Brassinosteroids (BRs) and polyamines, well-established growth regulators, play a key role in abiotic stress response in plants. In the present study, we examined the role of 24-epibrassinolide (EBL, an active BR) and/or putrescine (Put) in the salt-induced stress in cucumber. The 15-d-old plants were exposed to 100 mM NaCl and they were subsequently treated by exogenous EBL and/or Put. The salt stress reduced significantly plant growth and gas-exchange parameters, and increased proline content and electrolyte leakage in the leaves. Toxic effects induced by salt stress were completely overcome by the combination of EBL and Put. EBL and/or Put treatments improved the growth parameters of the NaCl-treated plants, such as shoot length, root length, fresh and dry mass. Our data also indicated that applications of EBL and Put upregulated the activities of the antioxidant enzymes, such as catalase, peroxidase, and superoxide dismutase under salt stress., Q. Fariduddin, B. A. Mir, M. Yusuf, A. Ahmad., and Obsahuje bibliografii
Seedlings of the hypoxia-sensitive cucumber cultivar were hydroponically grown under hypoxia for 7 d in the presence or absence of 24-epibrassinolide (EBR, 2.1 nM). Hypoxia significantly inhibited growth, while EBR partially counteracted this inhibition. Leaf net photosynthetic rate (PN), stomatal conductance, transpiration rate, and water-use efficiency declined greatly, while the stomatal limitation value increased significantly. The maximum net photosynthetic rate was strongly reduced by hypoxia, indicating that stomatal limitation was not the only cause of the PN decrease. EBR markedly diminished the harmful effects of hypoxia on PN as well as on stomata openness. It also greatly stimulated CO2 fixation by the way of increasing the carboxylation capacity of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), ribulose-1,5-bisphosphate regeneration, Rubisco activity, and the protection of Rubisco large subunit from degradation. Our data indicated that photosystem (PS) II was damaged by hypoxia, while EBR had the protective effect. EBR further increased nonphotochemical quenching that could reduce photodamage of the PSII reaction center. The proportion of absorbed light energy allocated for photochemical reaction (P) was reduced, while both nonphotochemical reaction dissipation of light energy and imbalanced partitioning of excitation energy between PSI and PSII increased. EBR increased P and alleviated this imbalance. The results suggest that both stomatal and nonstomatal factors limited the photosynthesis of cucumber seedlings under hypoxia. EBR alleviated the growth inhibition by improving CO2 asimilation and protecting leaves against PSII damage., Y. H. Ma, S. R. Guo., and Obsahuje bibliografii
Podyjí National Park is one of the hotspots of fungal diversity in the Czech Republic (so far we know about 1400 species from this area). The main reasons for this fact (well-preserved natural habitats, habitat and geological diversity) are introduced and briefly discussed in the article. high fungal diversity is documented based on several examples of rare or endangered species, which are typical for some of the local habitats and characterize the range of ecological conditions in the studied area. and Jan Běťák.
Since 2011, a unique project studying the effect of artificial canopy opening (Small-size clearings) on biodiversity in lowland forests has been carried out in the Podyjí NP. The response of communities of butterflies, moths, epigeic, floricolous and saproxylic beetles, birds, reptiles, and vascular plants was observed for three years. The results showed a positive effect of early stages in forest succession not only for the majority of groups studied, but also for many threatened species, and also demonstrated the importance of open forest remnants for biodiversity. In protected forests at low and middle elevations, conservation management should attempt to maintain a mosaic of forest at different stages of succession. and Pavel Šebek a kolektiv autorů.
The moths belong to the best-studied groups of insects in the Podyjí NP. In total, 2250 species of butterflies and moths (Lepidoptera) have hitherto been recorded here. Many species are closely associated with rocky steppe and heeathland, the most valuable natural habitats in this terriotory. Concurrently, the Podyjí NP is located on the western distribution border of many eastern and southern species. On the other hand, a total of 13 species of butterflies and moths have now become extinct here. and Jan Šumpich, Jan Liška, Zdeněk Laštůvka.