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Oleaster (Russian olive, Elaeagnus angustifolia) trees are highly tolerant against a variety of abiotic stresses (water, temperature, salt, and other chemicals). Therefore, they can be used for rehabilitation of contaminated and/or low quality soils (brownfields, dump sites, wastelands, etc.). In order to study responses of oleaster to environmental stress in vivo and in vitro, we successfully sterilized and initiated its callus cultures, regenerated shoots and roots and finally whole plants from the callus. Application of ammonium (in the form of sulfate salt) to the regenerated plantlets at concentrations higher than 10 mg L -1 inhibited root growth, reduced the leaf chlorophyll content and the activity of the enzyme glutamate dehydrogenase. At the same time, it induced activities of the stress marker enzyme glutathione S-transferase in the root and shoot tissues of the plant.

Response of 3 Arabidopsis clones to 41 strains of eight Rhizoctonia species was studied in model experiments. The seed germination was decelerated in most of the cases, although the inhibitory effect varied within large limits. The pre-emergence damping off and root neck rot leading to damping off were the most frequent symptoms of disease syndrome caused by toxic metabolites. The clone transformed with cDNA clone overexpressing gstf4 gene exhibited significantly improved tolerance as compared to parental one, meanwhile the sensitivity of Dmannose pyrophosphorylase/mannose-1-pyrophosphatase deficient clone dramatically increased. Strains of R. solani of AG-2, AG-4 and AG-7 and Athelia rolfsii produced the most toxic metabolites, however, no strict relationships were revealed between taxonomic position of Rhizoctonia strains and toxicity of their metabolites.

the Carpathian Basin were involved into our examination, which aimed at genotyping their accessions. DNA fingerprints of 101 varieties were determined with 6 microsatellite markers till 2005, resulting in successful discrimination of the accessions. Based on these results for pedigree determination, even more cultivars and primers were involved into the analyses. For studying the origin of Csabagyöngye and for proving the parent-progeny relations of Irsai Olivér and Mátrai muskotály, 19 microsatellite markers were applied, while 11 were selected for tracing the origin of Királyleányka. Genetic distances between the varieties were estimated with cluster analysis and demonstrated by dendrogram, proving that the varieties can be discriminated from each other based on the microsatellite allele sizes. Pedigree of Irsai Olivér and Mátrai muskotály has been confirmed by microsatellite allele size results, searching for the parents of Csabagyöngye and Királyleányka is in progress, since the molecular-marker based pedigree does not correspond with the putative origin of these cultivars. Our results excluded progeny-parent relationships in theCsabagyöngye-Bronnerstraube-Muscat ottonel (Ottonel muskotály) and the Királyleányka-Kövérszőlő combinations.

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