Saline stress is one of the most important abiotic factors limiting the growth and development of plants and associated microorganisms. While the impact of salinity on associations of arbuscular ...fungi is relatively well understood, knowledge of the ectomycorrhizal (EM) fungi of trees growing on saline land is limited. The main objective of this study was to determine the density and diversity of EM fungi associated with three tree species,
Salix alba
,
Salix caprea
and
Betula pendula
, growing in saline soil during two seasons, autumn and spring. The site was located in central Poland, and the increased salinity of the soil was of anthropogenic origin from soda production. The degree of EM colonisation of fine root tips varied between 9 and 34 % and depended on the tree species of interest (
S. caprea
<
S. alba
<
B. pendula
) and season (spring < autumn). Moreover, the ectomycorrhizal colonisation of
B. pendula
was positively correlated with pH and CaCO
3
, while for
S. caprea
and
S. alba,
colonisation was associated with most of the other soil parameters investigated; e.g. salinity, C
org
and N. Analysis of EM fungi revealed four to five different morphotypes per each season:
Tomentella
sp. Sa-A,
Hebeloma collariatum
Sc-A,
Geopora
sp. Sc-A,
Helotiales
sp. Bp-A in the autumn and
Tomentella
sp. Sa-S,
Tomentella
sp. Sc-S and three morphotypes from the families Thelephoraceae and Pyronemataceae in the spring. In conclusion, the density of EM is related to the level of salinity (EC
e
), season and tree species.
Tomentella
spp.,
Hebeloma
sp.,
Geopora
sp. and
Helotiales
sp. are groups of species highly adapted to saline conditions.
Salix caprea is well suited for phytoextraction strategies. In a previous survey we showed that genetically distinct S. caprea plants isolated from metal-polluted and unpolluted sites differed in ...their zinc (Zn) and cadmium (Cd) tolerance and accumulation abilities. To determine the molecular basis of this difference we examined putative homologues of genes involved in heavy metal responses and identified over 200 new candidates with a suppression subtractive hybridization (SSH) screen. Quantitative expression analyses of 20 genes in leaves revealed that some metallothioneins and cell wall modifying genes were induced irrespective of the genotype's origin and metal uptake capacity while a cysteine biosynthesis gene was expressed constitutively higher in the metallicolous genotype. The third and largest group of genes was only induced in the metallicolous genotype. These data demonstrate that naturally adapted woody non-model species can help to discover potential novel molecular mechanisms for metal accumulation and tolerance.
► The transcriptional Zn/Cd response of the willow Salix caprea was quantified. ► Two genotypes from a highly contaminated and a control environment were compared. ► In addition to candidate genes an SSH library revealed over 200 metal induced genes. ► Constitutive upregulation and isolate-specific induction of genes were revealed. ► Willows adapt to environmental Zn/Cd contamination on the transcriptional level.
Expression analyzes reveal different responses to Cd and Zn exposure of S. caprea genotypes with different heavy metal accumulation abilities.
In a long-term (2.4 years) laboratory experiment, we studied carbon (C) loss from microcosms in which intact litter was placed on the soil surface with or without earthworms (Lumbricus rubellus) or ...was fragmented and mechanically mixed into the soil to simulate the tillage. Two soil and leaf litter combinations common in post-mining sites near Sokolov (Czech Republic) were used: clay with alder (Alnus glutinosa) and sand with willow (Salix caprea).
During the first 20 weeks, respiration was highest with surface litter with earthworms, lowest with mechanical mixing, and intermediate with surface litter minus earthworms. From week 20–80, respiration did not differ among the treatments. From week 80–126, respiration was highest when fragmented litter was mechanically mixed into soil. These results applied to both combinations of soil and litter types. At week 126, C stock was highest with surface-applied litter minus earthworms but most of the litter remained on the soil surface. In the mineral soil, the active C pool was significantly lower with surface-applied litter minus earthworms than in the other treatments. Based on microbial biomass and ergosterol content, microcosms with surface-applied litter minus earthworms were dominated by fungi while those with earthworms or litter that was mechanically mixed into soil were dominated by bacteria. Overall, the results indicate that C sequestration in soil is greater when litter is mixed into the soil by earthworms than by mechanical mixing.
•Respiration of microcosms with liter repeatedly added was measured for 2.4 years.•Litter was added on soil surface, mixed or incorporated by earthworms.•Mixing has the lowest respiration at the beginning and the highest at the end.•Earthworm had higher respiration than mixing at the beginning and lower at the end.
Different response between woody core and bark of goat willow biomass to concentrated phosphoric acid pretreatment prior to enzymatic saccharification was investigated as changes of chemical ...compositions, carbohydrate compositions, and crystallinity of cellulose before and after pretreatment. Goat willow has different chemical composition between bark and woody core, higher polysaccharides content in woody core as 74.6% compared with 61.0% in bark. In bark, hydrophobic and hydrophilic extractives contents was 20.4% compared with 8.1% in woody core.
Parts of extractives and carbohydrates were removed by concentrated phosphoric acid pretreatment, and this trend was more obvious in bark than woody core. In bark, 60% of xylan and 30% of cellulose was removed by acid pretreatment but only 40% of xylan and 8.3% of cellulose in woody core. Removal of polysaccharides in cell wall and destruction of crystal structure (cellulose crystallinity reduction) in cellulose caused the more enzymatic saccharification by commercial cellulases cocktails. Bark showed three times higher cellulose to glucose conversion by cellulases but woody core was two times higher than those of untreated.
•Phosphoric acid pretreatment decreased the crystallinity of cellulose and removed xylan.•More xylan removal and decrystallization of cellulose occurred in bark than woody part.•Bark was more hydrolyzed than woody part by commercial cellulases.•Bark in Goat willow was good raw material for bio-alcohol production.
Salix matsudana Koidz. is a deciduous, rapidly growing, and drought resistant tree and is one of the most widely distributed and commonly cultivated willow species in China. Currently little ...transcriptomic and small RNAomic data are available to reveal the genes involve in the stress resistant in S. matsudana. Here, we report the RNA-seq analysis results of both transcriptome and small RNAome data using Illumina deep sequencing of shoot tips from two willow variants(Salix. matsudana and Salix matsudana Koidz. cultivar 'Tortuosa'). De novo gene assembly was used to generate the consensus transcriptome and small RNAome, which contained 106,403 unique transcripts with an average length of 944 bp and a total length of 100.45 MB, and 166 known miRNAs representing 35 miRNA families. Comparison of transcriptomes and small RNAomes combined with quantitative real-time PCR from the two Salix libraries revealed a total of 292 different expressed genes(DEGs) and 36 different expressed miRNAs (DEMs). Among the DEGs and DEMs, 196 genes and 24 miRNAs were up regulated, 96 genes and 12 miRNA were down regulated in S. matsudana. Functional analysis of DEGs and miRNA targets showed that many genes were involved in stress resistance in S. matsudana. Our global gene expression profiling presents a comprehensive view of the transcriptome and small RNAome which provide valuable information and sequence resources for uncovering the stress response genes in S. matsudana. Moreover the transcriptome and small RNAome data provide a basis for future study of genetic resistance in Salix.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
To explore the question how litter and macrofauna feces respond to temperature and how respiration differs for litter with a different CN ratio, we compared the decomposition rates of leaf litter ...(Alnus glutinosa, Salix caprea, and Acer campestre) and isopod (Armadillidium vulgare) feces produced from the same litter in response to three constant (8, 16, and 24 °C) and one fluctuating (first week 8 °C, the other week 24 °C) temperatures in a 50 week laboratory experiment and in a field trial. Microbial respiration of litter with lower CN ratio (alder and willow) was significantly higher than respiration of feces, no significant difference was found for maple litter with higher CN ratio. This was supported by field litter bag experiments where alder and willow litter decomposed faster than feces but the opposite was true for maple litter. Litter respiration was significantly affected by temperature but feces respiration was not. Fluctuating temperature caused either lower or equal respiration as compared to mean constant temperature. The content of phenolics was significantly higher in intact litter in comparison with decomposed litter and feces, either fresh or decomposed. The CN ratio decreased as litter turned to feces in maple and alder litter but increased in willow litter. In conclusion, microbial respiration of both litter and feces were substantially affected by litter quality; the litter was more sensitive to temperature than feces.
Nitrogen-fixing trees are often used in disturbed areas to promote soil development and to prepare the ground for more demanding tree species. However, their effect on the establishment of climax ...tree species has seldom been tested. We mapped the occurrence of volunteer seedlings of European beech (Fagus sylvatica) and English oak (Quercus robur) in patches reclaimed by planting alder (Alnus glutinosa and Alnus incana) and in unreclaimed forest patches (dominated by Salix caprea, Betula pendula and Populus tremula). Both communities were about 30 years old and occurred on one large spoil heap from coal mining near the town of Sokolov (Czech Republic). At the same time, we mapped mature beech and oak trees in the surrounding area. We planted oak and beеch seedling in an alder plantation, an unreclaimed forest stand and a grass-covered area without trees, and recorded their growth for two consecutive years. The closest mature beech grew 1km from the heap whereas seed-producing oaks occurred in its close vicinity and on the heap itself in a 30 to 40-year-old oak plantation. In both species, seedling density decreased with increasing distance from mature trees. Unreclaimed sites supported significantly higher seedling densities than reclaimed ones. Seedlings in the unreclaimed forest stand grew significantly better than in the other two habitats. Oak seedlings exhibited significantly higher mycorrhizal colonization in unreclaimed forest stands than in the other habitats. Unreclaimed forest stands are better habitat for the establishment of climax trees, than the reclaimed alder plantation. Using of spontaneous woody vegetation as nursing cover for climax trees can be recommended in restoration practice. Risk and benefits of nitrogen-fixing trees should be carefully considered.
Forest vegetation is known to increase hillslope stability by reinforcing soil shear resistance and by influencing hydrologie conditions of soil. Although the importance of plant root systems for ...hillslope stability has received considerable attention in recent years, the quantification of such an effect needs more investigation. In this paper, we present a synthesis of the data gathered in the last 5 years for some species in different locations of the Alps and Prealps of Lombardy (Northern Italy) with the aim to increase our knowledge on root tensile strength and on Root Area Ratio distribution within the soil. Concerning root tensile strength we developed tensile strength–diameter relationships for eight species: green alder (Alnus viridis (Chaix) D.C.), beech (Fagus sylvatica L.), red willow (Salix purpurea L.), goat willow (Salix caprea L.), hazel (Corylus avellana L.), European ash (Fraxinus excelsior L.), Norway spruce (Picea abies (L.) Karst.) and European larch (Larix decidua Mill.). Results show a great variability among the different species and also for the same species. In general, however, root strength (in terms of tension) tends to decrease with diameter according to a power law, as observed by other Authors. Comparing the power law fitting curves for the considered species, it can be observed that they fall in a relatively narrow band, with the exception of hazel, which appears the most resistant. Concerning the evaluation of root distribution within the soil we estimated the Root Area Ratio (the ratio between the area occupied by roots in a unit area of soil) according to its depth for five species (beech, Norway spruce, European larch, mixed hazel and ash) in three locations of Lombardy. Results show that there is a great variability of root density for the same species well as for different points at the same locality. The general behaviour of root density, in any case, is to decrease with depth according to a gamma function for all the studied species. The results presented in this paper contribute to expanding the knowledge on root resistance behaviour and on root density distribution within the soil. The studied location have allowed the implementation of soil–root reinforcement models and the evaluation of the vegetation contribution to soil stability.
Changes in the activity of extracellular enzymes (cellobiohydrolase, β-glucosidase, β-xylosidase, chitinase, arylsulfatase and phosphatases) and the changes in microbial community and abiotic ...properties in the topsoil layer, as well as soil abiotic properties during primary succession were investigated in a brown coal mine deposit area near Sokolov, Czech Republic. The study considered the chronosequence of 4 post-mining plots, 4-, 12-, 21- and 45-year old. The 4-year old site had no vegetation cover. Herbs and grasses (mainly
Calamagrostis epigeios) were present on the 12-year old plot, shrubs (
Salix caprea) occurred on the 21-year old plot and tree cover (
Betula spp. and
Populus tremuloides) developed on the 45-year old plot. Soil pH gradually decreased with site age, while the content of P, K, C and N peaked in the 21-year old site, being significantly lower in the 45-year old site and much lower in the 4- and 12-year old sites. Phosphatase activities were strongly affected by seasonality while the activities of all the other enzymes measured were more influenced by the effects of succession age and soil layer than by seasonality. Succession age was also the most important factor affecting the total and bacterial PLFA contents, followed by the effects of soil layer and season while for the fungal biomass content-related properties (ergosterol, fungal PLFA and the fungal/bacterial PLFA ratio), season was the most important. Activities of individual enzymes in the topsoil (0–5
cm depth) were significantly affected by both site age and season. Cellobiohydrolase and β-xylosidase were more affected by site age while chitinase and phosphatases were more affected by season. Enzyme activity increased with succession age. Comparison of the effect of site and season on enzyme activity showed that season played a principal role in the enzyme activity of the entire 0–5
cm component of topsoil, as well the soil layers when evaluated separately.
Human activities such as metals mining and milling operations provide one of the most important sources of contamination in the environment. Abandoned mines can be an important source of toxic ...elements. The threat of heavy metal pollution posed by mine soils generally concerns more than one metal.
The aim of this study was to assess total concentration of six potentially toxic metals (Cd, Cr, Cu, Pb, Zn and Fe) in the soil and plant samples of three dominant willow species (Salix purpurea L., Salix caprea L. and Salix eleagnos Scop.) collected from abandoned mixed sulphide mine dumps (Imperina Valley, North-east Italy).
Results demonstrate that metal concentrations in soils are in general above the Italian average limits and they are also significantly (except Cr), as compared with controls (p≤0.05), with averages of 2.12mgCdkg−1, 2267mgCukg−1, 9552mgPbkg−1, 1243mgZnkg−1 and 299,973mgFekg−1.
The phytoremediation ability of selected Salix species for heavy metals was estimated. The results have revealed significant differences among willow species (p≤0.05) regardless of the species selected. The transfer factor and bioaccumulation coefficient of selected metals varied among plant species and from different sites. Some of the investigated species have potential for soil stabilization and extraction of heavy metals. The results indicate that there is an increasing need for further research projects mainly focused on the mechanisms whereby such willows are able to survive in contaminated soils.
► Heavy metal content (Cd, Cu, Pb, Zn & Fe) of soils from an abandoned Italian mining site. ► Flux of potentially toxic elements from soil to wild plants. ► Test the ability of selected Salix spp to accumulate heavy metals in their tissues. ► Willow qualifies as good candidate for phytoremediation of polluted soils.
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