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  • Author or Editor: Z. Bratek x
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The spores of 6 species of arbuscular mycorrhizal (AM) fungi (Glomeromycota) were collected, described and illustrated in three different habitats of semiarid open sandy grasslands in Hungary (Nagykáta, Domonyvölgy, Fülöpháza). Glomus constrictum, G. corymbiforme, G. microcarpum, Sclerocystis sinuosa, Scutellospora dipurpurescens, and S. persica are reported firstly from Hungary.

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Symbionts and endophytes of Hungarian orchids were studied at diverse habitats. Mycobionts of roots and in situ germinated protocorms of 15 orchid species were identified by molecular methods. Four fungal groups could be distinguished from orchids living at diversely wet treeless habitats: Ceratobasidiaceae, Epulorhiza 1, Epulorhiza 2 and Sebacinaceae. While the groups Ceratobasidiaceae and Sebacinaceae were detected only at habitats with medium water supply, members of clade Epulorhiza occurred at all of the treeless study sites. These observations suggest that fungi belonging to the genus Epulorhiza are more tolerant of water-stress than the other investigated genera. An ascomycetous fungus from the family Pezizaceae could be identified from the roots of Orchis coriophora. Further Ascomycetes were identified at forest habitats. Tuber maculatum was detected from the roots of Epipactis helleborine and Cephalanthera damasonium, and Tuber excavatum from Epipactis microphylla.

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The taxonomy of the genus Bulbocodium , in which two European species, a smaller eastern (B. versicolor) and a more robust western (B. vernum) are included, has been controversial since the description of the eastern species in 1821. Nuclear encoded ribosomal DNA ITS1 and the entire chloroplast DNA ITS were sequenced from several European populations, from France to the Ukraine, and the leaf width of mature living individuals was measured and analysed by ANOVA and Tukey-test. Although the studied DNA regions proved to be invariable, leaf width shows extreme variability. We found no correlation between the leaf size of the individuals and the geographical position of the populations, and in addition, the sequenced DNA regions showed total uniformity. Thus, our results do not support the division of the genus Bulbocodium into two taxa, at least in the sampled area. The formerly described size variants can be treated taxonomically at the forma level.

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The work was aimed at investigating short-term metabolic changes caused by S-methylmethionine (SMM) and at clarifying the gene expression background of these changes in order to gain a better understanding of the protective effect of SMM against stress. When examining the expression of genes coding for the enzymes responsible for the biosynthesis of polyamines, which play an important role in responses to low temperature stress, and that of the C-repeat binding transcription factor (CBF1) gene, it was found that both SMM and cold treatment increased the expression of genes responsible for the polyamine synthesis pathway starting from arginine. It caused only a slight increase when applied alone, but when SMM pre-treatment was followed by cold stress, it resulted in a considerable extent of up-regulation. SMM caused a similar increase in the expression of CBF1. The changes in the expression of genes responsible for the polyamine synthesis were clearly reflected in changes in the putrescine and agmatine contents, while the greater increase in the spermidine content was indicative of the role of SMM as a direct precursor in spermidine biosynthesis. The results demonstrated that, in addition to its direct effect on the sulphur metabolism and on polyamine biosynthesis, the protective effect of exogenous SMM was chiefly manifested in its influence on the expression of genes responsible for the biosynthesis of the polyamines important for stress responses and on the CBF1 transcription factor gene that acts as a regulator in cold stress.

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