Platanus Acerifolia Research Articles

Sampling design of ground-based lidar measurements of forest canopy structure and its effect on shadowing

This research was undertaken to study the influence of the sampling design and laser beam density of ground-based light detection and ranging (lidar) measurements of forests on the quality of the collected laser datasets in terms of shadowing. Virtual forest stands generated by stochastic L-systems as tree descriptors are used as a basis depending on the study frame and requirements. The dynamic plant modeler and plant nursery natFX (Bionatics, CIRAD, Montpellier, France) was used to simulate deciduous forest stands of three tree species (Fagus sylvatica L., Platanus acerifolia (Ait.) Willd., and Populus nigra L.) with varying structural characteristics. Hemispherical laser measurements with different laser beam densities were simulated according to three different sampling patterns (single, diamond, corners) inside these virtual forest stands using ray-tracing technology. An adjusted sampling design has proven its effectiveness, since an average shadowing decrease of 29.10% was obtained in comparison with that for a single measurement. This finding contrasts with an average decrease of 13.27% by increasing laser beam density by a factor of 25. In the next step, contact frequency values were calculated from the virtual laser datasets. These values were used to model the shadowed parts of the canopy, demonstrating the potential of ground-based laser scans to capture the three-dimensional leaf distribution inside a forest stand in terms of leaf area density (LAD). On average, the LAD estimates underestimated the true LAD by 19.55%, 12.67%, and 10.54% for the single, diamond, and corners setups, respectively. In each of the cases, the LAD values from the single design resulted in a lower accuracy compared with those for the diamond and corners setups.

Oriental plane pollen allergy: Identification of allergens and cross-reactivity between relevant species

Pollen from different tree and grass species represent the greatest inducers of type I allergy worldwide. Oriental plane trees, as Platanus orientalis, are an important source of airborne allergens in cities of the southwest Asia and southeast Europe. This study was aimed to identify relevant allergens of P. orientalis pollen and to ascertain whether P. orientalis allergens have cross-reactivity with related plane trees, such as Platanus acerifolia and Platanus occidentalis pollen components. Nineteen patients with a clinical history of reaction to P. orientalis pollen and a positive skin-prick test (SPT) to P. orientalis pollen extract were included in this study. Identification of IgE-binding proteins in Platanus pollen extracts was elucidated by immunoblotting using sera from P. orientalis pollen-sensitive patients. Cross-reactivity studies among P. orientalis allergens and relevant species was evaluated by immunoblot-inhibition and ELISA inhibition assays. All the patients were polysensitive and exhibited positive SPT to grass and tree pollen allergens. The IgE-binding pattern of P. orientalis pollen extract was well defined. The inhibition experiments showed that the capacity of P. occidentalis was greater than P. acerifolia pollen extract in preventing the reactivity of immobilized P. orientalis pollen extract with the IgE antibodies of patients. The 28-kDa molecule was the most frequent allergen among nine IgE-binding proteins of P. orientalis pollen. The IgE-reactive components of P. orientalis pollen showed a higher level of cross-reactivity with P. occidentalis pollen in comparison with P. acerifolia pollen.

Measuring and modeling the variation in species-specific transpiration in temperate deciduous hardwoods

We investigated which parameters required by the MAESTRA model were most important in predicting leaf-area-based transpiration in 5-year-old trees of five deciduous hardwood species-yoshino cherry (Prunus x yedoensis Matsum.), red maple (Acer rubrum L. 'Autumn Flame'), trident maple (Acer buergeranum Miq.), Japanese flowering cherry (Prunus serrulata Lindl. 'Kwanzan') and London plane-tree (Platanus x acerifolia (Ait.) Willd.). Transpiration estimated from sap flow measured by the heat balance method in branches and trunks was compared with estimates predicted by the three-dimensional transpiration, photosynthesis and absorbed radiation model, MAESTRA. MAESTRA predicted species-specific transpiration from the interactions of leaf-level physiology and spatially explicit micro-scale weather patterns in a mixed deciduous hardwood plantation on a 15-min time step. The monthly differences between modeled mean daily transpiration estimates and measured mean daily sap flow ranged from a 35% underestimation for Acer buergeranum in June to a 25% overestimation for A. rubrum in July. The sensitivity of the modeled transpiration estimates was examined across a 30% error range for seven physiological input parameters. The minimum value of stomatal conductance as incident solar radiation tends to zero was determined to be eight times more influential than all other physiological model input parameters. This work quantified the major factors that influence modeled species-specific transpiration and confirmed the ability to scale leaf-level physiological attributes to whole-crown transpiration on a species-specific basis.

A comparison of phosphorus and DOC leachates from different types of leaf litter in an urban environment

Summary1. The leaching rates of filterable reactive phosphorus (FRP) and dissolved organic carbon (DOC) from five leaf litter types commonly occurring in urban environments in Mediterranean regions of Southern Australia were compared. The relative composition, bioavailability and oxygen demand of this DOC were also assessed. Four tree species were assessed, including the native river red gum (Eucalyptus camaldulensis) and three introduced deciduous species, the English elm (Ulmus procera), London plane (Platanus acerifolia) and white poplar (Populus alba). Grass cuttings (mixed species) were selected as a common garden waste.2. Except for English elm, the majority of FRP and DOC was released within the first 48 h. Grass cuttings released the highest amount of FRP with white poplar releasing the most DOC. Species that released relatively high amounts of DOC (white poplar, English elm, river red gum) released relatively low amounts of FRP. Conversely, species that released relatively low amounts of DOC (grass cuttings and London plane) tended to release relatively high amounts of FRP.3. Analysis of DOC composition, combined with the differing oxygen demand and DOC depletion curves, demonstrated that there were substantial differences in the DOC leached from the leaf litter of the different species. Biochemical oxygen demand and the biodegradability of the DOC was positively correlated with the proportion of hydrophilic and hydrophobic acids present in the leachate.4. These results demonstrate that simple measurements of nutrient release per gram of leaf litter would be insufficient to predict the ecological impact on receiving waters resulting from changes in dominant vegetation. Furthermore, the use of traps to prevent particulate leaf material from entering streams may have limited potential for reducing the load of dissolved nutrients. We conclude that any changes to vegetation type which substantially alter the timing of leaf fall or the composition of leaf leachates should be avoided.

Changes in leaf photosynthetic characteristics and water use efficiency along with tree height of 4 tree species

As main photosynthetic organs, leaves are very sensitive to exterior environments. Water deficiency obviously affects the biological and physiological characteristics of leaves. Xylem pathways increase when trees grow tall, which results in the increase in water gravity as well as pathway resistance. Accordingly, the physiological characteristics of leaves change along with tree height. In this research, the photosynthetic characteristics and carbon isotope ratio (δ 13C) in the leaves of 4 tree species, Platanus hispanica, Robinia pseudoacacia, Fraxinus chinensis and Ginkgo biloba, were measured. The results showed that the leaf photosynthetic rate ( Pn), transpiration rate ( Tr), stomatal conductance ( Cond) and internal CO 2 concentration ( Ci) reduced along with tree height, while the leaf δ 13C increased along with tree height. The One Way ANOVA and LSD tests showed that the leaf photosynthetic characteristics and δ 13C varied significantly at different tree heights ( P < 0.05). The decrease in leaf photosynthetic capability and the increase in δ 13C along with tree height indicate that the leaves at the tree tops suffer from water stress. These results support the hydraulic limitation hypothesis.

CERATO-PLATANIN TREATED PLANE LEAVES RESTRICT CERATOCYSTIS PLATANI GROWTH AND OVEREXPRESS DEFENCE-RELATED GENES

SUMMARY Cerato-platanin (CP) is a small protein of 120 amino acids, produced by the ascomycete Ceratocystis platani (Walter) Engelbrecht et Harrington (Cep), the agent of plane canker stain. CP is located in the cell walls of the conidia, hyphae and ascospores of Cep, is able to self-aggregate, and is released into the culture medium in the first growth stages of in vitro culture. CP is the founder member of the CP family, a group of proteins involved in the interaction between the producing microbe and the host cell. Leaves of Cep-susceptible Platanus acerifolia react to treatments with CP in a resistance-like manner, producing extracellular and intracellular phenolic compounds and undergoing cell plasmolysis and/or death. The present study provides evidence that in plane leaves the CP-activated defence-related events are strictly correlated with the inhibition of Cep growth on the leaves and with a high level of transcripts of 78 differentially expressed genes. Of the transcripts, 19.2% regarded as genes coding for defence and/or stress related proteins. The other genes concerned DNA/RNA synthesis and metabolism, protein synthesis/turnover, energy, primary cellular metabolism and the signalling pathways. The results demonstrated that after treatment of the plane leaves with CP, a substantial network of regulatory interaction and coordination was formed, as well as other defence-related molecular events.

Erysiphe platanicausing powdery mildew of London plane in Hungary

This is the first record of Erysiphe platani on London plane (Platanus × hispanica) trees in Hungary. Photographic documentation and description of the morphology of both the anamorph and the teleomorph stages of this fungus are provided in this paper.

Sensitization and Allergy to Cannabis sativa Leaves in a Population of Tomato (Lycopersicon esculentum)-Sensitized Patients

Background: Cases of allergy to Cannabis sativa have occasionally been reported, but both the allergenic profile and eventual cross-reactivity pattern remain unknown. Objective: To analyze the allergenic profile of a population of patients from Spain sensitized to C. sativa and to characterize the C. sativa leaf extract. Methods: A total of 32 subjects were enrolled in the study: group A, 10 individuals sensitized to tomato, reporting reactions by contact or inhalation to Cannabis; group B, 14 individuals sensitized to tomato, without reactions to Cannabis; group C, 8 individuals not sensitized to tomato and without reactions to Cannabis. Sensitivity to Cannabis, tomato and peach peel, Platanus hybrida and Artemisia vulgaris pollen extracts was measured by skin tests and specific IgE. Individual immunoblots and inhibition experiments with a pool of sera were conducted. Results: All tomato-sensitized subjects (and 1 negative) had positive skin tests to C. sativa leaves and hashish. Specific IgE to C. sativa and peach peel was more common than to tomato. Immunoblot experiments showed 2 prominent bands of 10 and 14 kDa and 2 weakly recognized bands of 30 and 45 kDa. Tomato, peach and A. vulgaris extracts inhibited most of the bands present in C. sativa. P. hybrida inhibited only the high-molecular-weight bands. Conclusion: Sensitization to C. sativa with or without symptoms is frequent among patients in Spain sensitized to tomato. C. sativa leaves are a potential allergenic source and their allergens may cross-react with other allergenic sources from plants (fruit peels and pollen).

AFLP assessment of genetic variability in old vs. new London plane trees (Platanus × acerfolia)

SummaryLondon plane tree (Platanus acerfolia) is a popular street tree and is a hybrid between the American sycamore and the Oriental plane tree. Using AFLP markers, genetic diversity and phenetic relationships were estimated in 38 London plane tree samples from Schenley Park, Pittsburgh, PA, USA, and from several nurseries. This investigation was intiated in order to manage, more effectively, the replanting of London plane trees in an existing (approx. 100 yearold) stand of approx. 100 trees. Four selective primer combinations generated a total of 492 amplification products, and 381 polymorphic markers were detected. Polymorphism ranged from 60 – 82%, with an average of 77%. A phenetic tree was constructed using Nei and Li’s coefficient of similarity with UPGMA. Other clustering algorithms were examined and all gave similar co-phenetic correlation values. The phenetic tree separated the nursery trees from the Schenley Park samples. Bootstrap analyses were completed, and the values gave strong support for this clade. We investigated the different propagating techniques applied between these samples. The Schenley Park plants had been grown from seed or seedlings, while the nursery plants were clonally propagated, which correlated with the observed differences in similarity coefficients. The level of genetic variability detected by AFLP analysis within these London plane tree samples suggested that this is a reliable, efficient, and effective marker system that can be used for better management of rural tree plantings.

Extraction of high-quality tissue-specific RNA from London plane trees (Platanus acerifolia), permitting the construction of a female inflorescence cDNA library.

The London plane tree (Platanus acerifolia Willd.) has global importance as an urban landscaping tree and is the subject of genetic-improvement programs for productive sterility, disease and/or insect resistance. Molecular analysis techniques are crucial to such programs, but may be impeded by specific difficulties encountered during nucleic acid isolation. A detailed RNA isolation and purification protocol, based on established cetyltrimethyl-ammonium bromide (CTAB) extraction techniques combined with additional purification steps using butanol and the ionic detergent CTAB, which overcomes these problems in the woody species P. acerifolia, was conducted. In short, phenolic compounds are bound to soluble polyvinylpyrrolidone and then separated out through LiCl precipitation of the RNA. Subsequently, protein- and carbohydrate-contaminants are removed by chloroform partitioning followed by LiCl-mediated precipitation. The resulting isolates of RNA were found to be of sufficient quality for successful use in reverse transcription PCR analysis. Furthermore, RNA isolates from female inflorescences were used for the construction of a cDNA library. This library was found to contain several full-length cDNA clones of MADS-box genes, consistent with the library being representative of inflorescence expression profiles.

ITS Evolution in Platanus (Platanaceae): Homoeologues, Pseudogenes and Ancient Hybridization

Platanaceae is an old family of angiosperms extending back to the Early Cretaceous but consisting of a single extant genus, Platanus. Species of Platanus have long been known to hybridize, and the London plane, Platanus x hispanica, is a well-known example of a hybrid species that formed in historical times. In addition, morphological studies have suggested past interspecific or interlineage hybridization and reticulation as possibly important factors in the evolution of the genus. This study aims at unravelling the complex evolutionary information contained in internal transcribed spacer (ITS) sequences. The ITS of the 35S nuclear ribosomal DNA are biparentally inherited, multi-copy markers with a high potential for resolving intrageneric relationships especially when ancient hybridization (reticulation) is involved. Phylogenetic trees, splits graphs and motif analysis are used to extract phylogenetic information from 223 cloned ITS sequences, representing ten species and varieties of Platanus. Non-pseudogenous and pseudogenous sequence motives are assessed to explain how different evolutionary modes contribute to possibly conflicting character state patterns in the ITS. It was found that putative non-functional ITS copies ('pseudogenes') form distinct groups in phylograms and splits graphs, and that pseudogenous lineages reflect ancient hybridization events conserved in the ITS. Specifically, pseudogenous clones of an 'Atlantic' North American clade share sequence motives with non-pseudogenous clones of the western ('Pacific') North American P. racemosa species aggregate. In addition, evidence was found for recent lateral gene flow as a possible factor in the evolution of the central Mexican P. rzedowskii. Broad ITS data sets that cover intra- and interindividual variability reveal past and ongoing speciation processes in Platanus. Evolutionary pathways can be visualized with splits graphs, but not with bifurcating trees.

Sensitization to tomato peel and pulp extracts in the Mediterranean Coast of Spain: prevalence and co‐sensitization with aeroallergens

Tomatoes (Lycopersicon esculentum) are consumed world-wide. The prevalence of sensitization to tomatoes remains unknown. To determine the prevalence of skin test reactivity to tomato and to describe the characteristics of tomato-sensitized subjects. Individuals attending for the first time during the period of the study to six Allergy centres, located along the Mediterranean coast of Spain, reporting respiratory and/or cutaneous symptoms, were included. All patients were skin prick tested with a battery of inhalant allergens and with peel and pulp of Canary tomato extracts. The study included 1734 individuals (757 males, 977 females; 31.9+/-17.8 years old). The prevalence of sensitization to tomato was 6.52% (113 patients; 65 males, 48 females; 29.5+/-13 years old). The peel extract was positive in 110 patients and the pulp extract in 47 patients; three patients were positive exclusively to pulp. Only 1.8% of individuals reported symptoms with tomato; 44% of them had skin test negative to both extracts. Among tomato-sensitized subjects, 16% reported symptoms with tomato, 97% were sensitized to inhalant aeroallergens, including 84% to pollens (mainly Artemisia vulgaris and Platanus hybrida), with differences between Northern and Southern centres. The prevalence found of skin test sensitivity to tomato is high. Peel extracts detected most of the sensitized subjects. Most of the sensitized subjects were asymptomatic and some patients reported symptoms without skin test sensitivity. Positive subjects were very frequently sensitized to pollens, suggesting allergen cross-reactivity. Regional differences may exist, possibly related to the pattern of sensitization to cross-reacting pollens.

The potential of 44 native and non-native tree species for woodland creation on a range of contrasting sites in lowland Britain

Summary A series of species trials were set up to investigate the establishment and early growth (up to 14 years old) of 44 native and non-native tree species on a variety of different site types in lowland Britain. On good quality lowland afforestation sites, Platanus x hispanica (London plane) established and grew more successfully than the native trees tested, and may be an example of a species that could theoretically be established in anticipation of future climate change. Experiments on a variety of community woodland sites indicated that a range of exotic species, such as X Cupressocyparis leylandii (Leyland cypress), may have the potential for establishing a woodland cover on poorly restored land where few other trees would grow. However, on less challenging, better restored sites, a wide range of native species also grew successfully. Further long-term and larger scale trials on a wider variety of sites are required to confi rm the potential of the species tested for British conditions. The results from these experiments also showed that relative growth rates of different species can vary through time, highlighting the danger in making premature judgements about species suitability based solely on very early tree growth.

Effect of nutrients on the sporulation and diversity of aquatic hyphomycetes on submerged substrata in a Mediterranean stream

Eutrophication in streams often results in enhanced decomposition rates and chemical conditions that greatly affect the suitability of the habitat for many species. We performed an enrichment experiment in a 50-m reach of a Mediterranean stream by the continuous addition of N and P (enriched reach) while another consecutive reach upstream served as the reference (unenriched reach). After 1.5 years of enrichment, conidia production and species composition of aquatic hyphomycetes were measured in communities colonizing four streambed substrata ( Platanus acerifolia and Populus nigra leaves, epipsammic and epilithic biofilms). Samples collected from the two reaches were subjected to two nutrient treatments in the laboratory [low nutrient (−NP) and high nutrient (+NP) concentrations] to test for short-term (48 h) nutrient effects. Long-term nutrient additions did not affect potential sporulation rates while short-term nutrient enrichment produced insignificant increase in these rates on most substrata collected in the unenriched reach. Major differences in potential sporulation rates were observed between substrata, the highest rate being for leaves (especially Platanus acerifolia). However, enrichment produced significant changes in fungal community composition. Clavariopsis aquatica, Alatospora acuminata and Lemonniera sp. were dominant in the enriched reach while Heliscella stellata, Trisceloporus acuminatus and Clavatospora longibrachiata were characteristic of the unenriched reach. Our results suggest that fungal N demands can be fulfilled at relatively low levels of dissolved nitrate and further increases in the nutrients availability may not result in enhanced fungal activity.

Elemental levels in tree-bark and epiphytic-lichen transplants at a mixed environment in mainland Portugal, and comparisons with an in situ lichen

Samples of Platanus hybrida Brot. bark and Flavoparmelia caperata (L.) Hale thalli, from a clean area in northern Portugal (Baião), were transplanted into an exposure location at the south-western Atlantic coast, impacted by urban-industrial emissions (Sines), for a 10-month long experiment. Bark pieces were confined into nylon bags (2-mm mesh), and lichen thalli kept with their bark substrate ( Pinus pinaster (Ait.) Sol.). Every two months, a double set of transplants (one for bark, one for lichens) was brought back into the laboratory, together with native samples of Evernia prunastri (L.) Ach. Following suitable cleansing and preparation procedures, field samples were put through INAA for elemental assessment. The results indicate that, regardless of signal magnitude, (1) concentrations in bark and lichen transplants are significantly correlated with atmospheric deposition for an appreciable number of elements; (2) there are a number of significant correlations between transplanted and native samples, and again between the latter and the deposition; and (3) the elements with biological patterns that follow the deposition in either transplanted or native samples (Co, V) are the very ones whose bioaccumulation seems to benefit from an alternation of wet-dry periods, which fits the precipitation record of the test site during the exposure term.

Copper, nickel and lead in lichen and tree bark transplants over different periods of time

This work aimed at comparing the dynamics of atmospheric metal accumulation by the lichen Flavoparmelia caperata and bark of Platanus hybrida over different periods of time. Transplants were exposed in three Portuguese coastal cities. Samples were retrieved (1) every 2 months (discontinuous exposure), or (2) after 2-, 4-, 6-, 8- and 10-month periods (continuous exposure), and analysed for Cu, Ni and Pb. Airborne accumulation of metals was essentially independent of climatic factors. For both biomonitors [Pb] > [Ni] > [Cu] but Pb was the only element for which a consistent pattern of accumulation was observed, with the bark outperforming the lichen. The longest exposure periods hardly ever corresponded to the highest accumulation. This might have been partly because the biomonitors bound and released metals throughout the exposure, each with its own dynamics of accumulation, but both according to the environmental metal availability.

Chlorophyll fluorescence imaging of photosynthetic activity in sun and shade leaves of trees

The differences in pigment levels, photosynthetic activity and the chlorophyll fluorescence decrease ratio R (Fd) (as indicator of photosynthetic rates) of green sun and shade leaves of three broadleaf trees (Platanus acerifolia Willd., Populus alba L., Tilia cordata Mill.) were compared. Sun leaves were characterized by higher levels of total chlorophylls a + b and total carotenoids x + c as well as higher values for the weight ratio chlorophyll (Chl) a/b (sun leaves 3.23-3.45; shade leaves: 2.74-2.81), and lower values for the ratio chlorophylls to carotenoids (a + b)/(x + c) (with 4.44-4.70 in sun leaves and 5.04-5.72 in shade leaves). Sun leaves exhibited higher photosynthetic rates P (N )on a leaf area basis (mean of 9.1-10.1 micromol CO(2) m(-2 )s(-1)) and Chl basis, which correlated well with the higher values of stomatal conductance G (s) (range 105-180 mmol m(-2 )s(-1)), as compared to shade leaves (G (s) range 25-77 mmol m(-2 )s(-1); P (N): 3.2-3.7 micromol CO(2) m(-2 )s(-1)). The higher photosynthetic rates could also be detected via imaging the Chl fluorescence decrease ratio R (Fd), which possessed higher values in sun leaves (2.8-3.0) as compared to shade leaves (1.4-1.8). In addition, via R (Fd) images it was shown that the photosynthetic activity of the leaves of all trees exhibits a large heterogeneity across the leaf area, and in general to a higher extent in sun leaves than in shade leaves.

Nuclear and non-nuclear techniques for assessing the differential uptake of anthropogenic elements by atmospheric biomonitors

The present study brings into focus tree-bark and lichen-thalli data from Parmelia caperata (L.) Ach. (syn. Flavoparmelia caperata (L.) Hale) and Platanus hybrida Brot. (syn. Platanus acerifolia (Ait.) Willd.), respectively, whose samples have been exposed at (transplanted into) a coastal location of south-western Portugal, impacted by urban-industrial emissions—Sines. Results for nickel (atomic absorption spectrophotometry; AAS) and vanadium (instrumental neutron activation analysis; INAA) are assessed and discussed here in terms of relative bioaccumulation, as well as in view of an influence of the precipitation regime on the corresponding elemental levels. Comparisons with similar experiments further afield suggest that enhanced levels of V in lichens could be due to an association of increased availability and alternate wet–dry periods. An overall reconciliation of [V] data from lichens seems therefore possible by assuming the former influence. Rainfall cycles did not appear to hinder or ease the Ni uptake though. Differential retention in lichens may thus be related to dissimilar mechanisms of accumulation, with Ni under some sort of homeostatic control and ionic forms of V competing for extracellular binding sites. Even if more conservative in absolute terms, bark indication closely follows lichens’ in either case. Mechanism(s) of elemental uptake are arguably different in bark, an aspect that requires further elucidation. Nickel and vanadium are signature elements that fingerprint fossil-fuel combustion, and have shown a typical [Ni]/[V] ratio around 0.3 in the Portuguese native lichen P. sulcata Taylor. Such ratio is approached by the present organisms in an exposed condition, after going through changes that may be viewed to reflect the above differential behaviour. The ratio is remarkably consistent in bulk deposition, pointing to a coal-burning signal superimposed on a general profile of oil-related industries.

Colchicine-induced chromosome doubling in Platanus acerifolia and its effect on plant morphology

We report the production of tetraploid plants of Platanus acerifolia, with the ultimate aim of improving the ornamental qualities of this important urban landscaping tree. Chromosome doubling was achieved by the application of colchicine to either pre-soaked seed or to the apical meristems of young seedlings. Treatment of the ungerminated seed was the more efficient method in terms of numbers of tetraploid seedlings (up to 40%, as determined by chromosome counting of the root-tip nuclei) but this method produced no mature tetraploid plants due to the deleterious effect of colchicine on subsequent root growth. When colchicine was applied directly to the apical growing tip of cotyledon-stage seedlings, leaf and stem growth was temporarily affected but the plants eventually recovered. We conducted a preliminary screen for putative tetraploids based on the observation in other plant species of a correlation of stomatal size and distribution with ploidy. Plants containing significantly larger stomata and at a lower density across the lower leaf epidermis, were selected for further analysis by flow cytometry and chromosome counting. These techniques confirmed that, of the 12 putative polyploids, four were tetraploid, five were mixoploid and three were, in fact, diploid. Morphological differences of the tetraploids included a more compact growth habit and broader, thicker leaves. These plants are being grown to full maturity in order to test their potential for use in a breeding programme aimed at producing sterile triploid lines.

Adventitious shoot regeneration of Platanus acerifolia Willd. facilitated by Timentin, an antibiotic for suppression of Agrobacterium tumefaciens in genetic transformation

The effects of Timentin and cefotaxime (Cef) on shoot regeneration of the London plane tree (Platanus acerifolia Willd.) and their use for the suppression of Agrobacterium tumefaciens in Agrobacterium-mediated genetic transformation were compared. Shoot regeneration was significantly reduced on the media with Cef at concentrations from 100 to 500 mg·L−1. Timentin showed negative effect on plant regeneration at concentrations of 100 and 500 mg·L−1; however, 300 mg·L−1 Timentin was shown to facilitate shoot regeneration significantly and the regeneration frequency increased from 64% (control) to 88%. Effective suppression of A. tumefaciens could be obtained with 500 mg·L−1 Cef, but plant regeneration was completely inhibited at this level. The A. tumefaciens on infected P. acerifolia leaf tissues was visually undetectable after three subcultures on a medium with 300 mg·L−1 Timentin. Considering the effect of Cef and Timentin on plant regeneration and suppression of Agrobacteria, Timentin at 300 mg·L−1 is the preferred application in A. tumefaciens-mediated transformation of P. acerifolia.