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.     

Dehydrins in Buds of Main Birch Species under Conditions of Karelia

The composition and seasonal dynamics of stress proteins-dehydrins in the buds of the main birch species (downy birch (Betula pubescens Ehrh.), silver birch (B. pendula Roth)) and its varieties (Karelian birch (B. pendula var. carelica (Mercklin) Hämet-Ahti)), growing in northwest Russia (on the example of the Republic of Karelia) were investigated for the first time. It was shown that the level of low-molecular dehydrins, mainly with a molecular mass of 17 kD, is subjected to major seasonal changes, regardless of the specific features of the birch. The maximal level of 17 kD dehydrin was formed during the autumn preparation of plants to dormancy and was persistently preserved during the cold period of the year. The content of medium-molecular weight dehydrins of 66–69 kD was almost at the same level all year round. Significant inter-and intraspecific polymorphism of the major dehydrins of 17 and 66–69 kD in the buds of downy birch, silver birch, and Karelian birch during dormancy was not found. The significant similarity in the composition of total proteins and dehydrins, as well as the uniform nature of their seasonal changes, mainly 17 kD dehydrin, indicates the phylogenetic proximity and similar mechanisms of adaptation of the main species of the genus Betula L. to the temperate continental climate of Karelia.     

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.     

The Role of Sucrose in Regulation of Trunk Tissue Development in Betula pendula Roth

Comparative ultrastructural analysis of the conducting and non-conducting phloem cells in the common straight-grained silver birch (Betula pendula var. pendula) and the Karelian birch (B. pendula var. carelica) with abnormal patterned wood was carried out, leading to the conclusion that there is an elevated sucrose content in the conducting phloem of the Karelian birch. A connection between sucrose levels and formation of abnormalities in the development of conducting tissues in the Karelian birch trunk was surmised. Experiments in which exogenous sucrose was applied to the silver birch trunk tissues have demonstrated the effects of different sucrose concentrations (0 g L⁻¹, 10 g L⁻¹, 25 g L⁻¹, 50 g L⁻¹, 100 g L⁻¹) on the formation of xylem and phloem structural elements, and they yielded the types of tissue development that correspond to the abnormal tissue development in the Karelian birch trunk.     

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.     

The effect of benzylaminopurine on fatty-acid composition of membrane lipids in shoots of Karelian birch in vitro

The effect of the synthetic analogue of natural cytokinin 6-benzylaminopurine (BAP) on the fatty-acid composition of membrane lipids in shoots of Karelian (Curly) birch Betula pendula Roth var. carelica (Mercklin) Hämet-Ahti under in vitro conditions was studied. It was found that the addition of BAP (in a concentration of 0.25, 0.5, 1.0, or 2 mg/L) to the nutrient medium leads to an increase in the proportion of saturated fatty acids in phospholipids, whereas in the control variant unsaturated fatty acids predominated in phospholipids. In glycolipids, on the contrary, BAP caused an increase in the synthesis of unsaturated fatty acids (predominantly, linolenic), but the degree of its effect depended on the concentration of the hormone. In particular, when the maximum amount of the studied concentration (2.0 mg/L) was used, the use of BAP was shown to decrease the proportion of linolenic acid. It is suggested that the revealed changes in the composition of glycolipids are indicators of the stimulating effect of cytokinin (up to a certain concentration) on the structure and function of chloroplasts. Due to the photomixotrophy of shoot cultures, chloroplasts are an important factor determining not only their photosynthetic activity, but also cell proliferation and the direction of in vitro morphogenesis.     

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.     

Quantification of Trends in Wood Production Within Trees of Silver Birch (Betula pendula Roth.)

Trends in rate and duration of wood production are analysedalong and between branches, and along main stems of silver birch(Betula pendula Roth.) trees (at early canopy closure and closedcanopy stages of growth). These data are discussed in relationto the control of knot size, log diameter and taper. To providea field guide to cambial reactivation, progress of vessel productionhas been related to stages of leaf expansion.Copyright 1994,1999 Academic Press Betula pendula (Roth.), silver birch, cambial activity, wood production, wood quality, vessel production     

High pressure effect on photosynthetic properties of green plant leaves

We investigated the effects of high pressure treatment on green plant leaves of two species, red rose (Rosa rubiginosa L.) and silver birch male (Betula pendula Roth). Both species were treated with pressure up to 100 bar in order to explore stress reactions, including desirable or undesirable metabolites in plant. When increasing the pressure, chlorophyll (Chl) fluorescence maximum shifts to the wavelength of about 680 nm for both red rose and silver birch, with shift rates–0.062 nm/bar and–0.082 nm/bar, respectively. High pressure induces the changes of the position for the second fluorescence maximum at approximately 730 nm in both species with the same shift rate–0.083 nm/bar. When increasing pressure the change of the photosynthetic apparatus efficiency decreases for both plant species slowly and nonlinearly. High-pressure treatments irreversibly damaged the leaf tissue and at this way induced changes of Chl fluorescence and photosynthetic efficiency.     

Effect of cadmium on fatty acid composition of lipids in the shoots of Karelian birch cultured in vitro

The effects of cadmium (10^?6, 10^?5, 10^?4, and 10^?3 M) on the growth and development of stem apical meristem and fatty acid (FA) composition of particular lipid fractions (neutral lipids, glyco-, and phospholipids) were investigated in the shoots of Karelian birch (Betula pendula var. carelica (Mercklin) Hämet-Ahti) produced in vitro. Low cadmium concentration (10^?6 M) slightly stimulated shoot morphogenesis. However, at the concentration of 10^?4 M, shoot growth and development was terminated, and the concentration of 10^?3 M turned out to be critical (the meristem died within the first 5 days). The presence of Cd in the medium considerably affected FA composition in the shoots. The most pronounced changes occurred in the fraction of glycolipids, and the extent of adverse influence significantly depended on metal concentration in the medium. At the Cd concentration of 10^?4 M, the content of di-and trienoic FAs decreased by 3–4 times, whereas the level of monoenoic FAs rose by 5 times. The revealed differences in the FA composition of lipids in birch were considered as an indicator of adverse effect of cadmium on the structure and functions of chloroplasts and therefore on photosynthesis.     

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.     

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.     

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.     

Fossil wood of <Emphasis Type="Italic">Betula erkovetskiensis</Emphasis> sp. nov. (Betulaceae) from the Miocene of the Erkovetskii Brown Coal Field,Amur Region,Russia

A new species, Betula erkovetskiensis Blokhina et O.V. Bondarenko (Betulaceae), from the deposits of the Sazanka Formation (upper Middle?Upper Miocene) of the Erkovetskii Brown Coal Field (Amur Region, Russia) is described based on anatomical features of fossil wood. The new species shows some wood anatomical characters of the extant birch subgenus Betula, B. davurica, B. nigra (section Dahuricae), and B. papyrifera (section Betula). Fossil wood of Betula is found in the Amur Region for the first time.     

Do moss samples,pollen traps and modern lake sediments all collect pollen in the same way? A comparison from the forest limit area of northernmost Europe

Moss polsters, pollen traps and lake surface sediment samples are commonly used as climate calibration data or as modern analogues for reconstructing vegetation from fossil profiles, but the differences in pollen content between these media have received little attention. This study aims to analyse how the three media differ in reflecting individual vegetation types and spatial differences in vegetation. 119 modern samples (64 moss polsters, 37 lake surface sediment samples and 18 pollen traps from which a collection was made annually) were taken from northern Fennoscandia and the Kola Peninsula as a broad transect crossing the northernmost forest limits of Betula pubescens ssp. czerepanovii (mountain birch), Pinus sylvestris (Scots pine) and Picea abies (Norway spruce). The pollen assemblages from these samples were compared with the surrounding vegetation visually and via PCA (principle components analysis) and cluster analysis. Both comparisons allow a correct distinction between pollen assemblages of arctic/alpine heath, mountain birch dominated areas, and boreal coniferous forests. The differences between the vegetation zones are stronger than the differences between the sampling media. Nevertheless, lake sediment samples from the mountain birch woodland zone tend to overestimate pine and underestimate birch. Pollen traps are biased towards lower tree pollen percentages and higher values of shrubs, herbs and Cyperaceae. This bias is especially strong in traps that have missing years in the data. Irrespective of the vegetation zone, pollen traps tend to have lower Pinus pollen percentages than in the adjacent moss polsters.     

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.     

Apoplastic Invertase Activity Regulation in the Cambial Zone of Karelian Birch

Russian Journal of Developmental Biology - We found that the regulation of apoplastic invertase (ApInv) activity in the cambial growth period in Karelian birch (Betula pendula var. carelica) is...     

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.     

Use of a geometric morphometric method to determine the developmental stability of <Emphasis Type="Italic">Betula pendula</Emphasis> Roth

A geometric morphometric method has been proposed to test the fluctuating asymmetry and the developmental stability of Betula pendula Roth populations. The main factors affecting the developmental stability were the industrial emission level, the relief altitude, and the interaction of both these factors. A strong correlation between the fluctuating asymmetry indices obtained by the normalizing difference method and geometric morphometric method has been revealed. The fluctuating asymmetry determined by the geometric morphometric method is sensitive to the presence of directional asymmetry, which makes it possible to use this method for precise bioindication mapping of the developmental stability.