Draft genome sequences of two Micromonospora strains isolated from the root nodules of Alnus glutinosa

In this paper, the draft genomes of Micromonospora RTGN7 and RTP1Z1, derived from Alnus glutinosa root nodules, are reported. The assembly of RTGN7 is 6.6 Mbp, composed of 59 contigs, with an N50 of 321,872. RTP1Z1's assembly is 6.3 Mbp, composed of 151 contigs, with an N50 of 76,442 bp.

Draft genome sequences of five Mycobacterium strains, isolated from Alnus glutinosa root nodules

Mycobacterium is a clinically relevant genus of bacteria, with this paper reporting draft genomes of five Mycobacterium strains derived from Alnus glutinosa root nodules. The genome sizes of the isolates ranged from 6.1 to 6.9 Mbp, composed of 22-59 contigs. The N50 values ranged from 303,875 to 865,751 bp, presenting a GC% of 66.07%-66.96%.

Draft genome sequence of Streptomyces poriferorum RTGN2, a bacterial endophyte isolated from Alnus glutinosa root nodules

Herein is reported the draft genome sequence of Streptomyces poriferum RTGN2, a bacterial isolate of Alnus glutinosa root nodules, collected from Saltwell Park, Gateshead, United Kingdom. The assembly is 9.5 Mbp in size, composed of 187 contigs, with a N50 of 189,630 bp, presenting a GC content of 71.2%.

Draft genome sequence of Amycolatopsis camponoti RTGN1, a bacterial endophyte isolated from Alnus glutinosa root nodules

Here, we report the draft genome sequence of Amycolatopsis camponoti RTGN1, a bacterial endophyte of Alnus glutinosa root nodules, collected from Saltwell Park, United Kingdom. The genome is 11.9 Mbp in size, composed of 147 contigs, with an N50 of 179,211 bp and presenting a GC content of 70.9%.

Risk Assessment for the Spread of Flavescence Dorée-Related Phytoplasmas from Alder to Grapevine by Alternative Insect Vectors in Germany

"Flavescence dorée" (FD)-related phytoplasmas are widespread in alder in Germany and their transmission to grapevine represents a high risk for FD outbreaks when the primary vector, Scaphoideus titanus, becomes present in the future. Therefore, the potential role of the Deltocephalinae leafhopper species in transmitting FD-related phytoplasmas from alder to grapevine was studied in extensive transmission trials conducted between 2017 and 2020. The transmission capacity of autochthonous Allygus spp. and the invasive Orientus ishidae captured on infected alder trees was tested under controlled conditions using various test designs, including grouped insects and single-insect studies. The latter experiments were analyzed in terms of survival probability, transmission success and phytoplasma load in the insects, measured by quantitative PCR. A minimum inoculation titer (MIT) required for successful transmission to alder was defined for both Allygus spp. and O. ishidae. While Allygus spp. exhibited slightly better survival on Vitis vinifera compared to O. ishidae, the latter displayed higher phytoplasma loads and greater transmission success. Although all species were capable of infecting alder seedlings, O. ishidae was able to transmit 16SrV-phytoplasmas directly to single grapevines. Infective adults of O. ishidae were captured from the beginning of July until the end of August, while Allygus spp. were only considered infective towards the end of the season. Thus, O. ishidae likely poses a higher risk for FD transmission from alder to grapevine, albeit at a very low level, as only five out of 90 transmission trials to V. vinifera were successful.

Comparison of Bioactive Secondary Metabolites and Cytotoxicity of Extracts from Inonotus obliquus Isolates from Different Host Species

Inonotus obliquus, a wood-decaying mushroom, has been used as a health-promoting supplement and nutraceutical for centuries. It is a source of bioactive compounds accumulated in both the conks (pseudosclerotia/sclerotia) and the biomass obtained in vitro. This study aimed to qualitatively and quantitatively analyze the bioelements and selected metabolites produced in mycelial cultures obtained from different host species. The mycochemical potential of mycelial cultures isolated from pseudosclerotia grown in Betula pendula, Alnus glutinosa, and Carpinus betulus was compared. Parent cultures were obtained in two types of medium (malt extract agar substrates without and with birch wood). Experimental cultures were developed in 2 L bioreactors for 10 days. The content of bioelements was determined using FAAS and FAES methods. Organic compounds were estimated using the RP-HPLC-DAD method. The cytotoxicity of the extracts was evaluated in human keratinocytes HaCaT, human skin fibroblasts BJ, human liver cancer HepG2, human melanoma A375, and mouse melanoma B16-F10. The extracts showed the presence of bioelements: sodium, potassium, magnesium, calcium, zinc, manganese, iron, and copper; phenolic acids: p-hydroxybenzoic, caffeic, p-coumaric, and protocatechuic; sterols: lanosterol, ergosterol, ergosterol peroxide; triterpene compounds: betulin, betulinic acid, inotodiol; indole compounds: L-tryptophan, tryptamine, 5-methyltryptamine, melatonin. The content of bioactive substances in the biomass was dependent on both the origin of the host species of the fungus isolate and the type of culture medium. Based on the results of this study, mycelial cultures can be proposed as a potential source of bioactive compounds and are promising naturally derived cytotoxic agents.

Influence of delta-hexachlorocyclohexane (δ-HCH) to Phytophthora ×alni resistant Alnus glutinosa genotypes - Evaluation of physiological parameters and remediation potential

Hexachlorocyclohexanes (HCHs) are persistent organochlorine pesticides with the adverse effects on human health and the environment. The effect of delta-isomer of hexachlorocyclohexane (δ-HCH) on germination, growth parameters and physiological parameters was studied in different Alnus glutinosa (L.) Gaertn. progeny of resistant genotypes to pathogen Phytophthora ×alni. Two experiments were performed: a short-term experiment to determine the effect of δ-HCH on total germination (GT), germination energy (GE), speed of germination (SG), shoot length and biomass of seedlings, and a long-term experiment devoted to remediation aspects. In addition, changes in the hormonal system of alders were monitored in both cases. Significant differences were found between the treated and control group in most of the evaluated characteristics. Also, the content of studied phytohormones differs between groups. Furthermore, the obtained results indicate genetically determined variability in response to δ-HCH. Of the six tested, the Březové and Tuřany progeny seem to be suitable candidates for phytoremediation because of the adaptation to stress conditions or high remediation efficiency. The rest of tested progeny seems to be unsuitable due to higher mortality, lower remediation efficiency and higher levels of stress hormones resulting in significant decrease in biomass and plant height. Moreover, results indicate the role of the plant as a remediation accelerator, probably through released exudates, and a positive effect on the soil microbiome as the presence of plants increased the remediation efficiency by 20.85 - 35.89%. The obtained research findings may be helpful in better understanding the processes involved in removing these pesticides from the soil. Further research should be focused on rhizosphere microbiome, mechanism of in-plant isomerization and metabolites identification.

A Nonspecific Lipid Transfer Protein with Potential Functions in Infection and Nodulation

The response of Alnus glutinosa to Frankia alni ACN14a is driven by several sequential physiological events from calcium spiking and root-hair deformation to the development of the nodule. Early stages of actinorhizal symbiosis were monitored at the transcriptional level to observe plant host responses to Frankia alni. Forty-two genes were significantly upregulated in inoculated compared with noninoculated roots. Most of these genes encode proteins involved in biological processes induced during microbial infection, such as oxidative stress or response to stimuli, but a large number of them are not differentially modulated or downregulated later in the process of nodulation. In contrast, several of them remained upregulated in mature nodules, and this included the gene most upregulated, which encodes a nonspecific lipid transfer protein (nsLTP). Classified as an antimicrobial peptide, this nsLTP was immunolocalized on the deformed root-hair surfaces that are points of contact for Frankia spp. during infection. Later in nodules, it binds to the surface of F. alni ACN14a vesicles, which are the specialized cells for nitrogen fixation. This nsLTP, named AgLTP24, was biologically produced in a heterologous host and purified for assay on F. alni ACN14a to identify physiological effects. Thus, the activation of the plant immunity response occurs upon first contact, while the recognition of F. alni ACN14a genes switches off part of the defense system during nodulation. AgLTP24 constitutes a part of the defense system that is maintained all along the symbiosis, with potential functions such as the formation of infection threads or nodule primordia to the control of F. alni proliferation. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Study of the Antioxidant Properties of Filipendula ulmaria and Alnus glutinosa

The demographic situation of the last few decades is characterized by the increased numbers of elderly and senile people, i.e., by the aging of the population. In humans, ageing is closely associated with the enhanced production of reactive oxygen species (ROS), development of systemic inflammation and related vascular atherosclerotic alterations and metabolic disorders, like obesity, diabetes mellitus and neurodegenerative diseases. As these age-related alterations are directly associated with up-regulation of ROS production and development of chronic oxidative stress, their onset can be essentially delayed by continuous daily consumption of dietary antioxidants-natural products of plant origin. Such antioxidants (in the form of plant extracts, biologically active complexes or individual compounds) can be supplemented to functional foods, i.e., dietary supplementations for daily diet aiming prolongation of active life and delay of the senescence onset. Thereby, use of widely spread medicinal plants might essentially improve cost efficiency of this strategy and availability of antioxidant-rich functional foods. Therefore, here we addressed, to the best of our knowledge for the first time, the antioxidant activity of the extracts prepared from the aerial parts of Filipendula ulmaria and Alnus glutinosa growing in the Kaliningrad region of Russia, and assessed the contents of the biologically active substances underlying these properties. It was found that the extract prepared with the leaves of Filipendula ulmaria and female catkins of Alnus glutinosa demonstrated high antioxidant activity, although the former plant was featured with a higher antioxidant potential. The highest antioxidant activity detected in the methanol extracts of Alnus glutinosa reached 1094.02 ± 14.53 µmol TE/g, radical scavenging of activity was 584.45 ± 35.3 µmol TE/g, reducing capacity at interaction with iron complex-471.63 ± 7.06 µmol TE/g. For the methanol extracts of Filipendula ulmaria the antioxidant activity reached 759.78 ± 19.08 µmol TE/g, antioxidant activity for free radical removal was 451.08 ± 24.45 µmol TE/g and antioxidant activity for restorative ability with iron complex was 332.28 ± 10.93 µmol TE/g. These values are consistent with the total yields of the extracts and their content of ellagic acid. The ethyl acetate extracts of the both plants showed just minimal antioxidant activity. Thus, the considered extracts have an essential potential. This creates good prospects for the further use of herbal extracts of Filipendula ulmaria and Alnus glutinosa as a source of natural antioxidants.

Comparative Analyses of Bioactive Compounds in Inonotus obliquus Conks Growing on Alnus and Betula

Inonotus obliquus grows in the Northern Hemisphere on some living broadleaved tree species as a pathogen, causing stem rot. In Estonia, the fungus is well known in the Betula species but can also be found on Alnus. Sterile conks of I. obliquus contain different bioactive compounds, but the quantitative and comparative research of these compounds in conks on different host species is limited. In the current work, I. obliquus was isolated and, evidently, determined from Alnus incana (L.) Moench., Alnus glutinosa (L.) Gaertn., and Betula pendula Roth, and the content of bioactive compounds in conks on these hosts were analysed. All the analysed conks sampled from A. incana and B. pendula contained betulin that varied from 111 to 159 µg/g. A significantly (p < 0.05) higher betulinic acid content was found in conks sampled from A. incana when compared with B. pendula: 474−635 and 20−132 µg/g, respectively. However, the conks from Betula were richer in total polyphenols, flavonols, and glucans. The content of inotodiol was quite similar in the conks from A. incana (7455−8961 µg/g) and B. pendula (7881−9057 µg/g). Also, no significant differences in the lanosterol content were found between the samples from these two tree species. To the best of our knowledge, this study is the first investigation of the chemical composition of I. obliquus parasitizing on Alnus. The results demonstrate that the bioactive compounds are promising in conks of I. obliquus growing not only on Betula but also on the Alnus species. It supports the opportunity to cultivate I. obliquus, also on the Alnus species, thus increasing the economic value of growing this tree species in forestry.

Anti-Toxoplasma gondii effect of lupane-type triterpenes from the bark of black alder (Alnus glutinosa) and identification of a potential target by reverse docking

Toxoplasmosis is a worldwide parasitosis that is generally benign. The infestation may pose a risk to immunocompromized patients and to fetuses when pregnant women have recently seroconverted. Current treatments have numerous side effects and chemoresistance is emerging, hence the need to find new anti-Toxoplasma gondii substances. This study focuses on the antiparasitic potential of lupane-type pentacyclic triterpenes isolated from the bark of black alder (Alnus glutinosa), as well as the hypothesis of their macromolecular target by an original method of reverse docking. Among the isolated triterpenes, betulone was the most active compound with an IC₅₀ of 2.7 ± 1.2 μM, a CC₅₀ greater than 80 μM, and a selectivity index of over 29.6. An additional study of the anti-T. gondii potential of commercially available compounds (betulonic acid methyl ester and betulonic acid) showed the important role of the C3 ketone function and the C28 oxidation level on the lupane-type triterpene in the antiparasitic activity since their IC₅₀ and CC₅₀ were similar to that of betulone. Finally, the most active compounds were subjected to the AMIDE reverse docking workflow. A dataset of 87 T. gondii proteins from the Protein Data Bank was created. It identified calcium-dependent protein kinase CDPK3 as the most likely target of betulin derivatives.

Key plant species and detritivores drive diversity effects on instream leaf litter decomposition more than functional diversity: A microcosm study

Anthropogenic impacts on freshwater ecosystems cause critical losses of biodiversity that can in turn impair key processes such as decomposition and nutrient cycling. Forest streams are mainly subsidized by terrestrial organic detritus, so their functioning and conservation status can be altered by changes in forest biodiversity and composition, particularly if these changes involve the replacement of functional groups or the loss of key species. We examined this issue using a microcosm experiment where we manipulated plant functional diversity (FD) (monocultures and low-FD and high-FD mixtures, resulting from different combinations of deciduous and evergreen Quercus species) and the presence of a key species (Alnus glutinosa), all in presence and absence of detritivores, and assessed effects on litter decomposition, nutrient cycling, and fungal and detritivore biomass. We found (i) positive diversity effects on detritivore-mediated decomposition, litter nutrient losses and detritivore biomass exclusively when A. glutinosa was present; and (ii) negative effects on the same processes when microbially mediated and on fungal biomass. Most positive trends could be explained by the higher litter palatability and litter trait variability obtained with the inclusion of alder leaves in the mixture. Our results support the hypothesis of a consistent slowing down of the decomposition process as a result of plant biodiversity loss, and hence effects on stream ecosystem functioning, especially when a key (N-fixing) species is lost; and underscore the importance of detritivores as drivers of plant diversity effects in the studied ecosystem processes.

Halophytophthora fluviatilis Pathogenicity and Distribution along a Mediterranean-Subalpine Gradient

Halophytophthora species have been traditionally regarded as brackish water oomycetes; however, recent reports in inland freshwater call for a better understanding of their ecology and possible pathogenicity. We studied the distribution of Halophytophthora fluviatilis in 117 forest streams by metabarcoding river filtrates taken in spring and autumn and by direct isolation from floating leaves. Pathogenicity on six Fagaceae species and Alnus glutinosa was assessed by stem inoculations. The distribution of H. fluviatilis was correlated with high mean annual temperatures (>93.5% of reports in Ta > 12.2 °C) and low precipitation records. H. fluviatilis was therefore widely distributed in forest streams in a warm–dry climate, but it was mostly absent in subalpine streams. H. fluviatilis was primarily detected in autumn with few findings in spring (28.4% vs. 2.7% of streams). H. fluviatilis was able to cause small lesions on some tree species such as Quercus pubescens, Q. suber and A. glutinosa. Our findings suggest that H. fluviatilis may be adapted to warm and dry conditions, and that it does not pose a significant threat to the most common Mediterranean broadleaved trees.

Short-lived peaks of stem methane emissions from mature black alder (Alnus glutinosa (L.) Gaertn.) - Irrelevant for ecosystem methane budgets?

Tree stems can be a source of the greenhouse gas methane (CH4). However, assessments of the global importance of stem CH4 emissions are complicated by a lack of research and high variability between individual ecosystems. Here, we determined the contribution of emissions from stems of mature black alder (Alnus glutinosa (L.) Gaertn.) to overall CH4 exchange in two temperate peatlands. We measured emissions from stems and soils using closed chambers in a drained and an undrained alder forest over 2 years. Furthermore, we studied the importance of alder leaves as substrate for methanogenesis in an incubation experiment. Stem CH4 emissions were short-lived and occurred only during times of inundation at the undrained site. The drained site did not show stem emissions and the soil acted as a small CH4 sink. The contribution of stem emissions to the overall CH4 budget was below 0.3% in both sites. Our results show that mature black alder can be an intermittent source of CH4 to the atmosphere. However, the low share of stem CH4 emissions in both investigated stands indicates that this pathway may be of minor relative importance in temperate peatlands, yet strongly depend on the hydrologic regime.

Acanthamoeba - pathogen and vector of highly pathogenic bacteria strains to healthy and immunocompromised individuals

Acanthamoeba is a free-living protist pathogen, which is present in every place on Earth. 50 to 100 percent of the adult population has serum antibodies, specific for Acanthamoeba antigens. Acanthamoeba is an etiological agent of keratitis and encephalitis diagnosed in human. Acanthamoeba keratitis occurs in healthy persons and may lead to visual impairment and blindness, because corneal infection with this parasite fails to induce cell-mediated immune response due to the absence of resident antigen-presenting cells in the cornea. Systemic immunization with Acanthamoeba antigens induces Th1 cell-mediated immunity and serum IgG antibody, but do not prevent the development of keratitis. Immunization via mucosal surfaces stimulates IgA antibodies in tears and protects against the development of keratitis.

Amoebae feed mainly on bacteria, fungi, and algae. By transferring intracellular bacteria, amoeba contributes to the spread of diseases dangerous to humans. Some microorganisms have evolved to become resistant to protist, since they are not internalized or able to survive, grow, and exit free-living protists after internalization. In many cases, the bacteria inside living amoebae survive longer, and multiply better, showing higher virulence. There is a hypothesis, which assumes that Acanthamoeba and symbiontic bacteria survive and multiply better in moist soil, rich in nitrogen compounds, particularly in the vicinity of the root systems of Alnus glutinosa, infected with nitrogen-fixing bacteria Frankia alni. Impact of soil environment created by nitrogen-fixing bacterium Frankia alni on specific relations between protists Acanthamoeba and highly pathogenic bacteria strains in Alnus glutinosa habitats in Poland continue to be established.

Feeding Behavioural Studies with Freshwater Gammarus spp.: The Importance of a Standardised Methodology

Freshwater Gammarids are common leaf-shredding detritivores, and they usually feed on naturally conditioned organic material, in other words leaf litter that is characterised by an increased palatability, due to the action and presence of microorganisms (Chaumot et al. 2015; Cummins 1974: Maltby et al. 2002). Gammarus spp. are biologically omnivorous organisms, so they are involved in shredding leaf litter and are also prone to cannibalism, predation behaviour (Kelly et al. 2002) and coprophagy when juveniles (McCahon and Pascoe 1988). Gammarus spp. is a keystone species (Woodward et al. 2008), and it plays an important role in the decomposition of organic matter (Alonso et al. 2009; Bundschuh et al. 2013) and is also a noteworthy prey for fish and birds (Andrén and Eriksson Wiklund 2013; Blarer and Burkhardt-Holm 2016). Gammarids are considered to be fairly sensitive to different contaminants (Ashauer et al. 2010; Bloor et al. 2005; Felten et al. 2008a; Lahive et al. 2015; Kunz et al. 2010); in fact Amphipods have been reported to be one of the most sensitive orders to metals and organic compounds (Wogram and Liess 2001), which makes them representative test organisms for ecotoxicological studies and valid sentinel species for assessing water quality status (Garcia-Galan et al. 2017).

Phytocomplex Influences Antimicrobial and Health Properties of Concentrated Glycerine Macerates

The purpose of this study was to correlate the chemical composition of four commercial concentrated glycerine macerates (C-GMs), produced through the same extraction method, with their in vitro antimicrobial, antioxidant, and immunomodulatory properties, in order to evaluate their potential for healing upper airway diseases. C-GMs of Carpinus betulus (CB), Ficus carica (FC), Alnus glutinosa (AG) and Ribes nigrum (RN) were studied. The quality was evaluated using HPLC and IM-SPME/GC-MS systems; anti-oxidant and anti-microbial activities were assessed by the respective DPPH test, and micro-broth dilution test performed against 10 strains of Streptococcus pyogenes and 10 probiotic strains. ELISA and MTT tests were used to assess the immunomodulatory activity and the cytotoxicity of C-GMs, respectively. A significant correlation was found between the number of active compounds and the in vitro C-GMs effectiveness. Furthermore, the C-GMs of AG showed the best anti-microbial activity on pathological strains and, together with CB, the best anti-oxidant activity. The ELISA test exhibited a good immunomodulatory activity of RN. In vitro data support the integrated use of C-GMs of CB, AG, and RN in presence of airway diseases, and highlight the importance of standard procedures in cultivation, harvest and post-harvest treatments, as a premise for C-GMs with consistent characteristics.

Host plant frequency and secondary metabolites are concurrently associated with insect herbivory in a dominant riparian tree

Herbivory is strongly influenced by different sources of plant variation, from traits such as secondary metabolites to features associated with population- and community-level variation. However, most studies have assessed the influence of these drivers in isolation. We conducted a large-scale study to evaluate the associations between multiple types of plant-based variation and insect leaf herbivory in alder ( Alnus glutinosa) trees sampled in riparian forests throughout northwestern Spain. We assessed the associations between insect leaf herbivory and alder mean production of leaf secondary metabolites (phenolic compounds), variation among neighbouring alder trees in leaf phenolics and community-related features including alder relative size and frequency and tree species phylogenetic diversity. Structural equation modelling indicated that increasing concentrations of alder leaf flavonoids (but not other types of phenolic compounds) and increasing variation in phenolics among neighbouring alders were both significantly negatively associated with herbivory. In addition, increasing relative frequency of alder was positively associated with leaf damage, whereas the size of alders relative to other trees and phylogenetic diversity were not significantly associated with herbivory. These results demonstrate the concurrent and independent influences of different sources of plant-based variation on insect herbivory and argue for further future work simultaneously addressing multiple plant-based bottom-up controls.

Selective Behaviour of Honeybees in Acquiring European Propolis Plant Precursors

Honey bees harvest resins from various plant species and use them in the hive as propolis. While there have been a number of studies concerning the chemical composition of this antimicrobial product, little is known about selective behavior and bee preference when different potential plant sources of resin are available. The main objective of this paper was to investigate some aspects of behavioral patterns of honeybees in the context of resin acquisition. Samples of propolis originating from temperate zones of Europe and the supposed botanical precursors of the product were analyzed. Taxonomical markers of bud resins of two white birch species, aspen, black poplar, horse-chestnut, black alder, and Scots pine were determined through GC-MS analysis. All these trees have been reported as sources of propolis, but comparisons of the chemical composition of their bud resins with the compositions of propolis samples from seven European countries have demonstrated the presence of taxonomical markers only from black poplar, aspen, and one species of birch. This suggests selective behavior during the collection of bud resins by honeybees. To examine the causes of such selectivity, the antimicrobial properties of bud resins were determined. Horse-chestnut resins had lower antimicrobial activity than the other resins which did not differ significantly.

Flow cytometry, microsatellites and niche models reveal the origins and geographical structure of Alnus glutinosa populations in Europe

BACKGROUND AND AIMS

Polyploidy in plants has been studied extensively. In many groups, two or more cytotypes represent separate biological entities with distinct distributions, histories and ecology. This study examines the distribution and origins of cytotypes of Alnus glutinosa in Europe, North Africa and western Asia.

METHODS

A combined approach was used involving flow cytometry and microsatellite analysis of 12 loci in 2200 plants from 209 populations combined with species distribution modelling using MIROC and CCSM climatic models, in order to analyse (1) ploidy and genetic variation, (2) the origin of tetraploid A. glutinosa, considering A. incana as a putative parent, and (3) past distributions of the species.

KEY RESULTS

The occurrence of tetraploid populations of A. glutinosa in Europe is determined for the first time. The distribution of tetraploids is far from random, forming two geographically well-delimited clusters located in the Iberian Peninsula and the Dinaric Alps. Based on microsatellite analysis, both tetraploid clusters are probably of autopolyploid origin, with no indication that A. incana was involved in their evolutionary history. A projection of the MIROC distribution model into the Last Glacial Maximum (LGM) showed that (1) populations occurring in the Iberian Peninsula and North Africa were probably interconnected during the LGM and (2) populations occurring in the Dinaric Alps did not exist throughout the last glacial periods, having retreated southwards into lowland areas of the Balkan Peninsula.

CONCLUSIONS

Newly discovered tetraploid populations are situated in the putative main glacial refugia, and neither of them was likely to have been involved in the colonization of central and northern Europe after glacial withdrawal. This could mean that neither the Iberian Peninsula nor the western part of the Balkan Peninsula served as effective refugial areas for northward post-glacial expansion of A. glutinosa.

Heavy metal stress in alders: Tolerance and vulnerability of the actinorhizal symbiosis

Alders have already demonstrated their potential for the revegetation of both mining and industrial sites. These actinorhizal trees and shrubs and the actinobacteria Frankia associate in a nitrogen-fixing symbiosis which could however be negatively affected by the presence of heavy metals, and accumulate them. In our hydroponic assay with black alders, quantification of the roots and shoots metal concentrations showed that, in the absence of stress, symbiosis increases Mo and Ni root content and simultaneously decreases Mo shoot content. Interestingly, the Mo shoot content also decreases in the presence of Ni, Cu, Pb, Zn and Cd for symbiotic alders. In symbiotic alders, Pb shoot translocation was promoted in presence of Pb. On the other hand, Cd exclusion in symbiotic root tissues was observed with Pb and Cd. In the presence of symbiosis, only Cd and Pb showed translocation into aerial tissues when present in the nutrient solution. Moreover, the translocation of Ni to shoot was prevented by symbiosis in the presence of Cd, Ni and Pb. The hydroponic experiment demonstrated that alders benefit from the symbiosis, producing more biomass (total, root and shoot) than non nodulated alders in control condition, and in the presence of metals (Cu, Ni, Zn, Pb and Cd). Heavy metals did not reduce the nodule numbers (SNN), but the presence of Zn or Cd did reduce nodule allocation. Our study suggests that the Frankia-alder symbiosis is a promising (and a compatible) plant-microorganism association for the revegetation of contaminated sites, with minimal risk of metal dispersion.

Ecotoxicity effects triggered in aquatic organisms by invasive Acer negundo and native Alnus glutinosa leaf leachates obtained in the process of aerobic decomposition

The replacement of autochthonous tree species by invasive ones in coastal zones of freshwater bodies induces additional alteration of hydrochemical and microbiological characteristics due to decomposition of fallen leaves of non-indigenous species, which can lead to ecotoxic response of the littoral biota. Leaves of invasive to Lithuania boxelder maple (Acer negundo) and autochthonous black alder (Alnus glutinosa) lost more than half of biomass and released stable amount of DOC (60-70 mg/L) throughout 90-day mesocosm experiment under aerobic conditions. This, along with the relatively small BOD7 values detected after some variation within the first month confirms effective biodegradation by fungi and bacteria. The ambient water was more enriched with different forms of N and P by decomposing boxelder maple than by alder leaves. During the first month, both leachates were more toxic to charophyte (Nitellopsis obtusa) at mortality and membrane depolarization levels, while later to two crustacean species. Biomarker response, H(+)-ATPase activity in membrane preparations from N. obtusa, was stronger for A. negundo. Generally, boxelder maple leaf leachates were more toxic to tested hydrobionts and this coincides with previous study on leaves of the same pair of tree species conducted under microaerobic conditions (Krevš et al., 2013).

Cytotoxic activity of hirsutanone, a diarylheptanoid isolated from Alnus glutinosa leaves

BACKGROUND

The low efficacy of cancer therapy for the treatment of patients with advanced disease makes the development of new anticancer agents necessary. Because natural products are a significant source of anticancer drugs, it is important to explore cytotoxic activity of novel compounds from natural origin.

PURPOSE

The aim of this work is to evaluate the cytotoxic capacity of hirsutanone, a diarylheptanoid isolated from Alnus glutinosa leaves. Hirsutanone cytotoxic way of action was also studied.

MATERIAL AND METHODS

The cytotoxic ability of Alnus glutinosa leaves ethyl acetate extract was studied over HeLa and PC-3 cell lines, with the MTT colorimetric assay. Hirsutanone was isolated from this extract using chromatographic methods, and its structure elucidated by spectroscopic analysis. HT-29 cell viability after hirsutanone treatment was determined using SRB assay. In order to understand hirsutanone way of action, cytotoxicity was evaluated adding the diarylheptanoid and antioxidants. DNA topoisomerase II (topo II) poison activity, was also evaluated using purified topo II and a supercoiled form of DNA that bears specific topo II recognition and binding region; topo II poisons stabilize normally transient DNA-topo II cleavage complexes, and lead an increased yield of linear form as a consequence of a lack of double-strand breaks rejoining.

RESULTS

The diarylheptanoid hirsutanone was isolated from Alnus glutinosa (L.) Gaertn. (Betulaceae) leaves extract that showed cytotoxic activity against PC-3 and HeLa cell lines. Hirsutanone showed cytotoxic activity against HT-29 human colon carcinoma cells. Pre-treatment with the antioxidants NAC (N-acetylcysteine) and MnTMPyP (Mn(III)tetrakis-(1-methyl-4-pyridyl)porthyrin) reduced this activity, suggesting that reactive oxygen species (ROS) participate in hirsutanone-induced cancer cell death. Using human topo II and a DNA supercoiled form, hirsutanone was found to stabilize topo II-DNA cleavage complexes, acting as a topo II poison.

CONCLUSION

Our data suggest that, like curcumin, an induction of oxidative stress and topo II-mediated DNA damage may play a role in hirsutanone-induced cancer cell death. Since both compounds share similar structure and cytotoxic profile, and curcumin is in clinical trials for the treatment of cancer, our results warrant further studies to evaluate the anticancer potential of hirsutanone.

Controls on methane emissions from Alnus glutinosa saplings

Recent studies have confirmed significant tree-mediated methane emissions in wetlands; however, conditions and processes controlling such emissions are unclear. Here we identify factors that control the emission of methane from Alnus glutinosa. Methane fluxes from the soil surface, tree stem surfaces, leaf surfaces and whole mesocosms, pore water methane concentrations and physiological factors (assimilation rate, stomatal conductance and transpiration) were measured from 4-yr old A. glutinosa trees grown under two artificially controlled water-table positions. Up to 64% of methane emitted from the high water-table mesocosms was transported to the atmosphere through A. glutinosa. Stem emissions from 2 to 22 cm above the soil surface accounted for up to 42% of total tree-mediated methane emissions. Methane emissions were not detected from leaves and no relationship existed between leaf surface area and rates of tree-mediated methane emissions. Tree stem methane flux strength was controlled by the amount of methane dissolved in pore water and the density of stem lenticels. Our data show that stem surfaces dominate methane egress from A. glutinosa, suggesting that leaf area index is not a suitable approach for scaling tree-mediated methane emissions from all types of forested wetland.

Characterization and identification of black alder ectomycorrhizas by PCR/RFLP analyses of the rDNA internal transcribed spacer (ITS)

The identity of black alder (Alnus glutinosa (L.) Gaertn.) ectomycorrhizas was investigated using PCR/RFLP analysis of the ITS region from 16 morphotypes sampled at a 60-yr-old black alder stand. A comparison was made with restriction patterns from sporocarps of 28 mycobionts, of which 16 originated from the same stand, the remaining 12 came from two geographically distant alder stands. Eight of the mycorrhizal types could thus be identified, whereas eight mycorrhizal types remained unidentified. The identified mycorrhizas belonged to the genera Russula, Lactarius, Naucoria and Cortinarius. Four of the identified ectomycorrhizal types had identical PCR/RFLP profiles to corresponding fruit bodies from all investigated stands with no detectable intraspecific variation, despite the geographical distance of c.300 km between the sampling locations. By contrast, intraspecific variation between sporocarps from the different locations was detected in Paxillus rubicundulus, mycorrhizas of which were not found. The diversity of fruiting alder mycobionts at the main experimental plot only partly matched the diversity observed from mycorrhizas when comparing their PCR/RFLP profiles. The results are discussed regarding sampling techniques, PCR/RFLP analyses and ecological aspects.

Resistance to an ineffective Frankia strain type in Alnus glutinosa (L.) Gaertn

Characteristics of natural resistance to the ineffective Frankia strain type AgI-WD1 were investigated in different progenies of the host species Alnus glutinosa (L.) Gaertn. with the aid of nodulation experiments. This strain type of Frankia was abundant in the soil of an A. glutinosa stand at Voorne, The Netherlands. Soil suspensions from this site produced high numbers of ineffective root nodules on some of the A. glutinosa seedlings used in biotests, but ii significant number of the seedlings did not produce ineffective nodules. Resistance (R) or susceptibility (S) of the seedlings to Frankia strain type AgI-WD1, as expressed by absence or presence of ineffective root nodules, proved to be persistent in cloned plants of each phenotype. Both R and S-seedlings were susceptible to effective Frankia strains in the soil suspensions. Variation in nodulation time was examined among cloned plants of S-seedlings selected for this trait. Average nodulation times of three selected clones were 11, 26 and 39 d, respectively. Relative growth rates of cloned plants showed no relationship with nodulation time. Both R and S phenotypes were present in all seed-lots of A. glutinosa under study, but the frequency of R phenotypes of seed-lots from different locations ranged from 24 to 100%. R-frequencies of seed-lots of nine trees from a small population of A. glutinosa segregated into two distinct frequency classes which suggested genotypic differentiation of the R-trait among these trees. A significant correlation was found between R-frequencies of seedlots from the same trees over successive years.

and Pinus contorta Doug, ex Loud seedlings connected by a common ectomycorrhizal mycelium

Uptake and translocation of nitrogen was studied in laboratory microcosms consisting of Alnus glutinosa (L.) Gaertn., Frankia sp., Paxillus involutus (Fr.) Fr. and Pinus contorta Dougl. ex Loud. P. involutus was shown to form a fully functional ectomycorrhizal association with alder as well as pine, and the seedlings thus became interconnected by a common mycelium. When microcosms were exposed to ¹⁵ N₂ gas, interplant translocation of ¹⁵ N was observed in two out of three experiments. ¹⁵ N₂ was fixed by Frankia and translocated to all other parts of the system. In the two experiments in which interplant translocation occurred, between 5 and 15% of the ¹⁵ N recovered was found in the pine seedlings. Within seven days, fixed N₂ was incorporated into amino acids in the Frankia nodules, translocated to both the A. glutinosa and P. contorta seedlings and incorporated into macromolecules. In alder seedlings, citrulline and ornithine were the free amino acids that had both the highest ¹⁵ N enrichment levels and concentrations. In pine, glutamine and citrulline had the highest ¹⁵ N concentrations, and glutamine had the highest level of ¹⁵ N enrichment. ¹⁵ N enrichment levels were greatest in the nodules, at between 5.5 and 29% in the different amino acids and 12% in the macromolecular fraction. Enrichment levels decreased with increasing distance from the nodules. The uptake and translocation of ¹⁵ N applied as ¹⁵ NH₄ Cl to the mycelium was also studied. ¹⁵ N was incorporated into amino acids in the mycelium and translocated further in this form. Generally, free amino acids had high ¹⁵ N enrichment levels in the mycelium, decreasing along the translocation pathway. Citrulline and glutamine were the amino acids with highest ¹⁵ N concentrations in all parts of the system. ¹⁵ N was also found in the macromolecular fraction.

ABSCISIC ACID AND DORMANCY IN ROOT-NODULATED ALNUS GLUTINOSA (L.) GAERTN

Treatment of three-month or six-month-old water culture plants of Alnus glutinosa with 0.1 mol m^-3 (±) abscisic acid (ABA) induced formation of resting buds after 30 to 60 d. Leaf dry weight per plant decreased by 40 to 45 % during this period but root and nodule dry weights were unchanged relative to control plants. [2-¹⁴ C] ABA was taken up by the root system within 5 d and after 30 or 60 d the ABA content of plants fed 01 mol m^-3 ABA was 60 and 119 times that of control plants. In control plants, the levels of 'free'cis(Z) ABA were similar to or exceeded 'free'trans(E) ABA in all plant parts while, in general, the converse was true for these isomers in 'bound' form. In ABA-treated plants, all isomeric forms of ABA were present at much higher amounts than in the controls but, whereas in leaves and shoot apices the amount of cis ABA in both 'free' and 'bound' forms was much greater than the trans isomer, in roots and nodules trans ABA was the dominant isomer in both 'bound' and 'free' forms. Most biologically active 'free'cis ABA thus accumulated in the leaves and shoot apex, where effects of ABA treatment on growth were most evident, whereas in roots and nodules where biologically inactive 'free' and 'bound'trans ABA were dominant, growth was relatively unaffected. Amounts of 'free' ABA in nodules were several times those recorded previously in nodules of dormant plants, in keeping with earlier suggestions that ABA is unlikely to have a precise regulatory role in growth and dormancy of nodules.