The effect of salinity on some morpho-physiological characteristics in lisianthus cultivars was investigated. Cultivars namely, Blue Picotee (C1), Champagne (C2), Lime Green (C3), and Pure White (C4), were subjected to salt stress (0-60 mM NaCl) in a sand culture and their responses were measured. Our results showed that as a salinity level increased, growth parameters, relative water content, photosynthetic pigments, and gas-exchange characteristics decreased in all cultivars, while root fresh mass, root/shoot length ratio, electrolyte leakage, and a malondialdehyde content increased. However, the changes were less pronounced in C3 and C4 compared to C1 and C2. The regression analysis of the relationship between salinity levels and seedling height or root/shoot length ratio defined two groups with different slope coefficients: C1 and C2 as salt-sensitive cultivars and C3 and C4 as salt-tolerant cultivars. Shoot dry mass and leaf area tolerance indices were less affected by salinity in C3 and C4 compared to those in C1 and C2. Further, C3 and C4 showed higher photosynthetic rates, greater stomatal conductances, and accumulated greater K+ and Ca2+ contents and K+/Na+ ratios in roots and shoots compared to those in C1 and C2. The results suggests that C3 and C4 could be recommended as resistant cultivars due to maintaining higher growth, water balance, leaf gas exchange, ion compartmentalization, and lower lipid peroxidation in response to salinity compared to C1 and C2., N. Ashrafi, A. Rezaei Nejad., and Obsahuje bibliografii
The aim of the present study was to define the stress-induced pattern of cytosolic glucocorticoid receptor (GR) and Hsp70 protein in the liver of male Wistar rats exposed to different stress models: acute (2 h/day) immobilization or cold (4 °C); chronic (21 days) isolation, crowding, swimming or isolation plus swimming and combined (chronic plus acute stress). Changes in plasma levels of corticosterone were studied by radioimmunoassay (RIA). The results obtained by Western immunoblotting showed that both acute stressors led to a significant decrease in cytosolic GR and Hsp70 levels. Compared to acute stress effects, only a weak decrease in the levels of GR and Hsp70 was demonstrated in chronic stress models. Chronically stressed rats, which were subsequently exposed to novel acute stressors (immobilization or cold), showed a lower extent of GR down-regulation when compared to acute stress. The exception was swimming, which partially restores this down-regulation. The observed changes in the levels of these major stress-related cellular proteins in liver cytosol lead to the conclusion that chronic stressors compromise intracellular GR down-regulation in the liver., D. Filipović, L. Gavrilović, S. Dronjak, M. Demajo, M. B. Radojčić., and Obsahuje bibliografii a bibliografické odkazy
Pigments absorbing 350-1,050 nm radiation have had an important role on the Earth for at least 3.5 billion years. The ion pumping rhodopsins absorb blue and green photons using retinal and pump ions across cell membranes. Bacteriochlorophylls (BChl), absorbing in the violet/blue and near infra red (NIR), power anoxygenic photosynthesis, with one photoreaction centre; and chlorophylls (Chl), absorbing in the violet/blue and red (occasionally NIR) power oxygenic photosynthesis, with two photoreaction centres. The accessory (bacterio)chlorophylls add to the spectral range (bandwidth) of photon absorption, e.g., in algae living at depth in clear oceanic water and in algae and photosynthetic (PS) bacteria in microbial mats. Organism size, via the package effect, determines the photon absorption benefit of the costs of synthesis of the pigment-protein complexes. There are unresolved issues as to the evolution of Chls vs. BChls and the role of violet/blue and NIR radiation in PS bacteria., A. W. D. Larkum, R. J. Ritchie, J. A. Raven., and Obsahuje bibliografické odkazy
Chloroplasts of barley plants grown under red light (RL, 660 nm) dramatically differed from the chloroplasts of plants raised under blue light (BL, 450 nm) or control plants (white light). The chloroplasts under RL had an extensive membrane system with high stacking degree and disordered irregular shaped stacks (shaggy-formed grana). After 5 h in darkness, dynamic rearrangements of chloroplast architecture in RL- and especially BL-grown plants were restricted compared with control plants. The light spectral quality affected the content and proportions of photosynthetic pigments. The leaves of RL-grown plants had the increased ratio of low-temperature fluorescence bands, F741/F683, corresponding to emission of PSI and PSII, respectively. This increase can be related to specific architecture of chloroplasts in RL-treated plants, providing close spacing between the two photosystems, which enhances energy transfer from PSII to PSI and facilitates the movement of LHCII toward PSI., G. V. Kochetova, O. B. Belyaeva, D. S. Gorshkova, T. A. Vlasova, E. M. Bassarskaya, T. V. Zhigalova, O. V. Avercheva., and Obsahuje bibliografii
Leaf senescence is always associated with decline in photosynthesis, consequently a loss of cellular sugar. On the other hand, execution of senescence program needs energy and leaves, therefore, tend to collect sugars from other sources to sustain energy homeostasis. This sugar reprogramming induced by loss of sugar involves operation of a complex catabolic network. The exact molecular mechanism of induction and regulation of the network, however, is not fully resolved but the current literature available suggests sugar starvation as a signal for induction of several senescence-associated genes including the genes coding for the enzymes for degradation of cellular constituents and their conversion to respiratory sugars. The late expression of genes coding for the cell wall hydrolases and enhancement in the activity of these enzymes late during senescence are indicative of the cell wall polysaccharides as the last source of sugars to sustain energy homeostasis for execution of the senescence program., B. Biswal, J. K. Pandey., and Obsahuje bibliografické odkazy
Carbon dioxide concentration and light conditions may greatly vary between mountainous and lowland areas determining the photosynthetic performance of plants species. This paper aimed to evaluate the photosynthetic responses of Lotus corniculatus, growing in a mountain and a lowland grassland, under low and high radiation and CO2 concentration. Net photosynthetic rate, stomatal conductance, transpiration rate, and intercellular CO2 concentration were measured while the water-use efficiency and the ratio of variable to maximal fluorescence were calculated. Photosynthetic response curves to different levels of radiation and intercellular CO2 partial pressure were estimated. Our results showed that high radiation and CO2 concentration enhanced
water-use efficiency of plants at both sites, enabling them to use more efficiently the available water reserves under drought conditions. The increase of radiation and CO2 concentration would enhance the photosynthetic performance of the mountainous population of L. corniculatus, which overall seems to express higher phenotypic plasticity., P. Kostopoulou, M. Karatassiou., and Obsahuje bibliografii
Semi-natural grasslands form an important part of the National Park and determine the landscape character of the area. Due to migration and human activities, plant species from the foothills and alpine areas have come into contact in the montane zone and coexist in new communities. The mechanisms behind the high diversity of local grasslands have been investigated since the 1980s. and Hana Skálová, František Krahulec.
V návaznosti na naše předchozí články tento příspěvek shrnuje a osvětluje pozoruhodné až rekordní vlastnosti vodních masožravých rostlin bublinatek (Utricularia, Lentibulariaceae) na úrovni ekofyziologické, biofyzikální i molekulárně genetické. Patří mezi ně velice rychlý vrcholový růst prýtu, rekordně vysoká rychlost fotosyntézy a velmi účinná reutilizace N a P ze starých prýtů, ale nikoliv K. Byl prokázán velmi rychlý průběh spuštění pastí, jejich spontánní spouštění bez mechanického podnětu po určité době, rozsáhlé vylučování organických látek do tekutiny pastí k podpoře pasťových mikrobních komenensálů i komplexní regulace tvorby pastí., As a follow-up to our previous papers, this paper summarises and elucidates remarkable and record-breaking eco-physiological, biophysical, and molecular characteristics of aquatic carnivorous bladderworts (Utricularia, Lentibulariaceae). These include the very rapid apical shoot growth, record high photosynthetic rate, and very effective N and P (but not K) reutilization in old shoots. Moreover, an extremely rapid time-course of trap firing, their spontaneous firing without any mechanical stimulus after certain time periods, extensive secretion of organic substances to the trap fluid to support microbial trap commensals, and a complex regulation of trap production are shown and discussed here., and Lubomír Adamec, Dagmara Sirová, Jaroslav Vrba, Jiří Bárta, Jiří Šantrůček, Karel Šimek.