Tree Tissues Research Articles

Biomonitoring and phytoremediation potential of the leaves, bark, and branch bark of street trees for heavy metal pollution in urban areas.

Tree tissues can accumulate heavy metals from the environment. We therefore aimed to evaluate the presence of the metals Pb, Cr, Mn, Cu, and Zn in four street tree species, namely Ailanthus altissima, Broussonetia papyrifera, Pinus tabuliformis, and Rhus typhina, along the highway side of Beijing, China. Sampling from the leaves, trunk bark, and branch annual segment bark of trees was conducted in the summer of 2021, and the concentration of heavy metals was determined. The results revealed the highest average concentration of total heavy metals in the R. typhina leaves (23.724 mg/kg) and barks (14.454 mg/kg). The maximum bio-concentration factor was noted for Zn in the B. papyrifera leaves (0.36) and P. tabuliformis barks (0.21). The maximum comprehensive bio-concentration index was observed for the B. papyrifera leaves (0.225) and P. tabuliformis bark (0.108). The maximum metal accumulation index was measured in the R. typhina leaves (29.682) and bark (12.407). Based on the air-originated metals, P. tabuliformis showed the highest dust collection capacity. In general, B. papyrifera and P. tabuliformis exhibited the highest absorption rate from the soil relative to the other studied species. R. typhina demonstrated the strongest phytoremediation ability for heavy metal pollution in air. In addition, our results proved that the branch annual segment bark of P. tabuliformis is an excellent record carrier that can be used to monitor heavy metal pollution in a specific time duration in an urban area.

Fungal Communities of Eucalyptus grandis Leaves Are Influenced by the Insect Pest Leptocybe invasa.

Fungal communities in above-ground tree tissues are hyperdiverse and are influenced by biotic interactions with other organisms living in or on these tissues. These biotic interactions are, however, still poorly understood. In this study, we aimed to understand how insect-associated gall formation on Eucalyptus foliage correlates with the diversity of foliar fungal communities in surrounding healthy leaf tissue, as well as the co-occurrence patterns among the members of the fungal community. We used ITS metabarcoding to characterise the foliar fungal communities of 179 individual E. grandis trees. These trees were assigned to infestation levels of the wasp Leptocybe invasa (Eulophidae: Hymenoptera), which causes gall formation on shoot tips and leaves of its host. Fungal community networks were calculated using a Pearson correlation coefficient. The composition and diversity of fungal communities were influenced by the severity of L. invasa infestations. We identified potential Eucalyptus pathogens with high sequence abundance at all disease severity levels, but network analysis indicated that the co-occurrence of potential pathogens between no to mild and medium to heavy infestation differed significantly. A better understanding of microbial interactions, especially the role of pathogens, can be useful for controlling disease- and beneficial host-associated microbial communities.

Apple cultivars and rootstocks assay for the identification of diverse viruses and healthy genotypes for breeding

The prevalence of harmful viruses, viz., apple stem grooving virus (ASGV), apple stem pitting virus (ASPV), apple chlorotic leaf spot virus (ACLSV), apple mosaic virus (ApMV), and tomato ringspot virus (ToRSV) in apple tree plantations in the Ryazan, Yaroslavl, and Moscow regions, Russian Federation, based on genotype features, planting type (industrial, collection, and repository), and tree age was studied during 2018–2021. The prevalence of harmful and latent viruses ranged from 49.6% to 53.8% in apple cultivars and from 8.3% to 100% in apple clonal rootstocks. The most common virus in the Moscow and Yaroslavl regions was ACLSV (34.7% and 53.8%) and that in the Ryazan region was ApMV (33.3%). Relative to that in young apple trees, the virus influence in older tree tissues was higher by 20% to 43% depending on virus type. Monoviral infection prevailed (59% of all trees were infected with one virus) in the studied apple tree cultivars. Of the cultivars, 25% were infected by a complex of two viruses (ASPV + ACLSV), 10% were infected by three viruses, and 6% were infected by four viruses. The highest prevalence of latent viruses was observed in old Russian cultivars (53.5%) and selections from old foreign cultivars (57.2%). Virus occurrence was slightly lower (51.6%) in new Russian cultivars than in other cultivars. Columnar apple tree cultivars had the lowest virus occurrence (30%) and were found to be more tolerant than other genotypes. The highest virus incidence was recorded in industrial orchards (63.4%), followed by that recorded in collection (20.8%) and repository (18.3%) plantations. By using ELISA, the apple genotypes that were free from harmful viruses were identified as source plants, i.e., 183 plants from 18 apple tree cultivars and 131 plants from clonal rootstocks. Results indicated that virus-free apple germplasm is highly effective for the successful implementation of breeding and genetic improvement.

Monitoring Colletotrichum Colonization and Reproduction in Different Rubber Tree Clones.

Anthracnose, caused by fungi of the genus Colletotrichum, is present in the major rubber tree crop areas in Brazil, especially in São Paulo, Mato Grosso do Sul, Paraná, Minas Gerais, Espírito Santo, and northern states. This disease can affect different tissues of the rubber tree, leading to production losses. Thus, a better understanding of the pathosystem Colletotrichum x rubber tree can provide evidence to subsequent epidemiological research and phytosanitary management studies of this disease in the field. The present study aimed to investigate C. tamarilloi colonization and reproduction steps in resistant clones (IAC 502, IAC 507, RRIM 937) and in one susceptible clone (RRIM 600) of the rubber tree, verifying the influence of temperature up to 48 h after inoculation of the fungus, under 24 h wetness. Samples were analyzed under a light, a UV and a scanning electron microscope. Data indicated that the fungus had a delay in its development in resistant clones and, although colonization was expressive 48 h after inoculation, the new spore formation rate in the analyzed samples was lower in resistant clones. For RRIM 600, rapid colonization and intensive sporulation could be observed.

Dissolved Organic Matter (DOM) in a Warm-Temperate Forested Watershed—A Possibility of Ultraviolet Absorbance as an Indicator of DOM

We investigated changes in the quantity and quality of dissolved organic matter (DOM) from rain to stream water in a forested watershed at Yamashiro Experimental Forest (YMS) in southern Kyoto prefecture. The dissolved organic carbon (DOC) concentration and specific UV absorbance at 254 nm (SUVA254) in rainwater increased in the order of bulk rain, throughfall, stemflow, and O layer leachate because of the DOM supply from tree tissue and O layer. Decreases in DOC concentration and SUVA254 with soil depth were not observed in the soil-percolating water. This finding may have been caused by the low free oxide content of the soil and the collection of soil water with a tension-free lysimeter. The DOC concentration was very low in both seepage and stream waters; seasonal variation with a high concentration in summer was observed in the stream water. An increase in K+ concentration in summer was also observed in the stream water; thus, we presumed that DOC seasonal variation was caused by the DOM supply with the accumulated decomposition of litter in the streambed. The significant correlation between DOC concentration and absorbance at 254 nm (UV254) was observed for all sample types of observation target in the watershed; the ratio of DOC concentration to UV254 was different, while the correlation coefficient between DOC concentration and UV254 value differed among sample types in the watershed. We concluded that UV254 which can be measured by simply and easily is a good indicator for estimating DOC concentration in liquid samples in forested watersheds.

The Phlorizin-Degrading Bacillus licheniformis XNRB-3 Mediates Soil Microorganisms to Alleviate Apple Replant Disease.

In this study, an endophytic phlorizin-degrading Bacillus licheniformis XNRB-3 was isolated from the root tissue of healthy apple trees, and its control effect on apple replant disease (ARD) and how it alleviates the pathogen pressure via changes in soil microbiomes were studied. The addition of strain XNRB-3 in Fusarium infested soils significantly reduced the number of pathogens in the soil, thus resulting in a lower disease incidence, and the relative control effect on Fusarium oxysporum reached the highest of 66.11%. The fermentation broth can also protect the roots of the plants from Fusarium oxysporum, Fusarium moniliforme, Fusarium proliferatum, and Fusarium solani infection. These antagonistic effects were further validated using an in vitro assay in which the pathogen control was related to growth and spore germination inhibition via directly secreted antimicrobial substances and indirectly affecting the growth of pathogens. The secreted antimicrobial substances were identified using gas chromatography-mass spectrometry (GC-MS) technology. Among them, alpha-bisabolol and 2,4-di-tert-butylphenol had significant inhibitory effects on many planted pathogenic fungi. Butanedioic acid, monomethyl ester, and dibutyl phthalate promoted root development of Arabidopsis plants. Strain XNRB-3 has multifarious plant growth promoting traits and antagonistic potential. In pot and field experiments, the addition of strain XNRB-3 significantly promoted the growth of plants, and the activity of enzymes related to disease resistance [superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)] was also significantly enhanced. It also reduced the abundance of four species of Fusarium and the content of phenolic acids in the rhizosphere soil, improved soil microbial community structure and nutritional conditions, and increased soil microbial diversity and activity, as well as the soil enzyme activity. The above results indicated that B. licheniformis XNRB-3 could be developed into a promising biocontrol and plant-growth-promoting agent.

On the potential of pristine Cocos nucifera L . tissues for green desalination

Coconut palm tree (Cocos nucifera L.) tissues were used as a readily available, low-cost and green adsorbent to desalinate seawater. The tree bark (CB), husk (CH), leaves (CL) and roots (CR) were examined in their fresh (F) and dry (D) forms. The salinity removal (adsorption) efficiency followed the trend: F_CB ≈ F_CR > F_CL > D_CR > F_CL > D_CR. The sorbents from the coastal region desalinated more efficiently than those from a non-coastal region. Also, the fresh tissues were more effective and efficient than the dry parts. The salinity retention ability (desalination:desorption) follows the trend: F_CR (22.2) > F_CB (19.0) ≫ D_CR (12.3) > D_CB (11.0) > D_CL (6.14) ≈ F_CL (6.10) > F_CH (4.3) > D_CH (2.1). Moreover, the desalination fitted the pseudo-second-order kinetics than the pseudo-first-order, suggesting the predominance of chemisorption over physical removal. Overall, water pH, conductivity, total dissolved solids and dissolved oxygen (DO) correlated positively and strongly with desalination. By contrast, the density and redox potential correlated negatively, whereas temperature and DO showed no definite influence. Conclusively, F_CR and F_CB are the most suitable coconut palm tree tissues for desalination. Future studies should include chemical characterization of the tissues and system optimization for upscaling. This article is part of the theme issue 'Developing resilient energy systems'.

Evaluation of Phoma sp. Biomass as an Endophytic Fungus for Synthesis of Extracellular Gold Nanoparticles with Antibacterial and Antifungal Properties.

The aim of our study was to examine the different concentrations of AuNPs as a new antimicrobial substance to control the pathogenic activity. The extracellular synthesis of AuNPs performed by using Phoma sp. as an endophytic fungus. Endophytic fungus was isolated from vascular tissue of peach trees (Prunus persica) from Baft, located in Kerman province, Iran. The UltraViolet-Visible Spectroscopy (UV–Vis spectroscopy) and Fourier transform infrared spectroscopy provided the absorbance peak at 526 nm, while the X-ray diffraction and transmission electron microscopy images released the formation of spherical AuNPs with sizes in the range of 10–100 nm. The findings of inhibition zone test of Au nanoparticles (AuNPs) showed a desirable antifungal and antibacterial activity against phytopathogens including Rhizoctonia solani AG1-IA (AG1-IA has been identified as the dominant anastomosis group) and Xanthomonas oryzae pv. oryzae. The highest inhibition level against sclerotia formation was 93% for AuNPs at a concentration of 80 μg/mL. Application of endophytic fungus biomass for synthesis of AuNPs is relatively inexpensive, single step and environmentally friendly. In vitro study of the antifungal activity of AuNPs at concentrations of 10, 20, 40 and 80 μg/mL was conducted against rice fungal pathogen R. solani to reduce sclerotia formation. The experimental data revealed that the Inhibition rate (RH) for sclerotia formation was (15, 33, 74 and 93%), respectively, for their corresponding AuNPs concentrations (10, 20, 40 and 80 μg/mL). Our findings obviously indicated that the RH strongly depend on AuNPs rates, and enhance upon an increase in AuNPs rates. The application of endophytic fungi biomass for green synthesis is our future goal.

Genomic insights into the plant-associated lifestyle of Kosakonia radicincitans MUSA4, a diazotrophic plant-growth-promoting bacterium

The process of nitrogen (N) fixation by plant-associated bacteria plays an indispensable role in the development of novel agricultural solutions worldwide. In this sense, it is of extreme importance to identify and understand the properties of efficient plant-growth-promoting bacteria (PGPB) that are able to fix N. In this study, the characterization and detailed genomic analysis of the diazotrophic bacterium Kosakonia radicincitans MUSA4, isolated from the internal leaf tissues of a banana tree in Brazil, were undertaken.K. radicincitans MUSA4 presented several plant-growth-promoting traits, including indoleacetic acid, siderophore, acetoin and polyamine biosynthesis, phosphate solubilization, and nitrogen fixation. The strain was able to increase cucumber plant growth significantly, demonstrating its potential in beneficial interactions with plant hosts. Detailed genomic analysis of strain MUSA4 revealed the abundant presence of genes involved in plant colonization, stress resistance and plant-growth-promoting abilities. Moreover, the genome harbored the nif and anf gene clusters, encoding the Fe-Mo nitrogenase and Fe-Fe nitrogenase systems, respectively. Comparative genomic analysis also showed that strain MUSA4 possessed several strain-specific genes, which could be related to its evolutionary history in Brazilian mangrove environments.The results obtained in the present study revealed the plant beneficial role and biotechnological potential of K. radicincitans MUSA4, and provided new insights into plant colonization and plant growth promoting mechanisms employed by diazotrophic Kosakonia.

Water use efficiency of poplars grown for biomass production in the Midwestern United States

AbstractWater availability and other site conditions influence poplar biomass productivity and affect clonal performance due to genotype × environment interactions. It is important to select genotypes with high water use efficiency (WUE) that maximizes yield with available amounts of water at sites, while avoiding drought stress and growth impacts to the trees. During drought, stomatal closure induces increased accumulation of δ13C carbon isotope in tree tissues, which is strongly correlated with WUE of trees and usually expressed through carbon isotope discrimination (Δ). Our primary objectives were to evaluate differences in WUE among poplar genotypes grown in the Midwestern United States, and to identify genotypes with high WUE for future deployment on water‐limited sites in the region. Sites included 10‐year‐old biomass plantations in Escanaba, Michigan; Waseca, Minnesota; and Ames, Iowa established from 2000 to 2001 with seven poplar genotypes’ three genomic groups. Following harvest, height, diameter, and biomass were determined. Wood samples were collected from individual growth rings to assess annual ring width and WUE through δ13C and Δ. Aboveground dry biomass varied among sites (p = .0007), clones (p < .0001), and their interactions (p = .0134), ranging from 3.1 to 14.0 Mg ha−1 year−1. Δ varied among sites (Δ = 18.9–19.7‰; p < .0001) and clones (Δ = 18.6–19.9‰; p < .0001), indicating effects of site conditions on WUE of tested genotypes. Clones varied in their water‐conserving strategies. Some clones were characterized as water consumers with high growth and high WUE (“C916000”; “C916400”), while other genotypes were water conservers using lower amounts of water with moderate biomass production (“NC13624”; “NC13649”; “NM2” to a certain extent). Although δ13C carbon isotope accumulation correlates with WUE, Δ should only be used for selection when it is integrated with other parameters such as productivity, soils information, and climate data.

Management of Deleterious Effect of Fusarium oxysporum Associated with Red Palm Weevil Infestation of Date Palm Trees

Red palm weevil (RPW) is a dangerous pest that infects the date palm tree and makes tunnels in the tree’s trunk. RPW infection is followed by secondary invaders of microorganisms that cause degradation of the trunk tissues leading to toppling the crown and death of the tree in a short time. This study showed that Fusarium oxysporum Schlecht. was the common fungal species isolated from the root and trunk tissues of the date trees infested with RPW, which recorded 100% of frequency. Pathogenicity of 4 isolates of F. oxysporum was confirmed on date palm seeds and seedlings. The results confirmed that all isolates involved in rot of the germinated seeds (40–100% incidence), root rot, and death of palm seedlings (20–100%) under artificial infection as well as degradation of date palm petioles. Application of 20 L/palm of systemic fungicide (Topsin) at 1% as foliar and soil drench of date palm for successive three times successfully reduced development of the deterioration and suppressed the growth of F. oxysporum. Interestingly this fungicide did not suppress the growth of Trichoderma viride Pers. So, our results recommend this fungicide to suppress the pathological and degradable activities of F. oxysporum during the integrated pest management of RPW on date palm trees.

Effects of urban wastewater application on growth, biomass, nutrition, and heavy-metal accumulation of Populus nigra L. “62/154,” P. alba L. “20/45,” P. euramericana (Dode) Guinier “92/40,” and Salix excelsa S.G. Gmel grown in heavy-metal contaminated soil

Iran is located in a dry climate zone, and climate change has substantially reduced its precipitation and water resources. Reusing wastewaters from urban communities can meet some requirements for irrigation and fertilization of tree plantations in arid environments, leading to sustainable wastewater recycling, enhanced biomass production, and reduced land degradation. The objective of this study was to test the growth, biomass, nutrition, and heavy-metal accumulation of poplars [Populus nigra L. “62/154,” P. alba L. “20/45,” P. euramericana (Dode) Guinier “92/40”], and willow (Salix excelsa S.G. Gmel) in a pot experiment at four and eight months after planting when grown in soils irrigated with tap water (SITW) and wastewater (SIWW). After four months, SIWW treatment had no significant effect on growth, biomass, nor absorption of macronutrients. After eight months, SIWW treatment of poplars and willow significantly (p = 0.000) increased: (1) height, (2) leaf area, (3) root, stem, leaf, and total biomass, and (5) phytoextraction and phytoaccumulation of macro-/micro-nutrients and heavy metals in tree tissues, over trees receiving the SITW treatment. There were significant differences in growth, biomass, and accumulation of micronutrients and heavy metals in poplar versus willow tissues, with the highest biomass production and tissue-specific content of heavy metals in P. nigra trees, and the greatest total concentrations of heavy metals in P. alba and S. excelsa trees. In contrast, uptake of Fe, Cu, Ni, Cr and Pb were similar between poplar and willow, and phytoaccumulation of these elements was primarily in the roots. Leaf concentrations were highest for Zn and Mn. While P. nigra outperformed all other species overall, tolerance index (TI; defined as the tolerance to the heavy metals as calculated by the ratio of the biomass of SIWW trees relative to SITW trees) values exceeding 100% for all one-year-old poplar and willow trees demonstrated that they can be considered for planting in soil affected by urban wastewaters with similar contaminant profiles as in the current study.

The Influence of Host Genotypes on the Endophytes in the Leaf Scar Tissues of Apple Trees and Correlation of the Endophytes with Apple Canker (Neonectria ditissima) Development

Bacterial and fungal endophytes may help their host in terms of improved tolerance to abiotic and biotic stresses and enhanced growth. European apple canker, caused by Neonectria ditissima, is widespread in apple-growing regions. Infection by N. ditissima occurs through artificial or natural wounds, including leaf scars, picking wounds, and pruning cuts. Using F1 progeny trees in an experimental orchard derived from a cross between a canker-susceptible genotype and a canker-tolerant or -resistant genotype, we assessed both bacterial and fungal endophyte communities in apple leaf scars, and determined correlations of endophytes with canker development. All trees were artificially inoculated with an N. ditissima isolate postplanting. Specific components of apple endophytes as well as a number of individual fungal or bacterial groups in leaf scars were partially genetically controlled by host genotypes. Several bacterial groups were significantly correlated with canker-related traits, mostly positively associated with canker tolerance. A few fungal groups may facilitate canker development whereas others may compete with canker. However, most of these microbial groups could not be identified to the species level with confidence; even for those groups which could be assigned to the species level, there is insufficient knowledge about their ecological characteristics in relation to plants. The present results may be used to inform further research using biocontrol to manage N. ditissima and breeding for resistance.

Spectrometric Prediction of Nitrogen Content in Different Tissues of Slash Pine Trees.

The internal cycling of nitrogen (N) storage and consumption in trees is an important physiological mechanism associated with tree growth. Here, we examined the capability of near-infrared spectroscopy (NIR) to quantify the N concentration across tissue types (needle, trunk, branch, and root) without time and cost-consuming. The NIR spectral data of different tissues from slash pine trees were collected, and the N concentration in each tissue was determined using standard analytical method in laboratory. Partial least squares regression (PLSR) models were performed on a set of training data randomly selected. The full-length spectra and the significant multivariate correlation (sMC) variable selected spectra were used for model calibration. Branch, needle, and trunk PLSR models performed well for the N concentration using both full length and sMC selected NIR spectra. The generic model preformatted a reliable accuracy with R2C and R2CV of 0.62 and 0.66 using the full-length spectra, and 0.61 and 0.65 using sMC-selected spectra, respectively. Individual tissue models did not perform well when being used in other tissues. Five significantly important regions, i.e., 1480, 1650, 1744, 2170, and 2390 nm, were found highly related to the N content in plant tissues. This study evaluates a rapid and efficient method for the estimation of N content in different tissues that can help to serve as a tool for tree N storage and recompilation study.

Concentration and gene expression analyses of dragon′s blood flavonoids in different tissues of Dracaena cochinchinensi

Background: Dragon′s blood is a well-known traditional Chinese medicine, isolated mainly from the trunks of Dracaena trees. Overexploitation of the Dracaena resource has resulted in this plant becoming endangered. This work aimed to assess the potential to use various tissues of the Dracaena cochinchinensis tree, such as leaves and roots, to produce dragon′s blood. Results: We found that many dragon′s blood components accumulated in the bark of trunk and roots of D. cochinchinensis under natural conditions. In addition, small amounts of loureirin A were detected in leaves, suggesting that the leaves could be a potential source of dragon′s blood. Real-time quantitative PCR analysis showed that most of the genes tested in this study, which encoded enzymes involved in the biosynthesis of dragon′s blood flavonoids, were highly expressed in the bark of roots and trunk. Conclusion: We confirmed that the bark of roots and trunk of D. cochinchinensis tree were the main tissues for the synthesis and storage of dragon′s blood under natural conditions. This study demonstrated the potential to extract dragon′s blood from the roots that have been abandoned due to mining difficulties without destroying the tree, a process which would be beneficial to the protection of the endangered wild D. cochinchinensis tree populations.

Biochemical Composition of Sweet Cherry Leaves Depending on the Method of Soil Maintenance in an Organic Garden

Conducting sustainable agriculture involves not only increasing the productivity of crops and increasing the volume of crop production, but also preserving ecosystems. Mulching the soil in orchards is one of the ways to preserve the natural balance of agricultural landscapes. But the effect of competition with grasses on the biochemical composition of fruit tree tissues has not yet been definitively elucidated. The purpose of this study was to determine the influence of soil retention under mulching (compared to pure steam) on the biochemical composition of cherry leaf tissues. The research was conducted in an organic cherry orchard (Prunus avium L. / Prunus mahaleb) during 2017-2019 in the conditions of the Southern Steppe of Ukraine. A significant decrease in the content of ascorbate, glutathione, sugars, total reducing activity and activity of antioxidant enzymes was established under conditions of prolonged drought and an increase in the content of titrated acids. The total reducing activity under mulching conditions tended to increase. A gradual increase in the content of titrated acids, ascorbate, sugars, phenolic substances, and glutathione was recorded in the leaves of cherry trees from the flowering phase to November. In the autumn phase, a significant increase in sugars and phenolic substances was established in cherry leaves under the conditions of mulching in 2017, and in 2018 – phenolic substances; in 2019 – phenolic substances and ascorbate. An increase in the content of malondialdehyde (MDA) and the activity of antioxidant enzymes was found during the growing season of cherries in both variants of the experiment. In the November phase only in 2019, the MDA content was significantly higher by 14% under the condition of mulching. Under mulching conditions, a significant increase in ascorbate peroxidase (by 28-30%) and polyphenol oxidase (by 45-46%) was determined. In 2018 and 2019, a 2.4-fold increase in peroxidase activity in cherry leaves was determined. Research results help to understand the mechanisms of adaptation of fruit plants to stress factors (drought, competition with natural grasses) and can be used as an argument in favour of mulching in organic cherry orchards.

The brown root rot fungus Phellinus noxius affects microbial communities in different root-associated niches of Ficus trees.

Brown root rot (BRR) caused by Phellinus noxius is a destructive tree disease in tropical and subtropical areas. To understand how BRR affects the composition of the plant rhizoplane-enriched microbiota, the microbiomes within five root-associated compartments (i.e., bulk soil, old/young root rhizosphere soil, old/young root tissue) of Ficus trees naturally infected by P. noxius were investigated. The level of P. noxius infection was determined by quantitative PCR. Illumina sequencing of the internal transcribed spacer and 16S rRNA revealed that P. noxius infection caused a significant reduction in fungal diversity in the bulk soil, the old root rhizosphere soil, and the old root tissue. Interestingly, Cosmospora was the only fungal genus positively correlated with P. noxius. The abundance and composition of dominant bacterial taxa such as Actinomadura, Bacillus, Rhodoplanes, and Streptomyces differed between BRR-diseased and healthy samples. Furthermore, 838 isolates belonging to 26 fungal and 35 bacterial genera were isolated and tested for interactions with P. noxius. Antagonistic activities were observed for isolates of Bacillus, Pseudomonas, Aspergillus, Penicillium, and Trichoderma. Cellophane overlay and cellulose/lignin utilization assays suggested that Cosmospora could tolerate the secretions of P. noxius and that the degradation of lignin by P. noxius may create suitable conditions for Cosmorpora growth.

Wood and bark water content and monthly stem growth in Amazonian tree species

ABSTRACT The knowledge of how trees respond to microclimate variability is important in the face of climate changes. The objectives of this study were to examine the variation in wood water content (WWC) and bark water content (BWC) in Amazonian trees, as well as to assess the effect of microclimatic variability on monthly diameter growth rates (DGR). We extracted a core sample from each of 120 trees (28 species) and determined WWC and BWC on a fresh matter basis. DGR was measured monthly during the 12 months of 2007. The effect of microclimatic variability on DGR was analyzed by redundancy analysis. Average BWC and WWC were 53.4% and 34.7%, respectively, with a large variation in stem water content among species (BWC = 36.2−67.1%; WWC = 26.4−50.8%). There was no significant relationship between stem diameter and WWC or BWC, nor between DGR and wood density (p > 0.05). However, wood density was negatively correlated with WWC (r s = −0.69, p < 0.001). The high BWC emphasizes the importance of the bark tissue in Amazonian trees. Contrary to expectations, variability of monthly irradiance, rainfall and temperature had no effect on DGR (p > 0.20). The unresponsiveness of DGR to microclimatic variability, even in an above-average rainy year such as 2007, indicates that other parts of the tree may have greater priority than the stem for carbon allocation during the dry season.

Description of Intra-Annual Changes in Cambial Activity and Differentiation of Secondary Conductive Tissues of Aesculus hippocastanum Trees Affected by the Leaf Miner Cameraria ohridella

Aesculus hippocastanum trees are commonly infested by the leaf miner Cameraria ohridella, whose larval activity causes the destruction of the leaf parenchyma and induces defoliation. Pest attacks result in, e.g., production of smaller fruits and tree re-flowering in autumn. Concerning pest influence on stem structure only scarce information of narrower annual growth rings of wood has been published. Therefore, we determined the effect of the presence of the leaf miner infestation on intra-annual cambial activity and on differentiation of conductive tissues. These data were compared with phenological phases and pest activity. Pest feeding resulted in changes in onset, cessation and duration of cambial divisions, and differentiation of secondary xylem. The duration of cambial activity was about a month shorter in heavily infested trees and was connected with premature tree defoliation. Affected trees were characterised by a reduction in cambial divisions and earlier cessation of wood differentiation resulting in narrower wood rings. Furthermore, the infested trees exhibited altered wood structure, with more vessels of smaller diameters, however these changes did not affect its theoretical hydraulic conductivity. Interestingly, pest attack did not influence secondary phloem differentiation. The probable influence of long-term infestation on tree growth and condition was discussed.

Fungal diversity inhabiting tissues of ebony (Diospyros celebica Bakh.) in urban forest

Eboni (Diospyros celebica Bakh.) is an endemic tree species of Sulawesi Island including Central Sulawesi, West Sulawesi and South Sulawesi. This species is also called fancy wood; its color is black-striped reddish brown, beautiful, and luxurious. In addition, tree growth is influenced by microbes, including fungi. Fungi are heterotrophic and eukaryotic organisms absorbing organic compounds from other organisms. The study aimed to identify ebony-associated fungi in Urban Forestry at the Tamalanrea Campus, Hasanuddin University, Makassar, Indonesia. This study consisted of the isolation stage both direct and dilution methods, the rejuvenation stage, and fungal identification. The study result indicated that there were 60 fungal isolates isolated from the ebony tree tissues, while 19 fungal isolates were isolated on the soil under the ebony stands. The direct isolation-based method was higher in term of number of fungal isolates than the dilution-based method. The isolated fungi belonged to the seven genera, namely Aspergillus, Penicillium, Gliocladium, Trichoderma, Fusarium, Rhizopus, and Phytophthora. Aspergillus and Penicillium was genera dominated both in tree tissues and in the soil under ebony stands.