bluuebunny/crossref_metadata_2025_split huggingface dataset:
Changes in Photosynthetic Electron Transport in Potato Cultivars with Different Field Resistance after Infection with Phytophthora infestans
Authors: Schnabel G. , Strittmatter G. , NOGA G. 
Published: May 2008

AbstractThe estimation of field resistance of potato cultivars to Phytophthora infestans are usually carried out in expensive and time consuming field experiments over several years. Therefore, a procedure is required for the fast and objective determination of qualitative and quantitative field resistance of new cultivars. This study correlated level of field resistance to P. infestans in leaf discs or leaflets of various potato cultivars to characteristic changes of Chlorophyll‐a fluorescence (CF) parameters Fm (maximal fluorescence) and Fv (maximal variable fluorescence). Two different inocula, both containing virulence genes 1‐11 were tested. The results were achieved when leaf discs from greenhouse or field plants were each inoculated with a P. infestans spore suspension and incubated for 24 h. In field measurements, comparable results were obtained 48 h after inoculation. The estimation of field resistance by measuring specific CF parameters could be an economical and rapid procedure to reduce or substitute visual lesion assessment for determining cultivar field resistance.
Induction of Systemic Resistance in Pea to Pea Powdery Mildew by Exogenous Application of Salicylic Acid
Authors: Frfy S. , Carver T. L. W. 
Published: May 2008

AbstractExogenous application of salicylic acid (SA) solutions to pea leaves induced systemic resistance to Erysiphe pisi. reducing by 20–30% the percentages of fungal germlings that successfully infected untreated leaves of SA‐treated plants. SA concentrations of 1.5 and 15 mM were similarly effective, but 0.15 mM had no detectable effect. While 15 mM SA solutions were phytotoxic. 1.5 mM solutions caused no apparent damage indicating that resistance induction was not due to tissue damage. The induced resistance persisted for at least 13 days after treatment, but excision of treated leaves 1 day after SA application prevented full induction of systemic resistance, and the resistance was not expressed if untreated leaves were inoculated fewer than 3 days after SA application. The effect of SA was transmitted to leaves at nodes both above and below treated leaves. Chemical induction of systemic resistance may provide an additional means for controlling pea diseases.
Differential Reaction of Barley Genotypes to Rhynchosporium secalis
Authors: Cselenyi L. , Friedt W. 
Published: May 2008

AbstractSpring barley cultivars currently grown in Germany are all more or less susceptible to Rhynchosporium secalis (Oudem.) J.J. Davis, but there are obvious differences in the degree of susceptibility under field conditions. Small genotypic differences may be caused by both genetic and environmental effects, respectively. To minimize the influence of environmental variation on disease expression, several inoculation methods were developed in the present study. In two experiments the effectiveness of the inoculation by spraying of single spore isolates was tested in the glasshouse and in the field, respectively. High infection levels were achieved in the glasshouse. Despite the infection of barley in the field, disease expression levels remained low due to unfavourable conditions. Another experiment showed the usefulness of infected straw applied in the autumn only for testing the seedling infection type of spring barley cultivars against R, secalis. Seedling assay scores and field infection levels were closely related (r = 0.796, P < 0.01; r = 0.911, P < 0.001). Therefore, both the spray infection technique in the glasshouse and the inoculation technique using infected straw in the field appear to be suitable to detect genetic differences in resistance/susceptibility of spring barley cultivars against leaf blotch.
Variation in Metabolite Production by Septoria nodorum Isolates Adapted to Wheat or to Barley
Authors: Bousquet J. F. , Kollmann A. 
Published: May 2008

AbstractThe production of secondary metabolites by S. nodorum strains was examined in relation to their adaptation to wheat or to barley. Eleven strains of each type previously characterized were tested for the production in culture of (‐)‐(3R)‐mellein (ochracin), (3R)‐O‐metbylmellein; (‐)‐(3R,4R)‐4‐hydroxyniellein, (‐)‐(3R,4S)‐4‐hydro‐xymellein, mycophenolic acid, septorine, N‐methoxy‐septorine, N‐methoxyseptorinol, and a new compound (=UN).Mellein was produced by every strain. Both 4‐hydro‐xymellein isomers were yielded by all wheat‐adapted strains and six barley‐adapted strains. Most of the strains produced mycophenolic acid. On the other hand the pigmentation of culture filtrates of wheat‐adapted strains was pale‐yellow whereas the pigmentation of barley‐adapted strains was grey‐blue. The productions of O‐methylmellein, septorine, N‐metboxyseptorine and N‐methoxyseptorinol were typical for wheat‐adapted strains. The detection of UN was restricted to the filtrates of barley‐adapted strains. If the pigmentation of filtrates and the production of septorines, UN and O‐methyl‐mellein are considered the strains fell into two groups. This classification is related to the host adaptation except for one barley‐adapted strain that showed characteristics of wheat‐adapted strains and one wheat‐adapted strain which did not produce septorines.
Biological Activities of Analogues of Ser‐Val‐Gly‐Glu (AS‐I), a Toxin Pathogenic to Sunflower
Authors: Liakopoulou‐Kyriakides M. , Metaxas A. , Sarigiannis Y. , Magafa V. , Stavropolulos G. , Laidou I. , Thanassoulopoulos C. C. 
Published: May 2008

AbstractThe tetrapeptides Ser‐Val‐Glu‐Gly, Hse‐Val‐Gly‐Glu, Thr‐Val‐Gly‐Glu, Val‐Ser‐Gly‐Glu and Ser‐Val‐Glu‐Gly, analogues of the AS‐1 toxin which is pathogenic to sunflower, were examined for biological activity on sunflower and eight other plant species. These peptides were synthesized in solution or on a solid phase. Of the species studied by leaf inoculation, sunflower and zucchini were the most susceptible and cotton the most resistant to ail of the toxins tested. The effect of Ser‐Val‐Glu‐Gly was similar to that reported for AS‐I, whereas the tetrapeptide Thr‐Val‐Gly‐Glu was the most toxic.
The Occurrence and Pathogenicity of Cylindrocarpon, Cylindrocladium and Fusarium on Calluna vulgaris and Erica spp. in England and Scotland
Authors: Litterick A. M. , Mcquilken M. P. 
Published: May 2008

Abstract Cylindrocarpon, Cylindrocladium and Fusarium spp. were often isolated from the woody roots, stem‐base and lower foliage of diseased container‐grown Calluna vulgaris and Erica spp. plants collected from English and Scottish nurseries. The highest isolation frequencies were obtained for Cylindrocarpon destructans, Cylindrocladium scoparium, Cylindrocladium ilicicola. Fusarium tricinctum, Fusarium avenaceum and Fusarium sporotrichioides. Isolations of these fungi were made more frequently from diseased plants that were at least 1‐year‐old. The percentage incidence of Cylindrocarpon, Cylindrocladium and Fusarium spp. did not differ between Scottish and English nurseries. Cylindrocarpon destructans. Cylindrocladium ilicicola and C. scoparium were more pathogenic to rooted C. vulgaris cuttings than F. tricinctum. F. avenaceum or F. sporotrichioides in laboratory and glasshouse tests. The high isolation frequency of Cylindrocarpon. Cylindrocladium and Fusarium spp., and their pathogenicity in tests, suggests that these fungi are involved in root, stem‐base and lower foliage diseases in crops of C. vulgaris and Erica spp. The importance of these findings for the integrated control of diseases on ericaceous plant nurseries is discussed.
Preliminary Evidence for Phytoalexin Production by Eucalyptus urophylla Leaves as a Response to Inoculation with the Incompatible Pathogen Acidovorax avenae pv. avenae
Authors: Romeiro R. S. , Lima V. B. 
Published: May 2008

AbstractLeaves of eucalyptus (Eucalyptus urophylla) were infiltrated with a cell suspension of the incompatible pathogen Acidovorax avenae pv. avenae and showed a typical hypersensitive response within 24h. Necrotic leaf areas were excised, vacuum infiltrated with 40% ethanol and left under continuous agitation at room temperature for 24h. The diffusate was concentrated, partitioned with ethyl‐acetate, concentrated to dryness and resuspended in a small volume of methanol. The biological activity of extracts was evaluated by an agar diffusion method against noncompatible bacteria (A. avenae pv. avenae and Xanthomonas axonopodis pv. manihotis) and fungi (Penicillium sp. and Aspergillus sp.). Inhibition haloes, when present, were always larger in extracts from leaves infiltrated with the incompatible bacterium than the water control. Thin layer chromatography resolution of crude extracts from leaves infiltrated with both incompatible pathogen cell suspension and water, followed by bioautography with Thieleviopsis paradoxa, consistently rendered, in both situations, a large, diffuse inhibition halo near the origin, assumed to be due to preformed antimicrobial substances. However, extracts from leaves infiltrated with the living cells of the incompatible pathogen gave rise to a smaller, second inhibition halo, near the front, that was interpreted as being one or several phytoalexins.
Induced Resistance Against Plasmopara helianthi in Sunflower Plants by DL‐β‐Amino‐n‐butyric acid
Authors: Tosi L. , Luigetti R. , Zazzerini A. 
Published: May 2008

AbstractSunflower plants treated with the nonprotein amitio add, DL‐β‐attiino‐n‐butyric acid (BABA) were protected against infection with Plasmopara helianthi. Soil drenches at the highest rates (150‐250 mg/kg soil), applied one day before the inoculation induced high levels of protection (80‐83%) against the disease and more than 90% control was observed when BABA was applied at 300 mg/kg soil. However, at this concentration phytotoxic symptoms were observed. This compound also provided a curative activity when applied one day post‐inoculation. BABA had no antifungal activity in vitro against P. helianthi. The effect of BABA on zoosporangia germination was evaluated by treating pre‐germinated seeds with the compound solution and the zoosporangia suspension for 3 h. Then, seeds were sown and the percentages of infected plants were determined. The other two aminobutyric acid isomers (a and g) were ineffective against downy mildew. The mechanisms by which DL‐β‐amino‐n‐butyric acid protect sunflowers against downy mildew awaits more detailed elucidation.
Echinochloa Hoja Blanca and Rice Hoja Blanca ViriKies Occupy Distinct Ecological Niches
Authors: Madriz J. A. , DE Miranda J. R. , Cabezas E. , Oliva M. , Hernandez M. , Espinoza A. M. 
Published: May 2008

AbstractThis study provides both direct and indirect evidence that, in Costa Rica, rice hoja blanca virus and Echinochloa hoja blanca virus occupy distinct ecological niches, implying that their molecular differences are the result of evolutionary divergence rather than variation within a single virus population. For this reason they should be considered separate virus species, rather than strains of a single species.
Biological and Serological Variability of Zucchini Yellow Mosaic Virus in Sudan
Authors: Mahgoub H. A. , Desbiez C. , Wipf‐Scheibel C. , Dafalla G. , Lecoq H. 
Published: May 2008

AbstractZucchini yellow mosaic potyvirus (ZYMV) is prevalent in different cucurbit growing agro‐ecosystems in Sudan. A study of the biological and serological variability of isolates originating from different regions was conducted to better understand ZYMV epidemiology and to develop adapted and durable control strategies. Variability was detected among isolates regarding symptomatology, host range and virulence towards the Zym resistance gene in melon (Cucumis melo L.) PI 414723. Serological variability was also revealed using a set of seven differential monoclonal antibodies (mAbs) raised against a French isolate (ZYMV‐E9). Six serotypes were differentiated, but a majority of isolates (88%) reacted with all the mAbs as did the reference strains from Italy and France. All isolates from Sudan were equally well controlled by the resistance genes described in squash (Cucurhita moschata (Duchesne) Duchesne ex Poir. cvs. Menina and Nigeria) and in cucumber (Cucumis sativus L. cv. TMG), or by cross protection with the mild ZYMV‐WK strain. All isolates were transmitted in a nonpersistent manner by Aphis gossypii Glover and Myzus persicae Sulzer.
Development of Early Infection Structures of Puccinia recondita f. sp. tritici in Non‐host Cereal Species
Authors: Hu G. G. , Rukenberg F. H. J. 
Published: May 2008

AbstractThe development of infection structures, derived from urediospores of Puccinia recondita f.sp. trilici in nearisogenic lines of susceptible and resistant wheat, and in non‐hosts (viz. maize, oat, sorghum and barley), was examined by fluorescence microscopy and scanning electron microscopy (SEM). The infection structure formation on and in five cereal species follows a similar pattern. In sorghum, fungal development is arrested at the stage of substomatal vesicle formation, while, in maize, most fungal structures collapse during the stage of primary hypha development. By contrast, in wheat, barley and oat, the fungus forms many branched infection hyphae and haustorial mother cells.
Sequence of a Plastocyanin cDNA From Wheat and the Use of the Gene Product to Determine Serologically Tissue Degradation after Infection with Pseudocercosporella herpotrichoidesa
Authors: Coff C. , Poupard P. , Xiao Qiu , Graner A. , Lind V. 
Published: May 2008

Abstract Pseudocercosporella herpotrkhoides, the causal agent of the eyespot disease of wheat, induces lesions at the stetn bases, in degraded tissue a specific protein (Pc) cannot more be detected whereas it is abundantly produced in the green tissue showing no disease symptotns. In plant satnples including the stem bases, the amount of protein Pc is therefore correlated with the degree of tissue degradation. A serological test (ELiSA) was developed for the quantitative determination of the protein. ELISA readings can be used as estimates of disease severity.By sequence analysis, Pc was identified as plastocyanin. Based on the nucleic acid sequence, wheat pre‐plastocyanin consists of a transit peptide of 61 amino acids and a tnature peptide of 97 residues. Comparison of the nucleotide sequences of plastocyanin of wheat and barley showed homology of 93.7%.
Conidium Germination and Appressorium Penetration of Colletotrichum gloeosporioides on Stylosanthes guianensis
Authors: Munaut F. , Maraite H. 
Published: May 2008

AbstractPre‐penetration and early penetration phases of two pathogenic strains of Colletotrichum gloeosporioides (HM 502, HM 514) from Zaire were investigated quantitatively on four Stylosanthes guianensis genotypes (cv. Schofield, cv. Graham, ClAT 184 and CIAT 10136) of various levels of susceptibility.The results demonstrated control of the rates and type of conidial germination by the fungus, influenced to a lesser extent by the host genotype. Cell reactions were visible as papillae and cytoplasmic aggregations closely associated with the penetration peg. No fungal growth was observed when deposits of papillae occurred under appressoria‐forming infection pegs, whereas the effect of the cytoplasmic aggregations varied according to the host genotype. In the interactions with strain HM 502, the highest rates of plant reaction were recorded on the resistant CIAT 184 genotype, while the highest level of penetration without reaction was observed on the most susceptible cv. Schofield. Cytoplasmic aggregations were also observed under a few ungerminated appressoria on this genotype. Differences were thus detected in the rates and types of conidial germination, in the rates and types of cell reactions under appressoria and in the appressorial penetration rates without cell reactions. However, these differences did not completely explain the range of macroscopic symptoms observed on the various genotypes.
Detection of Tobacco Mosaic Virus Movement Protein in Association with Tobacco Nuclei Isolated from Intact and Detached Leaves
Authors: Susi P. 
Published: May 2008

AbstractThe movement protein (MP) of tobacco mosaic virus was observed to cofractionate with nuclei from intact and detached tobacco (Nicotiana tahacum cv. Xanthi‐nn) leaves. When purified nuclei were treated with proteinase K, MP disappeared indicating that MP is localized close to but not inside nuclei. Moreover, the amount of MP was showti to increase greatly in nuclei isolated from detached leaves, thus facilitating the detection of MP. Accumulation close to nuclei was strongest early in infection, results indicating that it may be an early step in the pathway of MP from cell cytoplasm to plasmodesmata. Other TMV‐specific proteins were not detected in the nuclei fraction.
UP‐PCR Genotyping and rDNA Analysis of Ascochyta pisi Lib
Authors: Lübeck P. S. , Alekhina I. A. , Lubeck M. , Bulat S. A. 
Published: May 2008

AbstractIsolates of Ascochyta pisi, previously identified as separate pathotypes, were genotyped by rDNA‐RFLP and UP‐PCR using 8 UP‐primers and 2 arbitrary primers individually or in pair‐wise combinations. The appearance of polymorphic UP‐PCR products for all studied isolates facilitated their differentiation. The markers were suitable in identifying isolates, and may be useful for developing isolate‐ or pathotype‐specific PCR‐based diagnostic assays. In studying genetic relatedness by UP‐PCR among A. pisi isolates, two distinct clusters were revealed. rDNA analysis of the isolates based on endo‐ntjclease digestion of amplified ITSl and 1TS2‐25S nuclear rDNA regions did not separate the isolates, whereas the variabihty of the isolates using UP‐PCR was more than 40%.
Transformation of Erwinia carotovora ssp. atroseptica with the Green Fluorescent Protein Gene from Aequorea victoria
Authors: Pesnyakevich A. G. , Lyon G. D. 
Published: May 2008

Abstract Erwinia carotovora ssp. atroseptica has been transfortned with the green fluorescent protein (GFP) gene from Aequorea victoria. Transformants had very high levels of GFP expression but some plasmid instability was apparent when bacteria were not grown on atnpicillin. Confocal microscopy showed variation between cells in the level of expression of GFP. Transfonnants retained their pathogenicity on potatoes, rotting tubers and causing typical blackleg symptoms when inoculated into stems, but the level of fluorescence was not suitable for observing bacterial movement. In contrast, E. coli producing GFP could be used to follow bacterial movement within vascular tissue of potato leaves.
Single Spore Infections with Sunflower Downy Mildew
Authors: Spring O. , Rozynek B. , Zipper R. 
Published: May 2008

AbstractA technique was developed to select vital zoospores of Plasmopara haistedii after zoosporogenesis for the infection of sunflower leaf disks. Successful infections were performed with samples containing several zoospores originated from a single sporangium as well as with samples containing only one single zoospore. Infections were indicated by spontaneous sporulation at the surface of inoculated sunflower leaf discs and were secured by transfer to whole seedlings. Using this method it was possible to generate unithallic infections and genetically homogenous strains of sunflower downy mildew.
Changes in Metabolite Pools in Host and Pathogen during the Uredinio and Teliospore Development of the Bean Rust Fungus Uromyces appendiculatus
Authors: Götz M. , Boyle C. 
Published: May 2008

AbstractMetabolite pool sizes as well as indications for changes in the translocation of metabolites from the host to the parasite were investigated on primary leaves of decapitated bean plants infected with the bean rust fungus Uromyces appendiculatus var. appendiculatus (Pers.) Link with respect to changes in the spore type from uredinioto teliospores. Noninfected control leaves were compared to the directly influenced sorus region of infected leaves and the mycelium‐free areas of these leaves (‘leaf‐remainder’).The data show evidence for an intensive change in the metabolite pools, indicating translocation from the metabolically active leaf‐remainder to the sori, expressing characteristic changes according to the spore type produced. The importance of single metabolites and changes in their pool sizes is discussed and correlated to the respective pools within the uredinio‐ and teliospores. The data indicate that vegetative urediniospores contain mainly preformed metabolites and precursors, whereas teliospores need to undergo metabolite syntheses before germination.
Identification of Phytoplasma Infecting Lilium martagon in the Czech Republic
Authors: Poncarová‐Vorácková Z. , Franová J. , Valová P. , Mertelik J. , Navrátil M. , Nebesárová J. 
Published: May 2008

Abstract Lilium martagon (Turk's‐cap lily) found in West Bohemia showed untisual malformation in the shape of a very flattened stem. Scanning electron microscopy (SEM) and fluorescence microscopy (DAPI staining) revealed phytoplasma bodies in sieve tube elements of the diseased plant, but not in healthy ones. The diameter of the bodies ranged from 100 to 900 nm, with an average of 400 nm. Phytoplastna 16S rDNA detection by nested PCR resulted in 1.1 kbp product. Based on restriction analysis of amplified region, this phytoplasma is classified to the aster yellows cluster (16SrI), subgroup 1‐C, with clover phyilody phytoplasma as a type strain. Partial phytoplasma 16S rDNA sequence amplified by nested PCR was compared through restriction fragment length polymorphism. No virus infection was detected. This paper is the first report on clover phyilody phytoplasma in a monocotyledonous host identified on molecular level.
Abutilon Mosaic Geminivirus Proteins Expressed and Phosphorylated in Escherichia coli
Authors: Wege C. , Jeske H. 
Published: May 2008

AbstractIn order to get more detailed information on single proteins involved in the life cycle of Abutilon mosaic geminivirus, special conditions were established allowing expression of the proteins encoded by different viral open reading frames (AC2, AC3, AVI, BC1, and BV1) in Escherichia coli by use of the pET expression vector system. These include cotransformation of a tRNA supplementation plasmid to overcome codon usage problems in the case of AC2, Protocols were developed to purify the virus proteins for production of antisera. Phosphorylation of AbMV proteins AC3, AVI, BCl, and BV1 in E. coli could be shown by autoradiographic detection of stably incorporated inorganic 32PO34.
Two Cases of Non‐host Resistance against Potyviruses Operating at the Single Cell Level
Authors: Bak S. , Poulsen G. B. , Albrechtsen M. 
Published: May 2008

AbstractNonhost resistance of plants against viruses is a very common but poorly understood phenomenon. In this study Nicotiana tabacum L. and pea seed‐borne mosaic potyvirus (PSbMV) were chosen as a model system for a closer examination of nonhost resistance. Nicotiana tahacum was confirmed to be a nonhost for PSbMV by mechanical inoculations followed by analysis by enzyme‐linked immunosorbent assay and by immunofluorescence staining of mesophyll and epidermal protoplasts isolated from inoculated leaves. When tobacco protoplasts were inoculated with PSbMV virions or genomic RNA, only very few eells became infected. On the other hand, both PSbMV virions and genomic RNA could infeet protoplasts from the host plant Pisum sativum L. In parallel experiments, virions of another potyvirus, potato virus Y (PVY), infected tobacco protoplasts but not protoplasts from pea, a nonhost for PVY. The results suggest, that the inabihty of PSbMV to infect tobacco, and of PVY to infect pea, is at least partly caused by a failure of virus replication in the inoculated cells.