenae), which differ in symptoms. Using image segmentation and classification techniques, the software discriminated disease symptoms from the healthy leaf area. The number and size of lesions and severity, obtained using the image processing software, were compared with those calculated using a software planimeter or visual assessment. Significant linear relationships between planimeter and the imaging software were obtained for lesion number and severity in oat leaf rust and for severity in sunflower blight. Artefacts, mistakenly classified as blight lesions by the imaging software resulted in an over‐estimation of the number of lesions. Future research is aimed at improving accuracy through better illumination during image capture. A dedicated, compact and portable hardware is currently being developed for field use as a self‐contained device for disease assessment.
The Natural Occurrence of Turnip Mosaic Potyvirus in Allium ampeloprasum
Authors: Gera A. , Lesemann D.‐E. , Cohen J. , Franck A. , Levy S. , Salomon R. 
Published: May 2008

AbstractAn isolate of turnip mosaic potyvirus (TuMV) was obtained from Allium ampeloprasum grown in commercial greenhouses in Israel. Symptoms on infected plants include systemic chlorosis and yellow stripes, accompanied by growth reduction. Leaves were distorted, often showing necrotic flecking. The virus was readily transmitted mechanically, and in a non‐persistent manner by aphids, among Allium, Chenopodium. Gomphrena and some Nicotiana spp. Purified preparations contained numerous filamentous particles similar to those observed in crude extracts of infected leaves. Particles from crude plant extracts had a normal length of 806 nm. Cells of infected plants contained cylindrical cytoplasmic inclusions with pinwheel, scrolls and laminated aggregates which indicated the presence of a potyvirus of Edwardson's subgroup III. and which resemble those of turnip mosaic virus (TuMV), The virus reacted strongly with antiserum to typical isolates of TuMV in immunoelectron microscopy and western blotting but not with antisera to several other potyviruses. Based on serological reactivity, electron microscopy, aphid transmission and cytopathology, the virus was identified as an isolate of TuMV.
Phytophthora Canker Resistance in Cacao: Role of Peroxidase, Polyphenoloxidase and Phenylalanine Ammonia‐lyase
Authors: Okey E. N. , Duncan E. J. , Sirju‐Charran G. , Sreenivasan T. N. 
Published: May 2008

AbstractPeroxidase (PO) Polyphenoloxidase (PPO) and Phenylalanine ammonia‐lyase (PAL) activities in stem extracts of six cacao clones (IMC 67, ICS 1, TSH 1188, P 18, SCA 6 and TSH 1076) were measured spectrophotometrically in (i) healthy tissues; (ii) tissues wounded with a 3‐mm diameter cork borer and (iii) tissues inoculated with the canker pathogen Phytophthora palmivora. The results indicated significantly high (P < 0.05) activities of the three enzymes in extracts obtained from inoculated and wounded as opposed to those from healthy tissues. The activities of these enzymes were significantly higher in the extracts of IMC 67, low in TSH 1076, SCA 6 and P 18 and intermediate in TSH 1188 and ICS J. There was no significant difference in enzyme activities among the genotypes TSH 1076. SCA 6 and P 18 and also between ICS 1 and TSH 1188. Starch gel electrophoresis of PO indicated differences in banding pattern/band‐intensity amongst IMC 67, ICS 1 and SCA 6 and also between inoculated and uninoculated stems. These results are discussed in relation to lignin and phenol metabolism associated with plant resistance to pathogen attack.
Differential Responses of Guayule (Parthenium argentatum Gray) Genotypes to Culture Filtrate and Toxin from Macrophomina phaseolina (Tassi) Goidanich
Authors: Kuti J. O. , Schading R. L. , Latigo G. V. , Bradford J. M. 
Published: May 2008

AbstractThe potential for using cell‐free culture filtrate (CFCF) and toxin (phaseolinone) from Macrophomina phaseolina for rapid and effective screening procedures for charcoalrot resistance in guayule (Parthenium argentatum) germplasm was assessed. The CFCF and partially purified phaseolinone were incorporated into modified Murashige and Skoog solid medium aat the rates of 0‐100% (v/v) and 0‐1000 μg ml‐1 respectively. The medium pH was adjusted to 5.8 before solidifying with 0.8% agar. Fourweek‐old seedlings of 10 guayule genotypes were plantanted in the medium, incubated and rated for phytotoxic symptoms and tissue damage over a 15‐day period. In a green‐house study, seedling growth, phytotoxicity and damage severity were compared in 12‐week‐old guayule seedlings root‐inoculated with M. phaseolina microsclerotia. There were significant differences (P = 0.05) in genotypic responses to the fungus, the filtrate and the toxin inoculations. Time until phytotoxic symptoms developed was inversely related to the concentrations of CFCF and the toxin. Phytotoxic symptoms were produced 6 days after exposure to 50% CFCF and 48 h after exposure to 1000μg ml‐1 of partially purified phaseolinone. A comparison of photomicrographs of the control and toxintreated root tissues revealed no damage to the control roots and extensive damage to epidermal layers of the treated roots, which was evident 48 h after exposure to 100μg ml‐1 level of phaseolinone. Significant correlations were found between tolerance to the fungus and insensitivity to the culture filtrate (r = 0.89, P = 0.05) and the toxin (r = 0.95, P = 0.001) suggesting the possibility of screening for resistance to M. phaseolina using CFCF or phaseolinone. The genotypic reactions to the CFCF were also correlated with reactions to the toxin (r = 0.90, P = 0.05). Guayule breeding lines‘UC101 and‘P3‐1 exhibited the greatest tolerance to the pathogen and insensitivity to the CFCF or the toxin whereas‘Ca16′,‘Cal7′,‘N576′,‘N9‐5′, 11605’and‘N6‐5’were very susceptible to the pathogen and sensitive to the CFCF or the toxin.