In vitro selection of sterol-biosynthesis-inhibitor (SBI)-resistant mutants in Monilinia fructicola (Wint.) Honey     

C. Nuninger-Ney  F. -J. Schwinn  T. Staub 《European journal of plant pathology / European Foundation for Plant Pathology》1989,95(1):137-150

The inherent resistance risk forMonilinia fructicola against sterol-biosynthesis inhibitors (SBIs) was estimated inin vitro andin vivo laboratory studies. Several mutant strains were selected on media amended with the triazole fungicides penconazole, etaconazole or the morpholine fungicide fenpropimorph.The potential forM. fructicola to develop resistance to the triazoles or to the morpholines was similar.The level of resistance attained did not differ for the two classes of fungicides after a single cycle of treatment with nitrosoguanidine (NTG). Attemps to select mutants with a higher level of resistance to penconazole after successive mutagenic treatments were successful. Most of the mutants were less fit than wild-type strains. Mutants with a low level of resistance had an almost normal mycelial growth rate, whereas growth of mutants with a higher level of resistance was significantly reduced. Spore production was highest in the wild-type strains, similar to the latter in a few resistant strains and less in most others. Only one mutant with an intermediate level of resistance could successfully compete in a mixed population with a wild type strain during successive infection cycles on peaches. Resistance was not stable in highly resistant mutants. Cross resistance to the inhibitors of 14-methylsterol demethylation (DMIs) tested was confirmedin vitro andin vivo for all mutant strains. One DMI-resistant mutant was also resistant to fenpropimorph and two fenpropimorph-resistant mutants were resistant to penconazole.  相似文献   

A streak disease of pearl millet caused by a leafhopper-transmitted geminivirus     

Rob W. Briddon  Patricia Lunness  Ian D. Bedford  Leony C. L. Chamberlin  Theo Mesfin  Peter G. Markham 《European journal of plant pathology / European Foundation for Plant Pathology》1996,102(4):397-400

The cause of a streak disease of pearl millet (Pennisetum glaucum), originating from Nigeria, has been attributed to a geminivirus belonging to the African streak virus cluster. A full-length, infectious clone of the virus was obtained which was transmissible by the vectorCicadulina mbila (Naudé). Analysis of the complete nucleotide sequence of the coat protein gene of this virus shows it to be most closely related to sugarcane streak virus. The possible evolutionary implications of this finding are discussed.  相似文献   

Surgical correction of uterine inversion in a mare          下载免费PDF全文

Waelchli RO  Kaegi B  Staub M 《The Canadian veterinary journal. La revue veterinaire canadienne》1992,33(7):469-471

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A Greenhouse Test for Screening Sugar Beet (Beta Vulgaris) for Resistance to Rhizoctonia Solani     

Olga E. Scholten  Lee W. Panella  Theo S.M. De Bock  Wouter Lange 《European journal of plant pathology / European Foundation for Plant Pathology》2001,107(2):161-166

Rhizoctonia solani Kühn is a serious plant pathogenic fungus, causing various types of damage to sugar beet (Beta vulgaris L.). In Europe, the disease is spreading and becoming a threat for the growing of this crop. Plant resistance seems to be the most practical and economical way to control the disease. Experiments were carried out to optimise a greenhouse procedure to screen plants of sugar beet for resistance to R. solani. In the first experiment, two susceptible accessions were evaluated for root and leaf symptoms, after being grown in seven different soil mixtures and inoculated with R. solani. The fungus infected all plants. It was concluded that leaf symptoms were not reliable for the rating of disease severity. Statistically significant differences between the soil mixtures were observed, and there were no significant differences between the two accessions. The two soil mixtures, showing the most severe disease symptoms, were selected for a second experiment, including both resistant and susceptible accessions. As in the first experiment, root symptoms were recorded using a 1–7 scale, and a significant expression of resistance was observed. The average severity of the disease in the greenhouse experiment generally was comparable with the infection in field experiments, and the ranking of the accessions was the same in the two types of experiments. It was concluded that evaluation procedures in the greenhouse could be used as a rapid assay to screen sugar beet plants for resistance to R. solani.  相似文献   

Induced Disease Resistance in Plants by Chemicals   总被引：23，自引：0，他引：23  

Michael Oostendorp  Walter Kunz  Bob Dietrich  Theodor Staub 《European journal of plant pathology / European Foundation for Plant Pathology》2001,107(1):19-28

Plants can be induced locally and systemically to become more resistant to diseases through various biotic or abiotic stresses. The biological inducers include necrotizing pathogens, non- pathogens or root colonizing bacteria. Through at network of signal pathways they induce resistance spectra and marker proteins that are characteristic for the different plant species and activation systems. The best characterized signal pathway for systemically induced resistance is SAR (systemic acquired resistance) that is activated by localized infections with necrotizing pathogens. It is characterized by protection against a broad range of pathogens, by a set of induced proteins and by its dependence on salicylic acid (SA) Various chemicals have been discovered that seem to act at various points in these defense activating networks and mimic all or parts of the biological activation of resistance. Of these, only few have reached commercialization. The best- studied resistance activator is acibenzolar-5-methyl (BION). At low rates it activates resistance in many crops against a broad spectrum of diseases, including fungi, bacteria and viruses. In monocots, activated resistance by BION typically is very long lasting, while the lasting effect is less pronounced in dicots. BION is translocated systemically in plants and can take the place of SA in the natural SAR signal pathway, inducing the same spectrum of resistance and the same set of molecular markers. Probenazole (ORYZEMATE) is used mainly on rice against rice blast and bacterial leaf blight. Its mode of action is not well understood partly because biological systems of systemically induced resistance are not well defined in rice. Treated plants clearly respond faster and in a resistant manner to infections by the two pathogens. Other compounds like beta-aminobutyric acid as wdl as extracts from plants and microorganisms have also been described as resistance inducers. For most of these, neither the mode of action nor reliable pre-challenge markers are known and still other pathways for resistance activation are suspected. Resistance inducing chemicals that are able to induce broad disease resistance offer an additional option for the farmer to complement genetic disease resistance and the use of fungicides. If integrated properly in plant health management programs, they can prolong the useful life of both the resistance genes and the fungicides presently used.  相似文献   

Structure and Expression In planta of Botrytis cinerea Ubiquitin Genes     

Theo W. Prins  Lia Wagemakers  Jan A.L. van Kan 《European journal of plant pathology / European Foundation for Plant Pathology》2000,106(7):693-698

To identify genes of the necrotrophic pathogenic fungus Botrytis cinerea that are expressed during infection of tomato leaves, a differential screening of a genomic library with radioactively labelled cDNA was performed. This resulted in the identification of a B. cinerea gene, denominated Bcubi4, which encodes a precursor protein consisting of four identical head-to-tail repeats of a 76aa ubiquitin unit. Subsequently a gene denominated Bcubi1CEP79, encoding a single ubiquitin unit joined to a Carboxyl Extension Protein of 79 amino acids, was isolated. The expression of the two ubiquitin genes was studied during pathogenesis of B. cinerea on tomato. Bcubi1CEP79, but not Bcubi4, mRNA was transiently induced at 16h after inoculation. The increased expression of the Bcubi1CEP79 gene at this stage of pathogenesis might be required for enhanced ribosomal biogenesis.  相似文献   

The Effects of Growth Factor on Testicular Germ Cell Apoptosis in the Stallion     

Casey L. Donnelly MS  Christophe Staub PhD  Dickson Varner PhD  DVM  Terry Blanchard PhD  DVM  Larry Johnson PhD  David W. Forrest PhD   《Journal of Equine Veterinary Science》2007,27(5):212-216

Apoptosis is necessary for both initiation and control of spermatogenesis; however, an increase in apoptosis can lead to subfertility/infertility in stallions, causing substantial financial loss in the equine industry. The ability of stem cell factor (SCF), leukemia-inhibiting factor (LIF), granulocyte–macrophage colony-stimulating factor (GM-CSF), and estradiol (E₂), alone or in combination, to prevent apoptosis of germ cells in short-term equine testicular cultures was examined. Testicular tissue was sectioned into approximately 2-mm cubes and placed in media-filled culture chambers. Concentrations of SCF (100 ng/mL), LIF (10 ng/mL), GM-CSF (5 ng/mL), and E₂ (10⁻⁹ mol/l) were added alone or in combination to each well. After 6 hours in culture, the tissue was fixed and immunohistochemically (terminal deoxynucleotidyl transferase-mediated nick-end labeling; TUNEL) stained for apoptosis detection. Apoptotic cells per 100 Sertoli cell nuclei within seminiferous tubules were counted until the 500^th Sertoli cell nuclei was reached. This counting procedure was used for each slide. An analysis of variance (ANOVA) with a Tukey's test was used to compare apoptotic rates. In comparison with the control, GM-CSF alone lowered apoptosis by 34.77%. GM-CSF–treated tissue combined with SCF and LIF as well as GM-CSF combined with SCF, LIF, and E₂ reduced apoptosis when compared with the control (37.45% and 44.40%, respectively) or other treatment combinations. GM-CSF alone reduced apoptosis; results suggest possible synergy for the combinations of SCF and LIF with GM-CSF and for E₂ with SCF, LIF, and GM-CSF.  相似文献   

Assessment of Partial Resistance to Powdery Mildew (Podosphaera pannosa) in a Tetraploid Rose Population Using a Spore-suspension Inoculation Method     

Zifu Yan  Oene Dolstra  Theo W. Prins  Piet Stam  Peter B. Visser 《European journal of plant pathology / European Foundation for Plant Pathology》2006,114(3):301-308

Powdery mildew (Podosphaera pannosa) is the most important fungal disease in greenhouse roses and is in practice controlled by fungicides. The creation of novel cultivars with durable resistance to powdery mildew is highly desirable. To understand the inheritance of mildew resistance, a tetraploid rose population with a size of 181 seedlings was obtained by crossing two tetraploid genotypes each having partial resistance. The population and its parents were tested under greenhouse conditions with two well-defined monospore isolates (2 and F1) using artificial inoculation with spore suspensions. Disease score at 11 days post-inoculation, latent period and rate of symptom development were used to describe seedling resistance. The tests for both isolates exhibited a wide and significant variation among genotypes for resistance. The distribution of the genotypic means of the disease scores was continuous and showed a considerable transgression. Statistical analysis, scatter plot of disease scores for the isolates, and correlation analyses indicated that the two isolates differed in pathogenicity. The outcome of the tests showed that the inoculation assay with spore suspensions was a reliable and effective way to screen large numbers of genotypes under greenhouse conditions for genetic and breeding studies. This is the first report on spore-suspension inoculation to be used successfully in rose.  相似文献   

Response of black rot in cabbage to spatial distribution of inoculum     

Corné G. Kocks  Jan-Carel Zadoks  Theo A. Ruissen 《European journal of plant pathology / European Foundation for Plant Pathology》1998,104(7):713-723

Disease progress of black rot in cabbage crop was studied over three years in field plots to compare the effects of uni-focal and multi-focal inoculum applied in equal amounts per plot. Disease progress (plant incidence and leaf incidence) was plotted over time, three dimensional maps were made, and disease aggregation was studied by means of geostatistics, black-black counts and Moran's I statistic. Black rot progress was primarily due to focus expansion. Secondary foci may appear at short distances from the initial focus but they usually merge with the expanding initial focus. Anisotropy occurred occasionally but was of minor importance. Disease proceeds faster in plots with multi-focal inoculation than in those with uni-focal inoculation. Probably, serious epidemics in Dutch cabbage fields originate from large numbers of foci.  相似文献   

High level of treatment failure with commonly used anthelmintics on Irish sheep farms     

Orla M Keane  Jason D Keegan  Barbara Good  Theo de Waal  June Fanning  Michael Gottstein  Mícheál Casey  Christine Hurley  Maresa Sheehan 《Irish veterinary journal》2014,67(1):16

Background

In 2013 a Technology Adoption Program for sheep farmers was established to encourage the implementation of best management practices on sheep farms in Ireland. There were 4,500 participants in this programme in 2013. As part of this programme, farmers had the option to carry out a drench test to establish the efficacy of their anthelmintic treatment.

Results

Flock faecal samples were collected before and after treatment administration and gastrointestinal nematode eggs enumerated. In total there were 1,893 participants in the task, however only 1,585 included both a pre- and post-treatment faecal sample. Of those, 1,308 provided information on the anthelmintic product that they used with 46%, 23% and 28% using a benzimidazole (BZ), levamisole (LEV) and macrocyclic lactone (ML) product respectively. The remaining farmers used a product inapplicable for inclusion in the task such as a flukicide or BZ/LEV combination product. Samples were included for analysis of drench efficacy if the pre-treatment flock egg count was ≥200 eggs per gram and the interval post-sampling was 10–14 days for BZ products, 4–7 days for LEV products and 14–18 days for ML products. These criteria reduced the number of valid tests to 369, 19.5% of all tests conducted. If the reduction post-treatment was ≥95% the treatment was considered effective. Only 51% of treatments were considered effective using this criterion. There was a significant difference in efficacy between the anthelmintic drug classes with BZ effective in only 30% of treatments, LEV effective in 52% of cases and ML effective in 76% of cases.

Conclusions

Gastrointestinal nematode anthelmintic treatments, as practiced on Irish farms, have a high failure rate. There was a significant difference between the efficacies of the anthelmintic classes with BZ the least effective and ML the most effective.  相似文献