Alder Species Research Articles

Determination and Separation of Diarylheptanoids From Alder Growing in Latvia

The composition of diarylhepatnoids fraction isolated from bark of two alder species (grey alder and black alder) was studied. The efficiency of three extraction methods used for isolation of diarylhepatnoids from alder bark was compared. Two diarylhepatnoids: 1,7-bis-(3,4-dihydroxyphenyl)-heptan- 3-one-5-O-β-D-xylopyronoside (oregonin) and 1,7-bis-(3,4-dihydroxyphenyl)-3-hydroxyheptane-5-O-β-D- xylopyranoside were isolated from the bark of grey alder. The phenolic components of the extracts were analyzed by high-performance liquid chromatography (HPLC). Quantitative determination of oregonin was performed using an internal standard method. The results obtained show that alder barks are rich source of diarylhepatnoids.

Unusually early flowering of alder in Vienna: first report of Alnus × spaethii in Austria, combined LM and SEM study of alder species and impact on pollen allergy sufferers

Different species of alder cause hay fever symptoms in pollen allergy sufferers within Europe: Alnus glutinosa (black alder), A. incana (grey alder), A. viridis (green alder) and more recently A. × spaethii (japonica × subcordata; Spaeth’s alder). In Austria, the alder pollen season usually lasts from January to April (until June in the mountains due to later flowering of A. viridis). The pollen season started very early in 2014, namely by the end of December 2013 in Vienna with the first pollination of alder. Such an early flowering around Christmas is known for A. × spaethii and was first recognized as problem in Switzerland. Up to now, this alder species was not reported in Austria. A sample including twigs, leaves, catkins and pollen from Switzerland was compared with an unusually early flowering alder in Vienna. The pollen of these (Alnus × spaethii) and in addition from black and green alder was analysed by light microscopy and scanning electron microscopy to find possible morphological differences or similarities in their pollen morphology. The general morphology revealed that A. × spaethii is present in Austria (planted in a park) and was responsible for the first burden on pollen allergy sufferers during the alder pollen season in Vienna, although pollen data revealed no significant alder pollen concentrations. The results emphasize the importance of monitoring phenology for pollen information.

Heavy metal accumulation characteristics of Nepalese alder (Alnus nepalensis) growing in a lead-zinc spoil heap, Yunnan, south-western China

A fast-growing alder species native to the eastern Himalayas, Nepalese alder (Alnus nepalensis), has recently received considerable attention in the restoration of contaminated lands due to its significant economic benefits and ecological functions. The bioaccumulation characteristics and phytoremediation potential of naturally regenerated Nepalese alder were evaluated in a lead-zinc spoil heap located in Lancang county, Yunnan province, south-western China. Results showed that bioaccumulation factors (BFs) of A. nepalensis for Zn and Pb were always >1 in slightly contaminated soils (extractable Zn, Pb of 4.2-17.9 and 3.4-13.1 mg kg-1, respectively) and >1 for Cd in contaminated soils (extractable Cd 0.3- 6.8 mg kg-1). By contrast, translocation factors (TFs) for Zn were <1 in all sampling plots, but >1 for Pb in soil slightly contaminated by 13.1 mg kg-1 extractable Pb and >1 for Cd in contaminated soils (extractable Cd 2.6- 6.8 mg kg-1). Significant positive correlations were found between heavy metals (HMs) in roots and extractable HMs in soils (p<0.01) and between HMs in shoots and extractable HMs in soils (p<0.05) except for Cd. Based on the accumulation capacity revealed in this study, we suggest that A.nepalensis is a promising tree species for phytostabilization of zinc and lead in soils slightly contaminated with Zn and Pb and for phytoextraction of cadmium in Cd-polluted soil.

Cross-amplification and multiplexing of SSR markers for Alnus glutinosa and A. incana

We investigated 39 previously developed Betula, Alnus ,a ndCorylus simple sequence repeat (SSR) markers for their utility in the cross-generic amplification of two European alder species, i.e., Alnus glutinosa and A. incana. Of these markers, ten loci had successful amplification within Alnus species. Finally, we designed two multiplexes composed of eight and nine loci for A. glutinosa and A. incana, respectively. Multiplexes were tested on 100 samples from five different populations of each species across Europe. The majority of loci had a relatively high genetic diversity, were in Hardy-Weinberg equilibrium, and showed low error rates and low occurrence of null alleles. By comparing sequences of source species and both Alnus species, we concluded that repeat motifs of five of these ten loci differed from those described for the source species. These differences represent mainly the modifications of the original motifs and affected compound or interrupted re- peats as well as pure ones. The repeat motifs of three loci of the two alder species also differed. These mutations could lead to erroneous estimates of allele homology, be- cause alleles with identical lengths will not have the same number of repeat units. Hence, before using microsatellite markers in studies comparing two or more species, they should be carefully examined and sequenced to ensure that allele homology is really stable and not affected by various inserts that change the sequence.

Assessing the effect of Alnus roots on hillslope stability in order to use in soil bioengineering

The role of plant roots in stabilizing slopes is obvious, but the amount of the effect is varied in different species. The purpose of this study was to evaluate the effect of alder (Alnus subcordata) roots on hillslope stability. The profile trenching method was used to obtain root characteristics and a standard Instron testing machine was used for determining the tensile strength of roots. Direct shear test with undisturbed samples was used for determining the soil strength parameters. Using the results of biotechnical characteristics and the Wu model, the reinforcement effect was calculated. Using the reinforcement values and soil strength parameters and Slip4Ex program, factor of safety with and without vegetation was calculated. The obtained results indicated that the root density and number of roots decreased with increasing depth and the average root area ratio was 0.071% ± 0.01. Tensile strength decreased with increasing diameter of roots following the power function with an average of 16.29 ± 3.10 MPa. The minimum and maximum of reinforcement were 0.55 KPa and 110.76 KPa, respectively. The results of this paper augment the knowledge about biotechnical characteristics of root systems of Alder species and indicate that this species increases the factor of safety about 16.79%.

From Tolerance to Acute Metabolic Deregulation: Contribution of Proteomics To Dig into the Molecular Response of Alder Species under a Polymetallic Exposure

Alnus spp. are actinorhizal trees commonly found in wet habitats and able to grow effectively in soil slightly contaminated with metal trace- elements. Two clones belonging to two Alnus species, namely, A. incana and A. glutinosa, were grown in hydroponics and exposed for 9 weeks to a Cd + Ni + Zn polymetallic constraint. Although responding by a similar decrease in total biomass production, the proteomic analysis associated with the study of various biochemical parameters including carbohydrate and mineral analyses revealed that the two clones have a distinct stress-responsive behavior. All parameters indicated that the roots, the organ in direct contact with the media, are more affected than the leaves. In fact, in A. glutinosa the response was almost completely confined to the roots, whereas many proteins change significantly in the roots and in the leaves of the treated A. incana. In both clones, the changes affected a broad range of metabolic processes such as redox regulation and energy metabolism and induced the production of pathogenesis-related proteins. In particular, changes in the accumulation of bacterial proteins that were not identified as coming from the known symbionts of Alnus were reported. Further investigation should be performed to identify their origin and exact role in the plant response to the polymetallic exposure tested here.

Capabilities of alders (Alnus incana and A. glutinosa) to grow in metal-contaminated soil

This study examined the effects of metal-polluted soil on growth, biomass and uptake of trace metals and nutrients in Alnus incana and A. glutinosa seedlings. The rate of nitrogen fixation, counts of microbial groups, activities of phosphomonoesterases, and phenolic compounds in soil were also determined. Seedlings of various origin were grown for 158 days in forest soil (control) and in soil from a copper smelter area, with low nutrient content and high concentrations of Cu (1510mgkg−1) and Pb (490mgkg−1). Both alder species accumulated in their roots Cu and stored Pb, Zn (A. incana≈A. glutinosa) and Cd (A. glutinosa>A. incana). Concentrations of Cu, Pb, Zn and Cd were lower in shoots than in roots. Concentrations of Cu, Zn, Cd and Pb in leaves of both alder species were within normal ranges. Nutrient weight proportions P:K:Ca:Mg (N=100) for leaves of Alnus spp. growing in polluted soil were higher than in the control. Alder growth in polluted soil was characterized by slight changes in total biomass of seedlings and nodules. Nodules stored Cu, Cd (A. incana>A. glutinosa), Pb and Zn, while concentrations of P and Ca were lower in nodules than in the control. N levels in leaves of alders grown in polluted soil were generally lower than those of alders grown in control soils. We also recorded a reduction in the rate of N2 fixation in nodules when alders were grown in polluted soil. In the rhizosphere in polluted soil, actinobacteria (actinomycetes) and copiotrophs were less numerous, while oligotrophs were more numerous. Also activities of phosphomonoesterases were strongly reduced, while concentrations of water-soluble phenols increased. The results suggest that both species of Alnus grow well in heavily polluted soil, in spite of accumulation of toxic metals in their roots and nodules and a decreased rate of N2 fixation.

Bacterial community structure and its relationship to soil physico-chemical characteristics in alder stands with different management histories

The two alder species, black alder (Alnus glutinosa (L.) Gaertn.) and grey alder (Alnus incana (L.) Moench) are known to be pioneer species in the succession of new land areas, and important tree species in renewable biomass production, the restoration of post-mining sites and riparian forest ecosystems. We analyzed the influence of soil physico-chemical characteristics (soil water content, pHKCl, total N, soluble P, organic matter content, C and N ratio, and elemental content) on bacterial community structure based on pyrosequencing analysis of the 16S rRNA gene V2 and partly V3 region in two black and two grey alder stand soils with different management histories. The analyses revealed clear differences in all the measured chemical characteristics of studied soils. All the studied stands also had distinct soil bacterial communities, and the number of shared species was low. In all stands species from phylum Proteobacteria were dominant, and the next phyla by percentage were Bacteroidetes and Actinobacteria. At the family level, Chitinophagaceae and Bradyrhizobiaceae species dominated. The obtained bacterial community Inverted Simpson's diversity indices showed no difference between the studied sites. The alder species did not affect soil bacterial community structure. Distance-based regression analysis indicated that soil pH value, water content, soluble phosphorus concentration and also total boron, cadmium, and aluminium content were related to the variation of soil bacterial community structure in alder stand soils. The results of this study emphasize the importance of soil geomorphological properties in addition to soil physical and chemical characteristics in the formation of soil bacterial community structure during restoration of exhausted open mining areas, management of abandoned agricultural lands, and short rotation forests with different alder species.

Effects of light regimes on photosynthetic characteristics and antioxidant system in seedlings of two alder species

Aims Our objective was to investigate the effects of different light intensities on leaf morphology, photosynthetic capacity, heat dissipation and antioxidant enzyme activities in seedlings of Alnus formosana and A. cremastogyne from a hilly region near Lingyan Mountain in northwestern Sichuan Province in China. We also discuss photosynthetic acclimation and photoprotection strategies in seedlings of the two species Methods Three light regimes of 100%, 56.2% and 12.5% of natural light were simulated to match forest openings, forest gaps and forest canopies, respectively. After more than three months, we measured the parameters of gas exchange, including maximum net photosynthetic rate (Pmax), light saturation point (LSP), light compensation point (LCP), net photosynthetic rate (P n ), stomatal conductance (G s ), transpiration rate (T r ), intercellular CO 2 concentration (C i ), fluorescent non-photochemical quenching (NPQ), maximum efficiency of PSII photochemistry (F v /F m ) and light use efficiency (LUE), using a LI-6400 in seedling leaves. We also determined pigment contents per unit leaf area, lamina mass per unit area (LMA) and activity of antioxidant enzymes (superoxide dismutase, catalase and ascorbate peroxidase). Important findings LMA, carotenoid content (Cars), ratio of carotenoid to total chlorophyll (Car/Chl) and activities of superoxide dismutase, catalase and ascorbate peroxidase in leaves increased with the increase of light intensities. P max , LSP, LCP and NPQ tended to increase, while the chlorophyll content (Chl) and LUE decreased. However, the C i decreased with the increase of P n , G s and stomatal limitation value (L s ). We speculated that non-stomatal limitation was the main factor that inhibited P n . Seedlings of the two alder species could acclimate to different light regimes in this study through changing of physiological and morphological traits. Under all lightregimes, diurnal photoinhibition of photosynthesis, as judged by F v /F m , was significantly more severe in A. cremastogyne than in A. formosana. The acclimation capacity to high light regime was stronger in A. formosana than in A. cremastogyne. With the increase of light intensities, P max and antioxidant enzyme activities increased significantly, but not NPQ in A. formosana. The opposite trends occurred in A. cremastogyne. At the same light intensity, thermal dissipation was much lower, but P max was much higher in A. formosana than in A. cremastogyne. These results indicated that A. formosana seedlings might adapt resistance to photoinhibition through improving the use of solar energy by higher P max and antioxidant enzyme system, while A. cremastogyne seedling avoided photoinhibition mainly through converting excess light energy to heat energy in the form of non-radiative dissipation through the antenna system.

Increasing taxonomic resolution in pollen identification: Sample size, spatial sampling bias and implications for palaeoecology

Many studies proposing methods for differentiating fossil pollen of different species derive diagnostic identification criteria from small sample sizes and/or modern pollen collected from limited areas within species ranges. Here, we evaluate the importance of sample size and population representation in pollen identification methods, in an examination of morphological measurements on over 21,000 pollen from three alder species (Alnus viridis subsp. sinuata, Alnus incana subsp. tenuifolia and Alnus rubra) in western North America. We assess the sensitivity of morphometric analyses and multi-trait classification models of Alnus pollen to changes in sample size and spatial sampling breadth, by randomly reducing our large dataset in size and by splitting the dataset into regional subsets. Sensitivity analyses demonstrate that using small sample sizes to identify diagnostic morphological traits for pollen identification can result in misleading conclusions about interspecific morphological differences in pollen types and ultimately in misidentification of pollen. Pollen identification methods based on reference samples collected from limited regions are prone to bias, due to regional differences in modern pollen morphology. Our study reveals the importance of using large sample sizes from across species ranges when attempting to determine the diagnostic morphological features for fossil pollen identification. We recommend basing identification criteria on pollen from as many individual plants per species as possible, as opposed to numerous pollen grains from only a small number of individuals, because at least in Alnus, individual plants produce morphologically similar pollen.

Pollen morphology of the three subgenera of Alnus

The three subgenera of alder (Alnusroman Clethropsis and Alnobetula) are taxonomically distinctive, but how does their pollen match up with their gross morphology? This study links pollen characters with the taxonomic divisions of the genus alder based on nrDNA ITS sequence data. The value of the study is in the breadth of the taxonomic coverage of the three subgenera, as the samples per species only range from 1 to 6. From 29 Alnus species, the authors studied pollen from 59 modern reference collections (prepared by acetolysis) and recorded the number and type of apertures (pores), thickness of the arci, pollen size and polar arci. Tallies of the number of pores on the pollen grains in a reference collection typically have a range of ± 1 or 2. Exceptions are presumed hybrid collections in Alnus rugosa with a range of ± 5, which have malformed pollen cells suggesting infertility. The presumed hybrids show a greater range of both pore number and size of pollen grains. The dominant pore number is a key feature that separates the subgenus Alnobetula (= Alnaster) from the other two subgenera by consistently having predominantly 5-, 6- or 7-pored pollen grains, while all other Alnus taxa sampled have pollen with predominantly 4- or 5-pored pollen. The dominant pore number is a consistent feature within the subgenus Alnobetula (10 species), but is inconsistent in 3 out of 16 species of the subgenus Alnus and within the subgenus Clethropsis (3 species). Thickenings of the pore lip, aspidate (protruding) and vestibulate pores are important features of Alnus pollen on a species level. Alnus-like pollen morphology occurs occasionally in certain other betulaceous genera (Betula and Carpinus). Differences in character or thickness of arci (band-like thickenings on the pollen wall between pores) tend to be somewhat consistent within a species and vary within subgenera. Two Alnobetula species in the Alnus viridis complex (Alnus crispa and Alnus sinuata) have arci that are weakly developed or appear as simple folds; walls are fragile and pores are typically less aspidate. Pollen sizes in different species overlap greatly, may be partly influenced by processing methods and do not seem to be generally helpful in characterizing species. Circular doughnut-shaped arci thickenings on the polar area of pollen grains are a common feature (16–40%) in two closely related East Asian taxa of subgenus Alnobetula with large pollen (‘Clade A’: Alnus firma and Alnus sieboldii). These ‘Clade A’ features have been reported from Miocene collections of Alnus pollen from Alaska, and support megafossil evidence in determining the biogeography of this group along the Pacific Rim in the Neogene. The Miocene appearance of subgenus Alnobetula megafossils in both Alaska and Japan can only have occurred via a Bering Land Bridge. This relation is now confirmed by Reinink-Smith's Miocene ‘Clade-A-type’ pollen data of Alaska. These taxa had Pacific Rim distributions, similar fruiting carposamaras and now correspond to a DNA ITS subgroup within Alnobetula. Depending on the geographic location with limited number of local alder species, certain Holocene identifications are possible based on pore structure and arci thickness, e.g. the Alnus crispa-type in eastern Canada and the Alnus sinuata-type in the Pacific northwest.

Morphological differentiation of Alnus (alder) pollen from western North America

Increasing the taxonomic resolution of fossil pollen identification is critical for advancing Quaternary paleoecology to a point where species-specific ecologies can be addressed in the fossil record. Here, we determine the critical morphological features that permit species-level differentiation of Alnus pollen, an abundant pollen type in Quaternary records from western North America. We examined over 21,000 pollen grains from the region's three common alder species: Alnus viridis subsp. sinuata Regel, Alnus incana subsp. tenuifolia Nuttall and Alnus rubra Bongard. Modern pollen samples were collected from 27 to 35 individual plants from across the range of each species. Nine morphological traits were measured on 30 pollen grains from each plant, and the number of pores was determined for an additional 200 pollen grains from each individual. Nested ANOVA analyses suggest that for individual Alnus plants, pollen morphology appears relatively stable, compared to variation between species. Statistically significant differences exist between the pollen of all three alder species in most morphological traits, but there is a high degree of within-species variability and between-species overlap in pollen morphology. Since no morphological trait on its own was sufficient for pollen identification to species, classification and regression tree (CART) analysis was used to derive multi-trait classification models. CART analyses show that A. rubra and A. viridis subsp. sinuata pollen can be differentiated into two distinct morphotypes, analogous to species separation, based on annulus width, arci strength, exine thickness and overall diameter. The intermediate pollen morphology of Alnus incana subsp. tenuifolia prevents identification of Alnus pollen to species when all three species are present in the pollen source area. This research lends support to paleoecological studies in western North America that have differentiated Alnus pollen into two morphotypes and revealed distinct postglacial histories that are masked when Alnus pollen are not differentiated.

Comparative phylogenies and host specialization in the alder ectomycorrhizal fungi Alnicola, Alpova and Lactarius (Basidiomycota) in Europe.

BackgroundMycorrhizal fungi form intimate associations with their host plants that constitute their carbon resource and habitat. Alnus spp. (Betulaceae) are known to host an exceptional species-poor and specialized ectomycorrhizal (ECM) fungal community compared to other tree species, but the host-specificity pattern and its significance in terms of fungal diversification and speciation remain poorly documented. The degree of parallel speciation, host switching, and patterns of biogeography were explored in the historical associations between alders and three ECM taxa of Basidiomycetes: Alnicola (Agaricales), Alpova (Boletales), and Lactarius (Russulales). The aim was to develop an evolutionary framework on host specificity and diversification of Basidiomycetes in this highly specialized plant-fungus symbiosis.ResultsSporocarps of Alnicola (220), Lactarius (61) and Alpova (29) were collected from stands of the four European alder species (A. alnobetula including the endemic subsp. suaveolens in Corsica, A. cordata, A. glutinosa, A. incana) in Western Europe (mainly in France and Austria), from 1995 to 2009. Specimens were morphologically identified to the species level. From these, 402 sequences of four DNA regions (ITS, rpb2, gpd, and the V9 domain of the mit-SSU rDNA) were successfully obtained and analyzed in addition with 89 sequences available in GenBank and UNITE databases. Phylogenetic analyses were conducted on all sequence data sets (individual and combined) using maximum likelihood reconstruction and Bayesian inference. Fungal phylogenies are compared and discussed in relation to the host, with a focus on species boundaries by associating taxonomic, systematic and molecular information.ConclusionsPatterns of host specificity and phylogenies of Alnicola and Lactarius suggest coevolution as a basal factor of speciation in relation with the subgeneric diversification of Alnus, possibly due to the very selective pressure of the host. A second element of the historical associations between Alnus and its fungal symbionts is a host-dependent speciation (radiation without host change), here observed in Alnicola and Alpova in relation with Alnus subgen. Alnus. Finally host shifts from Alnus subgen. Alnus to A. alnobetula are found in most lineages of Alnicola (at least four times), Alpova (twice) and Lactarius (once), but they do not represent such a common event as could be expected by geographic proximity of trees from the two subgenera. However, active or very recent host extensions clearly occurred in Corsica, where some fungi usually associated with Alnus glutinosa on mainland Europe locally extend there to A. alnobetula subsp. suaveolens without significant genetic or morphological deviation.

Variations in alder pollen pore numbers—a possible new correlation tool for the Neogene Kenai lowland, Alaska

Alder (Alnus: Betulaceae) pollen grains are common in coal beds of the Miocene Beluga and the Pliocene Sterling formations exposed in the Kenai lowland, Alaska. All alder pollen grains of the Beluga Formation and the lower part of the overlying Sterling Formation are dominated by 4-pored grains (42–67% of total alder), with no exceptions. There is a striking transition to a 5-pored dominance (32–67%) with an accompanying increase in 6-, 7-, and even 8-pored grains in outcrops of the Sterling Formation along the Cook Inlet shore, north of Clam Gulch and at the head of Kachemak Bay, in upper Swift Creek Canyon, and in two canyon tributaries to Fox Creek. The general zone of this transition includes a previously correlated volcanic ash and gives credence to the rock strata being synchronous in these widely separated outcrops. It should thus be possible to correlate these strata across the Kenai lowland by the alder pore numbers combined with the volcanic ash. The cause of the transition to a ≥ 5-pored Alnus dominance in the Pliocene of the Kenai lowland can only be suggested. Using pore numbers to determine alder species is not an accurate method because pollen of different alder species may have similar percentages of pore numbers. Nevertheless, when taking into account percentages of 5-, 6-, and 7-pored grains combined with the presence or absence of polar arci, it can be suggested that a shift occurred from the 4-pore dominated subgenus Alnus, represented by Alnus incana, to the 5-pore dominated, cold–adapted subgenus Alnobetula through dispersion and hybridization of Asian species such as Alnus maximowiczii, Alnus firma, and possibly Alnus sieboldiana. The pollen of these three species contain between 2–40% circular polar arci, which are also present in high-pore-numbered grains above the transition in this study.

First Report of Phytophthora Rot on Alders Caused by Phytophthora alni subsp. alni in Spain.

Phytophthora alni, a soil- and waterborne pathogen, causes aggressive root and collar rot on riparian alder populations (1,2,4). The disease has been described from several European countries with a destructive impact in Great Britain (1,2). All European alder species and the red alder (Alnus rubra) are highly susceptible. P. alni has multiple variants that have been placed in three subspecies: P. alni subsp. alni, P. alni subsp. uniformis, and P. alni subsp. multiformis (1). In July 2009, a survey of symptoms of Phytophthora rot from A. glutinosa at 20 riparian stands along the Avia River in Galicia (northwest Spain) was conducted. Affected trees showed symptoms of Phytophthora rot including abnormally small, sparse, and yellowish foliage, dieback in the canopy, necroses of the inner bark and cambium, and bleeding cankers on the trunks (2,4). Phytophthora spp. were baited from saturated rhizosphere soil and watercourses using oak leaflets (4). Roots and tissue from fresh active inner bark lesions were transferred to selective medium V8-PARPH agar (4) and incubated for 7 days at 22°C in the dark. A Phytophthora sp. was isolated, transferred to carrot agar (CA), and incubated in the dark. Colonies were appressed, often irregular in outline, and with limited aerial mycelium (1). Growth on CA occurred from 4 to 31°C with optimum growth at 23 to 25°C. Chlamydospores were not observed. Ellipsoid, nonpapillate, noncaducous sporangia had a length/breadth average ratio of 1.4. Nesting and extended internal proliferation occurred. Oogonia, antheridia, and oospores were abundantly produced in a single culture. Oogonia with tapered stalks were spherical (mature oogonia 38 to 50 μm in diameter) and some had ornamented walls or bullate protuberances (1,2). Antheridia were large, amphigynous, and predominantly two-celled (23 to 37 × 16 to 23 μm). Oospores were plerotic. Distorted comma-shaped or smaller oogonia and aborted oospores were observed (1). Amplification of DNA was accomplished by using sequence-characterized amplification region-PCR primers (3). The amplicon sizes obtained were identical to P. alni subsp. alni (3). Internal transcribed spacer (ITS)-DNA and nadh1 mitochondrial gene were also amplified. DNA sequences of ITS and mt-DNA regions were deposited in GenBank (Nos. GU108602 and GU108603). Comparison of the sequences showed 100% homology with P. alni subsp. alni (GenBank Nos. FJ746679 and DQ202490). P. alni subsp. alni was recovered from trees at 3 of 20 riparian alder stands with symptoms. Pathogenicity of one representative isolate was confirmed by inoculating 10 3-year-old A. glutinosa seedlings grown in pots. One shallow cut was made into the bark at the collar level. A colonized agar plug, from the margin of an actively growing colony of P. alni subsp. alni, was inserted beneath the flap that was sealed with Parafilm. Five controls seedlings received only sterile CA agar plugs. Plants were incubated at 24°C and 95% humidity for 30 days. On inoculated plants, necroses progressed bidirectionally from the wound, and dead leaves and wilting of shoots were observed. P. alni subsp. alni was recovered from inoculated seedlings, but not from controls. To our knowledge, this is the first report of Phytophthora rot on alder caused by P. alni subsp. alni in Spain.

Does a fungal species drive ectomycorrhizal root traits in Alnus spp.?

Ectomycorrhizal (EcM) fungi contribute significantly to the shaping of short-root morphology, playing an important role in balancing the costs and benefits of root growth and nutrient uptake and exchange in boreal forests. We aimed to assess the effect of various EcM fungal taxa on root traits at seven sites dominated by grey alder, Alnus incana (L.) Moench, and black alder, Alnus glutinosa (L.) Gaertn. Mean root size, specific root length, specific root area, root tissue density, and root-tip frequency of EcM short roots were measured in EcM anatomotypes in relation to the effects of host species, soil moisture level, and nutrient status. Redundancy analysis revealed that anatomotype, alder species, site, and soil parameters (N, P, K, Ca, and Mg concentrations, pH, organic-matter content) accounted for 42.3% (p &lt; 0.001) of the total variation in EcM root morphology. Variation decreased in the following order: anatomotypes (27.9%) &gt; soil parameters and sites (19.9%) &gt; alder species (5.1%). EcM fungus species had the primary influence on EcM short-root size. EcM roots of the dominant anatomotype, Alnicola spp., had the highest specific root length and specific root area in both alder species. Short-root morphology depends most strongly on the fungal taxa involved, which indicates that the type of mycobiont has an important influence on the functional properties of fine roots.

Phytophthora alni subsp. uniformis Found in Alaska Beneath Thinleaf Alders

Phytophthora alni Brasier &amp; S. A. Kirk 2004 is an emergent pathogen causing a lethal root and collar disease of alder species in Europe. The species has not been previously found in North America, although an isolate tentatively referred to as P. alni was reported in a survey of nurseries in Minnesota. The potential establishment and spread of this complex of pathogens is perceived to represent a threat to all species of Alnus in the western hemisphere. Accepted for publication 2 October 2008. Published 12 December 2008.

Functional Diversity of Culturable Bacterial Communities in the Rhizosphere in Relation to Fine-root and Soil Parameters in Alder Stands on Forest, Abandoned Agricultural, and Oil-shale Mining Areas

Grey alder (Alnus incana) and black alder (Alnus glutinosa) stands on forest land, abandoned agricultural, and reclaimed oil-shale mining areas were investigated with the aim of analysing the functional diversity and activity of microbial communities in the soil–root interface and in the bulk soil in relation to fine-root parameters, alder species, and soil type. Biolog Ecoplates were used to determine community-level physiological profiles (CLPP) of culturable bacteria in soil–root interface and bulk soil samples. CLPP were summarized as AWCD (average well color development, OD 48 h−1) and by Shannon diversity index, which varied between 4.3 and 4.6 for soil–root interface. The soil–root interface/bulk soil ratio of AWCD was estimated. Substrate-induced respiration (SIR) and basal respiration (BAS) of bulk soil samples were measured and metabolic quotient (Q = BAS/SIR) was calculated. SIR and Q varied from 0.24 to 2.89 mg C g−1 and from 0.12 to 0.51, respectively. Short-root morphological studies were carried out by WinRHIZOTM Pro 2003b; mean specific root area (SRA) varied for grey alder and black alder from 69 to 103 and from 54 to 155 m2 kg−1, respectively. The greatest differences between AWCD values of culturable bacterial communities in soil–root interface and bulk soil were found for the young alder stands on oil-shale mining spoil and on abandoned agricultural land. Soil–root interface/bulk soil AWCD ratio, ratio for Shannon diversity indices, and SRA were positively correlated. Foliar assimilation efficiency (FOE) was negatively correlated with soil–root interface/bulk soil AWCD ratio. The impact of soil and alder species on short-root morphology was significant; short-root tip volume and mass were greater for black alder than grey alder. For the investigated microbiological characteristics, no alder-species-related differences were revealed.

Correlations between the ages ofAlnus host species and the genetic diversity of associated endosymbioticFrankia strains from nodules

Nodule samples were collected from four alder species: Alnus nepalensis, A. sibirica, A. tinctoria and A. mandshurica growing in different environments on Gaoligong Mountains, Yunnan Province of Southwest China and on Changbai Mountains, Jilin Province of Northeast China. PCR-RFLP analysis of the IGS between nifD and nifK genes was directly applied to uncultured Frankia strains in the nodules. A total of 21 restriction patterns were obtained. The Frankia population in the nodules of A. nepalensis had the highest genetic diversity among all four Frankia populations; by contrast, the population in the nodules of A. mandshurica had the lowest degree of divergence; the ones in the nodules of A. sibirica and A. tinctoria were intermediate. A dendrogram, which was constructed based on the genetic distance between the restriction patterns, indicated that Frankia strains from A. sibirica and A. tinctoria had a close genetic relationship. Frankia strains from A. nepalensis might be the ancestor of Frankia strains infecting other Alnus species. From these results and the inference of the ages of Alnus host species, it is deduced that there was a co-evolution between Alnus and its microsymbiont Frankia in China.

Accumulation of carbon, nitrogen and phosphorus during soil formation on alder spoil heaps after brown-coal mining, near Sokolov (Czech Republic)

The accumulation of carbon (C), nitrogen (N) and phosphorus (P) and their vertical distribution in the soil profile in relation to site age were studied in a chronosequence of 19 sites on reclaimed spoil heaps from open-cast coal mining, near Sokolov (Czech Republic) and compared to a semi-natural alder forest in the vicinity of the mining area. The reclaimed sites were located on tertiary clay or quaternary gravel–sand spoil material and afforested with alder species ( Alnus glutinosa, A. incana) 4–65 years ago. Rapid accumulation of C and N in the soil profile was registered within 15 years after reclamation. The rate of increase in C and N contents in the whole profile and the thickness of the litter and fermentation layers was slower in 25-year-old and older reclaimed sites. The soil of the semi-natural alder forest was richer in C and N in the 5–10-cm layer compared with 40-year-old (clays) and even with 65-year-old (gravel–sand) reclaimed soils. N accumulated more slowly in comparison with C, especially in deeper (5–10 cm) parts of the profile. Accumulation of organic C resulted in a decrease in substrate pH from alkaline, which was characteristic of young sites, to slightly acidic on older sites. The pH decreased gradually with increasing site age in all soil layers but increased with depth in the soil profile. In contrast to C and N, P content did not significantly change with site age in any layer of the soil profile. The highest amount of P was found in the fermentation layer, but there was no difference to the other layers. The soil profile of the semi-natural sites was richer in P in comparison to 40-year-old reclaimed ones.