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SESSION 1 - Discovery - New horizons in plant pathology - page 43 / 65





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ecological problems. In spite of improving and restoration of original structure forests, we have 15 % less of shadow trees opposite to original vegetative cover of area. The healthy state and quality of oak seedlings in forest nurseries and in nature is the main problem at the present. Based on repeated epidemiological observations of infection within 3 years in different natural and geographical conditions, we concluded that populations of oak powdery mildew behave dissimilarly to geographical altitude and age of tree (seedlings). Based on unclear biology of pathogen, we compared the primary infection and secondary infection based on first occurrence of infection, size of conidia, germinability and vitality of conidia in vitro, production and maturing of cleisthothecia, germinability and infectibility of ascospores emerging from cleisthothecia.  The ability of ascospores to cause infection on emerging leaves from the middle of May to middle of June refer to fact that sexual process is successfully finished and ascocarps are able to produce vital ascospore after winter dormancy. The 85 % of emerged ascospores were able to germinate and 63 % cause infection under laboratory conditions after dormancy period. The effect of ascospores on primary infection in compare to overwintering mycelia in the buds is not clear. Samples of conidia originated from primary or secondary infection and cleisthotecia collected from seedlings and from one to three year old oaks was subjected to PCR-RAPD analyses to find genetic backround of diverse behaviour of pathogen. The results showed different bands in case of samples which were collected in natural areas or forest nurseries from higher altitudes with cool weather during vegetation period than others. We work on development of specific markers to specify pathogenicity of oak powdery mildew and its host, because of genetic material of Q. robur and Q. petraea can be mostly (75 % of population) hybrids with various succeptibility to pathogen. Prevention and currative treatment in forest nurseries were tested by using biological control based on mycoparasitic fungi - Vertalec, Preferal, NeeM and its combinations. The effect of biological control was compared with treatment by sulfur, Amistar and Systane. Systemic fungicides provide the long time control of disease but it is not registered for forest ecosystems. The combination of mycoparasitic fungi with NeeM showed to be the most effective control in vegetative period.


Early and easily detection of Tilletia caries and Tilletia controversa in wheat

Kochanová, M., Zouhar, M., Prokinová, E., Ryšánek, P.

Czech University of Agriculture in Prague, Faculty of Agronomy, Department of  Plant Protection, Kamýcká 129, Prague 6 – Suchdol, Czech Republic e-mail: kochanova@af.czu.cz

Fungi from the genus Tilletia are basidiomycetous wheat pathogens belonging to the order Ustilaginales. In the Czech Republic there can occur three species of this genus, Tilletia caries (DC) Tul., Tilletia foetida (Wallr.) Liro and Tilletia controversa Kűhn. The main symptom of infection of plants is absence of grain underneath the lemma. There is sorus with mass of teliospores. It imparts fishy odour and bad taste to flour. This typical symptom is evidence on formed spike only. That is why detection of wheat on juvenile plant is very difficult. Molecular methods based on DNA analysis have provided very useful information for species identification of plant pathogens. Polymerase chain reaction (PCR) is a powerful tool that has made significant contribution of plant disease diagnosis. For DNA extraction were used whole plants in growing phase of the first leaves infected by T. caries and T.  controversa. Both of Tilletia were specifically detected in wheat plants by PCR using primers TILf (5´- CAC AAG ACT ACG GAG GGG TG - 3´) and TILr (5´- CTC CAA GCA ACC TTC TCT TTC - 3´) and gave product of expected length 361 bp. DNA from unifected wheat were not amplified. In reaction control plants naturaly infected by other species of fungi as Alternaria spp., Erysiphe graminis, Puccinia spp. and Fusarium spp. had not given unspecific products.  This method can be useful for seed producers. It can be applied on infected plants without any bunt presence symtoms.


Computational Tool for the Analysis of Plant Pathogen Populations

Dinoor A., Herrmann A., Kosman E., Schachtel G. A.

The analysis of plant pathogen populations is normally based on experimental data sets which are organized in large tables with two entries (differentials in columns, isolates in rows). Several computer programs for processing this kind of data were developed, e.g. VIRULA by Welz and Ellmer (1991); HaGiS by Herrmann et al. (1999); and KOIND by Kosman (2001), each focusing on only a few aspects of the data. Our collaborative project aims at supporting a more exhaustive, more effective, and more compatible evaluation and presentation of such data by developing a new unified package of tools that contains most functions of the mentioned programs but extends them with a number of additional features and some recently developed methods. Our software will include tools for the basic routine steps such as data entry, dichotomization, identification of phenotypes, and characterization of samples by graphical means and by indices. Inference-statistical procedures will provide estimates of various diversity indices and other parameters for sexually and for asexually reproducing populations. These estimates obtained by bootstrap methods (Efron and Gong 1983) will allow further statistical evaluations (e.g. significance tests and confidence intervals). Recommendation concerning minimal sample sizes for reliable estimations in specific experimental situation will be offered. To make results of different researchers more compatible a tool to convert pathotype names from one nomenclature to another will be installed (e.g. from binary/octal to binary/hexadecimal).


Molecular markers with haploid and diploid pathogens: Calculating similarity of banding profiles

Kosman E., Leonard K. J.

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