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The authors studied the composition of fatty acids (FAs) in four species of dominant obligate halophytes—Triglochin maritima, Plantago maritima, Tripoliumpannonicum subsp. tripolium, and Lysimachiamaritima—growing in different flood conditions in the littoral zone of the White Sea. It was found that the content of total FA varied from 13 to 22 mg/g a.d.w. with maximum values in L.maritima and minimal in P. maritima. All species have high values of UFA content (74–77%), double bond index (1.6–1.8), and a significant contribution of triene FAs (45–55%). A high diversity of long-chain FAs (C20–24) was established: 14 FAs. This analysis showed the similarity of all halophytes in the main parameters of FA composition and the high functional activity of halophyte membrane systems. Two clusters of species with different adaptive responses have been identified: the first includes P. maritima, Triglochin maritima and Tripoliumpannonicum and the second includes L.maritima. A comparison of data for two clusters showed that there are FAs that are involved in the adaptation of all types of C18:3(n-3), C16:0, C18:2(n-6), and FAs that differ among clusters. For species of the first cluster, 1 FA is C20:4(n-4), and, for the second cluster, 4 FAs are C18:1(n-9), C18:3(n-4), C20:1(n-9), and C22:0. The revealed differences may be associated with different ways of adaptation of halophytes of the two clusters to littoral conditions. [ABSTRACT FROM AUTHOR]

Structural and functional traits in leaves of sea plantain (Plantago maritima L.) inhabiting intertidal and supratidal zones of the White Sea coast were studied. At the intertidal, the plants were found to have smaller and thicker leaves with more frequent stomata and thinner cover tissues in comparison with the plants collected from the supratidal. Leaf fluorescence and stomatal conductance obeyed the circadian rhythm in plants residing in the supratidal. The tested parameters considerably changed according to tidal dynamics in the intertidal plants. Two stable states (high and low tides) and two transition states (while water level ascends or descends) were defined. In both stable states, the plants demonstrated high functional parameters of fluorescence (Fv/Fm, Y(II), and ETR) and open stomata. In the transitional states, the stomata were partly closed, and the functional activity was inhibited. Leaf structural peculiarities, leaf gas films, the inducible CO2-concentrating mechanism, and the determining role of the stomata are considered in terms of the hypotheses explaining the responses of sea plantain to tidal dynamics on the White Sea coast. [ABSTRACT FROM AUTHOR]

The content of photosynthetic pigments and the ratios between them were studied in 71 species of vascular plants, 17 species of Bryophyta, and 10 species of lichens inhabiting West Spitsbergen. With an increase in the level of organization from lichens to vascular plants, the content of photosynthetic pigments (chlorophylls (Chl) and carotenoids (Car)) increased; the Chl a/b ratios and light-harvesting complex values varied independently of organism taxonomy; the Chl/Car ratio tended to increase. The content of pigments is related to taxon advancement at the level of both divisions and higher plant families. In plants inhabiting Arctic region, the pigment content in primitive species was lower than in more advanced ones. In angiosperms inhabiting Spitsbergen, the amount of Chl was lower than in plants inhabiting other botanicgeographical regions. [ABSTRACT FROM AUTHOR]

The content of particular components of water-soluble carbohydrates and cold tolerance of cucumber ( Cucumis sativus L.) cotyledonary leaves were studied at early developmental stages in dynamics during 6-day-long treatment with a temperature reduced to 12°C at two regimes: short-term cooling (2 h in the end of the night period, DROP) or permanent low-temperature treatment (PLT). PLT cucumber plants were characterized by the accumulation of oligosaccharides, whereas DROP plants contained increased amounts of glucose, fructose, and raffinose, indicating their higher metabolic status. When changes in carbohydrate fractions were compared with the dynamics of cold tolerance, it was found that these changes were synchronous in PLT plants but asynchronous for glucose and oligosaccharides in DROP plants. We suppose that, in cotyledonary leaves of DROP plants, two pools of sugars are produced; one of them used for tolerance development and another one — in active metabolism. This provides for the combination of activated metabolism and high cold tolerance of these plants. In PLT plants, all components of water-soluble carbohydrates are involved in cold tolerance development. [ABSTRACT FROM AUTHOR]

The mechanisms of plant responses to short-term cold treatments applied daily in the period of active growth remain unknown. Cucumber ( Cucumis sativus L.) plants were subjected to brief drops of temperature (2 h, 12°C) at the end of each night over a 6-day period (DROP treatment) and to prolonged (6 days) cooling at 12°C (permanent low-temperature treatment, PLT). The plants exposed to cold treatments and control plants grown at 20°C were compared in terms of cold resistance and changes in gene expression. Cold resistance of plants was determined on the basis of LT50 temperature. The response of cucumber genetic machinery was assessed by means of a differential display method based on polymerase chain reaction (PCR). The changes in mRNA pool in cells of cucumber plants subjected to permanent and periodic chilling were assessed after comparing the populations of PCR fragments of cDNA. In both types of chilling protocols, the cold resistance started to increase from the 2nd day of low temperature treatment. At the end of the experiment (on the 6th day), the increment in cold resistance was three times larger for DROP compared to PLT treatment. Analysis of mRNA pool showed that the numbers of amplified fragments were nearly identical in both types of low-temperature treatment. The higher level of cold resistance under DROP conditions was assumed to depend on features of metabolism. [ABSTRACT FROM AUTHOR]

During the tidal cycle, Fucus vesiculosus L. lost moisture (up to 30% of wet weight) and was characterized by a sinusoidal pattern in photosynthetic activity. Three peaks in the photosynthesis capacity were observed at the beginning and middle of low tide and at the beginning of high tide. There were no structural changes in the photosynthetic apparatus. When analyzing the curves of CO2 gas exchange, the processes of photosynthesis in the algae exposed to the air was limited by the activity of the light and dark phases of photosynthesis. The increase in the content of lipid peroxidation products, catalase activity, and accumulation of proline in F. vesiculosus thalli indicated the presence of reversible oxidative stress during low tide. [ABSTRACT FROM AUTHOR]

The paper describes the ontogenesis of the epiphytic lichen Lobaria pulmonaria. The studies were carried out in the Karelian forest communities with the period since the last disturbance ranging from 80 to 450 years. Based on the concept of a discrete description of plants and lichens, four periods and 14 age-related states have been distinguished in L. pulmonaria's ontogenesis. Each ontogenetic state of L. pulmonaria is characterized by a certain thallus size as well as by the presence and the level of development of vegetative diaspores and apothecia on the thallus surface. The possible variants of the species ontogenesis are described. [ABSTRACT FROM AUTHOR]