Changes in the hardwood groves of the Martonvásár Manor Park (Hungary) in the last 30 years

The subject of the present study is the monitoring of the hardwood groves at the Martonvásár Manor Park with the involvement of 20 earlier (recorded in 1980–1981) and 20 current (recorded in 2011–2012) phytocoenological relevés. The manor park was created in the first half of the 19th century. Since then the woods along the St László stream have developed into species-rich and semi-natural forests, which can be identified as related to the oak-ash-elm groves (Scillo vindobonensis-Ulmetum) of the Zámoly Basin and the Csepel Island. The results of the current monitoring repeated 30 years after the first survey show momentous changes in forest dynamics such as the ageing-related opening of the upper canopy and an intense closure of the lower canopy and shrub layer. The ratio of the invasive species doubled. Present findings may provide additional information for long-term forest ecology research, however, results could be considered as changes of a semi-natural hardwood forest with minimal human impact

UV-B radiation modifies the acclimation processes to drought or cadmium in wheat

Under natural conditions plants are often subjected to multiple stress factors. The main aim of the present work was to reveal how UV-B radiation affects acclimation to other abiotic stressors. Wheat seedlings grown under normal light conditions or normal light supplemented with UV-B radiation were exposed to drought or Cd stress and were screened for changes in the contents of salicylic acid and its putative precursor ortho-hydroxy-cinnamic acid, and in the activity of the key synthesis enzyme, phenylalanine ammonia lyase. Certain other protective mechanisms, such as antioxidant enzyme activities and polyamines, were also investigated. PEG treatment under UV-B radiation did not cause wilting, but resulted in more pronounced salicylic acid accumulation, which may provide protection against drought stress in wheat plants. In contrast, the high level of salicylic acid accumulation in Cd-treated plants was not further enhanced by UV-B stress, but resulted in pronounced oxidative stress and the activation of antioxidant systems and polyamine synthesis. Changes in the levels of phenolic compounds are accompanied by increased phenylalanine ammonia lyase activity in the roots, but not in the leaves. The similar pattern observed for stress-induced changes in salicylic acid and ortho-hydroxy-cinnamic acid contents suggested that salicylic acid may play a decisive role via ortho-hydroxy-cinnamic acid. The results indicated that UV-B radiation might have either a positive or negative impact under the same conditions in wheat, depending on the type of secondary abiotic stress factor. The protective or damaging effects observed may be related to changes in the levels of phenolic compounds

Interaction of Temperature and Light in the Development of Freezing Tolerance in Plants

Abstract Freezing tolerance is the result of a wide range of physical and biochemical processes, such as the induction of antifreeze proteins, changes in membrane composition, the accumulation of osmoprotectants, and changes in the redox status, which allow plants to function at low temperatures. Even in frost-tolerant species, a certain period of growth at low but nonfreezing temperatures, known as frost or cold hardening, is required for the development of a high level of frost hardiness. It has long been known that frost hardening at low temperature under low light intensity is much less effective than under normal light conditions; it has also been shown that elevated light intensity at normal temperatures may partly replace the cold-hardening period. Earlier results indicated that cold acclimation reflects a response to a chloroplastic redox signal while the effects of excitation pressure extend beyond photosynthetic acclimation, influencing plant morphology and the expression of certain nuclear genes involved in cold acclimation. Recent results have shown that not only are parameters closely linked to the photosynthetic electron transport processes affected by light during hardening at low temperature, but light may also have an influence on the expression level of several other cold-related genes; several cold-acclimation processes can function efficiently only in the presence of light. The present review provides an overview of mechanisms that may explain how light improves the freezing tolerance of plants during the cold-hardening period

Role of salicylic acid in acclimation to low temperature

Low temperature is one of the most important limiting factors for plant growth throughout the world. Exposure to low temperature may cause various phenotypic and physiological symptoms, and may result in oxidative stress, leading to loss of membrane integrity and to the impairment of photosynthesis and general metabolic processes. Salicylic acid (SA),phenolic compound produced by a wide range of plant species, a may participate in many physiological and metabolic reactions in plants. It has been shown that exogenous SA may provide protection against low temperature injury in various plant species, while various stress factors may also modify the synthesis and metabolism of SA. In the present review, recent results on the effects of SA and related compounds in processes leading to acclimation to low temperatures will be discussed

Light and Temperature Signalling at the Level of CBF14 Gene Expression in Wheat and Barley

The wheat and barley CBF14 genes have been newly defined as key components of the light quality-dependent regulation of the freezing tolerance by the integration of phytochrome-mediated light and temperature signals. To further investigate the wavelength dependence of light-induced CBF14 expression in cereals, we carried out a detailed study using monochromatic light treatments at an inductive and a non-inductive temperature. Transcript levels of CBF14 gene in winter wheat Cheyenne, winter einkorn G3116 and winter barley Nure genotypes were monitored. We demonstrated that (1) CBF14 is most effectively induced by blue light and (2) provide evidence that this induction does not arise from light-controlled CRY gene expression. (3) We demonstrate that temperature shifts induce CBF14 transcription independent of the light conditions and that (4) the effect of temperature and light treatments are additive. Based on these data, it can be assumed that temperature and light signals are relayed to the level of CBF14 expression via separate signalling routes

Prevalence and Detection of Flaviviruses Occurring in Slovakia

The tick-borne encephalitis virus (TBEV) and West Nile virus (WNV) are arboviruses of the genus Flavivirus in the family Flaviviridae. Their hosts are vertebratesof which rodents are the reservoirs of TBEV and birds are the reservoirs of WNV. Both viruses are transmitted from reservoirs to mammals by vectors. TBEV is transmitted by ticks (mostly Ixodes spp.) and WNV by mosquitoes (mostly Culex spp.). Both viruses are capable of infecting mammals, including man. TBEV and WNV are neurotropic, however infection is, in most cases, subclinical or accompanied by only moderate general signs. However, in some cases they can cause serious disturbances of the CNS. Our study focused on the detection of the genomes of TBEV and WNV in vectors by means of the reverse-transcription polymerase chain reaction (RT-PCR). The flavivirus genome was detected by means of oligonucleotides delineating the sequence in NS5 gene that encodes viral RNA-dependent RNA-polymerase. For the detection of TBEV, we used the oligonucleotide pair detecting the structural envelope protein. The positive samples were subjected to the sequence and phylogenetic analysis. The WNV was not detected in any of the pooled samples prepared from 616 mosquitoes captured in the vicinity of the village Drienovec, district Košice-surroundings. The investigation of 676 ticks demonstrated the presence of one strain of TBEV. One blood-fed I. ricinus female was obtained from a goat grazing in a pasture in the Dúbrava area close to Prešov. The genetic analysis revealed the presence of a strain close to the endemic strainsof TBEV Hypr and Neudörfl. The results of our study can become a motivation for additional studies in model locations oriented on ecology and circulation of these important zoonotic flaviviruses