bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of the Long‐term Dynamics of Stem and Leaf Rusts of Wheat in North America Using a Time‐series Approach
Authors: Yang X. B. 
Published: May 2008

AbstractHistorical data on wheat stem rust in the US and wheat leaf rust in Canada were analysed using a time‐series approach to detect patterns in their long‐term dynamics. Three sets of historical data were analysed, the first of which described the annual appearance of wheat‐stem rust in six regions of the western Mississippi Basin from 1921 to 1961. Models developed from these data had significant autocorrelation components of AR(1) or AR(2), indicating that the date of disease appearance in 1 year wasstatistically related to the dates of appearance in the previous 1–2 years. The series of six regions were spatially significantly correlated with each other. Values of the cross‐correlation coefficient increased from 0.20 to 0.83 as the distance between, two regions decreased. The second data set represented relative diversity of physiological races of wheat stem rust from 1918 to 1982. Analysis suggested that a change in race diversity may occur in the US every 5–6 years, based on AR(5) and AR(6) patterns. The third data set had two series on the phenotypes of leaf rust in the eastern and prairie regions of Canada. Analysis indicated that there was a 2‐year autoregressive component AR(2) in each of these two time series. Analysis further suggestedthat the prairie population differed from the eastern population in having a 4‐year moving average component, MA(4), in the majority of individual races.
New Sources of Resistance in Cauliflower (Brassica oleracea var. botrytis) to Crucifer Downy Mildew Caused by Peronospora parasitica
Authors: Silué D. , Laviec C. , Tirilly Y. 
Published: May 2008

AbstractA total of 81 accessions of cauliflower (Brassica oleracea var. botrytis) were inoculated at the seedling stage with three isolates of Peronospora parasitica. All isolates used were derived from cauliflower crops in France and could be described as three distinct pathotypes, based on their virulence patterns on the accessions tested.The three isolates were virulent on F1 hybrids Vega and Billabong. In the UK, two isolates were found to be avirulent on Vega. This result indicates that pathotypes indentified in the UK are different from those in this study and that hybrid Vega has isolate‐specific resistance genes.Eleven differential responses to the pathogen were identified among cauliflower accessions. Thirty‐five accessions tested were susceptible to all three isolates. This susceptibility may be due to the presence of genes shared by these accessions and the resistance it confers is overcome by the three isolates.Twenty‐four accessions tested were derived from single plants selected from populations. Segregation for resistance was found in lines belonging to family F45. This result indicates that the parental plant of these lines was heterozygous. On the other hand, lines of families A 39 and 48 showed no segregation for resistance indicating that the parental plants of both families were homozygous for resistance to the isolates of the study.Four accessions were resistant to the three isolates tested. The differential accessions identified in this study are possible candidates for inclusion in a set of genotypes carrying known resistance genes of differentiating pathotypes.
Effects of Nitrogen Fertilization on Disease Severity and Infection Type of Yellow Rust on Wheat Genotypes Varying in Quantitative Resistance
Authors: Danial D.L. , Parlevliet J. E. 
Published: May 2008

AbstractTwo experiments were carried out to study the effect of nitrogen level on disease severity of genotypes of wheat (Triticum aestivum) varying in quantitative resistance to yellow rust, caused by Puccinia striiformis. In 1990, nine wheat genotypes were exposed to 0.20, 40 and 80 kg N per ha. In 1991, six genotypes, selected from experiment I, were examined at 0. 30 and 90 kg N per ha. The N was applied in the form of calcium ammonium nitrate (NH4NO3+CaCO3). In both years the disease severity increased strongly with increased N‐levels. The infection types also increased with increased N‐levels. Compared with the main effects, the Genotype X N‐level, the Genotype X Year and the Genotype X N‐level, X Year interactions were small, but highly significant (at P = 0.01). Selection for quantitative resistance therefore has to be carried out at the N‐levels used in the regions the breeding is aiming at.
Factors Affecting Potato Soft‐rot Resistance to Pectolytic Erwinia Species in a Tuber‐slice Assay
Authors: Allefs J. J. H. M. , van Dooueweert W. , de Jong E. R. , Prummel W. , Hoogendoorn J. 
Published: May 2008

AbstractPotato‐tuber slices and small tubers of 12 cultivars were inoculated with isolates of Erwinia carotovora subsp. atroseptica (Eca), E. c. subsp. carotovora (Ecc) and E. chrysanthemi (Ech). Cultivar resistance was expressed as the mean diameter of the rotted‐tissue area. Grouping of the cultivars into classes of relatively high, intermediate or low resistance, was different after incubation in air in comparison to incubation under anaerobic conditions, and depended on the (sub‐)species of bacteria used. When compared to the effect of inoculation with different (sub‐)species, grouping of the cultivars was less affected by isolates within (sub‐)species. Cultivar grouping was hardly affected by site of inoculation, being either in the medullary tissue or in the cortex. In general, the results of experiments with either field‐grown seed tubers or glasshouse‐grown small tubers from 2 years were reproducible, except when tuber tissue was inoculated with Ech and incubated, aerobically, in which case cultivars only showed relatively small differences for resistance. Correlation coefficients between the results from slice and small‐tuber screenings were 0.71 and 0.64 for Eca and Ecc, respectively. This implies, some potential for applying the method in the early stages of potato‐breeding programmes.The results of this study show that soft‐rot resistance of clones to different pectolytic Erwinia spp. can be determined efficiently and reproducibly if the oxygen concentration during incubation is standardized.
Production of Inter‐ and Intra‐strain Hybrids of Trichoderma spp. by Protoplast Fusion and Evaluation of Their Biocontrol Activity Against Soil‐borne and Foliar Pathogens
Authors: Migheli Q. , Whipps J. M. , Budge S. P. , Lynch J. M. 
Published: May 2008

AbstractProtoplast fusion techniques were used for the production of new antagonistic strains of Trichoderma spp. Two British and two Italian strains of Trichoderma with different biocontrol potential against Botrytis cinerea, Sclerotinia sclerotiorum and Pythium ultimum, were treated with u.v. radiation and mutants resistant to hygromycin B or propiconzole were selected. Protoplasts were obtained from these mutants after digestion of young hyphae with Novozym 234 and used in inter‐ and intra‐strain protoplast fusion experiments. Hybrids were obtained in 13 crosses isolated on fungicide‐amended media by the inheritance of resistance markers from both parental strains. Selected, fast‐growing, stable mutants were tested in biocontrol trials against P. ultimum on lettuce seedlings and B. cinera on grape bunches in comparison with their parental strains. Intra‐strain hybrids derived from cross XIII were tested in vitro for their mycoparasitic ability on sclerotia of S. sclerotiorum. A high degree of variability in the biocontrol and the mycoparasitic ability of the fusants was observed but no significant increase in the activity was accomplished after fusion, the hybrids being generally less activewas accomplished after fusion, the hybrids being generally less active than their parental strains.
Genetic Diversity in W‐ and R‐type Populations of Pseudocercosporella herpotrichoides Based on DNA Restriction Fragment Length Polymorphisms
Authors: Poupard P. , Frei U. , Cavelier* N. , Lind V. 
Published: May 2008

AbstractThirty‐seven isolates of Pseudocercosporella herpotrichoides belonging to W‐type and 31 isolates belonging to R‐type were analysed for DNA restriction fragment length polymorphisms (RFLPs). They represent diverse geographic origins and different phenotypes related to sensitivity to fungicides. Total DNA digested with EcoRI was hybridized with 22 random DNA probes from a P. herpotrichoides EcoRI‐restricted DNA library. Four probes showing polymorphisms among isolates within W‐type and R‐type and generating a total of 44 RFLPs were retained for cluster analysis. Two main groups were distinguished corresponding to W‐ and R‐types. The genetic diversity among isolates was greater for the W‐type than for the R‐type isolate, four and three distinct EcoRI‐restricted mitochondrial DNA patterns were identified in W‐ and R‐type isolates, respectively. The variability of profiles within each pathotype confirmed a higher degree of polymorphism in the W‐type.
Effect of Brown Stem Rot on Water Relations of Soybean
Authors: Higley P. M. , Martinson C. A. , Tachibana H. 
Published: May 2008

AbstractTo investigate the effects of brown stem rot, a vascular disease of soybean (Glycine max) induced by Phialophora gregata, on the water relations of diseased plants, stems of greenhouse‐grown plants of susceptible (Pride B216) and resistant (BSR 201) cultivars were injected with the pathogen at vegetative growth stage VI. Plants of both cultivars developed internal stem browning, but those of Pride B216 developed more severe symptoms of water stress (reduced leaf water potential and stem conductance). Inoculated plants of both cultivars also had reduced stem conductance and increased stomatal conductance and transpiration. Disease‐related water stress can be attributed to the combined effects of reduced stem conductance and increased water loss resulting from increased stomatal conductance.
Evidence for Differential Resistance to Peronospora parasitica (downy mildew) in Accessions of Brassica juncea (mustard) at the Cotyledon Stage
Authors: Nashaat N. I. , Awasthi* R. P. 
Published: May 2008

AbstractThirty‐one Brassica juncea accessions were screened at the cotyledon stage for resistance to four isolates of Peronospora parasitica. Isolates R1 and P003 were derived from crops of oilseed rape (B. napus ssp. oleifera) in the UK and isolates IP01 and IP02 were derived from crops of mustard (B. juncea) in India. B. napus cv. Ariana, which was used as a susceptible control for isolates from B. napus, was resistant to isolates from B. juncea. All, B. juncea accessions were resistant to isolates from B. napus except one accession which expressed moderate resistance to isolate P003. Five groups of B. juncea accessions with differential resistance were identified. Lines homogeneous for resistance were selected from seedling populations of accessions that exhibited a heterogeneous reaction to isolates from B. juncea. The differential resistance identified in the B. juncea‐P. parasitica combination can be used as a foundation for future studies of the genetics of the host‐pathogen interaction and for breeding for disease resistance.
Active Oxygen‐producing and ‐scavenging Enzymes in Pepper Leaves Infected with Xanthomonas campestris pv. vesicatoria
Authors: Buonaurio R. , Umesh Kumar N. N. 
Published: May 2008

AbstractLipoxygenase (LOX), peroxidase (POX), superoxide dismutase (SOD) and catalase (CAT) activities were determined in pepper (Capsicum annuum) leaves infected with Xanthomonas campestris pv. uesicatoria, from 3 to 15 days after inoculation, before symptom appearance and during the development of the disease. Strong Stimulation of LOX and POX activities was observed in infected leaves at an advanced stage of the disease (12–15 days after inoculation), when bacterial water‐soaked spots and a slight chlorosis of the inoculated leaf areas were evident and a decrease in chlorophyll content of infected tissue was detected. The infection also induced a significant increase in CAT activity at the day 9 and a decrease in SOD and CAT activities at the day 12. On the basis of the changes observed, uncontrolled production of active oxygen species at advanced stages of infection is hypothesized.
Restriction Fragment Length Polymorphism Analyses of the Plasmid DNAs in Strains of Xanthomonas campestris pv. vesicatoria from Different Geographic Areas
Authors: Hwang Byung Kook , Lee Jong Tag , Hwang Byung Gap , Koh Young Jin 
Published: May 2008

AbstractRestriction fragment length polymorphisms (RFLPs) of plasmid DNAs in Xanthomonas campestris pv. vesicatoria were analysed using 77 strains from the United states, Argentina, Australia, Taiwan, and Korea. One or more plasmids were detected in all tested strains, irrespective of geographic origin, host plant from which isolated, or chemical resistance. All Korean strains contained a few plasmids of similar high molecular weight, whereas some small plasmids occured only in strains from the United States, Argentina, and Taiwan. After digesting total plasmid DNAs with each of four restriction endonucleases, 18 fragments with sizes from about 1 to 23 kb were visualized. Seventy‐seven strains of diverse geographic origins, with different levels of resistance to streptomycin and copper, were classified into the 14 RFLP groups based on the restriction endonuclease digestion patterns of their plasmid DNAs. Strains belonging to each group shared DNA fragments of identical size, suggesting the possible presence of similar plasmids in these strains. A 5.8‐kb EcoRI plasmid DNA probe prepared from the United States strain 81‐23 hybridized to EcoRI plasmid digests from all tested strains. Other plasmid DNA fragments of the strain81‐2,3 used as probes had no homology to plasmid DNA fragments from several strains around the world. The variation in hybridization profiles of plasmid DNA was very similar to the results obtained by RFLP analysis of plasmid DNA digested by four restriction enzymes. Most of the Korean strains tested were highly sensitive to streptomycin and copper, whereas most strains from other geographic areas showed a high level of resistance to one or two of the chemicals. Cluster analysis of genetic distance between the strains based on the data obtained generated the dendrograms that separated all Korean strains from the other strains, suggesting that plasmid DNA of the Korean strains may be genetically very different from those of the others.
MLO‐Infected Weeds in the Vineyards of North‐western Italy
Authors: Arzone A. , Alma A. , Bosco D. , Patetta A. 
Published: May 2008

AbstractTen species of herbaceous plants and shrubs with MLO symptoms such as stunting, bushing, yellowing, reddening, virescence or phyllody were collected in both grapevine yellows (GY)‐infected and uninfected vineyards. By electron microscopy, MLOs were found in the sieve tubes of eight species. The presence of MLOs in Picris echioides is demonstrated for the first time. The possible role of MLO‐infected weeds in the spread of GY disease is discussed.
Histology of the Infection and Development of Puccinia recondita f. sp. tritici in a Wheat Line with Lr37
Authors: Kloppers F. J. , Pretorius Z. A. 
Published: May 2008

AbstractThe degree of adult‐plant resistance conferred by the gene Lr37 in RL6081 (Thatcher*8/Lr37) to four avirulent leaf rust pathotypes was quantified by assessing histological components as well as latent period, uredinium density and uredinium size. Histological observations on the adaxial flag leaf surfaces revealed significant arrest of fungal structures in RL6081 at early infection stages. Furthermore, host cell necrosis typical of a posthaustorial host‐resistance mechanism was conspicuous in sizeably reduced colonies on this genotype. Lr37 significantly decreased the rate of uredinial appearance of all four pathotypes. Compared with Thatcher, fewer uredinia of smaller dimensions developed on flag leaves of RL6081. Characterization of resistance indicated that disease development in genotypes with the gene Lr37 should be extremely limited.
Isolation of Race‐and Cultivar‐Specific Elicitors from Intercellular Fluids of Compatible Interactions of Pseudomonas syringae pv. pisi and Pea
Authors: Mwang'ombe A. W. , Archer S. A. 
Published: May 2008

AbstractIntercellular fluids obtained by an in vacuo infiltration technique from compatible race‐cultivar interactions of five races of Pseudomonas syringae pv. pisi and pea induced extensive light brown necrotic (hypersensitive type of) lesions in resistant but not susceptible cultivars. In susceptible cultivars the intercellular fluids induced extetensive water soaking symptoms. The intercellular fluids elicited intermediate reactions in pea cultivars of moderate resistance. The intensity of the light brown necrotic reactions in pea appears to be positively correlated with the degree of resistance.
Diagnosis of Phytophthora infections in raspberry and strawberry plants by ELISA tests
Authors: Olsson C. H. B. 
Published: May 2008

AbstractPlant diseases caused by Phytophthora spp. may be reproducibly diagnosed by DAS ELISA techniques, but this type of analysis has long been hampered by the presence of phenolic and related compounds in plants to be tested, not least in strawberry and raspberry plants. The compounds will interfere with the ELISA test procedure, leading to high non‐specific optical density readings. To overcome this, a series of experiments was performed. Phenolic and related compounds in the samples were first absorbed to polymers during antigen extraction and thereafter separated by filtration at slow rate. To inhibit non‐specific binding of enzyme‐conjugated antibodies, the plastic wells were preincubated with non‐sensitized wells, equally high background values of optical density were seen under untreated conditions and after the use of polymeric adsorbents. A marked reduction in optical density was, however, seen after blocking with non‐fat dry milk, but the optimal conditions for all concentrations ofantigen were seen first after combined pre‐treatment with polymeric adsorbents and non‐fat dry milk. When the threshold absorbance for positive detection was calculated, the low optical density values from healthy plants, at all antigen concentrations studied, contributed to an excellent discrimination between samples from diseased and healthy plants.
The ice Nucleation Activity of Pseudomonas fluorescens Migula and its Inhibition by Various Chemicals
Authors: Mittelstüdt H. 
Published: May 2008

AbstractThe ice nucleation activity (INA) of three strains of Pseudomonas fluorecens, nos 553, 554 and 606, isolated by the Institute for Pathogen Diagnostics in Ascherleben, Germany, was determined. Under equal growth conditions and at given test temperatures the ice nucleation frequency spectra of the isolates differed slightly. The fraction of cells which acted as ice nuclei increased with falling temperatures. Below −5°C the nucleation frequency rose from 10‐8 to 10‐3. Between, 0 and −10°C only a fraction of approximately 2 to 5 × 10‐3 cells performed ice nucleation activity.Fifteen newly synthesized chemicals showed no or only a very slight intrinsic INA at −5°C and −7°C. The compounds were used as antinucleators against INA‐exhibiting bacteria.In INA‐exhibiting suspensions of isolate 553 bacterial ice nuclei were reduced after treatment with the 15 compounds. Dependent on the compounds, a nucleation frequency of −8.32 to −5.10 was detected at −5°C. At −7°C, the frequency amounted to −7.89 to −5.05. As the temperature was lowered to −10°C in bacterial suspensions which were treated with 9 (of the 15) compounds, a remainder of 1.79 to 5.91 × 10‐6 cells retained ice nucleation activity. The most pronounced inhibitory effect was noted for the compounds 1989/6255, 1989/6436 and 1990/6158. In a 10‐fold dilution of isolate 553 the compound 1989/6153 inhibited ice nucleation between 0 and 10°C so strongly that it was about 100 times below the control.The ‘tube‐freezing’ method showed that on excised corn leaves treated with 1989/6259 and 1990/6155, the bacterial INA decreased while the super‐cooling was more pronounced.‘Frostgard’, 1986/6205, 1986/6199 and 1989/6259 inhibited most INA‐exhibiting bacteria on corn seedlings. Compared to inoculated plants, a significantly higher percentage of treated plants survived at −2 and −3°C.
The Occurrence of Bacterial Red Streak of Sugarcane Caused by Pseudomonas syringae pv. syringae in Iran
Authors: Rahimian H. 
Published: May 2008

AbstractA bacterial leaf streak disease characterized by reddish, narrow (1–2 mm wide) streaks of variable size, and occasionally with bleached centers, was found in sugarcane (Saccharum, interspecific hybrid) fields in northern Iran. The incitant bacterium was identified as Pseudomonas syringae pv. syringae (P. s. syringae). The disease is similar in aetiology to the sugarcane ‘red streak’ disease reported recently from Japan. Cultivardependent variations in symptoms were noted., Difference in pathogenicity as well as in electrophoretic profile of cell proteins between strains of P.s. syringae causing red streak in sugarcane and those causing canker on stone fruit trees, were observed.
Light‐Dependent Necrosis Formation by Magnaporthe grisea Toxin(s) in Rice cv. Sekiguchi‐asahi*
Authors: Iedome M. , Arase S. , Honda Y. , Nozu M. 
Published: May 2008

AbstractThe significance of light irradiation in neerosis formation by Magnaporthe grisea toxin(s) on rice cv. Sekiguchi‐asahi was investigated. The effective wave region for light‐dependent neerosis formation was 400 700 nm. An absorption band of the toxin(s) was restricted to the wave region shorter than 400 nm. Both of the phytosynthesis and necrosis formation were inhibited by photosynthetic inhibitors, and the inhibition of both activities was dependent on concentration of the inhibitors. The necrosis formation by the toxin(s) depended on light intensity. The toxin(s) induced the necrosis formation only on the cells with many chloroplasts, and the cells without chloroplasts did not form necrosis even under the light with sufficient intensity. The more the number of chloroplasts decreased, the more the size of necrotic spot decreased on the leaf sheath. From these results we concluded that the photosynthetic activity was involved in the necrosis formation by Magnaporthe grisea toxin(s) in rice cv. Sekiguchi‐asahi.
Pathogenicity of Alternaria alternata and Fusarium moniliforme and Phytotoxicity of AAL‐toxin and Fumonisin B1 on Tomato Cultivars
Authors: Abbas H. K. , Tanaka T. , Duke S. O. 
Published: May 2008

AbstractPhytotoxicity of AAL‐toxin and fumonisin B1 to six cultivars of tomato was compared with the pathogenicity of their fungal sources, Alternaria alternata and Fusarium moniliforme, respectively. These include two AAL‐toxin susceptible cultivars with genotypes(asc/asc), three resistant cultivars (Asc/Asc), and a heterozygous cultivar (Asc/asc.) A. alternata spores were pathogenic to the susceptible but not to the resistant cultivars F. moniliforme was not pathogenic to any of the tomatoes. Filtrates of both fungi grown on rice containing their respective toxins caused necrosis within 48 h and eventually mortality on susceptible cultivars but not on the resistant lines. The heterozygous cultivar Asc/asc showed minimal damage and no mortality after 14 days exposure to both filtrates and both toxins. The spores of both fungi had no effect on heterozygous intact plants. Tomato leaf disc bioassays with AAL‐toxin and fumonisin B1 at 1μM caused cellular leakage and reduced chlorophyll content in susceptible cultivars and minimal effects on the heterozygous and resistant varieties.