bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence for Complementation of Plant Potyvirus Pathogenic Strains in Mixed Infection
Authors: Mansky L. M. , Durand D. P. , Hill J. H. 
Published: May 2008

AbstractSeveral strains of soybean mosaic virus (SMV) can be differentiated on the basis of the phenotypic response of various soybean cultivars (e.g., the soybean line Williams ‘82 is susceptible to all SMV strains, whereas the lines P. I. 96983, L78‐379, and Davis are functionally immune to SMV strain G2 but susceptible to strains G7 and G7a). Inoculation of the immune lines with G2, followed 2 days later by inoculation with G7 or G7a, resulted in systemic spread of the avirulent SMV G2. Further evidence, suggests that complementation groups of SMV strains may exist.
Analysis of Variance‐Mean Relationships of Plant Diseases
Authors: Yang X. B. 
Published: May 2008

AbstractDisease variance‐mean relationships and the underlying mechanisms were examined using three approaches. First, data on four foliar diseases were collected, the variance of a disease increased geometrically, reached the maximum, and decreased geometrically when disease means were low, mediate, and high, respectively. There were great variations of variance values in the mediate ranges. Second, it was mathematically proven that the variance of a disease has an upper limit of variance (Vmax)that follows a quadratic function. When a disease is rated in a range from 0 to C, the upper limit of variance (Vmax) follows a quadratic function as Vmax=CM‐M2 where M is disease mean. For the scale 0–10 or percentage [0–100]. the functions are Vmax= 10M‐M2 or Vmax=100M‐M2, respectively. A variance‐mean relationship is dis‐tributed within the region defined by the V,max function. Third, a spatio‐temporal simulation model was used to examine the effect of three spatial components, dispersal capacity, aggregation of initial inoculum, and geographic distribution of initial inoculum, on disease variance‐mean relationship. The variance values inreased as the dispersal capacity decreased. The variance values inreased when pattern of mitial inoculum changed from regular pattern to aggregation or as the degree of aggregation increased. There was an interactive, effect between the two components on the variance values. Furthermore, when epi‐demics started from situations having the same degree of aggregation but different geographic distributions for initial inoculum, the variance‐mean relationships weredifferent. Variance values varied greatly even the degree of aggregation was constant. The inportance of these results in relation to interpretation of field experiments was discussed.
Further evidence for the recognition of Ullucus Mild Mottle Virus as a Distinct Tobamovirus
Authors: Offei S. K. , Ibidapo O. , Brunt A. A. , Coutts R. H. A. 
Published: May 2008

AbstractThe affinities of Ullucus mild mottle virus (UMMV). purified by a modified procedure. were examined by immunoblotting and probing with antisera to five distinct tobamoviruses. RNA. isolated from purified virus, was used for in vitro protein translation in a wheat germ system and the products examined by denaturing polyacrylamide gel electrophoresis. The results of these investigations, together with a study of the double‐stranded RNAs associated with infection. confirm that UMMV is a distinct, tobamovirus which has close affinities with tobacco mosaic, tomato mosaic and cucumber green mottle tobamoviruses and more distant relationships with ribgrass mosaic and odontoglossum ringspot tobamoviruses.
Identification of Xanthomonas campestris pv. Juglandis from (Persian) English Walnut Nursery Trees in South Africa
Authors: Du Plessis H. J. , van der Westhuizen T. J. 
Published: May 2008

AbstractBacterial isolates producing yellowish colonies on Nutrient Agar were recovered from symptoms of suspect walnut blight disease on leaves of nursery trees in the southwestern Cape Province of South Africa. The isolates were identified by pathogenicity tests on leaves of walnut and plum trees in the greenhouse. Fifteen isolates from four cultivars at two nurseries produced typical lesions of blight on walnut and one isolate. typical lesions of bacterial spot disease on plum leaves. Cluster analysis was done on 28 characteristics recorded from colony growth. colour. form. and elevation on four different culture media, and starch hydrolysis on a semi‐selective medium for the isolation of Xanthomonas campestris pv. juglandis. Total DNA of the isolates was digested with restriction endonuclease Spel and resolved by contour‐clamped homogeneous electric field (CHEF) electrophoresis. Two phenotypic clusters were distinguished among the 15 South African and one reference strain of X.c.pv. juglandis at the 54%Ssm level. The isolate which induced disease symptoms on plum grouped with reference strains of Xanthomonas campestris pv. pruni in a third cluster. Two‐thirds of the isolates were not characterized on the semi‐selective medium for X.c. pv. juglandis. DNA restriction fragment banding patterns were similar for most isolates of X.c.juglandis in the same phenotypic cluster. However, DNA banding patterns were non‐distinct for some isolates with similar phenotypic characters. Phenotypic characteristics and DNA restriction fragment banding patterns of the isolates were not correlated with geographical origin or cultivar specificity.
Detection of Tobacco Rattle Virus in Potato Tubers and Roots by Polymerase Chain Reaction (PCR)
Authors: Weidemann H.‐L. 
Published: May 2008

AbstractTobacco rattle virus (TRV) was detected by PCR in potato tubers and in root samples. Oligonucleotide primers were synthesized to nucleotides of the 16 k protein gene of RNA‐1 of the TRV strain ‘SYM’. After phenol extraction of the total nucleic acids of the samples and reverse transcription. the PCR reaction mixture was subjected to 25 cycles and the amplification product was detected by electrophoresis. TRV RNA was found in roots and in freshly harvested tubers in September, as well as in tubers which were stored until March. This indicates that there was no elimination of TRV during the storage period. The field samples of potato cv. Désirée tested in September were symptomlessly infected. whereas the stored tubers of various cultivars showed, internal symptoms. Nucleic acids extracts of latently‐infected and spraing‐affected tubers inoculated on tobacco plants led to local necrotic rings. Nucleic acids from infected tobacco cv. Samsun plants led to systemic symptoms as well. TRV was identified by ISEM and ELISA only in the systemically‐infected tobacco plants, but not in the locally infected tobacco plants. This suggests the presence of the ‘NM’ type of TRV in tubers, which produces only RNA‐1 but no complete virus particles.
Routing of the G Protein During Maturation of Festuca Leaf Streak Rhabdovirus in its Plant Host
Authors: Lundsgaard T. 
Published: May 2008

AbstractBy immunogold labelling the location of Festuca leaf streak virus glycoprotein (FLSV‐G) was investigated in developing phloem and mature leaf parenchyma of Festuca gigantea infected with Festuca leaf streak virus (FLSV: Rhabdotiridae). In developing phloem cells, FLSV‐G was detected in endoplasmic reticulum (ER). at perinuclear membranes, and in assembled virions, but neither in Golgi stacks and Golgi vesicles nor at the plasma membrane of infected cells. These results indicate that FLSV‐G stays in the ER after transmembrane synthesis, and is not routed through the secretory pathway in F. gigantea. The membranous inclusions, present in infected mature leaf parenchyma cells were found to contain FLSV‐G. It is suggested that the, virus‐induced membranous inclusions have developed from FLSV‐G‐containing ER.The residence of FLSV‐G in ER (present study) is in contrast to results with vesicular stomatitis virus (VSV; vertebrate rhabdovirus). Here the G protein is known to be routed to the plasma membrane through the secretory pathway.
A Stochastic Model Incorporating the Effect of Weather Conditions on Anthracnose Development in Stylosanthes scabra
Authors: Chakraborty S. , Smyth G. K. 
Published: May 2008

AbstractSpatial and temporal progress of anthracnose caused by Colletotrichum gloeosporioides in quantitatively resistant accessions of the tropical pasture legume Stylosanthes scabra were studied in a field experiment at the Southedge Research Station, Queensland, Australia. In a previously published work a conditional ordinal logistic regression model was developed to explain the probability of a plant developing a given disease severity level, depending on its previous disease state and that of its neighbours. In the present study this model is augmented to incorporate the effects of three weather variables which were measured daily during a growing season. Two approaches were used: (a) threshold values for relative humidity (RH), rainfall and net evaporation were used to classify days as suitable or unsuitable for anthracnose growth; (b) days were assumed to vary continuously in their rate of anthracnose growth depending on the numerical values of the weather variables. High 9am RH, low net evaporation and low 9am temperatures are significantly associated with anthracnose growth. Net evaporation proved to be a better index than rainfall and heavy rainfall was not conducive to high levels of anthracnose; however, rainfall was useful once evaporation was taken into account. The effect of 9am RH can be described either by a threshold value around 70% or by a quadratic function. A two‐variable model with net evaporation and log(rain+1) explains 97.6% of the available deviance.
Rhizoctonia spp. Associated with Container‐Grown Ericaceous Plants in Scotland
Authors: Litterick A. M. , McQuilken M. P. , Holmes S. J. 
Published: May 2008

AbstractFungi with Rhizoctonia‐like mycelia were isolated from the foliage, stem‐base and roots of ericaceous plants collected from nurseries in Scotland. Isolated fungi were identified as either binucleate Rhizoctonia spp. or Rhizoctonia solani on the basis of hyphal characteristics and nuclear number. The optimum temperature range for growth of binucleate Rhizoctonia spp. and R. solani was 20 and 25 C, resepctively. All isolates tested for pathogenicity caused foliar browning, and webs of mycelial growth were observed on dead and dying foliage. Binucleate Rhizoctonia spp. and R. solani are recorded for the first time on container‐grown ericaceous plants in Scotland.
Development of Hemileia vastatrix in Coffee Plants With Genetic or Induced Resistance
Authors: Martins E. M. F. , Moraes W. B. C. 
Published: May 2008

AbstractSystemic resistance to coffee rust (Hemileia vastatrix) was induced in susceptible cv, ‘Mundo Novo’ by spraying foliage with a yeast filtrate. The stages of fungal development were compared in leaves of untreated (MN), induced ‘Mundo Novo’ (MN‐I) and coffee rust resistant segregants of the hybrid ‘Sarchimor’ (Sch). Development of H. vastatrix was observed at intervals of 228 h after inoculation. The expression of resistance was detected 48–72 h after inoculation. In Sch, it occurred at the one haustorial mother cell (HMC) stage, whereas in MN‐I, it occurred at the 2nd HMC stage. In Sch the majority of aborted colonies were associated with necrotic host cells, and the collapsed fungal hyphae exhibited a yellow autofluorescence which was observed in necrotic cells of the host. In MN‐I, 80% of the colonies could not be visualized 72 h after inoculation and host cells at the infection sites were not necrotic.
Septoria Leaf Speck, a New Disease of Sunflower, Caused by Septoria helianthina sp. nov.
Authors: Petrov Marija , Arsenijevic M. 
Published: May 2008

AbstractMany strains of a pathogenic fungus were isolated from diseased sunflower leaf tissue. According to their characteristics they belonged to the genus Septoria. Leaf speck symptoms, characteristic for spontaneous infection, were also reproduced by artificial inoculation of sunflower plants in the greenhouse.Comparing the morphological, cultural and pathogenic properties of the isolated fungus with other sunflower pathogens, it was indicated that the strains, originating from diseased sunflower leaves represented a new, so far not described species. Therefore, for the causal agent of this disease, the name Septoria helianthina Petrov & Arsenijevic was suggested.
Molecular Characterization of the Plant Pathogen Verticillium dahliae Kleb. Using RAPD‐PCR and Sequencing of the 18SrRNA‐Gene
Authors: Messner R. , Schweigrofler W. , Ibl M. , Berg G. , Prillinger H. 
Published: May 2008

AbstractThirty‐four isolates of Verticillium dahliae Kleb. from nine different genera of dicotyledonous host plants and a broad range of geographic regions were analysed genotypically, Random amplified polymorphic DNA (RAPD) markers were used for the estimation of the genetic variability within the species. Using four primers for the analysis, 79 distinct fragments were obtained. The derived phenogram clustered the isolates in two main groups; one consisted almost entirely of V. dahliae isolates from oilseed rape (Brassica napus napus), the other group comprised isolates from a wide range of host plants. No correlation between geographic location of the isolates and the RAPD‐pattern was observed.Sequencing of the gene for the 18SrRNA and calculation of the phylogenetic tree integrated the deuteromycetous fungus V. dahliae into the sexual system of the filamentous ascomycetes.
Relationships Among Group IV Phytophthora Species Inferred by Restriction Analysis of the ITS2 Region
Authors: Tooley P. W. , Carras M. M. , Falkenstein K. F. 
Published: May 2008

AbstractThe polymerase chain reaction (PCR) was used to amplify the ITS2 region of nuclear ribosomal DNA from six Phytophthora species which comprise taxonomic Group IV. Digestion of the ca. 600 bp PCR product with restriction enzymes Alu I, Dra I, Hha I, Hinf I, Msp I, and Taq I revealed variation which allowed relationships among the species to be assessed. P. infestans, P. mirabilis and P. phaseoli were indistinguishable from one another with all enzymes tested. With Alu I and Taq I. P. ilicis, P. colocasiae. and P. hibernalis each showed unique banding patterns different from the common banding pattern shared by P. infestans. P. mirabilis. and P. hibernalis. Dra I allowed differentiation of P. ilicis and P. colocasiae from P. infestans, P. mirabilis, P. phaseoli, and P. hibernalis. all of which shared a common banding pattern. Hha I allowed differentiation of P. colocasiae and P. hibernalis from P. infestans, P. mirabilis, P. phaseoli, and P. ilicis. Hinf I allowed differentiation of P. ilicis and P. hibernalis, (each of which showed a unique banding pattern) from P. infestans, P. mirabilis, P. phaseoli, and P. colocasiae. Msp I allowed differentiation of P. hibernalis from the other five species. Species groupings determined by restriction analysis of ITS2 were consistent with those based on morphological criteria. These results show that restriction analysis of PCR‐amplified TS2 regions can be useful as an adjunct to morphological criteria in Phytophthora species identification.
Extraction of DNA from Phytophthora infestans Using QIAGEN Columns
Authors: Tooley P. W. , Carras M. M. 
Published: May 2008

AbstractHigh molecular weight DNA of Phytophthora infestans was extracted using a modification of the commercial QIAGEN column procedure. Both a ‘maxi’ and ‘mini’ procedure are described. The maxi procedure utilizes a QIAGEN‐tip 500 column while the mini procedure utilizes a QIAGEN‐tip 20 column. When fungal protoplasts were used as starting material from 9 g (fresh weight) of mycelium, nearly 500 μg of DNA in the size range of 20–200 kb was obtained and the product was successfully used in construction of a lambda genomic library. The modified QIAGBN method can replace the more timeconsuming, and expensive cesium chloride density gradient centrifugation for extraction of ultra‐pure DNA from P. infestans.
Incorporating an Asymptotic Parameter into the Weibull Model to Describe Plant Disease Progress
Authors: Xiao C. L. , Subbarao K. V. , Zeng S. M. 
Published: May 2008

AbstractThe Weibull model is a flexible growth model that describes both general population growth and plant disease progress. However, lack of an asymptotic parameter has limited its wider application. In the present study, an asymptotic parameter K was introduced into the original Weibull model, written as; y=K{1 − exp [− (t−a)c]}, in which a, b, c and K are location, scale, shape, and asymptotic parameters, respectively, y is the proportion of disease and t is time. A wide range of simulated disease progress data sets were generated using logistic, Gompertz and monomolecular models by specifying different parameter values, and fitted to both original and modified Weibull models. The modified model provided statistically better fits for all data than the original model. The modified model can thus improve the curve‐fitting ability of the original model which often failed to converge, especially when the asymptote is less than 1.0. Actual disease progress data on wheat leaf rust and tomato root rot with different asymptotic values were also used to compare the original and modified Weibull models. The modified model provided a statistically better fit than the original model, and model estimates of asymptotic parameter K were nearly identical to the actual disease maxima reflecting the characteristics of the host‐pathosystem. Comparison of logistic, Gompertz, and Weibull models including parameter K by fitting to the observed data on wheat leaf rust and tomato root rot revealed the applicability of the modified Weibull model, which in a majority of cases provided a statistically superior fit.
Characteristics of a PCR‐Based Assay for In Planta Detection of Xanthomonas campestris pv. pelargonii
Authors: Sulzinski M. A. , Moorman G. W. , Schlagnhaufer B. , Romaine C. P. 
Published: May 2008

AbstractPolymerase chain reaction (PCR) amplification was carried out with a primer pair targeting a sequence in the genome of Xanthomonas campestris pv. pelargonii, the causative agent of bacterial blight in geraniums. PCR amplification with the primer pair XcpMl/XcpM2 using total nucleic acid preparations from 22 geographicallydiverse isolates of X. campestris pv. pelargonii generated a major 197 bp DNA product. In contrast, no major amplification products were consistently generated from 12 other pathovars of X. campestris or from 19 isolates representing 10 different plant pathogenic bacteria, including two other bacterial pathogens of geraniums, Corynebacterium fascians and Pseudomonas cichorii. After PCR using this primer pair, between 1380 and 13800 copies of the X, campestris pv. pelargonii bacterial DNA target as template were detected by ethidium bromide staining of agarose gels, and between 13.8 and 138 copies by blot hybridization to a pathovar‐specific biotinylated probe. Similarly, between 630 and 6300 colonyforming units (CFU) of X. campestris pv. pelargonii could be detected after ethidium bromide staining of agarose gels, and between 63 and 630 CFU after blot hybridization. The PCR‐based assay was used to identify X. campestris pv. pelargonii in diseased geraniums; whereas discrete amplification products were not obtained with healthy plants.
Genetic Relatedness Among Strains of Heterobasidion annosum as Detected by Random Amplified Polymorphic DNA Markers
Authors: Karjalainen R. 
Published: May 2008

AbstractHeterobasidion annosum, the casual agent of root and butt rots of trees is one of the most important plant pathogens in temperate coniferous regions of the world. It is comprised of several intersterility groups with different host preferences. Of the H. annosum isolates from various geographical regions belonging to various intersterility groups, 36 showed group‐specific banding patterns in RAPD assay. More polymorphisms were found within the S‐ and F‐group isolates than in the P group. Genetic similarities among the isolates were determined by UPGMA clustering revealing the presence of four major clusters: P, S, F, and the North American S. The P group was the most distinctive of all the other groups, while the European S and F and the North American S were more closely related. The P group showed only 20% similarity to the other groups and may be referred to as a subspecies. The North American S group was separate from the European S group. The potential influence of the historical spread of coniferous trees in the isolate genetic differentiation in Europe is discussed.
Pathogenicity Process of Pseudomonas fuscovaginae, the Causal Agent of Sheath Brown Rot of Rice
Authors: Jaunet T. , Notteghem J. L. , Rapilly F. 
Published: May 2008

AbstractSheath brown rot of rice caused by Pseudomonas fuscovaginae has been described in areas where low temperatures occur during the rice booting and heading stages. To analyse the relationship between pathogenicity of P. fuscovaginae and low temperatures, pathogenicity process in rice at booting stage was studied in a growth chamber at midrange and low temperatures. Analysis performed at 13°C, 18°C and 23°C in two rice cultivars showed that pathogenicity of P. fuscovaginae was explained by the general model of the independent action. The inoculum dose necessary to obtain 50% of diseased sheaths decreased with increase of temperature Analysis of planta bacterial population dynamics and mean response time pointed out that low temperatures affected pathogen multiplication in host before and after symptoms development. In consideration of our results, it was concluded that low temperatures acted negatively on the pathogenicity process of P. fuscovaginae. Therefore, occurrence of P. fuscovaginae in areas where rice cultivation is restricted by low temperatures can not be explained by a direct effect of temperatures on pathogenicity.
A 4‐Year Study of the Association Between Gibberella Ear Rot Severity and Deoxynivalenol Concentration
Authors: Reid L. M. , Stewart D. W. , Hamilton R. I. 
Published: May 2008

AbstractTo determine the association between visual disease severity and deoxynivalenol (DON) concentration in Fusarium graminearum silk‐inoculated maize ears, 23 Ontario hybrids were assessed in 1989, 1991, 1992, and 1993. The relationship was exponential and consistent between years. Ears with more than 25% of the kernels visibly infected could have very high concentrations of DON. Both temperature and rainfall in July and August influence the level of disease severity and the subsequent DON accumulation. Visual disease severity ratings should be sufficient for the selection of more resistant genotypes in corn improvement programs during routine screenings. Thus, mycotoxin analyses can be reserved for initial selection of parental material and final verification of developed inbreds or hybrids. No relationship was found between hybrid maturity and disease severity or DON concentration.
Induction to Resistance to Crown Rust in Oat
Authors: Sebesta J. , Epstein A. H. , Formanova M. 
Published: May 2008

AbstractInduction of resistance to crown rust, caused by Puccinia coronata Cda. var, avenae Frazer et Led., occurred in seedlings of three genetic lines of oats (Avena sativa L.) inoculated sequentially with one of three inducer‐challenger combinations of the pathogen. There was significant reduction in both the number of pustules per leaf and the weight of urediospores harvested in all three host genotypes tested. There were highly significant differences between individual spore harvests correlated with age of the pustules. Development of telia by the challenger was found to occur considerably later, and was less intense, when the challenger was inoculated alone in contrast to treatments in which the challenger followed pre‐inoculation with the inducer. There was no correlation between the numbers of resistant and susceptible lesions within the range of inoculum density used in these experiments.