Search Results

You are looking at 1 - 6 of 6 items for

  • Author or Editor: E. Kósa x
  • All content x
Clear All Modify Search

S-methylmethionine (SMM), a naturally occurring, biologically active compound, is a free amino acid derivative, which is increasingly recognised as playing an important part in the plant metabolism. SMM, which is synthesised from methionine, is involved in crucial processes in the S metabolism, such as the regulation of methionine and S-adenosyl methionine levels, the methylation processes taking place in cells, and the transport and storage of sulphur in certain phases of development. It is of great importance in the development of resistance to abiotic and biotic stress factors, as it is a direct precursor in the biosynthesis of the osmoprotectants and other S-containing compounds involved in defence mechanisms, while also influencing the biosynthesis of major plant hormones such as polyamines and ethylene. The present paper discusses our increasing understanding of the role played by SMM in the plant metabolism and its possible role in the improvement of traits that enable plants to overcome stress.

Restricted access

S-methylmethionine (SMM) is an important intermediary compound in the sulphur metabolism and has been shown to play a possible role in moderating the damaging effects of low temperature stress. The present work investigated the extent to which SMM is capable of influencing the activity of antioxidant enzymes when the subtropical species maize is exposed to chilling temperatures during the early developmental phase. SMM was found to contribute to the protection of maize seedlings against low (<14°C) temperature stress by enhancing the activity of certain antioxidant enzymes to varying extents, and thus helping to neutralise the reactive oxygen species (ROS) formed at this temperature. Results obtained in a gradient plant growth chamber revealed that, with the exception of catalase, SMM increased the activity of all the antioxidants studied (glutathione reductase, glutathione-S-transferase, guaiacol peroxidase, ascorbate peroxidase), particularly in the lower ranges of the temperature gradient (6–14°C).

Restricted access

Several Hungarian and foreign researchers have already studied the cardiorespiratory parameters of elite handball players. There are only a few studies though, which would separately review the changes in the functions of different organ systems. The aim of this study is to investigate the effect of an intervention (physical activity) on the cardiorespiratory system. In this study, 16 elite female handball players participated, whose body compositions were measured and took two vita maxima tests. During the analysis, each cardiorespiratory parameter was monitored for every 20 s. Between the two examinations, 6 weeks passed and an intervention took place. There was a significant decrease in relative body fat and a significant increase in relative muscle mass. Remarkable positive changes occurred in the values of ventilation, oxygen pulse, and in both absolute and relative aerobic capacities as well. The mean values of the team developed as expected, but the individual changes in body composition and cardiorespiratory parameters are just as important. First, we chose four players, who had the most outstanding changes. Second, we analyzed such parameters, which were expected to show adequate results in terms of the apparatus(es) functioning.

Restricted access
Acta Agronomica Hungarica
Authors: J. Pintér, E. Kósa, G. Hadi, Z. Hegyi, T. Spitkó, Z. Tóth, Z. Szigeti, E. Páldi, and L. Marton

The level of UV-B radiation reaching the surface of the earth is increasing due to the thinning of the ozone layer in the stratosphere over recent decades. This has numerous negative effects on living organisms.Some of the Hungarian inbred maize lines examined under the climatic conditions in Chile exhibited an unusually high proportion of pollen mortality, flowering asynchrony and barrenness. The evidence suggests that this can be attributed to the approx. 30% greater UV-B radiation in Chile.The investigation of this problem within the framework of abiotic stress breeding programmes is extremely important in the light of the global rise in UV-B radiation, which may make it necessary to elaborate a selection programme to develop inbred lines with better tolerance of this type of radiation.In the course of the experiment the same ten inbred lines, having different maturity dates and genetic backgrounds, were tested for five years in Chile and Hungary. The tests focussed on anthocyanin, a flavonoid derivative involved in the absorption of damaging UV-B radiation.Averaged over years and varieties, the total anthocyanin content in the leaf samples was significantly higher in Chile than in Hungary. This was presumably a response at the metabolic level to the negative stress represented by higher UV-B radiation.In the five early-maturing flint lines the anthocyanin contents were more than 45% greater than those recorded in Hungary. This suggests that these genotypes, originating from northern regions, were not sufficiently adapted to the higher radiation level. In these samples higher UV-B caused a sharp rise in the quantity of anthocyanin, which absorbs the dangerous radiation. In late-maturing genotypes the initial content of the protective compound anthocyanin was higher at both locations, so in these types the high radiation level was not a problem and did not cause any substantial change.Similar conclusions were drawn from the results of fluorescence imaging. The F440/F690 ratio indicative of the stress level was higher in late lines with a high anthocyanin content, good tolerance and good adaptability.

Restricted access
Acta Botanica Hungarica
Authors: K. Török, K. Szilágyi, K. Halász, V. Zsigmond, G. Kósa, T. Rédei, E. Peti, J. Schellenberger, Z. Tóth, and K. Szitár

Seed bank collections have multiple benefits: store genetic material for conservation and research, and their data can also provide valuable scientific information. The Pannon Seed Bank was established during an EU LIFE+ project between 2010 and 2014 with the target to collect and store seeds of approx. 50% of the wild native vascular flora of the Pannonian Biogeographic Region, seed accessions of at least 800 storable species. This task was fully achieved by the end of the project, as altogether 1,853 seed accessions of 910 species are stored. The aim of the present paper is to provide access to the collection data and metadata of the Pannon Seed Bank as it was completed by the end of the project. The collection campaign involved about 40 experts and covered the whole country. Collection and storing applied standard methodology, based on the ENSCONET project. The collection data published in this paper can be used manifold. Geographical data on species occurrences are major input for nature conservation and research. Seed collection date is valuable for ecological studies of phytophagous insects, frugivorous birds and mammals, etc. The database can be partner to international databases (like GBIF) or research infrastructures (e.g. LifeWatch). Hopefully, this data paper will contribute to further motivate the development of native seed collections and their use for conservation and research in Hungary.

Restricted access