Epigenetically-determined apogamy in aposporous regenerants of the moss Pottia intermedia persists during vegetative propagation, the capacity of apogamy being inherited by individual aposporous protonemal cells. To test Bauer-Lazarenko's proposal that stable apogamy in mosses may be due to some self-replicating cytoplasmic factor, the effects of different metabolic stress treatments on the expression of apogamy have been tested. Chronic metabolic stress caused by long-term growth of autotrophic aposporous protonema on mineral medium with 0.25% of casamino acids and on Murashiga-Skoog (MS) medium with sucrose and phytohormones, as well as by transitory action of high kinetin concentration, have a much stronger influence on the expression of apogamy, than short-term stress treatments with RNase and Pb(2+). Apogamy has been found to be lost stably, after prolonged growth on MS medium containing kinetin and ABA. The proposal that the capacity for apogamy is related to the release of aposporous protonemal cells from a putative factor for apogamy is discussed.
Taxonomic, biomorphological and ecological structures of bryophytes, their reproductive strategy and the main mechanisms of tolerance in the conditions of salinization were investigated. Bryophytes are the pioneers that have colonized the territory of a tailing storage that holds liquid waste from potassium-magnesium concentrate production of the Mining and Chemical Enterprise "Polymineral". Due to excess salts, the soil solution in the shore area of the tailing pond acquires high osmotic pressure. Three experimental plots which differed significantly in the level of the substrate salinity were laid at the distance of 3, 6 and 9 m from the reservoir for experimental studies. Water extracts of the substrates from the test sites showed the highest concentrations for sulfates – 10.4–64.6 mg Eq/100 g of soil and chlorides – 7.6–43.3 mg Eq/100 g of soil. It was established that the investigated areas of the tailing storage territory differed in the biochemical activity of the substrate, which was evaluated by its redox potential. On the areas of the uncovered substrate it was the lowest – 230 mV, which indicates anaerobiosis in conditions of very high salinization and moisture. Higher ROP values were determined at the sites of bryophyte cover distribution – 295–330 mV. The aim of the study was to determine the features of taxonomic, biomorphological and ecological structures of bryophytes, their reproductive strategy and to establish the main mechanisms of adaptation to the conditions of salinization on the tailing storage territory. 24 species and 3 varieties of bryophytes, belonging to 12 families and 16 genera were found on the shore of the tailing storage pond. The results of biomorphological and ecological analysis of bryophytes indicate the uneven conditions of the habitats and their considerable ecological plasticity. Among the bryophytes, mesophytes, xeromesophytes and meso-eutrophs, eutrophs with a life-form of low dense and loose turf dominated. In salinization conditions, dioicous acrocarpous mosses prevailed, the fertile turf of which, depending on the influence of abiotic factors, differed significantly in the number of sexual shoots, their ratio and productivity. Bulbils were found only on the tips of Bryum argenteum shoots. Along with Salicornia europaea L., a euhalophyte, the leading role in the initial stage of overgrowth of the tailing storage area most often belonged to Didymodon rigidulus, Bryum argenteum, Funaria hygrometrica and Barbula unguiculata. The process of formation of bryophyte cover occurred along a gradient of decrease in salt concentration at the experimental sites. Adaptation of bryophytes to substrate salinity is due to a change in metabolic processes, which is manifested in an increase of the total content of carbohydrates and an increase of the cation exchange capacity of moss cell walls, which is the primary barrier that reduces the toxic effect of ions under salt stress.
Gravi-morphoses affect the variability of plants and are the morphogenetic adaptation to different environmental conditions. Gravity-dependent phenotypic plasticity of gametophytes as well as gravi-sensitivity of moss protonemata in microgravity and simulated microgravity conditions are discussed. The moss protonema, a filamentous multicellular system, representing a juvenile stage of moss development, develops as a result of the elongation and division of the apical cell. This apical cell of the protonema is a unique object for research on moss gravi-sensitivity, as graviperception and gravitropic growth occur within the same single cell. Attention is focused on the influence of gravity on bryophyte ontogenesis, including the gravitropic reactivity of moss protonemata, gravi-sensitivity at the stage of leafy shoot development and sporogonium formation, gravity-influenced morphogenesis of apical cell budding, and gravity-dependent spiral growth patterns. The role of gravireceptors in the growth processes of mosses at the cellular level under microgravity conditions are being discussed, as well as the involvement of auxin transport, Ca2+-induced gravitropism and the cytoskeleton in gravitropic reactions.
Stable bryophyte communities on rock dumps of the Chervonograd mining area were investigated; their rank as epigeic briosynusiae was specified. Structure and composition of the moss cover of the region were analysed. Floristic composition, projective coverage and life forms of bryophytes, features of ecological and coenotic differentiation of the bryoflora were defined. It was established that in biomorphic structure of mosses, species with growth forms of turfs and mats predominate, while among ecomorphs, dominating are heliophytes, mezophytes and xeromezophytes as well as epigeic ones. Results of geographic analysis indicate that the studied bryoflora is boreal (13 species, 65%). A noticeable proportion of boreal moss species and wide distribution of cosmopolitans, compared to zonal vegetation, resulted from the high level of anthropogenic transformation of the coal mining area.
The adaptive physiological reactions of the moss Bryum caespiticium Hedw. from Antarctica to the influence of UV radiation and gravimorphoses as a factor of adaptive plasticity, associated with environmental conditions, were studied. As a control, B. caespiticium plants were collected in the Nature Reserve “Roztochchia” (Lviv region). In investigations, we used a sterile laboratory culture of mosses grown under controlled conditions in a phytotron. Moss shoots were irradiated with UV rays generated by an ultraviolet lamp OSRAM with an intensity of 4 kW/m2, which caused 50 % inhibition of plant regeneration (ED50). Physiological parameters were determined 24 h after exposure to UV radiation. The influence of gravity on the morphological form of B. caespiticium gametophyte turf and the interaction of light and gravity in gravi-/phototropism as a manifestation of gravimorphoses adaptability were analyzed. One of the objectives was to investigate the formation of gravimorphoses as a result of the initiation of cells’ branching processes and the formation of gametophore buds and to evaluate their role in the life cycle of B. caespiticium under extreme conditions. For this, we determined the branching coefficient of the gravitropic protonema, the inclination angle of the branches and the buds’ development depending on the interaction of photo- and gravitropism, under the influence of red and blue light, and the effect of UV on gravisensitivity. The influence of physiologically active red and blue light on the branching activity and bud formation on the gravitropic protonema of the Antarctic moss B. caespiticium was investigated. It was found that red light mainly inhibited graviperception and gravitropic growth of protonemata cells, resulting in a change of the response to gravity, but initiated high branching activity and, accordingly, another morphological form of turf. After the influence of the blue light, intensive bud formation and gametophore development were observed. Thus, gravitation promoted morphological variability and changes in the functional activity of cells at the juvenile stage of the protonemata development, which is important for the survival of the moss under extreme environmental conditions. After UV irradiation the gravisensitivity of the B. caespiticium protonemata decreased. However, due to the resistance of the moss sample from Antarctica to the prolonged influence of UV rays, gravitropic growth was not completely blocked, as in plants from the Lviv region. The effect of the ultraviolet irradiation on the antioxidant activity, the content of soluble (vacuolar) and cell wall-bound fractions of UV-absorbing phenolic components, flavonoids content and their absorption spectra, as well as the amount of carotenoids and anthocyanins in B. caespiticium shoots, were determined. It was established that B. caespiticium plants from Antarctica have 1.5 times higher antioxidant activity compared to plants from the Lviv region, which confirms the high level of protection against oxidative damage. UV irradiation activates the synthesis of UV-absorbing phenolic compounds in mosses. The shoots of B. caespiticium from Antarctica defined a higher content of phenols compared to samples from the Lviv region and their significant increase under the influence of UV radiation. The content of UV-absorbing compounds bound with the cell wall was higher than the concentration of soluble phenolic compounds, both in plants from Antarctica and in samples from the Lviv region, which indicates their participation in the mechanisms of cells protection from UV radiation. It was shown that the influence of UV irradiation induced an increase of flavonoids’ content in the shoots of both samples of B. caespiticium, but for plants from Antarctica, the concentration of flavonoids after stress was 1.7 times higher than in plants from the Lviv region. The absorption spectra of flavonoids revealed flavonols rutin and quercetin and flavone luteolin in both samples of B. caespiticium, which provide effective cells absorption of UV rays. The higher content of anthocyanins and carotenoids in moss shoots from Antarctica both in the control sample and after the exposure to UV radiation promotes the protection against damage and formation of the adaptive potential.
Bryophytes possess a wide ecological diapason allowing them to populate substrates of technogenic origins which are scarcely suitable or completely unsuitable for viability of vascular plants. 49 bryophyte species, which belong to 2 divisions, 3 classes, 8 orders, 17 families, and 33 genera have been found on the dump territory of sulphur extraction of the mining-chemical enterprise “Sirka” (Yavoriv district, Lviv region). Seven transects, three on the north slope (base, slope, top), three on the south slope and one on the plateau were laid for sample selections. 20 investigated 0.5 × 0.5 m plots located 2 m apart were analyzed within each 10 × 10 m transect. Specific composition, life forms, projective cover, biomass of bryophytes, numbers of male, female and sterile plants, moisture content in the turfs, pH and physiological investigation of mosses were determined on each plot. The quantitative analysis of the biomorphological structure allowed us to establish the dependence of the spread of life forms on exposition and slope height; essential variability of the projective cover and moss biomass. Bryophyte cover plays an essential part in optimization of the moisture regime and surface layer temperature of technogenic substrates, improving the conditions of growth localities. We established that on the dump the dominant moss species are dioecious with a high level of reproductive effort (sexual and sexless), with short ontogenesis and age of first reproduction, which provides the chance to produce the maximum number of progeny in the minimum period and to form a complete moss cover. The analysis of seasonal moss photosynthesis dynamics has demonstrated the adaptability of moss photosynthetic apparatus to contrasting climatic conditions and the ability to support the intensity of photosynthetic processes on a rather stable level during the vegetative period. Our research showed that bryophytes play an important role in productivity of plant cover on the post-technogenic territories of sulphur extraction. It was found that bryophytes play a role in accumulation of organic carbon and biogenic elements in the substrate of the sulphur extraction dump . Carrying out research of specific composition dynamics and species activity is the precondition for revealing the essence of the dynamic processes taking place in the structure of the bryophyte communities on devastated territories and the influence of these processes on the formation of vegetation on dump complexes.
Gravisensitivity of mosses at different stages of their ontogenesis has an adaptive value and contributes to the functional activity of the gametophyte and its stability under extreme conditions in microhabitats. The aim of our research was to determine the participation of gravimorphoses in the adaptive plasticity of mosses depending on thermal conditions of their habitats and UV radiation effect. The objects of the study were sterile cultures of the following moss protonemata: Weissia tortilis, collected in different thermal conditions of Zaporizhzhya and Lviv regions (Ukraine), Bryum caespiticium from Lviv Region (Ukraine), as well as B. caespiticium and Polytrichum arcticum collected in Antarctica (Galindez Island). In all moss cultures, the gravisensitivity of protonemata, the morphological structure and morphogenesis of stolons were analysed. The protonemata of W. tortilis from two populations in Ukraine and of B. caespiticium from Antarctica and Ukraine, growing under conditions of different UV levels, were compared in terms of their sensitivity to UV radiation. Gravity-dependent morphoses of terrestrial dendrites of W. tortilis under arid conditions, branching of apical cells of gravitropic stolons of Antarctic mosses P. arcticum and B. caespiticium as well as the rapid development of shoots on them demonstrate participation of gravimorphogenesis in adaptation of mosses to stressful environmental conditions. Gravisensitivity and ability to form buds at the apex of a gravitropic stolon are considered an important adaptive morphogenetic process. It has been found that plants of W. tortilis from Zaporizhzhya Region were more resistant to UV irradiation than those from Lviv Region. Antarctic moss after UV irradiation showed significantly higher antioxidants activity and contained larger amount of phenolic compounds and flavonoids.
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