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The suitability of five genes—GAPDH1, Actin1, Ef1a (1), Ef1a (2), and 18SrRNA—have been studied for normalization of target gene expression data by reverse transcription followed by real-time PCR. In order to detect stably expressed reference genes, leaves and stem tissues from B. pendula var. pendula and B. pendula var. carelica were used. The stability in the expression of potential reference genes was assessed using two software packages NormFinder and BestKeeper. Using both stably and less stably expressed reference genes, the expression of the gene encoding cell wall invertase in tree trunk tissues of Betula pendula Roth was compared during the period of active cambial growth. It has been shown that the best results are obtained when using a combination of two genes GAPDH1 and Ef1a (1).

Background Class III peroxidases (POD) proteins are widely present in the plant kingdom that are involved in a broad range of physiological processes including stress responses and lignin polymerization throughout the plant life cycle. At present, POD genes have been studied in Arabidopsis, rice, poplar, maize and Chinese pear, but there are no reports on the identification and function of POD gene family in Betula pendula. Results We identified 90 nonredundant POD genes in Betula pendula. (designated BpPODs). According to phylogenetic relationships, these POD genes were classified into 12 groups. The BpPODs are distributed in different numbers on the 14 chromosomes, and some BpPODs were located sequentially in tandem on chromosomes. In addition, we analyzed the conserved domains of BpPOD proteins and found that they contain highly conserved motifs. We also investigated their expression patterns in different tissues, the results showed that some BpPODs might play an important role in xylem, leaf, root and flower. Furthermore, under low temperature conditions, some BpPODs showed different expression patterns at different times. Conclusions The research on the structure and function of the POD genes in Betula pendula plays a very important role in understanding the growth and development process and the molecular mechanism of stress resistance. These results lay the theoretical foundation for the genetic improvement of Betula pendula.

Background In addition to known allergens, other proteins in pollen can aid the development of an immune response in allergic individuals. The contribution of the “unknown” protein allergens is apparent in phylogenetically related species where, despite of high homology of the lead allergens, the degree of allergenic potential can vary greatly. The aim of this study was to identify other potentially allergenic proteins in pollen of three common and highly related allergenic tree species: birch (Betula pendula), hazel (Corylus avellana) and alder (Alnus glutinosa). Methods For that purpose, we carried out a comprehensive, comparative proteomic screening of the pollen from the three species. In order to maximize protein recovery and coverage, different protein extraction and isolation strategies during sample preparation were employed. Results As a result, we report 2500–3000 identified proteins per each of the pollen species. Identified proteins were further used for a number of annotation steps, providing insight into differential distribution of peptidases, peptidase inhibitors and other potential allergenic proteins across the three species. Moreover, we carried out functional enrichment analyses that, interestingly, corroborated high species similarity in spite of their relatively distinct protein profiles. Conclusion We provide to our knowledge first insight into proteomes of two very important allergenic pollen types, hazel and alder, where not even transcriptomics data are available, and compared them to birch. Datasets from this study can be readily used as protein databases and as such serve as basis for further functional studies., This study aims to identify and annotate novel potentially allergenic proteins in the three highly related pollen species: birch, hazel, and alder. Immunoblotting of pollen protein extracts with serum from allergenic patients corroborates differential allergenic potential despite of the high similarity of the three species. Comprehensive proteomics analysis provides the first available protein database of pollens of alder and hazel and enables thorough annotation of proteases and allergens as well as comparative functional analysis of expressed proteins across the three pollens. Abbreviations: LC‐MS, liquid chromatography‐mass spectrometry; SDS‐PAGE, sodium dodecyl sulfate polyacrylamide gel electrophoresis.

The fatty acid composition (FAC) of fractions of organic compounds isolated from total lipids (TL) by successive solvents—chloroform, acetone, and methanol, taken as neutral lipids (NL), glycolipids (GL), and phospholipids (PL)—was studied by the phases of the opening of buds in plants of the Betula L. genus [1]. It was found that the FAC of the TL fractions of opening buds of trees with morphological features of Betula pubescens Ehrh., Betula pendula Roth, and Betula pendula Roth var. carelica (Mercklin) Hamet-Ahti is represented mainly by unsaturated fatty acids (USFAs) (up to 88% of the total fatty acids). Linolenic and linoleic acids (up to 55 and 47% of the total fatty acids, respectively) constituted the main share of USFAs. Palmitic acid predominated quantitatively among saturated fatty acids (SFAs) (up to 42%). The content of linoleic acid in all SL fractions decreased with the development of buds in all three birches, while the content of linolenic acid in the composition of the GL and PL fractions increased. In birches differing in morphological characteristics, the specific features of the FAC from the SL fractions of the buds were studied by the opening phases.

A significant role in the pathogenesis of diseases of woody plants belongs to phytopathogenic bacteria and fungi. It has been scientifically confirmed that the organs and tissues of woody plants have a certain myco- and microbiota, the components of which are systematically interconnected both with each other and with the plant. The species composition and quantitative ratio are constantly changing both in the process of ontogenesis of the tree and with changes in its physiology. The aim of the work was to study the species composition and the formation of diversity and systemic interactions of microbiota associated with bacterial dropsy in the pathology of Betula pendula Roth. Methods. Classical microbiological, phytopathological, biochemical, statistical methods were used in the work. Combined diagnostic methods were also used, in particular careful microscopic examination of the affected parts of plants, isolation and identification of the pathogen. Results. Bacterial origin of wet wood in the trunk of birches was detected. Samples of wood and exudate were taken for laboratory studies from plants that had pronounced signs of pathology (cracks, swellings). It has been experimentally proved that the causative agent of bacterial dropsy of silver birch is the phytopathogenic polybiotrophic bacterium Lelliottia nimipressuralis, which causes dropsy of coniferous and deciduous woody plants and experimentally found pathogenic properties to B. pendula. Xanthomonas campestris, Pantoea agglomerans and Bacillus subtilis are associated with bacterial dropsy pathology of B. pendula. The pathogenic properties of P. agglomerans and X. campestris on B. pendula are variable, which indicates the possibility of the expansion of the circle of plants sensitive for these species of bacteria. It was established that L. nimipressuralis both during spring and autumn inoculation showed high pathogenicity to B. pendula. In only one case, on isolated on the border of healthy and affected wood from young B. pendula (bast part) the results of artificial injury were less pronounced. Other bacteria isolated from bacterial dropsy, in particular X. campestris, were non-pathogenic for B. pendula. At the same time, we noted traces of artificial infection with X. campestris in the samples isolated on the border of healthy and affected wood from middle-age B. pendula (cambial part). This may indicate an expansion of the circle of sensitive plants or the increased sensitivity of certain forms of birch for the mentioned bacteria, which is quite likely, since the bacteria have a significant forms variety. In 10 places of inoculation no pathology caused by B. subtilis was found. Bacteria of the Bacillus genus were non-pathogenic for B. pendula in all experiment. Our studies have shown that they can be a regulatory factor in the development of bacterial dropsy. Conclusions. A certain variability of isolated strains in the assimilation of some carbohydrates and alcohols can be explained by the specific conditions of the existence of bacteria, including the influence of environmental factors on their biochemical properties. It is known that the ecological niche affects even the antigenic composition of bacteria; therefore, such an effect should also be expected on other properties. Our studies confirmed that causative agent of bacterial dropsy is L. nimipressuralis and clarified the information about this bacteria cells size.

Aims Pioneer tree species such as Betula pendula and Pinus sylvestris encroach soils contaminated with heavy metals (HMs). This is facilitated by ectomycorrhizal fungi colonizing tree roots. Thus, we evaluated the ectomycorrhizal fungal (EMF) communities of B. pendula and P. sylvestris growing in HM-contaminated soils compared to non-contaminated soils. We also studied the effect of HMs and soil properties on EMF communities and soil fungal biomass. Methods Roots of B. pendula and P. sylvestris were collected from three HM-contaminated sites and from two non-contaminated sites located in Poland. EMF species were identified using DNA barcoding. Soil fungal biomass was determined by soil ergosterol. Results B. pendula and P. sylvestris growing in HM-contaminated soils had similar EMF communities, where Scleroderma, Rhizopogon and Russula as well as ectomycorrhizae of the long-distance exploration type dominated. Among all of the examined soil factors studied, toxicity index (TITotal) was the most significant factor shaping the composition of EMF communities. Despite significant differences in the structure of the EMF communities of trees growing in HM-contaminated sites compared to control sites, no differences in overall diversity were observed. Conclusions Only well-adapted EMF species can survive toxic conditions and form ectomycorrhizal symbiosis with encroaching trees facilitating the forest succession on contaminated soils.

The article is focused on microbiological and silvicultural properties of bacterial wetwood of silver birch (Betula pendula), also known as European white birch. During the active phase of the disease, bacterial wetwood (i.e. bacterial dropsy, vascular parenchymatous bacteriosis or flux slime) is characterised by crust and periderm bloating, necrotic wet stains and abundance of exudate. The disease is more likely to occur in older (r = 0.56, p < 0.01) and less-dense (r = −0.29, p < 0.01) stands. The statistical model showed that the chance of bacterial wetwood increases with birch age by 0.36% per year. The stands with birch proportion of over 70% demonstrated 15.3% lower infection rate compared to the stands with lower birch presence. The stands with lower stocking demonstrated a higher proportion of infected tree distribution by 7.5% compared to the stands with higher birch representation. The most vulnerable were larger, older B. pendula trees with longitudinally fissured bark that grow on poorer soils and experience frequent water stress. Birch associations with Pteridium aquilinum and Vaccinium myrtillus were more susceptible to infection (31.6% and 44.3%, respectively), whereas associations with Brachypodium sylvaticum, Sphagnum palustre and Calluna vulgaris were at lower risk. Strong ecological and trophic association of bacterial wetwood was present between silver birch and Tremex spp., particularly Tremex fuscicornis. Mycobiota was represented by Rhizopus microsporus, Mucor mucedo, Penicillium aurantiogriseum, Penicillium purpurogenum and Acremonium strictum. Enterobacter, Xanthomonas, Pantoea and Bacillus spp. associated with bacterial wetwood of silver birch were isolated. Enterobacter nimipressuralis was found to be the primary causative agent through means of artificial infection, while other bacteria were found to be either weak pathogens or concomitant. E. nimipressuralis formed the largest number of colony-forming units (CFU) for bark and cambium (164 and 127 CFU, respectively) and was also found in a small amount as a vital obligate in the automicrobiota in healthy birch trees.

Key message Sustainability and safety aspects of plant cell cultures as food are presented. Applicability of dairy side streams as carbon source and use of natural growth enhancers in cultivation are shown. Abstract Biotechnologically produced cellular products are currently emerging to replace and add into the portfolio of agriculturally derived commodities. Plant cell cultures used for food could supplement current food production. However, still many aspects need to be resolved before this new food concept can enter the market. Issues related to sustainability and safety for human consumption are relevant for both consumers and regulators. In this study, two plant cell cultures, deriving from arctic bramble (Rubus arcticus) and birch (Betula pendula), were cultivated using lactose-rich dairy side streams as alternative carbon sources to replace sucrose. Biomasses were comparable to those of original plant cell culture media when up to 83% and 75% of the original sucrose was replaced by these side streams for arctic bramble and birch cell cultures, respectively. Furthermore, nutritional composition or sensory properties were not compromised. Synthetic plant growth regulators were replaced by natural components, such as coconut water and IAA for several subculture cycles. Finally, it was shown that only trace amounts of free growth regulators are present in the cells at the harvesting point and assessment by freshwater crustaceans assay indicated that toxicity of the cells was not exceeding that of traditionally consumed bilberry fruit.

The allelopathic effect of extracts from leaf litter of Betula pendula on the initial stages of ontogenesis (seed germination and growth and development of seedlings) of Rumex aquaticus has been studied in laboratory conditions. A significant decrease in laboratory germination by 1.5–36.3 times, depending on the concentration of the extract, is found. The change in the coefficient of inhibition confirmed the phytotoxicity of the investigated extract. The inhibitory effect on the seedlings at a concentration ≥50% of control is manifested in a decrease in the morphometric parameters of both the underground (root system and hypocotyl) and aboveground (cotyledon) parts of the seedlings.

We identified 15 genes encoding enzymes for phenylpropanoid biosynthesis in the genome of birch by combining phylogenetic analysis and tissue-specific expression data. Lignin is one of the most abundant terrestrial biopolymers and is essential for plant structure and defense. An essential step in lignin formation is phenylpropanoid synthesis, we identified 120 gene models in 10 protein families encoding enzymes for phenylpropanoid biosynthesis in the genome of Betula pendula. The transcript abundance was determined for all 120 genes in xylem, root, leaf, and flower tissues using RNA-seq technology. We identified 15 genes that likely encode phenylpropanoid biosynthesis enzymes during wood formation. Ten of these genes are evolutionarily conserved compared to the lignin genes in Populus trichocarpa.

We tested the seasonal variability of frost resistance and photosynthesis characteristics, namely net photosynthetic rate at saturating irradiance and ambient atmospheric CO2 concentrations, maximum carboxylation rate, and measurements based on the JIP-test, namely maximum quantum yield of PSII and the performance index. Additionally, we measured leaf functional traits, namely specific leaf area, leaf dry matter content, stomatal pore area index, and chlorophyll content. We assessed all traits weekly on two evergreen species Berberis vulgaris and Quercus × hispanica as well as the two summer green species Betula pendula and Quercus pubescens. We found that there was a high seasonal variability in all traits except stomatal pore area index. In a multivariate analysis, we could show trade-offs between growth rates and leaf thickness on the first axis, as well as resistance and performance on the second axis. The findings help understand ecophysiological processes and fine-tune biosphere models.

The article presents the results of investigation of the population structure of Betula pendula at four iron ore mine dumps (tailings) of the Kryvyi Rih area, of the Northern and Central Mining-and-Processing combines (NorthMPC and CMPC). Totally, eleven population loci on the Petrivskyi and Avtomobilnyi dumps of the Pershotravnevyi quarry, dump No. 7 and Petrivskyi-2 dump of the Hleyuvatskyi quarry of CMPC were investigated. The area of population loci, number and density of different aged individuals in each locus, as well as their percentage for each dump were ascertained. The morphometric parameters of the largest trees of Betula pendula on the Petrivskyi dump and trees of the generative age in all population loci were studied. A high-level vitality state of adult (mature) individuals in all population loci has been noted. We observed frequent changes of life forms of Betula pendula: sprout-forming, trees with few trunks (up to 3) and multi-stemmed trees (more than 3 trunks) formed as a result of the development of additional trunks from resting or adventitious buds under specific conditions of iron ore dumps in the Kryvyi Rih area. One-sided, bilateral and versatile dominant directions of the spread of self-seedlings in various loci were revealed. An analysis of the age structure demonstrated that out of eleven population loci, ten are young, in six of them plants are capable of complete self-renewal; a single locus is ripening, in which only 58% of generative individuals can recover. According to results of the study of the vitality structure, eight population loci belong to the flourishing type and three – to the depressive one. It has been found that the vitality of individuals depends on the environmental conditions as well as physical and chemical properties of the substrate. Due to constant self-renewal and self-maintenance in all the eleven population loci, Betula pendula can form stable primary populations under extreme conditions and thus is perspective for recultivation of technogenically disturbed landscapes.

In post-disturbance areas, salvage logging is a common management practice that can negatively affect ecosystem services and alter successional pathways of natural regeneration. In this study, we aim to investigate the effects of salvage logging in post-fire areas on the regeneration and height of Scots pine (Pinus sylvestris L.) on dry-poor, wet-poor, and peat soils. We used the Poisson generalised linear mixed-effects model and linear mixed-effect model to assess the effects of salvage logging on the abundance and height of Scots pine. In all forest types in post-fire areas, Scots pine and birch (Betula pendula Roth and Betula pubescens Ehrh.) were the most common tree species, accounting for 70–100% of the total regeneration abundance. Salvage logging resulted in significantly higher abundance of Scots pine only on mesic-peat soil. Mean height of Scots pine was significantly lower in stands with larger abundance of remnant living trees. In our study, we did not find conclusive evidence of negative effects of salvage logging on the abundance and height of Scots pine.

In this pilot study, microplastic beads (5–50μm) were tagged withfluorescent dye and introduced to the soil of pottedBetula pendulaRoth. (silver birch) saplings during the growing season. Afterfive months, root samples were examined usingfluorescence- and confocal laser scanning microscopy. This paper presents thefirst documented indication of the incorporation of microplastic into root tissues of woody plants and discusses the phytoremediation potential of birch in soil with microplastic contamination.

Despite active research, antiherbivore activity of specific plant phenolics remains largely unresolved. We constructed silver birch (Betula pendula) lines with modified phenolic metabolism to study the effects of foliar flavonoids and condensed tannins on consumption and growth of larvae of a generalist herbivore, the autumnal moth (Epirrita autumnata). We conducted a feeding experiment using birch lines in which expression of dihydroflavonol reductase (DFR), anthocyanidin synthase (ANS) or anthocyanidin reductase (ANR) had been decreased by RNA interference. Modification-specific effects on plant phenolics, nutrients and phenotype, and on larval consumption and growth were analyzed using uni- and multivariate methods. Inhibiting DFR expression increased the concentration of flavonoids at the expense of condensed tannins, and silencing DFR and ANR decreased leaf and plant size. E. autumnata larvae consumed on average 82% less of DFRi plants than of unmodified controls, suggesting that flavonoids or glandular trichomes deter larval feeding. However, larval growth efficiency was highest on low-tannin DFRi plants, indicating that condensed tannins (or their monomers) are physiologically more harmful than non-tannin flavonoids for E. autumnata larvae. Our results show that genetic manipulation of the flavonoid pathway in plants can effectively be used to produce altered phenolic profiles required for elucidating the roles of low-molecular weight phenolics and condensed tannins in plant–herbivore relationships, and suggest that phenolic secondary metabolites participate in regulation of plant growth.

Propolis is a resinous mixture, made by the honeybees from substances collected from tree or other plant buds, plant exudates, or resins found in the stem, branches, or leaves of different plants. The geographical origin of propolis is given by plant sources from respective areas. Different studies have classified this bee product according to the vegetal material from the same areas. Poplar-type propolis has the widest spread in the world, in the temperate zones from Europe, Asia, or North America. The name is given by the main plant source from where the bees are collecting the resins, although other vegetal sources are present in the mentioned areas. Different Pinus spp., Prunus spp., Acacia spp. and also Betula pendula, Aesculus hippocastanum, and Salix alba are important sources of resins for “poplar-type” propolis. The aim of this review is to identify the vegetal material’s chemical composition and activities of plant resins and balms used by the bees to produce poplar-type propolis and to compare it with the final product from similar geographical regions. The relevance of this review is to find the similarities between the chemical composition and properties of plant sources and propolis. The latest determination methods of bioactive compounds from plants and propolis are also reviewed.

Betula aetnensis is an endemic tree of high conservation value, which thrives on the nutrient-poor volcanic soils of Mount Etna. Since plant–microbe interactions could play a crucial role in plant growth, resource uptake, and resistance to abiotic stresses, we aimed to characterize the root and rhizosphere microbial communities. Individuals from natural habitat (NAT) and forest nursery (NURS) were surveyed through microscopy observations and molecular tools: bacterial and fungal automated ribosomal intergenic spacer analysis (ARISA), fungal denaturing gradient gel electrophoresis (DGGE). B. aetnensis was found to be simultaneously colonized by arbuscular (AM), ectomycorrhizal (ECM), ericoid (ERM) fungi, and dark septate endophytes (DSE). A high diversity of the bacterial community was observed whilst the root fungal assemblage of NAT plants was richer than that of NURS. Root and rhizosphere fungal communities from NAT plants were characterized by Illumina MiSeq sequencing. Most of the identified sequences were affiliated to Helotiales, Pezizales, and Malasseziales. Ascomycota and Basidiomycota dominated roots and rhizosphere but differed in community structure and composition. ECM in the roots mainly belonged to Tylospora and Leccinum, while Rhizopogon was abundant in the rhizosphere. The Helotiales, including ERM (mostly Oidiodendron) and DSE (mostly Phialocephala), appeared the dominant component of the fungal community. B. aetnensis harbors an extraordinarily wide array of root-associated soil microorganisms, which are likely to be involved in the adaptation and resistance mechanisms to the extreme environmental conditions in volcano Etna. We argue that nursery-produced seedlings could lack the necessary microbiota for growth and development in natural conditions.

Research Highlights: a forest is an ecosystem that allows for the assessment of radioactive contamination of the environment over several decades. (1) Background and Objectives: measurements of the activity of the 137Cs isotope in various elements of a forest ecosystem are one of the most important parameters in the assessment of radioisotope contamination. The translocation of 137Cs in the environment is determined by the activity of the natural 40K isotope in soil. The activities of 137Cs and 40K isotopes were assessed in two stands of Betula pendula and Pinus sylvestris, differing in age (30, 50, and 80 years old), (2) Materials and Methods: the research was conducted in one of the forest districts of eastern Poland. Wood, litter, and soil were collected for the tests from the sampling sites. The activity of 137Cs and 40K was determined using the γ-spectrometric method. Based on the activity of these isotopes in wood and soil, the values of translocation factors (TF) were determined, (3) Results: the highest activity of 137Cs was recorded in the wood of the oldest stands, the growth period of which coincided with the time period of intensive testing with nuclear weapons. With the growing age of the stand, the value of TF 137Cs increased, while the value of TF 40K was not dependent on the age of the stands. Birch wood accumulated more 137Cs and 40K isotopes than pine wood. (4) Conclusions: the results show a much greater radioactive contamination of the environment in eastern Poland during the testing with nuclear weapons than after the Chernobyl nuclear reactor explosion. The greater accumulation of radiocesium in birch wood than in pine wood predisposes this species to be more useful when assessing the radioactive contamination of the environment from the past.

International audience; Tree species diversity generally has positive effects on forest primary productivity and resistance to natural perturbations, but diversity-function relationships can vary with site conditions. Recently, studies in forest diversity experiments have shown that tree diversity and local climate, in particular drought intensity, interactively affect insect herbivory. On the other hand, many studies focused on the response of forests to drought in terms of tree growth but without analysing the concomitant effects on susceptibility to pests. It is of particular interest to understand the combined effects of drought and tree diversity on the growth of the host tree, since host resource concentration is a determining factor of a pest & rsquo;s host choice.We used a tree diversity experiment where tree species diversity and drought conditions were both manipulated to evaluate their interactive effects on the susceptibility of maritime pine (Pinus pinaster A & iuml;t.) forests to two primary pests (i.e. infesting healthy trees): the pine stem borer (PSB) Dioryctria sylvestrella, and the pine processionary moth (PPM; a leaf chewer), Thaumetopoea pityocampa. Using structural equation models, we investigated the direct and indirect effects (i.e. mediated by host resources) of the presence of birch and drought on the total number of attacks of PPM and PSB, in the same plots and in the same year.We showed that pine-birch plots were more resistant to both PPM and PSB attacks than pine monocultures. Furthermore, we found that this associational resistance pattern was due to direct effects of birch trees on attacks, possibly related to disrupting non-host volatiles (NHVs), but also to indirect, resource-mediated effects whereby the presence of birch trees reduced the amount of host pine resources available to the pests. Drought conditions modulated birch mediated effects on resistance of maritime pine forests only for PSB attacks. Overall, our work improves our understanding of tree diversity-herbivory relationships and helps explain how climate might modulate such relationships.

Witches' broom of birch (Betula spp.) caused by Taphrina betulina is an understudied disease that causes the formation of woody tumours, from which ectopic axillary buds and branches grow to form a broom-like structure. We have addressed two aspects of this disease using naturally infected mature trees in the field. Broom symptoms offer a convenient means of scoring susceptibility in the field. Variation in broom symptom presentation suggests possible variation in resistance against witches' broom disease. We tracked the local distribution of susceptible individuals among 721 trees at 159 independent sites. The analysis supports the hypothesis that there was genetic resistance segregating in these birch populations. Anatomical changes in broom symptom bearing branches of European silver birch (Betula pendula) were also addressed by comparing sections of tissues from three locations in the same branch, which were normal, swollen in infected tissue adjacent to a tumour, and inside a tumour. Examination of tumours revealed disorganized and swollen xylem, expanded secondary phloem and expanded periderm. Swollen tissues newly infected from spreading disease adjacent to tumours exhibited enhanced growth only in secondary phloem and the periderm, which also exhibited distortions. This finding suggests that tumour formation and possibly pathogen colonization may initiate in these tissues.

In natural environments, plants develop adaptive mechanisms at the cellular and molecular levels to cope with many external factors, e.g., insects and soil pathogens. We studied physiological stress induced by different levels of foliage removal (defoliation 30% and 60%) and by infection of root rot pathogen Phytophthora plurivora on the common Polish tree species, Betula pendula, grown in an open greenhouse. This study showed that P. plurivora damaged the root system which negatively impacted all morphological parameters. However the loss of 30% of the leaves had a positive effect on defense responses. Chlorophyll-a fluorescence parameters indicated a decrease in photosynthetic efficiency in defoliated plants, but plants inoculated with the pathogen had a higher performance index showing increased vigor of the infected plant than birches. The study demonstrated the intense immunity response of birch to P. plurivora through the expression of Hsp90 and Hsp83 genes. The trees weakened by P. plurivora became more susceptible to infection by Erysiphe ornata var. ornata.

The validity of some concepts underlying the enemy release hypothesis was tested using the example of Acer negundo, an invasive tree species in Eurasia. For this purpose, the frequency of leaf damage and the proportion of leaf area removed by phyllophagous invertebrates were compared between A. negundo and two native species, Betula pendula and Salix caprea. The leaves of these trees were collected in the city of Miass, the Southern Urals, where three rounds of sampling were carried out in the same habitats during the same growing season. A total of 10 000 leaves were examined to record damage by leaf chewers, miners, or gall makers, other kinds of damage, and the proportion of removed leaf area. By the end of the growing season, the proportion of damaged leaves in A. negundo was estimated at 37%, compared to 66% in B. pendula and 78% in S. caprea, with damage by specialized endophagous species (leaf miners and gall makers) in the first species being very low or absent; the proportion of removed leaf area (relative to the total) in A. negundo was less than 1%, compared to 5.8% in B. pendula and 7.5% in S. caprea. Thus, the level of leaf damage by phyllophagous invertebrates in A. negundo growing in the Southern Urals proved to be lower than in tree species native to this region. Therefore, the absence or low activity of natural enemies for A. negundo may be one of the factors accounting for the success of its invasion in Eurasia.

Desorption atmospheric pressure photoionization (DAPPI) is an ambient mass spectrometry (MS) technique that allows the analysis of both polar and nonpolar compounds directly from the surfaces of various sample types. Here, DAPPI was used to study the chemical profiles in different parts of birch and alder tree barks. Four distinct fractions of Betula pendula (silver birch) bark were collected from three different developmental stages of the stem, after which the chemical profiles of the different tissue types were measured. Of special interest were triterpenoids, a class of important defensive substances, which are found in the bark of the silver birch. Additionally, the chemical profiles of lenticels and the surrounding surfaces in the phellem of B. pendula (silver birch), Alnus glutinosa (black alder), and Alnus incana (gray alder) were screened with DAPPI. Another ambient MS technique, laser ablation atmospheric pressure photoionization (LAAPPI), was further used for the mass spectrometry imaging of lenticels on the B. pendula phellem. All the studied birch bark fractions showed individual chemical profiles in DAPPI. The mass spectra from the young apical stem and the transition zone resembled each other more than the mature stem. Instead, the phellem was found to contain a high amount of triterpenoids in all the developmental stages of the stem. The most intense peaks in the DAPPI mass spectra of the birch bark fractions were those of betulin and lupeol. Betulinic and betulonic acid peaks were intense as well, and these compounds were detected especially in the lenticels of the tree samples.

The study aimed to assess response of juvenile progeny of seven forest tree species, Pinus sylvestris, Picea abies, Betula pendula, Alnus glutinosa, Populus tremula, Quercus robur and Fraxinus excelsior, and their populations to different combinations of climate change-related multiple stressors, simulated in a phytotron under elevated CO2 concentration: (1) heat + elevated humidity (HW); (2) heat + frost + drought (HFD); (3) heat + elevated humidity + increased UV-B radiation doses + elevated ozone concentration (HWUO); and (4) heat + frost + drought + increased UV-B radiation doses + elevated ozone concentration (HFDUO). Effects of the complex treatments, species and species-by-treatment interaction were highly significant in most of the growth, physiological and biochemical traits studied, indicating general and species-specific responses to the applied treatments. For deciduous trees, height increment was much higher under HW treatment than in ambient conditions (control) indicating a positive effect of elevated temperature and better water and CO2 availability. HFD treatment caused reduction of height increment in comparison to HW treatment in most species except for Q. robur and F. excelsior which benefited from lower humidity. Treatments HWUO and HFDUO have caused substantial damages to leaves in fast growing deciduous P. tremula, A. glutinosa and B. pendula, and resulted in their lower height increment than in HW treatment, although it was the same or even higher than that in the control. Rates of photosynthesis in most of the tree species were greatest in HFD treatment. A lower photosynthetic rate (compared to control) was observed in B. pendula, P. tremula and F. excelsior in HW treatment, and in most species—in HWUO treatment. Compared to control, intrinsic water use efficiency in all treatments was significantly lower in P. tremula, A. glutinosa and F. excelsior and higher in conifers P. sylvestris and P. abies. Significant population-by-treatment interactions found for most traits showed variation in response of populations, implying that this reflects adaptive potential of each tree species. The observed responses may not always be considered as adaptive as deteriorating growth of some populations or species may lead to loss of their competitiveness thus compromising regeneration and natural successions.

Background: Pretreatment is the critically important step for the production of ethanol from lignocelluloses. In this study, hardwood birch (Betula pendula) and softwood spruce (Norway spruce) woods were pretreated with a newly synthesized morpholinium ionic liquid, 1-H-3-methylmorpholinium chloride ([HMMorph][Cl]), followed by enzymatic hydrolysis and fermentation to ethanol. Results: [HMMorph][Cl] was synthesized using inexpensive raw materials, i.e., hydrochloric acid and N-methyl morpholine, following a simple process. The influence of pretreatment time (2, 3, 5, and 8 h) and temperature (120 and 140°C) in terms of hydrolysis efficiency was investigated. Glucose yields from enzymatic hydrolysis were improved from 13.7% to 45.7% and 12.9% to 51.8% after pretreatment of birch and spruce woods, respectively, under optimum pretreatment conditions (i.e., at 140°C for 3 h) as compared to those from pristine woods. Moreover, the yields of ethanol production from birch and spruce were increased to 34.8% and 44.2%, respectively, while the yields were negligible for untreated woods. Conclusions: This study demonstrated the ability of [HMMorph][Cl] as an inexpensive agent to pretreat both softwood and hardwood.How to cite: Mohammadi M, Shafiei M, Karimi K. Improvement of ethanol production from birch and spruce pretreated with 1‐H‐3‐methylmorpholinium chloride. Electron J Biotechnol 2019;41. https://doi.org/10.1016/j.ejbt.2019.07.004. Keywords: Betula, Biofuels, Cellulase, Cellulose, Ethanol, Hydrolysis, Ionic liquid, Lignin, Lignocellulose, Morpholinium ionic liquid, Pretreatment

The aim of the research was to determine the rate of the damage of xylophagous insects for silver birch (Betula pendula Roth.) stands in the Left Bank Forest-steppe of Ukraine. Evaluation of physiological harmfulness considered a health condition of inhabited trees, features of maturating feeding and pathogens vectoring for the cases of so-called ‘provoked aggressiveness’ and its absence. Evaluation of technical harmfulness considered a location and depth of larval galleries and pupal chambers, colonized sapwood surface, and stem part. Evaluation of general harmfulness considered physiological harmfulness, technical harmfulness and generation number. Among 22 xylophagous insect species, 4 species were widespread (Agrilus viridis (Linnaeus, 1758), Xylotrechus rusticus (Linnaeus, 1758), Xyleborinus saxeseni (Ratzeburg, 1837), and Xyleborinus attenuatus (Blandford, 1894)); 3 species were common, 6 species were rare and 9 species were single. The highest physiological harmfulness is expected for Tremex fuscicornis (Fabricius, 1787) and Tremex magus (Fabricius, 1787), Сhrysobothris affinis (Fabricius, 1774), Agrilus viridis (Linnaeus, 1758), Xylotrechus rusticus, and bark beetles. The highest technical harmfulness is expected for wood wasps – Tremex spp., jewel beetles Dicerca furcata (Thunberg, 1787) and Dicerca alni (Fischer von Waldheim, 1824), longhorn beetle Xylotrechus rusticus, and xylomycetophages – Xyleborinus sp. All widespread species are evaluated by a wide range of physiological harmfulness. Three of them (all except Agrilus viridis) are evaluated by highly technical harmfulness and from moderate to highly general harmfulness. Among the species having a common occurrence, Tremex fuscicornis can be highly harmful only in the case of tree weakening by negative factors, another two species can be non-harmful, and Xiphydria longicollis (Geoffroy, 1785) can be low harmful in the case of tree weakening by negative factors. Among the rare species, Scolytus ratzeburgi Janson, 1856 can be low or moderately harmful and Tremex magus can be low or highly harmful depending on the presence or absence of other negative factors. Among single species, Zeuzera pyrina (Linnaeus, 1761) can be moderately harmful because it colonizes almost healthy trees. The rest three species can be moderately harmful in the case of tree weakening by negative factors.

The amount of total soluble protein cytogenetic indices, germination ability in the seed progeny of Betula pendula in areas with different levels of anthropogenic pollution was studied. The seed progeny of Betula pendula has an increased germination ability and total protein in areas with low pollution levels as compared to the control group (seeds collected in the ecologically clean territory) and to the same parameters for the areas with high levels of anthropogenic pressure. A high positive correlation was established between seed germination and the amount of total soluble protein. The parameter “amount of total protein” is characterized as a marker of seed germination, which determines the possibility of their germination. Cytogenetic parameters (mitotic activity, percentage ratio of cell number at mitosis stages, level of mitosis pathologies, level of cells with persistent nucleoli at metaphase - anaphase mitosis stage) of seed seedlings of weeping birch were studied as marker signs of anthropogenic pollution of territories. Relations between cytogenetic and biochemical characteristics were found. The impact of the environment, caused mainly by heavy metal pollution, on birch trees and their seed progeny, can be defined as hormesis by biochemical and cytogenetic indices. A comprehensive study of cytogenetic and biochemical parameters can allow a quick and adequate evaluation of the seed quality of unknown origin which is especially important for plant industry and forestry as it allows selecting stable planting material and for the collection of material for pharmacognostic purposes in areas with different ecological pressure. Determining cytogenetic indices and the amount of total protein allows forecasting the germination capacities and germination abilities of the seeds of the weeping birch.

Figured wood of Karelian birch (Betula pendula Roth var. carelica (Merckl.) Hamet-Ahti) is highly appraised for its ornamental properties. The reasons for its formation remain largely unclear; judging by available data, we are dealing here with auxin inactivation through its interaction with sugars. The aim of this study has been to reveal the correlations between abnormal wood formation in Karelian birch and auxin conjugation producing IAA-glucose. Karelian birch trees with figured and non-figured wood in the trunk were used. Figured plants had a much higher expression of the gene encoding for the enzyme IAA-glucose synthase, which catalyzes IAA-glucose synthesis. The data obtained suggest that auxin conjugation in Karelian birch via a chain of biochemical reactions may be associated with hexoses produced in the apoplast through sucrose cleavage by cell wall invertase. The activity of the enzyme in figured Karelian birch trees is several times higher than in non-figured plants. Vessel differentiation requires free auxin. We assume that a reduced number of vessels in figured wood may be caused by auxin conjugation in the zone of xylem cell growth and differentiation. Figured wood of Karelian birch was found to have an increased transcript level of the PIN3 gene, which encodes for the auxin efflux carrier protein PIN3 responsible for lateral transport of the hormone. In this regard, PIN3 may generate auxin fluxes with a complex configuration. Microscopic analysis provides evidence that PIN3 overexpression in trunk tissues of Karelian birch is associated with active differentiation of parenchyma cells and disruption of wood structure.

Despite the differences in ploidy and in the timing of flowering, two species of white birch, Betula pendula and Betula pubescens often form viable hybrids in places of their joint growth. Recognition of such hybrids by their morphological features is very difficult or impossible. On the other hand, it could be assumed that substantial differences can be found in the secondary metabolites whose composition is determined mainly by genetic factors. However, the inheritability of biosynthesis of secondary birch metabolites is unknown. We investigated the bud volatile organic compounds (VOCs) of the artificial hybrids of these birches and compared them with specific metabolites of pure parent species. The bud VOCs were determined by a combination of head-space microextraction with gas chromatography-mass spectrometry. As the result, we found that: (a) hybrids clearly show dominant inheritance along the maternal line and (b) the buds of hybrid plants have characteristic features of VOCs composition, which allows for definitive conclusions about hybrid origins in some cases.

The results of studies of the species composition of wood-destroying fungus in the Park of Recreation and Leisure named after Mykhailo Chekman in the city of Khmelnytskyi are presented here. In the Park, 29 species of wood-destroying fungus were found, which are widespread on 14 tree species. The most common types of destroying fungus were: Fomitopsis pinicola, Bjercandera adusta, Bjercandera fumosa, Phellinus igniarius, and Stereum hirsutum. These types of wood-destroying fungus are found on almost all tree species of the park which have been damaged by the fungi. The tree species, which are most susceptible to wood-destroying fungus, are: Betula pendula Roth., Fraxinus excelsior L., Salix alba L., Populus nigra and Quercus robur L. The lowest occurance of wood-destroying fungi was found on вільсі чорній and грабові звичайному. It has been proved that the role of wood-destroying fungus in urban plantations is negative. Most species of wood-destroying fungus cause a variety of rot. Such trees have no external signs of weakening for a long time. It is possible to find affected trees with wood-destroying mushrooms by the presence of fruit bodies. The methods of dealing with wood-destroying fungus are presented here. The main method is conducting periodic forest-pathological surveys to detect the species composition of wood-destroying fungus and the degree of affliction of plantations. In the park, along with the implementation of sanitary measures, the individual protection of trees is important. Methods of protection are; wound healing, wound rubbing after pruning and filling of tree hollows. Protection of trees on the basis of chemical methods should be carried out with single defeat. Measures to regulate recreational loads and prevent mechanical and other tree damage are also important in Chekman Park. The obtained research results broaden the idea of the species diversity of wood-destroying fungi in the park plantations of Khmelnytskyi and can be used in the organization and implementation of forest-pathological monitoring, as well as determining the locations of future sanitary and recreational activities.

The essential oil from birch (Betula pendula Roth.) buds was obtained by Clevenger-type hydrodistillation. Its qualitative and quantitative composition was determined by gas chromatography in combination with mass spectrometry (GC/MS) and flame ionization detection (GC/FID), respectively. Twenty-seven compounds, mainly sesquiterpene hydrocarbons (78.7%) and oxygenated sesquiterpenes (14.8%), were identified comprising 93.5% of total identified components in the essential oil. The most abundant compounds were germacrene D (21.7%) and -cadinene (17.0%). Antimicrobial activity of isolated essential oil against Gram-positive and Gram-negative bacteria as well as fungus Candida albicans was determined using the disc-diffusion method. The isolated essential oil has shown antimicrobial activity against the following microorganisms: Proteus vulgaris, Bacillus luteus and Klebsiella pneumoniae. Antioxidative activity of the essential oil was determined using the DPPH assay, after adding DPPH radical and after 20min, 30min and 60min incubation with radical. Essential oil showed antioxidant activity.

Summary Insect herbivore damage and abundance are often reduced in diverse plant stands. However, few studies have explored whether this phenomenon is a result of plant diversity effects on host plant traits.We explored indirect effects of tree species diversity on herbivory via changes in leaf traits in a long‐term forest diversity experiment in Finland. We measured 16 leaf traits and leaf damage by four insect guilds (chewers, gall formers, leaf miners and rollers) on silver birch (Betula pendula) trees growing in one‐, two‐, three‐ and five‐species mixtures.A decline in the frequency of birch in mixed stands resulted in reduced leaf area. This, in turn, mediated the reduction in chewing damage in mixed stands. In contrast, associational resistance of birch to leaf miners was not trait‐mediated but driven directly by concurrent declines in birch frequency as tree species richness increased.Our results show that leaf trait variation across the diversity gradient might promote associational resistance, but these patterns are driven by an increase in the relative abundance of heterospecifics rather than by tree species richness per se. Therefore, accounting for concurrent changes in stand structure and key foliar traits is important for the interpretation of plant diversity effects and predictions of associational patterns.

We found that the regulation of apoplastic invertase (ApInv) activity in the cambial growth period in Karelian birch (Betula pendula var. carelica) is provided by the expression of encoding genes. In Karelian birches with normal wood, the content of CWIN1, CWIN1.1, and CWIN4 gene transcripts in xylem is lower than in birches with patterned wood. The regulation of ApInv activity in common silver birch (B. pendula var. pendula) is mainly provided at the posttranslational level by protein inhibitors (cell-wall inhibitor of β-fructosidase, CIF). In the trunk tissues of common silver birch, the expression level of ApInv encoding genes is similar to that of Karelian birch, but the concentration of CIF gene transcripts is increased; high expression rate of the CIF gene is caused by increased sucrose concentration in the apoplast. High activity rate of ApInv in Karelian birch provides high acceptor capacity of the cambial zone; a large amount of formed hexoses is intensely used for the formation of starch, a reserve metabolite. An increase in the wood pattern intensity correlates with the sucrose metabolization rate in the apoplastic pathway. In the trunks of birches with patterned wood, there are only local changes in the ratio of ApInv and sucrose synthase activity rates (ApInv activity higher) in the cambial growth period.

Background and aims The increasing frequency of disturbances in temperate forests is responsible for the greater numbers of trees with mechanically damaged cambial zones. Adjustment of wood anatomical structure to balance between safe and efficient water conductivity is one mechanism trees employ to cope with mechanical damage. The relative role of disturbances, tree age and climate in shaping xylem conduits and affecting xylem hydraulic conductivity remains unknown. Methods We performed an experiment with five different mechanical treatments simulating natural disturbances of juvenile Betula pendula trees (stem scarring, tilting, decapitation, root exposure and stem-base burial). After 3 years, trees were cut down, conduit size and density were measured, and specific hydraulic conductivity of each tree ring was calculated. Between-tree and between-year variability in xylem conductivity was decomposed into effects of tree age, climate and disturbances using linear mixed-effects models. Key results Xylem-specific hydraulic conductivity decreased significantly after treatment in decapitated, tilted and scarred trees. In the last treatment, wood anatomical adjustment was restricted to the area next to the callus tissue zone; in contrast, specific hydraulic conductivity declined over the entire stem circumference after tilting or decapitation. The response of trees with buried stems and exposed roots was generally weak. The overall effect of disturbances on inter-annual variability of wood anatomical structure was greater than the contribution of tree age and climate. Conclusions The results indicate that disturbances are important drivers of xylem hydraulic conductivity. Expected increases in the frequency and intensity of disturbances may alter the theoretical capacity of forest stands for water conductance with a feedback to climate.

Auxin polar transport genes PIN (PIN-FORMED) determine the concentration gradient of auxin in plants. To understand the relationship between the development of different tissues in Betula pendula ‘Dalecartica’, BpPIN gene expression and indole-3-acetic acid (IAA) content were analyzed using qRT-PCR, ELISA, and GUS staining. Gene expression of BpPIN genes and IAA levels in the leaves, buds, stems, xylem, and roots of B. pendula ‘Dalecartica’ and B. pendula as a control were measured. BpPIN1, BpPIN5 and BpPIN6 were upregulated during development in both species, suggesting a dominant role in the development of B. pendula ‘Dalecartica’ leaves. Moreover, BpPIN1 gene expression was positively associated with IAA levels during leaf, vein and petiole development in B. pendula ‘Dalecartica’ only. The correlation coefficient of the first three leaves was 0.69 (P = 0.04), while that of the first three petioles was 0.85 (P = 0.001). In addition, GUS staining of the pro-DR5::GUS transgenic line of cultivar was correlated with the results of BpPIN1 expression. Overall, these findings suggest that BpPIN1 is associated with the formation of lobed leaves in B. pendula ‘Dalecartica’.

We examined the effects of photosynthetic activity of the host tree on the bacterial communities in ectomycorrhizal (ECM) roots and in rhizosphere soil. The seedlings of two host tree species, birch (Betula pendula) and pine (Pinus sylvestris), were subjected to winter hardening treatments for inducing total (birch) or partial (pine) restriction of the photosynthesis. Additionally, physical defoliation was performed to prevent both tree species from photosynthetic activity entirely. The bacterial communities were analyzed by RT-PCR of 16S rRNA followed by DGGE. After winter hardening, the bacterial communities in ECM roots of both host species shifted considerably while no consistent change was observed after physical defoliation. In contrast, no significant separation of the communities in rhizosphere soil was observed after winter hardening in either of the host species although the communities were significantly altered after physical defoliation compared to those of non-defoliated control in both tree species. It is therefore interesting and curious that the bacteria communities of ectomycorrhizal roots respond differently than the rhizosphere soil, to both defoliation and winter-hardening

SUMMARY Seedlings of birch (Betula pendula Roth.) were grown for 12 weeks in small volumes of field soils heated in a microwave (MW) oven for different times and then either supplemented or not with inocula of ectomycorrhizal fungi and, in one case, with fresh agricultural soil. Growth of roots and shoots was assessed, and the incidence of different mycorrhizal types, distinguished by colour and morphology, was recorded. Bacterial and fungal populations were determined by dilution plating after MW treatment of soils. In four soils, shoot and root growth were markedly enhanced by MW treatments that raised the soil temperature to 60°C or more, irrespective of the exposure times (20–50 s) needed for this. Shoot dry weights were increased 1·9- to 2·9-fold by MW treatment of two soils from young (11–16 years) birch stands, compared with 8·0- and 11·4-fold for two soils from old birchwoods. But MW treatment of a colliery spoil reduced shoot growth 5-fold. The growth responses were not related to the size of seedlings in untreated soils. The responses coincided with substantial reductions in the total populations of bacteria and fungi. Hebeloma subsaponaceum Karsten developed similar numbers of mycorrhizas from mycelial inoculum added to untreated and MW treated soil. But Lactarius pubescent (Fr. ex Krombh.) Fr. developed significantly more mycorrhizas from inoculum added to MW-treated soil than to untreated soil. This difference between the fungi accords with their classification as, respectively, early stage and late stage in reported mycorrhizal successions on birch. Some mycorrhizal types developed on seedlings from resident inoculum in soil. Their incidence was reduced by different amounts following MW treatment, suggesting differences in heat-tolerance of their propagules. Hebeloma sacchariolens Quel., which forms sclerotium-like bodies and which probably developed from resident inoculum, was unaffected by MW treatment of soil. Some mycorrhizal fungi, notably Thelephora terrestris (Ehrh.) Fr., developed in place of others in soils treated for long times (80–180 s), and they probably developed from airborne spores.

Summary • Impacts of ozone and late frost on six birch (Betula pendula) genotypes from south-eastern Finland were studied in an 8-wk chamber experiment. • The plants were measured for bud burst, growth, visible foliar injuries caused by ozone and frost, structural leaf properties and changes in chloroplasts. • Ozone delayed bud burst but stimulated subsequent growth. Acute frost injuries were compensated by increased leaf production. Early bud burst predisposed to frost damage, whereas late bud burst increased the vulnerability to ozone. In combined ozone + frost treatment, freezing reduced visible ozone injuries, counteracted ozone-induced growth enhancement and stomatal changes, and exacerbated ozone-caused reduction in palisade cell, chloroplast and starch grain size. Rapid changes in epidermal cell differentiation towards stomata and/or glandular trichomes occurred to enhance ozone/frost tolerance. • The results showed large genetic variation within birch population in response to frost and ozone. Generally, birch seem to recover from acute frost occurrence efficiently through compensating leaf production, but co-occurring ozone enhancement may disturb the recovery processes mechanistically through structural damage in photosynthetic tissue, especially in chloroplasts.

Timber production and profitability were evaluated for spontaneously-regenerated mixtures on two formerly clearcut areas. The abandoned areas developed into birch-dominated ( Roth and Ehrh.) stands with successional ingrowth of Norway spruce ( (L.) H. Karst.). An experiment with randomized treatments within blocks was established, using three management strategies and one unthinned control, resulting in variation in optimal rotation age, merchantable volume and species composition. The management strategies were evaluated based on total production (volume) by using measured growth data 42 years after clearcutting and the modelled future stand development. The long-term effects of spontaneous regeneration and management strategies were evaluated based on land expectation value (LEV) and compared with a fifth management strategy using artificial regeneration and intense thinnings. 12 years after treatment, at a stand age of 42 years, the unthinned control had produced the highest total stem volume. At interest rates of 2% or higher, the unmanaged forest was an economically viable strategy, even compared to an intensive management strategy with a preferred merchantable timber species. Interest rates clearly impacted the profitability of the different management strategies. This study shows that when spontaneous regeneration is successful and dense, the first competition release can have a high impact on the development of future crop trees and on the species mixture.Betula pendulaBetula pubescensPicea abies

We have estimated the reproductive capacity of Betulapendula Roth and its relationship with an integrated measure of developmental stability, i.e., fluctuating asymmetry (FA) of the leaf. On the territory of a city with moderate anthropogenic pollution, a change has been detected in the integrated fluctuating asymmetry (IFA) of the morphology of the female reproductive sphere and reproductive capacity of Betula pendula. In conditions of anthropogenic stress, the birch is observed to produce a large yield of fruits annually, which is not subject to year-to-year fluctuations. Morphological variety of size and shape of fruit-producing organs increases along the gradient of industrial and transport pollution, part of morphotypes of infructescences and seeds is characterized by lowered or zero capacity for reproduction determined by seed quality (germination energy and germination capacity). The statistical data processing involved correlation, Shapiro&ndash, Wilk test, Levene&rsquo, s test, factorial ANOVA, Scheffe test, Kruskal&ndash, Wallis ANOVA, Mann&ndash, Whitney test, &chi, 2 method. Analysis of IFA has allowed us to reasonably well assess the state of the plant organism and to characterize environmental quality. A negative correlation between IFA and quantitative parameters of the functions of the reproductive sphere of B. pendula (infructescence diameter, seed quality) has been found, and positive correlation with qualitative parameters (the number of morphs of infructescences and seeds, the share of rare morphs of infructescences). Pessimization of urban environment creates the conditions for an increase in the share of defective infructescences and non-germinating seeds, a compensatory mechanism for this is an increase in reproductive effort of B. pendula. The consistency of responses in the vegetative and reproductive spheres reflects the disturbances in developmental stability of plants in urban communities.

There are no records of established plant pathogenic Phytophthora species in Finnish forests, but they are likely in the future. Therefore, the effects of Phytophthora inoculations on young, ca. 2-month-old silver birch (Betula pendula) seedling roots and shoots were investigated. Visual inspection of dark discoloration, direct PCR and re-isolation, and detailed root morphology analyses were used to evaluate the effects of Phytophthora inoculation on roots. Symptoms in leaves and stems were also recorded. Phytophthora was successfully re-isolated from 67% of the surface-sterilized roots of inoculated seedlings, but not from the non-inoculated control seedlings. Dark discolorations were found more often in the root segments of inoculated seedlings than in control seedlings. In the Phytophthora-treated seedlings, discoloured root segments were usually linked and found primarily in the main root or lateral roots attached to it, whereas in the control seedlings a few single discoloured root segments were scattered throughout the root systems. The number of root segments was lower in the inoculated than in the control seedlings, indicating root loss after Phytophthora inoculation. In the shoots of inoculated birches, leaf and shoot wilting was observed. The appearance of wilting in shoots without visible dark discoloration in the base of stems indicated that symptoms originated from roots inoculated with Phytophthora.

Cellulose is an essential structural component of the plant cell wall and is an important resource for the production of paper, textiles, bioplastics and other biomaterials. The synthesis of cellulose is among the most important but poorly understood biochemical processes, which is precisely regulated by internal and external cues. Here we identified 46 gene models in 7 gene families which encoding cellulose synthase and related enzymes of Betula pendula, and the transcript abundance of these genes in xylem, root, leaf and flower tissues also be determined. Based on these RNA-seq data, we have identified 8 genes that most likely participate in cell wall synthesis. In parallel, a gene co-expression network was also constructed based on transcriptome sequencing.FundingThis work was supported by the National Natural Science Foundation of China, grant number 31870659, The Fundamental Research Funds for the Central Universities, grant number 2572019CG08 funded this research and Heilongjiang Touyan Innovation Team Program (Tree Genetics and Breeding Innovation Team).Conflicts of interest / Competing interestsThe authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.Consent to participateNot applicable.Consent for publicationNot applicable.Availability of data and materialAll data generated or analyzed during this study are included in this published article.Code availabilityNot applicable.Authors’ contributionsAll authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Song Chen. Conceived and supervised were performed by Xiyang Zhao and Su Chen.

The aim of the study was to assess changes in performance and competition for light of juveniles of seven forest tree species, Pinus sylvestris, Picea abies, Betula pendula, Alnus glutinosa, Populus tremula, Quercus robur and Fraxinus excelsior, grown in mono-species and mixed cultures with isolated potted roots under the impact of different combinations of climate change-related stressors, simulated in a phytotron under the elevated CO2 concentration during one growing season, as follows: i) heat + elevated humidity (HW); ii) heat + frost + drought (HFD); iii) heat + elevated humidity + increased UV-B radiation doses + elevated ozone concentration (HWUO); and iv) heat + frost + drought + increased UV-B radiation doses + elevated ozone concentration (HFDUO). For the mixed cultures, three typical species' mixtures were used: i) P. sylvestris, B. pendula and P. abies, ii) P. abies, B. pendula and Q. robur and iii) F. excelsior, A. glutinosa and P. tremula. For the control, the same material was grown outside the phytotron in ambient conditions. Analysis of variance (ANOVA) revealed that the effects of the complex treatments, species and species by treatment interactions were highly significant in most of the biomass, growth, physiological and biochemical traits studied. Pattern of species culture had highly significant effect on physiological and biochemical traits (except for H2O2 concentration); meanwhile it was of low significance for biomass and growth traits. Pattern of species culture by treatment interaction was highly significant in all traits, suggesting that the effects of the applied complex treatments vary depending on the pattern of species culture. Under the hot wet conditions the highest stem volume index, tree biomass, and growth were observed in deciduous P. tremula, A. glutinosa and B. pendula with more clearly pronounced differences in performance between different patterns of species cultures than in ambient conditions showing that the enhanced growth conditions facilitate revealing the potential and specific requirements of the fast-growers. P. abies in all treatments had lower stem volume index and tree biomass than in ambient conditions with no significant differences between the patterns of species culture, indicating that it suffered irrespectively of light availability in different cultures. The differences between performances of most tree species in mono- and mixed cultures in HFD treatment were rather small and nonsignificant. A complex HWUO treatment caused further reduction in tree biomass in all species and culture patterns except for mono-species cultures of A. glutinosa and B. pendula. The most complex HFDUO treatment had the strongest negative effect on biomass of almost all tree species compared to that observed in HW treatment, except for Q. robur and P. sylvestris which biomass and height increments remained higher than those in ambient conditions. This was due to relatively high drought tolerance and compensatory effects of the increased CO2 concentration and temperature. Physiological and biochemical responses of species in different patterns of species cultures across treatments were very variable although often did not reflect in the effects on growth and biomass traits . The observed changes in performance of different tree species in different patterns of species cultures under various complex treatments allowed inferring that climate change may condition certain changes in competitiveness of some tree species resulting in atypical ecological successions of species and forest ecosystems. Keywords: trees, complex treatments, controlled environment, competition, biomass, growth, physiology, biochemistry, phytotron.

Soil is one of the most important factors in plant cultivation, and its content affects plant growth significantly. However, soil composition and characteristics vary depending on the environmental conditions in the area where the soil is located. In this study, urease and catalase enzyme activities in plant soils grown under different shade conditions were examined. The Prunus cerasifera, Tilia tomentosa, Gleditsia triacanthos, Euonymus japonica, and Betula pendula species were grown in five different light conditions during one vegetation period, and the urease and catalase enzyme activities and Ph, EC (mS.cm 1), CaCO3 (%), OM (%), P (ppm), and K (ppm) changes were examined within the scope of the study. As a result, it was found that characteristics other than Ph, which was the subject of the study, changed to a great extent depending on the plant species and light conditions; however, in the areas where different plant species were grown, the soil characters changed at different levels depending on the light. As a result of the study, the highest values in many characteristics were obtained under 45% and 65% light conditions.

Xylem vulnerability to drought-induced embolism did not differ between stems and petioles of four woody species ( Betula pendula , Liriodendron tulipifera , Populus tremula and Olea europaea ). Our results, together with data compiled from published literature, indicate that hydraulic segmentation during drought stress is not consistently driven by difference in vulnerability to embolism between stem and terminal organs. Hydraulic failure and disconnection of distal organs during protracted drought stress is thought to protect large branches or trunks by reducing water loss and restricting the spread of embolism. Hydraulic segmentation and preferential sacrifice of distal organs such as leaves can be driven by two mechanisms: more negative water potentials at the terminal section of the hydraulic pathway and/or by higher vulnerability to xylem embolism of distal organs. Although vulnerability segmentation has been reported in the literature, the generality of this phenomenon is unclear, in part due to the methodological limitations related to direct measurement of xylem vulnerability to embolism in intact plants. The objective of this study was to evaluate vulnerability segmentation between petioles and stems using non-invasive micro computed tomography (microCT). Vulnerability to embolism was measured in leaf petioles and subtending stems of four woody species (Betula pendula R., Liriodendron tulipifera L., Populus tremula L. and Olea europaea L.) with contrasting drought tolerances. In addition, previously published vulnerability data for petioles and stems were compiled from the literature to investigate the commonality of hydraulic segmentation across a wide range of woody species, with the vulnerability curve methodology distinguished. Using non-invasive imaging on intact plants, we found no evidence of hydraulic segmentation between petioles and stems of four angiosperm tree species, regardless of mechanism. Moreover, the literature dataset indicated that little or no difference in vulnerability to embolism is present between petioles and stems when vulnerability curves were constructed using methods specifically measuring the dynamics of xylem tissue during dehydration (e.g. optical visualization, MicroCT). Our results suggest that vulnerability segmentation between stems and distal organs (petioles and leaves) is limited when only xylem tissue is considered. Large differences in vulnerability between stems and leaves are likely to be driven by extra-xylary components, rather than xylem embolism.

This paper examines the salinity stress effect in vitro culture of microshoots of 10 birch clones: Betula pendula L., B. pendula Roth var. carelica (Mercklin) Hämet-Ahti, B. pendula f. ’dalecarlica’ (L.f.) Schneid., B. pubescens Ehrh. We used economically valuable and genetically diverse (various species, varieties, hybrids, polyploids) birch material from in vitro clone collection. We tested 3 in vitro selection methods on 1/2 MS hormone-free nutrient medium: mild – with a prolonged exposure to 0.2% NaCl; gradual – with a step-by-step increase in osmotic concentration (from 0.2% to 1%); severe – with a sublethal (1%) NaCl concentration. We established that the gradual method of NaCl exposure according to the following pattern: 0.2% → 0% → 0.5% → 0% → 0.75% → 0% → 1.0% resulted in the best selective effect for birch, as it provides a clear differentiation of clones in terms of their salinity tolerance. We identified that the genotype had a significant impact on the preservation of the explants and their ability to regenerate under salinity stress. The study showed that tetraploid clones of downy birch and a triploid clone of Karelian birch of a pronounced mixoploid nature had the greatest salinity tolerance.

Associational resistance theory predicts that insect herbivory decreases with increasing tree diversity in forest ecosystems. However, the generality of this effect and its underlying mechanisms are still debated, particularly since evidence has accumulated that climate may influence the direction and strength of the relationship between diversity and herbivory.We quantified insect leaf herbivory and leaf chemical defences (phenolic compounds) of silver birch Betula pendula in pure and mixed plots with different tree species composition across 12 tree diversity experiments in different climates. We investigated whether the effects of neighbouring tree species diversity on insect herbivory in birch, that is, associational effects, were dependent on the climatic context, and whether neighbour-induced changes in birch chemical defences were involved in associational resistance to insect herbivory.We showed that herbivory on birch decreased with tree species richness (i.e. associational resistance) in colder environments but that this relationship faded as mean annual temperature increased.Birch leaf chemical defences increased with tree species richness but decreased with the phylogenetic distinctiveness of birch from its neighbours, particularly in warmer and more humid environments.Herbivory was negatively correlated with leaf chemical defences, particularly when birch was associated with closely related species. The interactive effect of tree diversity and climate on herbivory was partially mediated by changes in leaf chemical defences.Our findings confirm that tree species diversity can modify the leaf chemistry of a focal species, hence its quality for herbivores. They further stress that such neighbour-induced changes are dependent on climate and that tree diversity effects on insect herbivory are partially mediated by these neighbour-induced changes in chemical defences. ispartof: FUNCTIONAL ECOLOGY vol:35 issue:1 pages:67-81 ispartof: location:England status: published

Research Highlights: This study identified the cell cycle genes in birch that likely play important roles during the plant’s growth and development. This analysis provides a basis for understanding the regulatory mechanism of various cell cycles in Betula pendula Roth. Background and Objectives: The cell cycle factors not only influence cell cycles progression together, but also regulate accretion, division, and differentiation of cells, and then regulate growth and development of the plant. In this study, we identified the putative cell cycle genes in the B. pendula genome, based on the annotated cell cycle genes in Arabidopsis thaliana (L.) Heynh. It can be used as a basis for further functional research. Materials and Methods: RNA-seq technology was used to determine the transcription abundance of all cell cycle genes in xylem, roots, leaves, and floral tissues. Results: We identified 59 cell cycle gene models in the genome of B. pendula, with 17 highly expression genes among them. These genes were BpCDKA.1, BpCDKB1.1, BpCDKB2.1, BpCKS1.2, BpCYCB1.1, BpCYCB1.2, BpCYCB2.1, BpCYCD3.1, BpCYCD3.5, BpDEL1, BpDpa2, BpE2Fa, BpE2Fb, BpKRP1, BpKRP2, BpRb1, and BpWEE1. Conclusions: By combining phylogenetic analysis and tissue-specific expression data, we identified 17 core cell cycle genes in the Betulapendula genome.

We studied the effect of gibberellin on cambial activity towards the xylem formation in adult birch trees (Betula pendula Roth var. pendula, common birch). The injection of exogenous solutions was used as a methodological technique. To do this, “chambers” were made on tree trunks by cutting out the outer layers of the bark up to the inner parts of the non-conductive phloem, leaving the conductive phloem and cambial zone intact. GA3 gibberellin solutions (0.005%, 0.01%, 0.02%, 0.05%, 0.1%, 0.2 %) and a mixture of gibberellin with sucrose (GA3 0.01% + sucrose 1% - 20%) were injected into the chambers using a syringe. A strong stimulating effect of the hormone on the formation of xylem increment has been established. It was not possible to identify the dependence of the growth increment on the concentrations used, since their values obviously exceeded the level at which the maximum possible response of the cambial zone to the action of gibberellin was achieved with a given metabolic status of cells and tissues. This is confirmed by the effect of the residual action of exogenous solutions, which manifested itself after the termination of their administration: in variants with higher concentrations of the hormone, the final increase in xylem was greater. It was demonstrated for the first time that high sucrose concentrations (10% and 20%) reduce the stimulating effect of gibberellin. It has been suggested that in this case, sucrose can act through an increase in the level of UDP-glucose, the interaction of which with gibberellin leads to its conjugation (inactivation). The reaction of UDP-glucose with auxin cannot also be excluded, as a result of which it’s the conjugate IAA-glucose is formed, since gibberellin provides acceleration of cambial growth only in the presence of physiologically active (free) auxin in the tissue.

The complexity of ecological conditions in urban areas imposes the plant species need for the development of various biochemical and physiological adaptive strategies. The aim of our research was to examine the antioxidative and antifungal metabolism of species Pinus nigra, Picea omorika, Tilia cordata and Betula pendula from the area of Banja Luka City (urban area) during two vegetation seasons (spring and autumn) and compared with the same species from forest habitats. Changes in the protein concentration, activity and isoenzyme profiles of peroxidases (POD, EC 1.11.1.7), content and antioxidative activity of total phenols and antifungal activity in leaves and needles of the plants from the urban area and forest habitats were monitored. The obtained results indicate that urban areas induce changes in antioxidative metabolism in all examined species, but that the response is species specific. The most sensitive parameter that indicates different adaptation strategy of Pinus nigra, Picea omorika, Tilia cordata and Betula pendula to environment conditions in the urban area were peroxidase isoenzyme patterns. Less specific parameter was phenol content even though there are some indications for role of their antioxidative capacity in the adjustment to specific habitat. In addition, each species had different metabolic strategy to cope with the changes caused by the urban environment.