Polycyclic aromatic hydrocarbon (PAH) phytoaccumulation in urban areas by Platanus × acerifolia, Celtis australis, and Tilia grandifolia leaves and branches.

Polycyclic aromatic hydrocarbon (PAH) concentrations in the leaves and 1-year-old branches of three common tree species growing in a middle-sized city located in a moderate climate zone were estimated. For this purpose, PAH phytoaccumulation in Platanus × acerifolia, Celtis australis, and Tilia grandifolia species from highly urbanized, traffic congested, and highly PAH-contaminated streets was compared with trees from non-contaminated parks in the same urban core. The gathered data was used to define 17 PAH profiles, identify the main PAH pollution emission sources, and determine the organ and species specificity of PAHs accumulation. Due to the direct absorption of polluted air via stomata, the leaves accumulated up to 30% more PAHs compared to the 1-year-old branches. As expected, PAH concentrations were much higher in street trees, while heavy weight PAHs (with five and six rings) were accumulated in the highest concentrations. The highest foliar Σ17 PAH concentrations were detected in street-grown C. australis, followed by P. acerifolia and T. grandifolia (502.68, 488.45, and 339.47 ng g-1 dry weight (DW), respectively). The same pattern was noted for Σ17 PAHs in branches (414.89, 327.58, and 342.99 ng g-1 DW, respectively). Thus, T. grandifolia emerged as the least effective PAH sink as it accumulated up to ~ 40% less PAHs than P. acerifolia and C. australis leaves/branches. Among the 17 tracked PAHs, benzo[a]anthracene, benzo[a]pyrene, dibenzo[a,h]anthracene, and pyrene were found to have accumulated in the highest concentrations in all analyzed species irrespective of the site, and accounted for more than 50% of the total detected PAHs. Finally, a "black box" about species and organ specificity, as well as specific drivers that limit PAHs uptake capacity by trees, was opened, while this work provides insights into further PAH phytoremediation strategies.

Gall-inducing Eriophyes tiliae stimulates the metabolism of Tilia platyphyllos leaves towards oxidative protection.

Red galls have high levels of anthocyanins which perform different physiological functions, such as antioxidants and protection against UVB radiation. High levels of anthocyanins and other polyphenols have been associated with low photosynthetic pigment content. In environments with high levels of UVB radiation, it would thus be expected that red galls would have high anthocyanin and polyphenol levels and low photosynthetic pigment contents, enabling the gall with high antioxidant capacity compared to its host organ. The red galls induced by Eriophyes tiliae, and their host environment of Tilia platyphyllos leaves in the Mediterranean climate of Chile, were investigated in relation to their anatomy, histochemistry, pigment, sugar, protein, and polyphenol contents, and antioxidant capacity. The anthocyanin, sugars, and polyphenol contents and the antioxidant capacity were increased in galls. Photosynthetic pigment and protein contents were higher in non-galled leaves. The high levels of anthocyanin and total polyphenols increase the galls' antioxidant capacity in the high UV radiation environment of a Mediterranean climate. The establishment of E. tiliae induced redifferentiation of nutritive tissue, rich in sugars, proteins, and lipids, and an inner epidermis with trichomes and long emergences. E. tiliae galls' structural and metabolic features are probably enhanced towards mite nutrition and protection. The current results shed light on the role of anthocyanin in the antioxidant protection of plant galls in environments with high UV irradiance.

The protective effect of Tilia amurensis honey on influenza A virus infection through stimulation of interferon-mediated IFITM3 signaling.

Recently, attention has focused on the prevention and treatment of respiratory viruses including influenza viruses. We evaluated the antiviral effect of Tilia amurensis honey (TH) against influenza A virus in murine macrophages. Influenza A virus infection was reduced following pretreatment with TH. Pretreatment of murine macrophages with TH increased the production and secretion of type-1 interferon (IFN) and proinflammatory cytokines and increased phosphorylation of the type-1 IFN-related proteins, TANK-binding kinase (TBK), and STAT. Moreover, TH increased the expression of IFN-stimulating genes and increased the expression of IFN-inducible transmembrane (IFITM3), a protein that interferes with virus replication and entry. Taken together, these findings suggest that TH suppresses influenza A virus infection by regulating the innate immune response in macrophages. This supports the development of preventive and therapeutic agents for influenza A virus and enhances the economic value of TH.

Nutlets of Tilia cordata Mill. and Tilia platyphyllos Scop. - Source of bioactive compounds.

The aim of this study was to analyse contents of phytosterols, carotenoids, tocochromanols and fatty acid composition in oil from nutlets of linden. Standard determination methods for these compounds were applied using liquid and gas chromatography. In the analysed oils from small and large-leaved lime the dominant acids included linoleic (53.1 and 54.1%), oleic (18.5 and 22.2%), palmitic (15.3 and 11.8%). Linden seed oil was characterised by very high contents of phytosterols (2-2.5 g/100 g). ß-Sitosterol was the dominant phytosterol (80-83%). Additionally squalene was detected at 806 and 607 mg/100 g, respectively, for Tilia cordata and T.platyphyllos. It was found that linden seed oil contains tocopherols (93%) and tocotrienols (7%). In terms of tocochromanol contents this oil is surpassed only by wheat germ oil. In terms of the α-T equivalent these oils contain 95 (Tilia cordata) and 50.6 mg/100 g vitamin E (Tilia platyphyllos).

Branch-Localized Induction Promotes Efficacy of Volatile Defences and Herbivore Predation in Trees.

Induction of plant defences can show various levels of localization, which can optimize their efficiency. Locally induced responses may be particularly important in large plants, such as trees, that show high variability in traits and herbivory rates across their canopies. We studied the branch-localized induction of polyphenols, volatiles (VOCs), and changes in leaf protein content in Carpinus betulus L., Quercus robur L., and Tilia cordata L. in a common garden experiment. To induce the trees, we treated ten individuals per species on one branch with methyl jasmonate. Five other individuals per species served as controls. We measured the traits in the treated branches, in control branches on treated trees, and in control trees. Additionally, we ran predation assays and caterpillar food-choice trials to assess the effects of our treatment on other trophic levels. Induced VOCs included mainly mono- and sesquiterpenes. Their production was strongly localized to the treated branches in all three tree species studied. Treated trees showed more predation events than control trees. The polyphenol levels and total protein content showed a limited response to the treatment. Yet, winter moth caterpillars preferred leaves from control branches over leaves from treated branches within C. betulus individuals and leaves from control Q. robur individuals over leaves from treated Q. robur individuals. Our results suggest that there is a significant level of localization in induction of VOCs and probably also in unknown traits with direct effects on herbivores. Such localization allows trees to upregulate defences wherever and whenever they are needed.

Comparative metabolomics of Tilia platyphyllos Scop. bracts during phenological development.

The medicinal plant drug "Tiliae flos" consists of the botanical flowers and bracts of Tilia sp., gathered almost exclusively during flowering. In this study, we examined the changes in the metabolome of specialized products in the bracts of Tilia platyphyllos from the appearance of the organ till the onset of senescence by LC-ESI-MS and data mining. A set of 504 natural products were detected, 241 of which showed significant seasonal variation (p < 9.92E-5). Seven compounds were quantified and an additional 45 were putatively identified. These included flavonoid glycosides, catechins, procyanidins, quinic acid derivatives (including chlorogenic acid) and coumarins. Compared to bracts during flowering, young tissues were characterized by a relatively high diversity of polyphenolic substances. Higher amounts of flavonol glycosides (quercetin, kaempferol), catechins and derivatives have been observed. Deoxyhexosides were almost exclusive to this phenological stage. Changes of about one order of magnitude were not uncommon. For some substances, 5-fold differences were observed (calibration with authentic standards). Some compounds (e.g. the coumarin fraxin) were more prominent at the late fruit growth stage. It was shown that bracts gathered before or after flowering could potentially be therapeutically useful. Changes are rapid during the early phase of bract development: three different groups of compounds presented their maxima during the first 32 days. Considering seasonal variation is of extreme importance during bioactivity tests and screening candidate sources for bioactive natural products. In the case of T. platyphyllos, young and old bracts can be of interest because of their high diversity of distinct specialized metabolites.

Linden (Tilia cordata) associated bumble bee mortality: Metabolomic analysis of nectar and bee muscle.

Linden (Tilia spp.), a profusely flowering temperate tree that provides bees with vital pollen and nectar, has been associated with bumble bee (Bombus spp.) mortality in Europe and North America. Bee deaths have been attributed, with inadequate evidence, to toxicity from mannose in nectar or starvation due to low nectar in late blooming linden. Here, we investigated both factors via untargeted metabolomic analyses of nectar from five T. cordata trees beneath which crawling/dead bumble bees (B. vosnesenskii) were observed, and of thoracic muscle of 28 healthy foraging and 29 crawling bees collected from linden trees on cool mornings (< 30°C). Nectar contained the pyridine alkaloid trigonelline, a weak acetylcholinesterase inhibitor, but no mannose. Principal component analysis of muscle metabolites produced distinct clustering of healthy and crawling bees, with significant differences (P<0.05) in 34 of 123 identified metabolites. Of these, TCA (Krebs) cycle intermediates were strongly represented (pathway analysis; P<0.01), suggesting that the central metabolism is affected in crawling bees. Hence, we propose the following explanation: when ambient temperature is low, bees with energy deficit are unable to maintain the thoracic temperature required for flight, and consequently fall, crawl, and ultimately, die. Energy deficit could occur when bees continue to forage on linden despite limited nectar availability either due to loyalty to a previously energy-rich source or trigonelline-triggered memory/learning impairment, documented earlier with other alkaloids. Thus, the combination of low temperature and nectar volume, resource fidelity, and alkaloids in nectar could explain the unique phenomenon of bumble bee mortality associated with linden.

Compound-specific δ15N values express differences in amino acid metabolism in plants of varying lignin content.

Amino acid δ15N values of foliage of various plant taxa, grown at the experimental farm stations of North Wyke, UK and Bad Lauchstädt, Germany were determined by GC-C-IRMS. The difference between δ15N values of glutamate (Glx) and phenylalanine (Phe) were found to differ significantly between woody and herbaceous plants, with mean Δ15NGlx-Phe (i.e. δ15NPhe - δ15NGlx) values of -9.3 ±â€¯1.6‰ and -5.8 ±â€¯2.1‰, respectively. These differences in values are hypothesised to be due to the involvement of Phe in the phenylpropanoid pathway, by which lignin and other phenolic secondary metabolites are produced, leading to isotopic fractionation and enrichment of the remaining Phe pool available for protein biosynthesis. This results in the more negative Δ15NGlx-Phe values observed in woody plants relative to herbaceous plants, as the former are assumed to produce more lignin. To test this assumption, plant leaf tissue lignin concentrations were estimated by solid state 13C cross-polarisation, magic-angle-spinning (CPMAS) NMR spectroscopy for a subset of plants, which showed that tree foliage has a higher concentration of lignin (12.6 wt%) than herbaceous foliage (6.3 wt%). The correlation of lignin concentration with Δ15NGlx-Phe values demonstrates that the difference in these values with plant type is indeed due to differential production of lignin. The ability to estimate the lignin content of plants from amino acid δ15N values will, to give one example, allow refinement of estimates of herbivore diet in present and past ecosystems, enabling more accurate environmental niche modelling.

Antioxidative and antifungal response of woody species to environmental conditions in the urban area.

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

The fate of recently fixed carbon after drought release: towards unravelling C storage regulation in Tilia platyphyllos and Pinus sylvestris.

Carbon reserves are important for maintaining tree function during and after stress. Increasing tree mortality driven by drought globally has renewed the interest in how plants regulate allocation of recently fixed C to reserve formation. Three-year-old seedlings of two species (Tilia platyphyllos and Pinus sylvestris) were exposed to two intensities of experimental drought during ~10 weeks, and 13 C pulse labelling was subsequently applied with rewetting. Tracking the 13 C label across different organs and C compounds (soluble sugars, starch, myo-inositol, lipids and cellulose), together with the monitoring of gas exchange and C mass balances over time, allowed for the identification of variations in C allocation priorities and tree C balances that are associated with drought effects and subsequent drought release. The results demonstrate that soluble sugars accumulated in P. sylvestris under drought conditions independently of growth trends; thus, non-structural carbohydrates (NSC) formation cannot be simply considered a passive overflow process in this species. Once drought ceased, C allocation to storage was still prioritized at the expense of growth, which suggested the presence of 'drought memory effects', possibly to ensure future growth and survival. On the contrary, NSC and growth dynamics in T. platyphyllos were consistent with a passive (overflow) view of NSC formation.

Quantitative and qualitative characteristics of cell wall components and prenyl lipids in the leaves of Tilia x euchlora trees growing under salt stress.

The study was focused on assessing the presence of arabinogalactan proteins (AGPs) and pectins within the cell walls as well as prenyl lipids, sodium and chlorine content in leaves of Tilia x euchlora trees. The leaves that were analyzed were collected from trees with and without signs of damage that were all growing in the same salt stress conditions. The reason for undertaking these investigations was the observations over many years that indicated that there are trees that present a healthy appearance and trees that have visible symptoms of decay in the same habitat. Leaf samples were collected from trees growing in the median strip between roadways that have been intensively salted during the winter season for many years. The sodium content was determined using atomic spectrophotometry, chloride using potentiometric titration and poly-isoprenoids using HPLC/UV. AGPs and pectins were determined using immunohistochemistry methods. The immunohistochemical analysis showed that rhamnogalacturonans I (RG-I) and homogalacturonans were differentially distributed in leaves from healthy trees in contrast to leaves from injured trees. In the case of AGPs, the most visible difference was the presence of the JIM16 epitope. Chemical analyses of sodium and chloride showed that in the leaves from injured trees, the level of these ions was higher than in the leaves from healthy trees. Based on chromatographic analysis, four poly-isoprenoid alcohols were identified in the leaves of T. x euchlora. The levels of these lipids were higher in the leaves from healthy trees. The results suggest that the differences that were detected in the apoplast and symplasm may be part of the defensive strategy of T. x euchlora trees to salt stress, which rely on changes in the chemical composition of the cell wall with respect to the pectic and AGP epitopes and an increased synthesis of prenyl lipids.

The acclimation of Tilia cordata stomatal opening in response to light, and stomatal anatomy to vegetational shade and its components.

Stomatal anatomical traits and rapid responses to several components of visible light were measured in Tilia cordata Mill. seedlings grown in an open, fully sunlit field (C-set), or under different kinds of shade. The main questions were: (i) stomatal responses to which visible light spectrum regions are modified by growth-environment shade and (ii) which separate component of vegetational shade is most effective in eliciting the acclimation effects of the full vegetational shade. We found that stomatal opening in response to red or green light did not differ between the plants grown in the different environments. Stomatal response to blue light was increased (in comparison with that of C-set) in the leaves grown in full vegetational shade (IABW-set), in attenuated UVAB irradiance (AB-set) or in decreased light intensity (neutral shade) plus attenuated UVAB irradiance (IAB-set). In all sets, the addition of green light-two or four times stronger-into induction light barely changed the rate of the blue-light-stimulated stomatal opening. In the AB-set, stomatal response to blue light equalled the strong IABW-set response. In attenuated UVB-grown leaves, stomatal response fell midway between IABW- and C-set results. Blue light response by neutral shade-grown leaves did not differ from that of the C-set, and the response by the IAB-set did not differ from that of the AB-set. Stomatal size was not modified by growth environments. Stomatal density and index were remarkably decreased only in the IABW- and IAB-sets. It was concluded that differences in white light responses between T. cordata leaves grown in different light environments are caused only by their different blue light response. Differences in stomatal sensitivity are not dependent on altered stomatal anatomy. Attenuated UVAB irradiance is the most efficient component of vegetational shade in stimulating acclimation of stomata, whereas decreased light intensity plays a minor role.

The Level of Particulate Matter on Foliage Depends on the Distance from the Source of Emission.

One of the most dangerous inhaled pollutants is particulate matter (PM). PM in inhaled air have a negative impact on human wellbeing and health, and may even cause deaths. Where pollutants have been emitted into the outdoor atmosphere, the only possible method for cleaning the air is through phytoremediation, a form of environmental biotechnology, where plants act as biological filters for pollutants. This study compared PM levels on the leaves of Tilia cordata Mill. trees growing in locations at increasing distances from the source of the PM emission. Significant differences between individual trees growing at a distance of between 3 m and 500 m from the road edge were found in: (i) the mass of PM that accumulated on leaves (total, surface, in-wax and the three determined size fractions) and (ii) the amount of waxes deposited on leaves.

Anticonvulsant and antioxidant effects of Tilia americana var. mexicana and flavonoids constituents in the pentylenetetrazole-induced seizures.

Tilia genus is commonly used around the world for its central nervous system properties; it is prepared as tea and used as tranquilizing, anticonvulsant, and analgesic. In this study, anticonvulsant activity of the Tilia americana var. mexicana inflorescences and leaves was investigated by evaluating organic and aqueous extracts (100, 300, and 600 mg/kg, i.p.) and some flavonoids in the pentylenetetrazole-induced seizures in mice. Moreover, antioxidant effect of these extracts and flavonoids was examined in an in vitro study by using spectrophotometric technique. Significant activity was observed in the methanol extract from inflorescences. An HPLC analysis of the methanol extract from inflorescences and leaves of Tilia allowed demonstrating the respective presence of some partial responsible flavonoid constituents: quercetin (20.09 ± 1.20 µg/mg and 3.39 ± 0.10 µg/mg), rutin (3.52 ± 0.21 µg/mg and 8.94 ± 0.45 µg/mg), and isoquercitrin (1.74 ± 0.01 µg/mg and 1.24 ± 0.13 µg/mg). In addition, significant but different antioxidant properties were obtained among the flavonoids and the extracts investigated. Our results provide evidence of the anticonvulsant activity of Tilia reinforcing its utility for central nervous system diseases whose mechanism of action might involve partial antioxidant effects due to the presence of flavonoids.

Daily and seasonal dynamics of remotely sensed photosynthetic efficiency in tree canopies.

The photosynthesis of various species or even a single plant varies dramatically in time and space, creating great spatial heterogeneity within a plant canopy. Continuous and spatially explicit monitoring is, therefore, required to assess the dynamic response of plant photosynthesis to the changing environment. This is a very challenging task when using the existing portable field instrumentation. This paper reports on the application of a technique, laser-induced fluorescence transient (LIFT), developed for ground remote measurement of photosynthetic efficiency at a distance of up to 50 m. The LIFT technique was used to monitor the seasonal dynamics of selected leaf groups within inaccessible canopies of deciduous and evergreen tree species. Electron transport rates computed from LIFT measurements varied over the growth period between the different species studied. The LIFT canopy data and light-use efficiency measured under field conditions correlated reasonably well with the single-leaf pulse amplitude-modulated measurements of broadleaf species, but differed significantly in the case of conifer tree species. The LIFT method has proven to be applicable for a remote sensing assessment of photosynthetic parameters on a diurnal and seasonal scale; further investigation is, however, needed to evaluate the influence of complex heterogeneous canopy structures on LIFT-measured chlorophyll fluorescence parameters.

Electron transport efficiency at opposite leaf sides: effect of vertical distribution of leaf angle, structure, chlorophyll content and species in a forest canopy.

We investigated changes in chlorophyll a fluorescence from alternate leaf surfaces to assess the intraleaf light acclimation patterns in combination with natural variations in radiation, leaf angles, leaf mass per area (LMA), chlorophyll content (Chl) and leaf optical parameters. Measurements were conducted on bottom- and top-layer leaves of Tilia cordata Mill. (a shade-tolerant sub-canopy species, sampled at heights of 11 and 16 m) and Populus tremula L. (a light-demanding upper canopy species, sampled at canopy heights of 19 and 26 m). The upper canopy species P. tremula had a six times higher PSII quantum yield (Φ(II)) and ratio of open reaction centres (qP), and a two times higher LMA than T. cordata. These species-specific differences were also present when the leaves of both species were in similar light conditions. Leaf adaxial/abaxial fluorescence ratio was significantly larger in the case of more horizontal leaves. Populus tremula (more vertical leaves), had smaller differences in fluorescence parameters between alternate leaf sides compared with T. cordata (more horizontal leaves). However, optical properties on alternate leaf sides showed a larger difference for P. tremula. Intraspecifically, the measured optical parameters were better correlated with LMA than with leaf Chl. Species-specific differences in leaf anatomy appear to enhance the photosynthetic potential of leaf biochemistry by decreasing the interception of excess light in P. tremula and increasing the light absorptance in T. cordata. Our results indicate that intraleaf light absorption gradient, described here as leaf adaxial/abaxial side ratio of chlorophyll a fluorescence, varies significantly with changes in leaf light environment in a multi-layer multi-species tree canopy. However, this variation cannot be described merely as a simple function of radiation, leaf angle, Chl or LMA, and species-specific differences in light acclimation strategies should also be considered.

Chlorophyll catabolites in senescent leaves of the lime tree (Tilia cordata).

In cold extracts of senescent leaves of the Lime tree (Tilia cordata), two colorless nonfluorescent chlorophyll catabolites (NCCs) were identified, named Tc-NCC-1 and Tc-NCC-2, as well as a polar yellow chlorophyll catabolite (YCC), named Tc-YCC. The constitution of the two NCCs was determined by spectroscopic means. In addition, a tentative structure was derived for Tc-YCC. The three chlorophyll degradation products exhibited tetrapyrrolic structures, as are typical of NCCs or YCCs, and turned out to be rather polar, due to a glucopyranosyl group at their 8(2)-position. At their 3-positions, the more polar Tc-NCC-1 carried a 1,2-dihydroxyethyl group and the less polar Tc-NCC-2 a vinyl group. Tc-YCC was identified as the product of an oxidation of Tc-NCC-1.

Photosynthetic acclimation to light in woody and herbaceous species: a comparison of leaf structure, pigment content and chlorophyll fluorescence characteristics measured in the field.

Acclimation of foliage photosynthetic properties occurs with varying time kinetics, but structural, chemical and physiological factors controlling the kinetics of acclimation are poorly understood, especially in field environments. We measured chlorophyll fluorescence characteristics, leaf total carotenoid (Car), chlorophyll (Chl) and nitrogen (N) content and leaf dry mass per area (LMA) along vertical light gradients in natural canopies of the herb species, Inula salicina and Centaurea jacea, and tree species, Populus tremula and Tilia cordata, in the middle of the growing season. Presence of stress was assessed on the basis of night measurements of chlorophyll fluorescence. Our aim was to compare the light acclimation of leaf traits, which respond to light availability at long (LMA and N), medium (Chl a/b ratio, Car/Chl ratio) and short time scales (fluorescence characteristics). We found that light acclimation of nitrogen content per unit leaf area (N(area)), chlorophyll content per unit dry mass (Chl(mass)) and Chl/N ratio were related to modifications in LMA. The maximum PSII quantum yield (F(v) /F(m)) increased with increasing growth irradiance in I. salicina and P. tremula but decreased in T. cordata. Leaf growth irradiance, N content and plant species explained the majority of variability in chlorophyll fluorescence characteristics, up to 90% for steady-state fluorescence yield, while the contribution of leaf total carotenoid content was generally not significant. Chlorophyll fluorescence characteristics did not differ strongly between growth forms, but differed among species within a given growth form. These data highlight that foliage acclimation to light is driven by interactions between traits with varying time kinetics.

Effect of controlled inoculation with specific mycorrhizal fungi from the urban environment on growth and physiology of containerized shade tree species growing under different water regimes.

The aim of this work was to evaluate the effects of selected mycorrhiza obtained in the urban environment on growth, leaf gas exchange, and drought tolerance of containerized plants growing in the nursery. Two-year-old uniform Acer campestre L., Tilia cordata Mill., and Quercus robur L. were inoculated with a mixture of infected roots and mycelium of selected arbuscular (maple, linden) and/or ectomycorrhiza (linden, oak) fungi and grown in well-watered or water shortage conditions. Plant biomass and leaf area were measured 1 and 2 years after inoculation. Leaf gas exchange, chlorophyll fluorescence, and water relations were measured during the first and second growing seasons after inoculation. Our data suggest that the mycelium-based inoculum used in this experiment was able to colonize the roots of the tree species growing in the nursery. Plant biomass was affected by water shortage, but not by inoculation. Leaf area was affected by water regime and, in oak and linden, by inoculation. Leaf gas exchange was affected by inoculation and water stress. V(cmax) and J(max) were increased by inoculation and decreased by water shortage in all species. F(v)/F(m) was also generally higher in inoculated plants than in control. Changes in PSII photochemistry and photosynthesis may be related to the capacity of inoculated plants to maintain less negative leaf water potential under drought conditions. The overall data suggest that inoculated plants were better able to maintain physiological activity during water stress in comparison to non-inoculated plants.

Thermal behavior of biodegraded lime wood.

The effects of the soft-rot fungus Trichoderma viride Pers., on the thermal behavior of lime wood (Tillia cordata Mill.) were investigated. The lime wood pieces were inoculated with the fungus over a 12-week period. At pre-established time intervals two samples were withdrawn from the medium and analyzed by thermogravimetry and differential calorimetry, and the results were correlated with mass loss. Fungal activity was indicated by continuous decrease of sample mass. Modification of the wood because of the presence of the fungus was evidenced by structural changes that affected its thermal properties, both in respect to the hydrophilicity of the wood (evidenced mainly in desorption process) and in its decomposition behavior. The shape of DTG curves depends on the exposure time of wood to the action of microorganisms. The peak temperature assigned to the decomposition of wood components increases, while the global kinetic parameters for the main peak decrease with increasing exposure time of the wood to the attack by microorganisms. The increased characteristic temperatures of water desorption and cellulose decomposition processes and lower thermal stability could be explained by newly formed structures, mainly the oxidized ones.