Dehydrin stress proteins in birch buds in regions with contrasting climate

Dehydrin stress proteins were identified in buds of silver birch (Betula pendula Roth) grown in regions with contrasting climate, Karelia and Central Yakutia, using specific antibodies. Two types of dehydrins present in the plant buds, proteins with average (56–73 kDa) and low (14–21 kDa) molecular weight, as well as 17-kDa dehydrin, were detected in all studied plants. The most sensitive to seasonal changes are 14- to 21-kDa dehydrins, the level of which, regardless of the region where the birch grows, significantly increased during the autumn–winter period. The intraspecific polymorphism of dehydrins was more pronounced in B. pendula grown under the sharply continental climate of Yakutia, which is probably due to the peculiarities of the adaptation of woody plants to the extremely low temperatures of the cryolitic zone.     

Sucrose-Caused Changes in the Frequency and Localization of Anticlinal Divisions in the Cambial Zone of Silver Birch

This study continues our previous experiments intended to elucidate the role of sucrose in a figured wood formation in silver birch (Betula pendula Roth var. carelica). The purpose of the study was the investigation of the role of sucrose in the regulation of cell division in the cambial zone. Using an earlier-developed technique, sucrose solutions of different concentrations have been delivered into trunk tissues of silver birch. A microscopic analysis of samples collected 28 days after the beginning of the experiment has shown that an increased sucrose concentration in an exogenous solution causes an increase in the frequency of anticlinal cell divisions in the cambial zone. In the case of high sucrose concentrations (10 or 20%), the zone of anticlinal divisions is significantly wider than in variants with low sucrose concentrations, since anticlinal divisions are observed on both phloem and xylem sides and at a larger distance from rays. A comparison of the obtained results with the previous experiments shows that the increased frequency of anticlinal divisions in cambial cells observed in the case of application of 10 or 20% sucrose solutions coincides with an increased parenchymatization of tissues. A revealed localization of anticlinal divisions within the cambial zone indicates that, in the case of the exogenous sucrose uptake, the morphogenesis of conductive tissues in silver birch (Betula pendula Roth var. pendula) occurs in the same way as in Karelian birch (Betula pendula Roth var. carelica). Data presented in this paper agree with the earlier hypothesis that the formation of figured wood similar to that of Karelian birch occurs due to increased sucrose content in trunk tissues.     

Structural and functional peculiarities of plants from the genus <Emphasis Type="Italic">Betula</Emphasis> L. at early stages of ontogenesis

The morphological, biochemical, and physiological characteristics of silver birch (Betula pendula Roth), curly birch (B. pendula Roth var. carelica), and downy birch (B. pubescens Ehrh.) at early stages of ontogenesis in natural conditions were investigated. Some intra- and interspecific peculiarities of the morphophysiological properties were determined. Priority development of the underground mass for the seedlings of curly birch and that of the aboveground mass for the seedlings of silver birch and downy birch were found. The leaf of curly birch is developed more actively as compared with those in the other two species under equal potential possibility of the growth of their leaves by elongation. A high similarity of the mineral composition (C, N, P, K) of different forms and species of birches was demonstrated. For silver birch the maximum values of the stomatal conductance, rate of photosynthesis, and transpiration under similar atmospheric and soil conditions were obtained. In downy birch we found a higher efficiency of water use. The highest values of the maximum rate of ribulose 1,5-bisphosphate carboxylase/oxygenase carboxylation were found in curly birch. This may serve as an indicator of its shade tolerance, as compared with silver birch and downy birch.     

Excess of exogenous nitrates inhibits formation of abnormal wood in the Karelian birch

The effect of exogenous nitrate on the sucrose-metabolizing enzyme activities—sucrose synthase (SS) and apoplastic invertase (ApInv)—in the xylem and phloem of the silver (Betula pendula Roth var. pendula) and Karelian (B. pendula var. carelica) birches (the latter is well known for its abnormal, patterned wood) has been studied. A stable correlation between the enzyme activities and deviations in the growth and development of stem vascular tissues during cambial growth has been demonstrated. Formation of the birch wood with a common structure is associated with high SS activity. In this case, the reaction yields UDP glucose, which is utilized mainly for synthesis of the cell wall components of vessels and fiber tracheids. As for the Karelian birch, the SS activity in the xylem formation zone is decreased, which complies with a higher sucrose level in the tissue. The excess sucrose is released into the apoplast to be cleaved by ApInv. The resulting hexoses induce storage metabolism, thereby increasing the amount of storage substances and the share of storage parenchyma cells in the xylem. As a result, the Karelian birch wood acquires large inclusions in the parenchyma, which render a characteristic pattern. A change in the ratio of SS to ApInv activities underlies a great variety in the degree of wood patterning observed in Karelian birch trees. In the common silver birch, the nitrate application increases the sucrose utilization via SS pathway, which results in an increase in wood growth. In the Karelian birch xylem, nitrates lead to a decrease in both the SS (a decrease in wood growth) and ApInv (a decrease in the amount of parenchyma, i.e., normalization of the wood structure). The sucrose metabolizing in the xylem decreases on the background of an increase in its utilization in the phloem, where both enzyme activities elevate. It is assumed that the fact that the Karelian birch distribution range is limited by rich soils can be determined by a shift from intensive apoplastic sucrose utilization zone towards the phloem caused by high doses of nitrogen nutrition.     

Dehydrin stress proteins in <Emphasis Type="Italic">Pinus sylvestris</Emphasis> L. needles under conditions of extreme climate of Yakutia

This is the first study to investigate stress proteins dehydrins with the use of specific antibodies in the Scots pine (Pinus sylvestris L.) needles and their changes in the annual cycle under extreme climate of Yakutia. No pronounced polymorphism of major dehydrins (14–15 and 66 kDa) has been found during the winter dormancy period of P. sylvestris. A clear correlation between the seasonal variations in dehydrins and changes in the water content in needles was revealed. Consistently high levels of dehydrins was retained throughout the period of low negative temperatures. It is assumed that dehydrins can participate in the formation of P. sylvestris L. resistance to the permafrost conditions.     

Identification of birch pollen species using FTIR spectroscopy

In this study, the morphology and chemical composition of pollen grains of six birch species (Betula utilis Doorenbos, B. dahurica, B. maximowicziana, B. pendula, B. pubescens and B. humilis) were examined to verify which of these features allow distinguishing them in a more unambiguous way. For this purpose, scanning electron microscopy and light microscopy, as well as Fourier transform infrared (FTIR) spectroscopy and curve-fitting analysis of amide I profile, were performed. The microscopy images show that the pollen grains of B. pubescens, B. pendula and B. humilis are similar in diameter and significantly smaller than those of others species, with the largest diameter observed for B. utilis Doorenbos. However, the results obtained from FTIR spectroscopy indicate that the chemical compositions of B. pubescens and B. pendula are similar, but B. humilis is outlaying. Summarizing, it is not possible to unambiguously state, which feature or which technique is the best for differentiating between the six chosen birch species. However, the study showed that both techniques have potential for identification of birch pollen species.     

Potato dehydrins present high intrinsic disorder and are differentially expressed under ABA and abiotic stresses

Dehydrins (DHNs) correspond to late embryogenesis abundant proteins (LEA) of group 2, they are known as glycin rich proteins. Despite their expression during the late seed maturation stages, they are also involved in plant response to a number of abiotic stresses such as drought, salinity and cold. In the present study, we identified five full-length cDNAs encoding dehydrins (designated StDHN2a, StDHN1, TAS14, StDHN25 and StLEA27) isolated from potato. These dehydrins were composed of serine amino acids called S domain and lysine-rich segment corresponding to a K domain. Three DHNs (StDHN1, TAS14 and StLEA27) contained Y segments. In silico analysis showed that these StDHN sequences share high homology with other Solanum dehydrin proteins species. The analysis of gene expression using quantitative RT-PCR showed that they were upregulated by dehydration and salinity. Moreover, the search for putative regulatory element in the promoter sequence of dehydrin genes was investigated.     

Investigation of the photosynthetic activity of bark phelloderm of arboreous plants using the fluorescent method

Seasonal changes in the characteristics of chlorophyll fluorescence were studied in the bark of several species of trees originating in various climatic zones: Siberian cedar (Pinus sibirica), larch (Larix sibirica), eastern arborvitae (Thuja occidentalis), pendent white birch (Betula pendula), wild black cherry (Padus virginiana), horse chestnut (Aesculus hippocastanum), red oak (Quercus rubra), Manchurian catalpa (Catalpa bungei), linden (Tilia cordata), goat willow (Salix caprea), Amur cherry (Padus maackii), and apple Korichnaya (Malus domestrica B.). Tree bark has a sufficient amount of chlorophyll for measuring the parameters of chlorophyll fluorescence throughout the year. The relative yield of the variable fluorescence of chlorophyll (F _v/F _m) can be used to assess seasonal changes in the physiological state of various trees.     

Extractive compounds of birch buds (<Emphasis Type="Italic">Betula pendula</Emphasis> Roth.): I. Composition of fatty acids,hydrocarbons, and esters

This is the first report devoted to study of the hydrocarbon composition of the extract of buds of European birch Betula pendula (family Betulacea). We have identified saturated (C₁₆ to C₂₈, even number of carbon atoms) and unsaturated (linoleic and linolenic) fatty acids, β-caryophyllene, α-humulene, and the components of epicuticular waxes of cover scales, such as n-alkanes (C₂₁ to C₂₆), esters of fatty acids (C₁₆ to C₂₈, even number of carbon atoms), and fatty alcohols (C₁₈ to C₃₀, even number of carbon atoms). The gas chromatographic retention indices of all identified compounds have been determined.     

The use of parameters of chlorophyll <Emphasis Type="Italic">a</Emphasis> fluorescence induction to evaluate the state of plants under anthropogenic load

The physiological state of the leaves of the small-leaved linden (Tilia cordata), silver birch (Betula pendula), and northern white cedar (Thuja occidentalis) under urban conditions was assessed via recording the kinetics of chlorophyll under fluorescence induction. Different sensitivities of the plants to adverse growing conditions were revealed. The most sensitive parameters of the fluorescence JIP test, viz., PI _ABS , F _V/F ₀, and F _V/F _M, were identified as indicators of the physiological state of the urban phytocoenosis. Recommendations for the application of the method for monitoring studies are presented.     

Genetic variability and differentiation of three Russian populations of potato cyst nematode <Emphasis Type="Italic">Globodera rostochiensis</Emphasis> as revealed by nuclear markers

Genetic variability of yellow potato cyst nematode G. rostochiensis from three Russian populations (Karelia, Vladimir oblast, and Moscow oblast) was investigated using two types of nuclear markers. Using RAPD markers identified with the help of six random primers (P-29, OPA-10, OPT-14, OPA-11, OPB-11, and OPH-20), it was possible to distinguish Karelian population from the group consisting of the populations from two adjacent regions (Moscow oblast and Vladimir oblast). Based on the combined matrix, containing 294 RAPD fragments, dendrogram of genetic differences was constructed, and the indices of genetic divergence and partition (P, H, and G _st), as well as the gene flow indices N _m between the nematode samples examined, were calculated. The dendrogram structure, genetic diversity indices, and variations of genetic distances between single individuals in each population from Karelia and Central Russia pointed to genetic isolation and higher genetic diversity of the nematodes from Karelia.Based on polymorphism of rDNA first intergenic spacer ITS1, attribution of all populations examined to the species G. rostochiensis was proved. Small variations of the ITS1 sequence in different geographic populations of nematodes from different regions of the species world range did not allow isolation of separate groups within the species. Possible factors (including interregional transportations of seed potato) affecting nematode population structure in Russia are discussed.     

Phylogenetic relationships,molecular taxonomy,biogeography of <Emphasis Type="Italic">Betula</Emphasis>, with emphasis on phylogenetic position of Iranian populations

Birch trees inhabiting the high-altitude Hyrcanian forest (the southern shores of the Caspian Sea of Iran and Azerbaijan) are classified in the EN (endangered) category of the International Union for Conservation of Nature (IUCN). Taxonomic status and phylogenetic relationship of Iranian populations, molecular taxonomy, and biogeography of the genus Betula in the world have been considered. Four remnant populations of Betula were selected from north and northwestern parts of Iran. The internal ITS and trnH-psbA intergenic spacer regions were sequenced. Based on the trnH-psbA and ITS, Iranian birch and white birch were placed in a clade, but based on trnH-psbA divided into two subclades. Phylogenetic trees based on ITS and trnH-psbA data did not completely support the morphological classification. Network analysis confirms a close relationship of B. pendula with B. platyphylla and B. papyrifera with B. humilis, and B. ermanii were in a group with the other tetraploid species of the subgenus Neurobetula. Divergence time analysis showed that about 75 Ma ago the Betula genus separated from the other genus of Betulaceae and then divided into two main clades in Oligocene. Our divergence analysis supports that two subgenera of Betulenta and Betulaster are the oldest subgenera in the genus Betula and they date back to Eocene. The ancestral reconstruction suggests that ancestors of the genus Betula originated from Southeast Asia.     

The Influence of Location,Tree Age and Forest Habitat Type on Basic Fuel Properties of the Wood of the Silver Birch (<Emphasis Type="Italic">Betula pendula</Emphasis> Roth.) in Poland

The most extensive study to be carried out in Poland, and one of only a few worldwide, regarding the influence of location, tree age and forest habitat type on the basic fuel properties of silver birch (Betula pendula Roth.) wood was conducted in 12 Forestry Districts of the Polish State Forests. The field study included trees in three age groups of approximately 30, 50 and 70 years. The research was carried out in a fresh broadleaved forest (FBF) habitat type, where in Poland silver birch stands predominate in respect of coverage area and merchantable volume. Additionally, for five selected Forestry Districts, a comparative study was conducted in a fresh mixed broadleaved forest (FMBF), the second most important habitat of this tree species. A total of 306 test trees were examined. For every sample, calorific value and contents of ash, carbon, hydrogen, nitrogen, sulphur and chlorine were determined. The results indicated a statistically significant influence of location on the calorific value (p?=?0.0001) and on the contents of ash (p?<?0.0001), carbon (p?<?0.0001), hydrogen (p?<?0.0001), nitrogen (p?<?0.0001) and chlorine (p?<?0.0001) in the analysed wood. Moreover, statistically significant differences were observed between values of ash content (p?=?0.046) and of calorific value (p?=?0.0026) depending on the forest habitat type. Tree age was found to have no significant influence on the calorific value of silver birch wood.     

Relationship between seasonal progression of floral meristem development and <Emphasis Type="Italic">FLOWERING LOCUS T</Emphasis> expression in the deciduous tree <Emphasis Type="Italic">Fagus crenata</Emphasis>

Estimating the timing of flower bud formation in plants is essential to identify environmental factors that regulate floral transition. The presence of winter dormancy between the initiation of flowers and anthesis, characteristic of most trees in the temperate forests, hampers accurate estimation of the timing of floral transition. To overcome this difficulty, expression levels of flowering-time genes could be used as indicators of the timing of floral transition. Here, we evaluated the usefulness of molecular markers in estimating the timing of floral transition in Fagus crenata, a deciduous tree that shows intermittent and synchronized flowering at the population level. We selected FLOWERING LOCUS T (FT) as a candidate molecular marker and quantified the expression levels of its ortholog in F. crenata (FcFT). Subsequently, we analyzed the relationship between morphogenetic changes that occur between the vegetative state of the buds and the initiation of floral organs, and compared the FcFT expression levels in reproductive and vegetative buds, collected from spring to autumn. FcFT expression in leaves peaked at least two weeks before the morphological changes associated with flowering were visible in the buds in late July. FcFT expression levels were significantly higher in the reproductive buds than in the vegetative buds in July. These results suggest that the FcFT expression in July is a reliable indicator of the timing and occurrence of floral transition. This study highlights the utility of molecular tools in unraveling reproductive dynamics in plants, in combination with ecological and physiological approaches.