White birch (Betula papyrifera) is a dominant tree species of the Boreal Forest. Recent studies have shown that it is fairly resistant to heavy metal contamination, specifically to nickel. Knowledge ...of regulation of genes associated with metal resistance in higher plants is very sketchy. Availability and annotation of the dwarf birch (B. nana) enables the use of high throughout sequencing approaches to understanding responses to environmental challenges in other Betula species such as B. papyrifera. The main objectives of this study are to 1) develop and characterize the B. papyrifera transcriptome, 2) assess gene expression dynamics of B. papyrifera in response to nickel stress, and 3) describe gene function based on ontology. Nickel resistant and susceptible genotypes were selected and used for transcriptome analysis. A total of 208,058 trinity genes were identified and were assembled to 275,545 total trinity transcripts. The transcripts were mapped to protein sequences and based on best match; we annotated the B. papyrifera genes and assigned gene ontology. In total, 215,700 transcripts were annotated and were compared to the published B. nana genome. Overall, a genomic match for 61% transcripts with the reference genome was found. Expression profiles were generated and 62,587 genes were found to be significantly differentially expressed among the nickel resistant, susceptible, and untreated libraries. The main nickel resistance mechanism in B. papyrifera is a downregulation of genes associated with translation (in ribosome), binding, and transporter activities. Five candidate genes associated to nickel resistance were identified. They include Glutathione S-transferase, thioredoxin family protein, putative transmembrane protein and two Nramp transporters. These genes could be useful for genetic engineering of birch trees.
FOXP3+ regulatory T cells (Tregs) maintain tolerance against self-antigens and innocuous environmental antigens. However, it is still unknown whether Treg-mediated tolerance is antigen specific and ...how Treg specificity contributes to the selective loss of tolerance, as observed in human immunopathologies such as allergies. Here, we used antigen-reactive T cell enrichment to identify antigen-specific human Tregs. We demonstrate dominant Treg-mediated tolerance against particulate aeroallergens, such as pollen, house dust mites, and fungal spores. Surprisingly, we found no evidence of functional impairment of Treg responses in allergic donors. Rather, major allergenic proteins, known to rapidly dissociate from inhaled allergenic particles, have a generally reduced capability to generate Treg responses. Most strikingly, in individual allergic donors, Th2 cells and Tregs always target disparate proteins. Thus, our data highlight the importance of Treg antigen-specificity for tolerance in humans and identify antigen-specific escape from Treg control as an important mechanism enabling antigen-specific loss of tolerance in human allergy.
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•A comprehensive characterization of antigen-specific human Treg responses•Harmless aeroantigens are major tolerogenic Treg targets•Allergic patients have intact Treg responses against aeroantigens•Th2 responses escape Treg control due to divergent antigen specificities
Analyses of human blood identify T regulatory cells specific to aeroantigens, such as pollen, that are fully functional in allergic individuals, suggesting that it is the induction of Th2 responses and not Treg function per se that could be the underlying cause of allergy.
Pollen from various Fagales tree species prolongs the season and makes tree pollen allergy a major health problem. Despite involving the same causative allergens, allergy immunotherapy (AIT) ...treatment habits differ significantly across different geographical regions. Diagnosis and treatment with AIT in patients allergic to tree pollen were discussed by a group of German medical experts who give practical recommendations based on the available data. Regulatory perspective: According to current guidelines on allergen products, birch pollen are the representative allergen source of the birch homologous group including several Fagales trees based on sequence and structural similarity of their allergen proteins. Immunological perspective: A high level of IgE cross‐reactivity towards allergens from the birch homologous group has been observed in basic research and clinical trials. Clinical perspective: Clinical trial data show that the efficacy of birch pollen AIT is not only related to birch pollen allergy but extends to pollen from other trees, especially alder, hazel and oak. In order to optimize diagnosis and treatment of tree pollen allergy, the experts recommend to focus diagnosis and respective treatment with AIT primarily to birch as the representative allergen of the Fagales tree homologous group, but further diagnostics may be needed for some patients to determine adequate treatment.
Birch, alder, hazel, hornbeam and oak pollen allergens are forming the birch homologous group due to protein sequence and structural similarity and high degree of IgE cross‐reactivity. The efficacy of birch pollen allergy immunotherapy is not only related to birch pollen allergy, but extends to other trees, especially alder, hazel, and oak according to recent clinical trial data. The diagnosis and respective treatment of tree pollen allergy is recommended by a panel of medical experts to be focussed on birch as representative species of the birch homologous group.
Background
IgE cross‐sensitization to major birch pollen allergen Bet v 1 and pathogenesis‐related (PR10) plant food allergens is responsible for the pollen‐food allergy syndrome.
Methods
We designed ...a recombinant protein, AB‐PreS, consisting of non‐allergenic peptides derived from the IgE‐binding sites of Bet v 1 and the cross‐reactive apple allergen, Mal d 1, fused to the PreS domain of HBV surface protein as immunological carrier. AB‐PreS was expressed in E. coli and purified by chromatography. The allergenic and inflammatory activity of AB‐PreS was tested using basophils and PBMCs from birch pollen allergic patients. The ability of antibodies induced by immunization of rabbits with AB‐PreS and birch pollen extract‐based vaccines to inhibit allergic patients IgE binding to Bet v 1 and Mal d 1 was assessed by ELISA.
Results
IgE‐binding experiments and basophil activation test revealed the hypoallergenic nature of AB‐PreS. AB‐PreS induced lower T‐cell activation and inflammatory cytokine production in cultured PBMCs from allergic patients. IgG antibodies induced by five injections with AB‐PreS inhibited allergic patients' IgE binding to Bet v 1 and Mal d 1 better than did IgG induced by up to 30 injections of six licensed birch pollen allergen extract‐based vaccines. Additionally, immunization with AB‐PreS induced HBV‐specific antibodies potentially protecting from infection with HBV.
Conclusion
The recombinant AB‐PreS‐based vaccine is hypoallergenic and superior over currently registered allergen extract‐based vaccines regarding the induction of blocking antibodies to Bet v 1 and Mal d 1 in animals.
We designed a vaccine consisting of peptides derived from IgE epitopes of birch and apple allergens fused with HBV‐derived PreS. Aluminum hydroxide‐adsorbed AB‐PreS induces IgG antibodies specific for Bet v 1, Mal d 1, and HBV. IgG antibodies induced by AB‐PreS inhibit IgE binding of allergic patients IgE to Bet v 1 and Mal d 1 better than extract‐based vaccines. Anti‐PreS IgG may protect against HBV infection.Abbreviations: Ab‐PreS, recombinant protein, consisting of non‐allergenic peptides derived from the IgE binding sites of Bet v 1 and Mal d 1, fused to the PreS domain of HBV surface protein as immunological carrier; Bet v 1, major birch pollen allergen; HBV, hepatitis B virus; Ig, immunoglobulin; Mal d 1, cross‐reactive apple allergen; OD, optical density.
Key message
Silver birch growing on extremely nutrient-poor stands of inland dunes was characterized by low contents of these nutrients in its biomass. The nutrient accumulation also depended on its ...age.
Silver birch (
B. pendula)
often colonizes inland dunes, as geomorphologically sensitive and unstable environments. Considering its importance in the protection of ecosystems associated with such landforms, we aimed to evaluate the nutrient distribution and bioaccumulation in the organs of that tree. The study covered three stands, aged 12, 20, and 34 years. Ten average trees were sampled from each stand, including fine and coarse roots, stemwood, bark, coarse and fine branches, and leaves along with soil samples at depths of 0–10, 10–20, 20–40, and 40–80 cm. The contents of macro- and micronutrients were analyzed in collected soil and biomass samples. The soils were strongly acidic and very poor in the studied elements. The nutrient distribution in the birch biomass was highly variable. For most of the elements, the highest contents were recorded in leaves. The highest amounts of Fe were found in fine roots, while Mn and Zn were the most abundant in the bark. Wide variability was also apparent in the bioaccumulation factors. These were usually the highest in the leaves or bark and the lowest in the stemwood. Among the studied elements, N was the most bioaccumulated, followed by S, Zn, Cu, Mn, and P. Nutrient distribution in the birch biomass was typical for tree species. Nutrient levels were generally low, however, significantly higher than their concentrations in the soil, indicating a strong bioaccumulation. The relationship between nutrient accumulation and stand age was observed.
Precommercial thinning could be a valuable tool for climate change adaptation, as it can promote stand diversity while increasing productivity. Softwood and hardwood stands are usually thinned ...following different methods, and we lack recommendations for application in mixedwood stands. We evaluated the effects of precommercial thinning on the growth and composition of balsam fir (Abies balsamea L.)-birch stands dominated by paper and yellow birch (Betula papyrifera Marsh. and Betula alleghaniensis Britt.), comparing methods and production objectives (systematic release-softwood, systematic release mixedwood, crop-tree release-mixedwood, and crop-tree release-hardwood) in Quebec (Canada). Precommercial thinning increased tree-level and stand-level growth, especially for both birches. Compared to the non-thinned control, thinning increased tree diameter at breast height annual increments by 60%-107%, with similar results among modalities. Thinning changed initial stand composition, but mixedwood production plots composition was similar to that of the control 15 years after treatment. Promoting diversity is often perceived to be made at the expense of wood production. Our results suggest that we can obtain both increased growth and maintain diversity. Precommercial thinning is currently suggested as an adaptation tool that can foster drought resistance. Based on our study, we suggest it could serve another purpose in climate-adapted forest management, that is, maintaining diversity and thus increasing resilience to disturbances.
Abstract
Plant–microbial interactions in soils are considered to play a central role in regulating biodiversity in many global ecosystems. However, studies on plant–soil feedbacks (PSFs) and how ...these affect forest stand patterns in boreal regions are rare.
We conducted a fully reciprocal PSF glasshouse experiment using four boreal tree species.
Alnus glutinosa
,
Betula pendula
,
Picea abies
and
Pinus sylvestris
seedlings were grown under controlled conditions in sterilised soil with or without soil inoculum collected under mature trees of each of the four species. Bacterial, fungal and oomycete communities in the rhizosphere were investigated using metabarcoding and correlated with differences in plant biomass.
Alder grew best in conspecific soil, whereas birch grew equally well in all soil types. Pine and spruce grew best in heterospecific soil, particularly in soil from their successional predecessor. Ectomycorrhizal fungi (EMF) enhanced the growth of most seedlings, and Actinomycetota supported alder and birch growth and fungal plant pathogens hampered pine growth. Increased growth was linked to the ability of trees to recruit specific EMF and root‐associated fungi in heterospecific soils.
Synthesis
. This study experimentally examines the influence of root‐associated microbiota on the growth of boreal tree species. The observed plant–soil feedbacks mirror the successional patterns found in boreal forests, suggesting a possible contribution of soil microbiota to the successional progression. Species‐specific ectomycorrhizal fungi and a few bacteria rather than fungal plant pathogens or oomycetes seem to drive the feedbacks by promoting seedling growth in heterospecific soils.
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