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The genus Arbutus (Ericaceae) has been traditionally used in folk medicine due to its phytomedicinal properties, especially Arbutus pavarii Pamp. However, this plant has not been evaluated for its efficacy, quality, and consistency to support the traditional uses, potentially in treating diabetes. Despite previous studies that revealed the biological activities of A. pavarii as antioxidant and α-glucosidase inhibitory agents, scientific reports on the bioactive compounds that contribute to its health benefits are still scarce. Therefore, this research focused on the evaluation of antioxidant and α-glucosidase inhibitory activities of the methanol crude extracts and various fractions of the leaf and stem bark, as well as on metabolite profiling of the methanol crude extracts. The extracts and fractions were evaluated for total phenolic (TPC) and total flavonoid (TFC) contents, as well as the DPPH free radical scavenging, ferric reducing antioxidant power (FRAP), and α-glucosidase inhibitory activities. Methanol crude extracts of the leaf and stem bark were then subjected to UHPLC–ESI–MS/MS. To the best of our knowledge, the comparative evaluation of the antioxidant and α-glucosidase inhibitory activities of the leaf and stem bark of A. pavarii, as well as of the respective solvent fractions, is reported herein for the first time. Out of these extracts, the methanolic crude extracts and polar fractions (ethyl acetate and butanol fractions) showed significant bioactivities. The DPPH free radical and α-glucosidase inhibitions was highest in the leaf ethyl acetate fraction, with IC50 of 6.39 and 4.93 µg/mL, respectively, while the leaf methanol crude extract and butanol fraction exhibited the highest FRAP with 82.95 and 82.17 mmol Fe (II)/g extract. The UHPLC–ESI–MS/MS analysis resulted in the putative identification of a total of 76 compounds from the leaf and stem bark, comprising a large proportion of plant phenolics (flavonoids and phenolic acids), terpenoids, and fatty acid derivatives. Results from the present study showed that the different parts of A. pavarii had potent antioxidant and α-glucosidase inhibitory activities, which could potentially prevent oxidative damage or diabetes-related problems. These findings may strengthen the traditional claim on the medicinal value of A. pavarii.

Strawberry tree (Arbutus unedo L.), an evergreen shrub/small tree of the family Ericaceae, is a main constituent of the Mediterranean basin flora; although it is also found in southwestern Prance, Macaronesia, and Ireland. The small fruits are edible but mostly used for preparation of preserves and jams, and for liquors such as the Portuguese traditional "aguardente de medronho". Traditionally cultivated by small farmers, often in consociation with Quercus sp., strawberry tree is presently emerging as a new important fruit crop cultivated in large orchards by modern export-oriented enterprises. This change of paradigm requires a growing role of plant breeding, upstream of the production process. Genomic tools for this species are mostly limited to the chloroplast genome sequence and to genomic data described in this work. In order to identify strawberry tree microsatellite (SSR) loci we performed partial genome next-generation sequencing using the Ion Torrent technology. The sequenced similar to 24.6M nucleotides resulted in the identification of 1185 microsatellite markers mostly constituted by dinucleotide motifs. The relative amount of microsatellite dinucleotide motifs (AG/CT - 71.7%, AC/GT - 20.5%, AT/AT - 2.9%, and CG/CG - 0.3%) is similar to the one observed in other Ericaceae species. Among a tested sample of 40 SSR primer pairs, 20 amplified well-defined PCR products, 12 (30%) were validated as polymorphic. Used in our collaborative project for molecular identification of selected and improved clones, the identified SSR loci constitute a strong tool for a large panoply of applied and fundamental studies of this emerging fruit crop. Pluriannual Funding Program of the Portuguese National Foundation for Science and Technology info:eu-repo/semantics/publishedVersion

In addition to nutrients, plant foods contain compounds that may provide additional health benefits improving the quality of life. Species from Arbutus genus (Ericaceae) represent a promising source of healthy phytochemicals. Bioactive compounds including such as anthocyanins, iridoids, phenols, triterpenes, sterols, and fatty acids are reported from Arbutus species. Some Arbutus species revealed promising biological activities including antioxidant, anti-inflammatory, anti-proliferative, anti-diabetic, and antimicrobial activities, and deserve for that reason further consideration for new drug discovery. However, only few species are investigated scientifically for their chemical profile and biological activities. The aim of this article is to summarize the current knowledge of the components and biological properties of Arbutus species common in Mediterranean area, as well as the future prospects on their applications as potentially valuable products.

This study focuses on botanical features gleaned from the literary source Hypnerotomachia Poliphili (1499); the analysis reveals that Hypnerotomachia Poliphili includes 285 botanical entities associated with 672 textual passages, which have not hitherto been reported. Roses, myrtle, pines, cypresses, laurel, acanthus, oaks, junipers, ivy, thyme, violets, sandalwoods and orange trees are the most frequently cited plants. Shrubs dominate with 43%, while herbs and trees follow with 28% and 26%, respectively. Arbutus, dittany, cypress, fig tree, labdanum, laurel, myrtle, oaks, oleander, wild and cultivated olive trees, oregano, pine, thyme, grapevines are associated with the diversity of Mediterranean ecosystems. In addition, numerous textual passages of Hypnerotomachia Poliphili mentioning flowering and fruiting plants reveal the seasonality of the Mediterranean region. Exotic plants, such as frankincense tree, myrrh, banana, pepper, sandalwood and jasmines are also included. Thorny plants, sharp thistles and cedars are cited in the text as occurring among ancient monuments and historical ruins. The botanical content of Hypnerotomachia Poliphili constitutes an alternate source of botanical observation, which includes historical, allegoric and symbolic information. © 2016 Société botanique de France.

The iconic tree species, Arbutus menziesii (Pacific madrona, madrone arbutus), has been in decline in the Pacific Northwest of North America for the past 40 years. It is thought that the fungal pathogen Neofusicoccum arbuti has contributed to the decline of this tree species. In recent years, there have been reports of declining arbutus in the coastal region of southern British Columbia, Canada. We conducted intensive sampling in a park with severely affected arbutus trees to determine the cause and prevalence of decline. The majority of arbutus trees sampled in this study had cankers associated with N. arbuti infection. We also sought to determine if N. arbuti has additional hosts that could act as a reservoir for this pathogen. Six new hosts of N. arbuti were identified, and a seventh was confirmed; these hosts spanned four taxonomic orders and included Amelanchier alnifolia, Cytisus scoparius (confirmed), Gaultheria shallon, Ilex aquifolium, Rosa sp., Sorbus sitchensis and Spiraea douglasii. Re...

Honey is a natural pure food produced by honeybees from the nectar of various plants, and its chemical composition includes carbohydrates, water, and some minor compounds, which are very important for honey quality and authentication. Most of honey&rsquo, s minor components are related to the botanic origin, climate, and geographic diversity. In this work, we report an original case study on monofloral honey samples of twelve different botanic origins produced in Tuscany (Italy) based on the &lsquo, semi-quantitative&rsquo, analysis of emission, excitation, and synchronous front-face fluorescence spectra. This is the first front-face fluorescence study of Italian honey samples and, to our knowledge, the first fluorescence investigation of honey from inula (Inula viscosa (L.) Aiton), marruca (Paliurus spina-christi Mill.), lavender (Lavandula L. 1753), sulla (Hedysarum coronarium L.), arbutus (or strawberry tree) (Arbutus unedo L., 1753), and alfalfa (Medicago sativa L.) plants. Results obtained from fluorescence spectroscopy are discussed in terms of characteristic spectral emission profiles typical of honey of different botanic origins. Moreover, the spectral analysis based on the decomposition of the front-face fluorescence (FFF) spectra in terms of single main fluorophores&rsquo, components is here proposed to identify several minor compounds, such as amino acids, phenolic acids, vitamins, and other fluorescent bioactive molecules.

Features of the adaxial and abaxial surface microstructure of Arbutus unedo L. and Arbutus andrachne L. are evaluated as possible consistent parameters contributing to the wetness of leaves. The abaxial leaf surface of A. andrachne and A. unedo was determined to be more hydrophobic than the adaxial leaf surface. Hydrophobicity may be of particular importance for the ecophysiological status of the hypostomatic leaves of both Arbutus species, which exhibit a long lifespan and are exposed to various environmental stimuli. Water repellence may also be correlated to the increased presence of surface wax. Lipid analysis of the leaves of both plant species revealed an abundance of α-linolenic acid, with palmitic acid as the second major contributor, followed by linoleic and oleic acid. Oleic and linoleic acid were present in slightly larger percentages in A. andrachne compared with A. unedo, whereas myristic, palmitic and α-linolenic acids were found in elevated percentages in A. unedo. The fatty acid co...

© 2016 John Wiley & Sons Ltd Mesophyll conductance to CO2(gm) may respond to light either through regulated dynamic mechanisms or due to anatomical and structural factors. At low light, some layers of cells in the leaf cross-section approach photocompensation and contribute minimally to bulk leaf photosynthesis and little to whole leaf gm(gm,leaf). Thus, the bulk gm,leafwill appear to respond to light despite being based upon cells having an anatomically fixed mesophyll conductance. Such behaviour was observed in species with contrasting leaf structure using the variable J or stable isotope method of measuring gm,leaf. A species with bifacial structure, Arbutus × ‘Marina’, and an isobilateral species, Triticum durum L., had contrasting responses of gm,leafupon varying adaxial or abaxial illumination. Anatomical observations, when coupled with the proposed model of gm,leafto photosynthetic photon flux density (PPFD) response, successfully represented the observed gas exchange data. The theoretical and observed evidence that gm,leafapparently responds to light has large implications for how gm,leafvalues are interpreted, particularly limitation analyses, and indicates the importance of measuring gmunder full light saturation. Responses of gm,leafto the environment should be treated as an emergent property of a distributed 3D structure, and not solely a leaf area-based phenomenon.

A total of 30 samples of honey were collected from the beekeepers throughout different regions of Albania and analysed for their pollen grains content and control of botanical origin. Honey sediments obtained from honey samples were processed based on the method of basic fuchsine and acetolysis. Quantitative and qualitative analysis of pollen grains in honey was done based on the methodology given by Maurizio and the terms of the pollen grains frequencies approved by the International Commission for Bee Botany. 16 out of 30 samples of honey were polyfloral and the rest unifloral. The majority of monofloral honey was characterised by the presence of genus of Castanea, Arbutus and Erica pollen. The presence of few pollen grains of genus such as Tilia, Rubus and Artemisia, were identified in only one honey sample. It was concluded that the most preferable plants for the bees are those of the genus of Erica, Arbutus, Castanea, Artemisia, Tilia, Rubus, Lotus, Trifolium, Filipendula, Crepis, Thymus, Quercus, Rosa, Centaurea, Coronilla, Anchusa etc. Honey samples collected from different regions of Albania were natural, pure and unprocessed termically. DOI: 10.5901/ajis.2016.v5n3s1p261

Physicochemical properties (pH, free, lactonic and total acidity, electrical conductivity and moisture), main mineral content (potassium, sodium, calcium, magnesium and iron) and antioxidant activity (total phenolics, 1,1diphenyl-2-picrylhydrazyl radical scavenging and ferric reduction antioxidant power) were determined for 39 Portuguese monofloral honeys (rosemary, orange, thyme, arbutus, locust podshrub and heather) with different geographical origins. Portuguese honeys showed good chemical and nutritional qualities fulfilling the criteria described in Directive 2001/110/CE. Potassium was the main mineral component representing 85% of total minerals. The mineral composition of sodium (4.63–200.60 mg/kg), calcium (0.43–72.30 mg/kg), magnesium (3.05–82.20 mg/kg) and iron (below 7.06 mg/kg) were higher for heather, eucalypt and arbutus honeys. Monofloral honeys of arbutus ( Arbutus unedo ), locust podshrub ( Ceratonia siliqua L.) and heather ( Erica umbellata ) showed higher antioxidant activity with phenolic contents higher than 600 mg gallic acid equivalents (GAE)/kg, a DPPH scavenging activity higher than 50% and a ferric reduction antioxidant power above 600 μM Fe 2+ . Furthermore, the chemometric analysis revealed that total phenolic content was a crucial variable explaining the antioxidant activity of arbutus and locust podshrub honeys characteristic of the south of Portugal.

Se describe e ilustra a Arbutus bicolor S. González, M. González et P. D. Sørensen, sp. nov., especie relacionada con A. xalapensis H.B.K., que ha sido por largo tiempo identificada erróneamente como A. glandulosa M. Martens & Galeotti, un sinónimo de esta última. Se diferencia de A. xalapensis por tener las ramillas y pecíolos densamente glandular pubescentes, las hojas marcadamente bicolores con envés blanquecino a ocre pálido debido a la presencia de indumento denso y uniforme de pelos apretadamente crespos, las hojas de color rojo intenso en la senescencia, así como las flores de color rosa o raramente blanco. Arbutus bicolor está ampliamente distribuida en la Sierra Madre Occidental y el Eje Neovolcánico, alcanzando la vertiente occidental de la Sierra Madre Oriental. Se registran híbridos esporádicos con A. madrensis S. González, A. occidentalis McVaugh & Rosatti, A. tessellata Sørensen y A. xalapensis. Se incluye una clave para distinguir a A. bicolor de otras especies arbóreas de Arbutus de México.

The aim of the present study was to obtain two distilled alcoholic beverages from red raspberry and arbutus berry by solid-state fermentation and subsequent distillation of the fermented fruits. The mean concentrations of ethanol and volatile substances in the distillates from red raspberry (41.3 and 200.1 g/hL aa) and arbutus berry (44.3 and 267.1 g/hL aa) were higher than the corresponding minimum limits (38.5 and 200 g/hL aa) fixed by the European Council (Regulation 110/2008) for fruit distillates. In addition, the mean concentrations of methanol in the two alcoholic beverages (113.9 g/hL aa in case of red raspberry, and 320.5 g/hL aa in case of arbutus berry) were much lower than the maximum levels of acceptability that the aforementioned regulation fixed for red raspberry (1200 g/hL aa) and arbutus berry (1000 g/hL aa) distillates. These results showed that both fruits can be used as fermentation substrates for producing two alcoholic beverages with high quality, which are safe for the consumers without any repercussion to their health from methanol concentrations.

Two new microfungi, a fungicolous Scolecobasidium, S. rostricola sp. nov., colonising the ostiolar necks of a new coelomycete, Caducirostrum foliicola gen. & sp. nov., on leaf litter of Viburnum tinus, Arbutus unedo, Prunus laurocerasus and P. lusitanica from the U.K. and Italy, are described, illustrated and compared with other relevant taxa. Rhabdostromina, with new combinations for Dendroseptoria arrhenatheri and D. oryzopsidis, is resurrected.

The relationship between net photosynthetic (P N) and leaf respiration (R) rates of Quercus ilex, Phillyrea latifolia, Myrtus communis, Arbutus unedo, and Cistus incanus was monitored in the period February 2006 to February 2007. The species investigated had low R and P N during winter, increasing from March to May, when mean air temperature reached 19.2 °C. During the favourable period, C. incanus and A. unedo had a higher mean P N (16.4±2.4 µmol m−2 s−1) than P. latifolia, Q. ilex, and M. communis (10.0±1.3 µmol m−2 s−1). The highest R (1.89±0.30 µmol m−2 s−1, mean of the species), associated to a significant P N decrease (62 % of the maximum, mean value of the species), was measured in July (mean R/P N ratio 0.447±0.091). Q10, indicating the respiration sensitivity to short-term temperature increase, was in the range 1.49 to 2.21. Global change might modify R/P N determining differences in dry matter accumulation among the species, and Q. ilex and P. latifolia might be the most favoured species by their ability to maintain sufficiently higher P N and lower R during stress periods.

Mediterranean native shrubs can be very useful for green roofs in hot and arid regions. Our data show that both Arbutus unedo L. and Salvia officinalis L. could be successfully utilized, although the choice of species should be based on the drought-resistant strategy relative to the desired technical performance of the green roof. Moreover, substrate selection was found to have a crucial role in the success of green roof installations in the Mediterranean area., Recent studies have highlighted the ecological, economic and social benefits assured by green roof technology to urban areas. However, green roofs are very hostile environments for plant growth because of shallow substrate depths, high temperatures and irradiance and wind exposure. This study provides experimental evidence for the importance of accurate selection of plant species and substrates for implementing green roofs in hot and arid regions, like the Mediterranean area. Experiments were performed on two shrub species (Arbutus unedo L. and Salvia officinalis L.) grown in green roof experimental modules with two substrates slightly differing in their water retention properties, as derived from moisture release curves. Physiological measurements were performed on both well-watered and drought-stressed plants. Gas exchange, leaf and xylem water potential and also plant hydraulic conductance were measured at different time intervals following the last irrigation. The substrate type significantly affected water status. Arbutus unedo and S. officinalis showed different hydraulic responses to drought stress, with the former species being substantially isohydric and the latter one anisohydric. Both A. unedo and S. officinalis were found to be suitable species for green roofs in the Mediterranean area. However, our data suggest that appropriate choice of substrate is key to the success of green roof installations in arid environments, especially if anisohydric species are employed.

The total nitrogen (N) concentration and nitrate/ammonium ratio (NO3 −/NH4 +) in nutrient solutions were optimized in sand cultures and in 15N experiments for laurustinus (Viburnum tinus), tobir (Pittosporum tobira), and strawberry tree (Arbutus unedoL.) under controlled conditions during three growing cycles. Results from the 15N experiment suggest that Arbutus unedo and, to a minor extent, Pittosporum could regulate the N-NH4 + absorption independently of the external concentration and reduce the toxic effects of N-NH4 +. For Viburnum tinus plants, however, higher external N-NH4 + concentration increased root N-NH4 + and, therefore, could have toxic effects. The optimal N concentration in nutrient solutions and in nitrate-only nutrition would be close to 4.6 mmolc L−1 for Viburnum tinus and close to 5.8 mmolc L−1 for Pittosporum tobira, with a 70/30 (%) NO3 −/NH4 + ratio. For Arbutus unedoL., a total N concentration higher than 9 mmolc L −1 is suggested, with a 70/30 NO 3 −/NH 4 + ratio. Plant-...

Arbutus ( Arbutus menziesii Pursh. (Ericaceae)) is the only broadleaved evergreen tree native to Canada. It occurs in three red-listed (endangered) plant communities in British Columbia (BC), threatened by urban encroachment, fire suppression, grazing, and exotic invasive species. Its growth is sensitive to environmental changes: more severe summer drought caused by climate change could further threaten this species. Amplified fragment length polymorphisms (AFLPs) were assayed in 10 populations in BC and 1 in Washington to obtain baseline population genetic and mating system data. We found that genetic diversity within populations was low (mean H = 0.094) for a woody perennial. Genetic variation among populations (FST= 0.15) was comparable to woody perennials on average (0.19). Pairwise kinship coefficients were significantly associated with distance (p < 0.01). The multilocus outcrossing rate for one BC island population was high (tm= 0.97), but inbreeding due to consanguineous matings was also quite high (tm– ts= 0.10). These data can be used to guide conservation strategies and future research priorities for arbutus.

The mineral, total amino acid, and sterol compositions of pollen collected by Apis mellifera L. were compared with the pollen of a plant consumed by Bombus terrestris (L.): Arbutus unedo L. This plant provides the predominant food resource for the main autumn generation of B. terrestris in southern France. Honey bees also forage on this plant, although only for nectar. The mineral composition of 30 pollen samples collected by honey bees is close to the presently known requirements of A. mellifera, except for Cu and Mn, which are substantially lower. The total amino acid mean composition of a set of 54 pollen samples fits the basic requirements of honey bees except for valine, isoleucine, and methionine, which are present in lower concentrations in all the samples. For pollen of A. unedo, the amino acid balance is not very different from that of the survey. The main sterolic component in pollen of A. unedo, β-sitosterol, is known to have antifeedant effects on A. mellifera. Honey bees cannot dealk...

Pacific madrone (Arbutus menziesii) is a broadleaf evergreen tree native to western North America that has been in decline for the past 30 years. A fungus has been isolated and was verified as the cause of cankers on dying trees. It was determined to belong in the genus Fusicoccum, an asexual state of Botryosphaeria. This genus in both its sexual and asexual states commonly causes canker diseases of deciduous woody plants. Using morphological and molecular data the fungus causing cankers on Pacific madrone is characterized, described and illustrated as a new species of Fusicoccum, F. arbuti D.F. Farr & M. Elliott sp. nov. No sexual state is known for F. arbuti. Evidence from the literature, cultures and specimens suggests that F. arbuti, often mistakenly identified as Nattrassia mangiferae, has been causing madrone canker since at least 1968. Authentic isolates of Nattrassia mangiferae as the synanamorph Scytalidium dimidiatum were sequenced and determined to be different from Fusicoccum arbuti and to belong in Botryosphaeria/Fusicoccum. In addition to molecular sequence data, the morphology of the pycnidial and arthric conidial states of Nattrassia mangiferae/ Scytalidium dimidiatum resembles that of Fusicoccum. Therefore the correct name for Nattrassia mangiferae and its numerous synonyms (Dothiorella mangiferae, Torula dimidata, Scytilidium dimidiatum, Fusicoccum eucalypti, Hendersonula toruloidea, H. cypria, Exosporina fawcetii, H. agathidia, and S. lignicola) is Fusicoccum dimidiatum (Penz.) D.F. Farr, comb. nov.

The UV-absorbing capacity (measured as A(310) cm(-2) and A(365) cm(-2) or AUVR cm(-2)) of the shade leaves of four representative evergreen sclerophylls of the Mediterranean region (Quercus coccifera, Q. ilex, Arbutus andrachne and A. unedo) was considerably lower than the corresponding one of sun leaves of the same species. However, fibre optic microprobe measurements showed that adaxial as well as abaxial epidermis of shade leaves of all examined plants, except abaxial epidermis of A. andrachne, were almost as effective as the corresponding ones of the sun leaves in screening out most of the incident UV-B radiation. There is probably a threshold, under which the concentration of the UV-B absorbing compounds in the protective tissues is not furthermore reduced, in spite of the low levels of the stress factor (UV-B radiation) in the environment. On the other hand, the ability of both abaxial and adaxial epidermis to attenuate UV-A radiation, except of adaxial leaf epidermis of Quercus species, depended on the UV absorbing capacity of the whole-leaf extracts, with different correlation patterns between the two Quercus species and the two Arbutus species. This could be explained by the fact that shade leaves showed not only quantitative, but also qualitative differences (higher A(310)/A(365) ratio) in the absorbance of their methanolic extracts compared to these of sun leaves. The results of the present study showed that we should not always correlate the depth of penetration of UV radiation into sun and shade leaves according to the corresponding UV absorbing capacity of the whole leaf methanolic extracts, without taking into account all the anatomical, developmental and biochemical (such as different composition and distribution of the UV-absorbing compounds among the different protective tissues) peculiarities of the leaves of each species. (Less)

Summary • We tested the hypothesis that unavoidably soft young leaves, which are therefore vulnerable to herbivory, should rely heavily on chemical defense to avoid overconsumption by herbivores. • Along with area lost to herbivores, parameters related to chemical and mechanical defense were monitored in two evergreen Mediterranean sclerophylls (Arbutus unedo and Arbutus andrachne) during spring and early summer, when newly growing and old leaves co-occur on the same branches. • During the lag phase of growth, young leaves were soft, rich in phenolics and gallotannins (up to 50% and 14% w/w, respectively) and highly astringent. During this period, the main consumer, a cricket (Poecilimon sp., Phaneropterinae) fed almost exclusively on the much tougher old leaves, which were low in phenolics (16%), gallotannins (6%) and astringency. During the rapid phase of leaf expansion, toughness increased and phenolics, gallotannins and astringency dropped to levels characteristic of old leaves. At that time, a shift in insect preferences towards young leaves was evident. Nitrogen content was independent of leaf age. • We conclude that leaf toughness is less important than chemical composition in the Arbutus–Poecilimon system, where gallotannins may play a decisive role.

A new species of Struthanthus from the state of Guerrero, Mexico, is described and illustrated: Struthanthus ramiro-cruzii. It grows in oak and pine-oak forests, in the physiographic province of the Southern Coastal Range in the Guerrerense region. It is morphologically similar to S. deppeanus, but differs by having leaves with a subcordate to truncate base, a sessile central flower of the triad and a strongly convoluted style. A key to distinguish the new species from other species of the genus present in the state of Guerrero is included.

In the Panasqueira mine area, Arbutus unedo L. (arbutus tree) grows on soils developed on waste materials and on soils impacted by mining activity. The arbutus berry brandy is considered a product with economic value. The aims of this study were to evaluate the biogeochemical impact of the mining activity on soils and arbutus trees, to assess the possible risks associated with human consumption of the fruits and the derived brandy, and to evaluate the potential of the arbutus tree in phytostabilization. Soil samples (10-15 cm deep) developed on waste materials, on schists affected by seepage water or treatment plant effluents and on colluvium-alluvium materials were characterized (fraction < 2 mm) for pH, particle size distribution, organic carbon (C-org), cation exchange capacity (CEC) and NPK by classical methodologies. Plant (A. unedo) samples (roots, leaves and twigs, and fruits) were collected at the same sites as the sampled soils, washed with tap and distilled water and dried at 40 A degrees C. The elements' concentrations in soils (total fraction-four-acid digestion and available fraction-diethylenetriaminepentaacetic acid extraction), plants (ashing followed by acid digestion) and brandy samples produced with fruits collected on contaminated and non-contaminated sites were determined by inductively coupled plasma atomic emission spectroscopy. The soils are mainly acid, silty loam, with variable values for C-org, CEC and NPK. They are contaminated with As (158-7,790 mg/kg), Cd (0.6-79 mg/kg), Cu (51-4,080 mg/kg), W (19-1,450 mg/kg) and Zn (142-12,300 mg/kg). The available fraction of the soils is quite variable between < 0.04 and 76 % of the total, depending on the element. Trace elements' concentrations, in leaves and twigs, are within the normal range for plants, except for Cd and Zn that, in some samples, are above the normal values, but without phytotoxic symptoms. Trace elements' concentrations in fruits are low. The calculated hazard quotient for all trace elements in arbutus berry was < 0.1. In the brandy, elemental concentrations are within the legal standards, except for Pb, whose higher concentrations may result from distillery equipment. According to the EC 466/2001 legislation and with a hazard quotient of < 1, the arbutus berry consumption does not constitute health risks for humans. The fruits can be used to produce local brandy. The concentration of copper in brandy is within the range established by the Portuguese legislation. Arbutus unedo can be used in the phytostabilization programs in the Panasqueira area, for it is a pioneer species and a non-accumulator of trace elements.

This study aims at the determination of some physical and chemical characteristics of strawberry-tree fruit (Arbutus unedo L.), a typical Mediterranean climate species, namely of the Portuguese region of Algarve. It intends to be a contribution to its valorization and other applications following research by other scientists and local development associations as far as a better quality of alcoholic distillate of arbutus berry is concerned. Arbutus berry appears to be a good source of vitamins, namely niacin, ascorbic acid and β -carotene (content of 9.1, 346.3 and 70.9 mg/100 g, respectively), organic acids (nearly 9%), total sugars (c. 42%) and tannins (1.75 mg g−1).

The invertase activity was determined for 499 honeys (27 multifloral and 472 unifloral from Arbutus, Carduus, Castanea, Citrus, Erica, Eucalyptus, Hedysarum, Helianthus, Rhododendron, Robinia, Rosmarinus, Taraxacum, Thymus, Tilia, fir honeydew and honeydew produced by Met- calfa pruinosa), in order to determine its variability and establish the range characteristic for each honey type. The results show that invertase activity varies considerably in the different honey types (from less than 0.5 to more than 30 IN). Robinia, Arbutus, Citrus, Erica and Rosmarinus have the lowest values (usually less than 10) and the two honeydew honeys the highest (more than 18). The diastase content of the samples was also measured, to compare the content of the two enzymes, and a certain correlation was observed (r = 0.835, P < 0.001). The IN/DN ratio ranges from less than 0.1 to more than 2. The possible role of invertase and IN/DN ratio in honey quality evaluation is discussed. © Inra/DIB/AGIB/Elsevier, Paris

1. We investigated whether reserves stored in the lignotubers of two Mediterranean shrubs, Arbutus unedo and Erica arborea, were significantly mobilized to support the demands of regrowth and respiration after clipping the tops at different frequencies. 2. After a single clipping, Arbutus showed a 29% decrease of phosphorus concentration by the end of the first growing season. Two years after recovery from clipping, the starch levels remained lower than those of unclipped plants. Similarly, Erica showed depletion of starch, but no nutrient reserves were depleted significantly. 3. Regrowth after multiple clippings mobilized a large fraction of the starch and nutrients stored in the lignotuber. Mean starch concentrations were depleted by 87–93% after multiple clippings and concentrations of nitrogen, phosphorus, potassium and magnesium were depleted by 10–45%, 27–41%, 19–39% and 23–31%, respectively. 4. An average-sized lignotuber produced 288 resprouts for Arbutus and 1990 resprouts for Erica during a 27 month period of multiple clippings, at the end of which the first plants died. 5. Plant mortality after multiple clipping was 10% for Arbutus and 30% for Erica, and was primarily attributed to exhaustion of carbon reserves because starch concentrations decreased by 96% in dead plants.

Se presentan los resultados del estudio anatómico de la madera de Alnus acuminata Kunth, Ostrya virginiana Rose, Quercus dysophylla Benth., Quercus glabrescens Benth., Arbutus glandulosa DC., Arbutus tessellata Sorensen, Styrax argenteus Presl. y Buddleia wrightii Robinson, de muestras provenientes de los estados de Jalisco y Puebla. Para cada taxa estudiado, se describe n los caracteres anatómicos de los vasos, parénquima axial , radios y fibras; también se sugieren algunos usos para la madera de estas especies.

In the Mediterranean region the fruits of the strawberry tree (Arbutus unedo L.) may be fermented and distilled to produce a traditional beverage very much appreciated in Southern Europe. The aim of the present work was to study the diversity of the yeast population and the killer activity of the isolates identified as Saccharomyces cerevisiae, obtained during solid state industrial fermentations of the arbutus berries. The identification of the isolates was performed by the 5.8S rRNA-ITS region restriction analysis and by sequencing the D1/D2 region of the large subunit of the rRNA gene. At the start of the fermentations, various non-Saccharomyces species were detected including Aureobasidium pullulans, Dothichiza pithyophila, Dioszegia zsoltii, Hanseniaspora uvarum and yeasts belonging to the genera Metschnikowia, Cryptococcus and Rhodotorula. However, as the biological processes progressed the number of different species decreased with S. cerevisiae and Pichia membranaefaciens becoming dominant at advanced stages of the must fermentation that is characterized by high concentrations of ethanol. Forty three isolates identified as S. cerevisiae were tested for killer activity against two sensitive reference strains and Zygosaccharomyces bailii. Their killer sensitivity in relation to five killer referenced toxins (K2, K5, K8, K9 and K10) was also studied. Out of the isolates analyzed, 95.3% were sensitive and 4.7% were tolerant against the killer toxins tested. Only three isolates revealed killer activity against one sensitive strain and two of them against the spoiler yeast Z. bailii. The microbiota obtained revealed an interesting potential to be used as starter cultures to overcome unpredictable uncontrolled fermentations of the arbutus fruits as well as in other applications of biotechnological interest. (C) 2012 Elsevier Ltd. All rights reserved.

Leaves of Cistus incanus (summer), Arbutus andrachnoides (winter), A. andrachnae (spring) and a summer or autumn harvest of A. unedo, Carpinus duinensis, Quercus coccifera and Fraxinus ornus were analysed for neutral and acid detergent fibre (NDF, ADF), lignin, crude protein (CP), total extractable phenols (TEPH), total extractable tannins (TETa) and total extractable condensed tannins (vanillin-HCl TECTa), and total extractable proanthocyanidins (TEPA) or total proanthocyanidins (TOPA). Gas production (in vitro) from the samples was measured during 96 h incubation with or without addition of insoluble polyvinylpolypyrrolidone (PVP). Concentrations of the phenolics and the fibre components were variable ( P −1 dry matter (DM), but was always decreased by 15–25% with maturity, whereas concentrations of TECTa, TEPA and TOPA increased ( P A. unedo, C. duinensis and Q. coccifera , but not in F. ornus ( P > 0.05). Concentrations of phenolics were negatively related ( P > 0.05) to gas production. The correlation coefficient of the relationship was highest with TETa ( P > 0.05; r = −0.38) and TOPA ( P > 0.05; r = −0.55) at 96 h incubation. Excluding C. incanus , gas production was related ( P r = −0.63) and TOPA ( r = −0.68) at 96 h incubation. The increase in gas production on PVP treatment was highest (22%) from Q. coccifera (summer) (22%) after 24 h and C. incanus (22%) after 96 h incubation. However, despite their high content of tannins, the increase from the Arbutus species was low. On the other hand, when PVP was added to F. ornus , which had the lowest tannin content, it produced 14% more gas after 24 h incubation. In addition, the highest increase in gas production after treatment with PVP was produced at different periods of the incubation. As a result, the increase in gas production was not related ( P > 0.05) to any of the phenolic assays used, and the biological response to polyphenolic compounds depends on their nature and varies between plant species. However, although several aspects of the treatment with PVP should be further studied, the gas production technique in combination with PVP appears to have good potential for providing better insight into the effects of phenolics-related antinutritive factors in biological systems.

During field work in Tenerife, Canary Islands, we have located a population of Arbutus unedo L. until now unknow to us. We observed that among the individuals of this population some possessed characteristics similar to A. canariensis Veill. After a detailed study of these individuals we decided that they represented a new interspecific hybrid. The present paper constitutes a first step toward a revision of the genus Arbutus in the Canary Archipelago.

Arbutoid mycorrhizae were synthesized in growth pouches between Arbutus menziesii Pursch. (Pacific madrone) and two broad host range basidiomycete fungi, Pisolithus tinctorius (Pers.) Coker and Couch and Piloderma bicolor (Peck) Julich. P. tinctorius induced the formation of dense, pinnate mycorrhizal root clusters enveloped by a thick fungal mantle. P. bicolor mycorrhizae were usually unbranched, and had a thin or non-existent mantle. Both associations had the well-developed para-epidermal Hartig nets and intracellular penetration of host epidermal cells by hyphae typical of arbutoid interactions. A. menziesii roots developed a suberized exodermis which acted as a barrier to cortical cell penetration by the fungi. Ultrastructurally, the suberin appeared non-lamellar, but this may have been due to the imbedding resin. Histochemical analyses indicated that phenolic substances present in epidermal cells may be an important factor in mycorrhiza establishment. Analyses with X-ray energy dispersive spectroscopy showed that some of the granular inclusions present in fungal hyphae of the mantle and Hartig net were polyphosphate. Other inclusions were either protein or polysaccharides.

The fruits and leaves of Arbutus species are well known in folk medicine as antiseptics, diuretics, and laxatives in many parts of Turkey. Some chemical properties including pH, soluble solid content, titratable acidity, protein, moisture, ash, ascorbic acid, fructose, glucose, sucrose, total phenols, total antioxidant activity, and minerals were determined in fully matured Arbutus unedo L. and Arbutus andrachnae L. fruits collected from different sites of Canakkale, Turkey in 2006 and 2007. Total soluble solids, titratable acidity, protein, moisture, and ash content of A. unedo and A. andrachnae berries were on average 16.0% and 14.0%, 0.4% and 0.6%, 2.38% and 3.77%, 47.21% and 38.21%, and 2.82% and 4.35%, respectively. The mean values of ascorbic acid were 270.50 mg/100 g for A. unedo and 140.30 mg/100 g for A. andrachnae, which suggested that Arbutus berries contain high amounts of vitamin C. In the strawberry tree fruits, fructose and glucose were determined to be the major sugars. The analysis showed that fructose and glucose occurred in concentrations of 24.09% and 19.09%, respectively. However, ripe A. andrachnae fruits contained small amounts of fructose (4.12%), glucose (2.73%), and sucrose (0.16%) detectable by high-performance liquid chromatography analysis. The general order of abundance of the minerals was KCaPMgNa in whole fruit of the strawberry tree. The chemical composition of Arbutus fruits indicates that the fruits are good sources of minerals and ascorbic acid and that they are high in phenolics and antioxidant capacity and low in soluble sugars, especially A. andrachnae. The data should be useful for research purposes and for compiling local food composition tables. In view of its chemical composition, the use of Arbutus fruits in some food products may be suggested.

International audience; The resorption of nutrients (mainly N and P) from senescing leaves may be a key component of adaptive mechanisms that conserve scarce nutrients. Resorption may be expressed in two ways as resorption efficiency (RE) which is the ratio of the resorbed amounts of nutrient losses during leaf senescence in relation to its prior amount deposited in leaves and resorption proficiency (RP) is the level to which nutrient concentration per unit leaf mass is reduced in senescent leaves.* There is still much debate whether or not different life-forms (i.e. deciduous and evergreen species) show different foliar resorption patterns. Two sympatric species, namely Quercus petraea (Mattuschka) Liebl. subsp. iberica (Steven ex Bieb.) Krassiln. (deciduous) and Arbutus andrachne L. (evergreen) along an elevational gradient were compared with each other to determine whether or not nitrogen and phosphorus resorption efficiency and proficiency varies along the elevational gradient and which leaf parameters were as related to RE and RP.* NRE was found to be rather low in Q. petraea subsp. iberica compared to other deciduous species. Similarly, PRE in A. andrachne was rather low compared to other evergreen species. Mean residence time (MRT) measures how long a unit of nitrogen (MRTN) and phosphorus (MRTP) is present in the plant. MRTN and MRTP were found to be considerably higher in A. andrachne compared to Q. petraea subsp. iberica. In both species, the foliar N/P ratio was below 14 along the elevational gradient and, according to this threshold value, N-limitation occurred in the study area. Although both species in the present study show incomplete resorption deciduous species was more proficient as compared to evergreen one due to low N and P concentrations in senescent leaves. Based on the significant correlations (p < 0.05 and 0.01) between MRT and foliar resorption, it can be concluded that MRT could interfere with the mechanisms controlling nutrient resorption.; La résorption des éléments nutritifs (essentiellement N et P) par sénescence des feuilles peut être une composante clé des mécanismes d'adaptation qui permettent de conserver les rares éléments nutritifs. La résorption peut être exprimée de deux façons : l'efficience de résorption (RE) qui est le rapport entre la quantité résorbée des pertes d'éléments nutritifs au cours de la sénescence des feuilles par rapport à son montant déposé auparavant dans les feuilles et la capacité de résorption (RP) qui est le niveau auquel la concentration des éléments nutritifs par unité de masse de feuilles est réduite dans les feuilles sénescentes.* Il reste encore beaucoup de débat pour déterminer si les différentes formes de vie (c'est-à-dire les espèces décidues et les espèces sempervirentes) présentent différents modes de résorption foliaire. Deux espèces sympatriques, à savoir Quercus petraea (Mattuschka) Liebl. subsp. iberica (Steven ex Bieb.) Krassiln. (décidue) et Arbutus andrachne L. (sempervirente), ont été comparées l'une à l'autre, le long d'un gradient altitudinal, afin de déterminer si l'efficience de résorption de l'azote et du phosphore et la capacité de résorption varient le long d'un gradient altitudinal et quels paramètres de la feuille sont liés à RE et RP.* NRE a été trouvé plutôt faible chez Q. petraea subsp. iberica par rapport à d'autres espèces décidues. De même, chez A. andrachne PRE a été plutôt faible par rapport à d'autres espèces sempervirentes. Le temps de résidence moyen (MRT) mesure combien de temps une unité d'azote (MRTP) et de phosphore (MRTP) est présente dans la plante. MRTP et MRTP étaient considérablement plus élevés chez A. andrachne par rapport à Q. petraea subsp. iberica. Chez les deux espèces, le ratio foliaire N/P était inférieur à 14 le long du gradient altitudinal, en fonction de la valeur de ce seuil, une limitation d'azote s'est produite dans la zone d'étude. Bien que les deux espèces, dans la présente étude, montrent une résorption incomplète, l'espèce décidue avait une meilleure capacité de résorption comparativement à l'espèce sempervirente en raison de la faible concentration de N et de P dans les feuilles sénescentes. Sur la base des corrélations significatives (p < 0.05 et 0.01) entre MRT et la résorption foliaire, il peut être conclu que MRT pourrait interférer avec les mécanismes de contrôle de la résorption des éléments nutritifs.

Adequate leaf hydraulic conductance (Kleaf) is critical for preventing transpiration-induced desiccation and subsequent stomatal closure that would restrict carbon gain. A few studies have reported midday depression of Kleaf (or petiole conductivity) and its subsequent recovery in situ, but the extent to which this phenomenon is universal is not known. The objectives of this study were to measure Kleaf, using a rehydration kinetics method, (1) in the laboratory (under controlled conditions) across a range of water potentials to construct vulnerability curves (VC) and (2) over the course of the day in the field along with leaf water potential and stomatal conductance (gs). Two broadleaf (one evergreen, Arbutus menziesii Pursh., and one deciduous, Quercus garryana Dougl.) and two coniferous species (Pinus ponderosa Dougl. and Pseudotsuga menziesii [Mirbel]) were chosen as representative of different plant types. In addition, Kleaf in the laboratory and leaf water potential in the field were measured for three tropical evergreen species (Protium panamense (Rose), Tachigalia versicolor Standley and L.O. Williams and Vochysia ferruginea Mart) to predict their daily changes in field Kleaf in situ. It was hypothesized that in the field, leaves would close their stomata at water potential thresholds at which Kleaf begins to decline sharply in laboratory-generated VC, thus preventing substantial losses of Kleaf. The temperate species showed a 15-66% decline in Kleaf by midday, before stomatal closure. Although there were substantial midday declines in Kleaf, recovery was nearly complete by late afternoon. Stomatal conductance began to decrease in Pseudotsuga, Pinus and Quercus once Kleaf began to decline; however, there was no detectable reduction in gs in Arbutus. Predicted Kleaf in the tropical species, based on laboratory-generated VC, decreased by 74% of maximum Kleaf in Tachigalia, but only 22-32% in Vochysia and Protium. The results presented here, from the previous work of the authors and from other published studies, were consistent with two different strategies regarding daily maintenance of Kleaf: (1) substantial loss and subsequent recovery or (2) a more conservative strategy of loss avoidance.

Several Mediterranean shrubs, both autochthonous and naturalized, have been traditionally used as food, flavouring and/or spicing agents, and as phytopharmaceuticals. The interest around ‘natural’ and ‘biological’ products is steadily increasing in developed countries. Therefore, it seems reasonable to screen some shrubs with regard to the actual information about their content of phytochemicals, in relation to both real and putative beneficial properties, and with particular concern to their ‘antioxidant’ power. Moreover, striking molecules from the examined shrubs are compared according to their occurrence in the various genera. Also, their structures and structure/activity relationship are discussed in the light of possible practical application.

Nitrification is a key biological process for the control of soil NO 3- availability and N losses from terrestrial ecosystems. The study investigates the causes for the absence of net nitrification activity in the soil of a Mediterranean monospecific woodland of Arbutus unedo, focusing in particular on the possible role of chemicals produced by this plant. The mineral N pool, net rates of mineralization and nitrification were measured in the soil top 10 cm over 18 months. Raw extracts of leaves and roots of Arbutus unedo and soil underneath Arbutus plant canopy were purified using chromatographic techniques and the structure of chemicals was defined using spectroscopic and spectrometric methods. Leaf extracts (raw, aqueous and organic fractions) were tested for their toxicity on net nitrification, using a test soil. Field and laboratory incubations showed soil NO3- concentration below the detection limit over the whole study period, despite the significant NH4+ availability. Toxicity tests indicated that more than 400 μg of extract g-1 dry soil were needed to have more than 50% reduction of net NO3- production. Gallocatechin and catechin were among the most abundant chemicals in the extracts of leaves, roots and soil. Their soil concentration was significantly higher than the annual calculated input via leaf litter, and it was in the range of toxic concentrations, as deduced from the dose-response curve of the toxicity test. Data support the hypothesis that plant produced chemicals might be involved in the limited net nitrate production in this Mediterranean woodland. © 2008 Springer Science+Business Media B.V.

This chapter discusses the current understanding of ectendomycorrhizas and arbutoid mycorrhizas. These two categories of mycorrhizas exhibit many of the characteristics of ectomycorrhizas (ECM), but also exhibit a high degree of intracellular penetration. Ectendomycorrhiza occurs primarily on Pinus and Larix and is distinguished by the fact that, in addition to a usually thin fungal mantle and well-developed Hartig net of the ECM type, the epidermal and cortical cells are occupied by intracellular hyphae. The second category, referred to as arbutoid, is found in the ericaceous genera Arbutus and Arctostaphylos and in several genera of the ericaceous subfamily Pyrolae . It is distinguished from the first category by the restriction of intracellular penetration to the epidermal layers of the root and by the involvement of a distinct suite of largely basidiomycetous fungi, more normally found as ECM symbionts of trees. Little is known of the function of ectendomycorrhizas, but it may be productive to make comparative estimates of the drain of organic C in relation to mineral nutrient absorption, to see if ectendomycorrhizas are in fact less C demanding than the ectomycorrhizas that develop on older plants, which have reached their full photosynthetic potential. The extremely widespread occurrence of dark septate (DS) fungi as associates of roots, a feature already recognized in the early literature, continues to cause interest. Much progress has been made towards accurate identification of the taxa involved through the application of molecular methods. The question of the function of these associations remains to be answered unequivocally, but the vast majority of studies point to these organisms as being facultative biotrophs rather than mycorrhizal symbionts.

Goats foraging on Mediterranean shrubs containing secondary compounds (toxins) may consume a variety of shrubs that contain different phytotoxins to increase shrub intake and avoid toxicosis. We conducted eight experiments to examine whether goats offered different mixtures of shrubs containing different phytotoxins (tannins and saponins) would consume more shrub biomass than goats offered one shrub with a single phytotoxin (tannin or saponin). In the first three experiments, goats fed a mixture of three tannin-rich shrubs (Quercus ilex, Arbutus unedo, and Pistacia lentiscus) ate more foliage (P < 0.01) than goats offered only one shrub (23.2 vs.10.7 g/kg BW ; 25.2 vs.13.4 g/kg BW, and 27.9 vs. 7.9 g/kg BW), regardless of tannin concentration in individual shrub species. Goats also consumed more foliage (P < 0.01) when offered the same three tannin-rich shrubs than when offered the saponin-rich shrub Hedera helix in Exp. 4 (25.4 vs. 8.0 g/kg BW). However, goats offered a mixture of the same three tannin-rich shrubs consumed less foliage (P < 0.01) than goats offered a mixture of two shrubs containing tannins and saponins (Exp. 5-7): Quercus and Hedera (21.6 vs. 27.1 g/kg BW), Arbutus and Hedera (21.8 vs. 27.1 g/kg BW), and Pistacia and Hedera (19.7 vs. 22.0 g/kg BW). Comparison of intake of shrubs containing only tannins (Exp. 1, 2, and 3) or saponins (Exp. 4) to intake of shrubs containing both tannins and saponins (Exp. 5, 6, and 7) indicated goats consumed more total biomass (P < 0.01) when fed shrubs with both classes of compounds than with either tannins or saponins alone. Our results suggest goats can increase intake of Mediterranean shrubs high in secondary compounds by selecting those with different classes of phytotoxins. Simultaneous ingestion of shrubs containing tannins and saponins may promote chemical interactions that inhibit toxic effects of these phytotoxins in the intestinal tract. In addition to complementary interactions between tannins and saponins, biological diversity within Mediterranean maquis vegetation also plays a positive role in increasing shrub intake by goats.

The role of abscisic acid (ABA) as a stress hormone is now well established. Its synthesis and transport to the sites of action are stimulated under stress conditions. In leaves, ABA induces stomatal closure, thereby reducing transpiration and improving water relations. Ion- and water-uptake and root growth are also affected by ABA. These phenomena have all been studied intensively under laboratory and glasshouse conditions, but confirmation of the findings was not possible until recently because of analytical problems. With the availability of sensitive ABA assays we have investigated the role of ABA under natural conditions in almond trees and several species from the Negev desert (Israel), Ceanothus shrubs from the Chaparall in South California and Prunus and Cornus trees from a steep, dry and sun exposed habitat in the Main valley north of Wurzburg. In all cases we investigated the relations between xylem sap ABA concentration, water potential and leaf conductance (g). ABA rises slightly with decreasing water potential until a threshold is reached, but thereafter a dramatic increase in xylem sap ABA can be observed. The threshold depends on both species and conditions. In some cases clear relations can only be observed between predawn water potential (a measure of soil water potential) and xylem sap ABA. When xylem sap ABA is plotted against g, in most cases there is a highly sensitive phase where tiny increases in ABA are sufficient to decrease g dramatically. ABA can be increased above this range in many cases, except in the Prunus and Cornus trees from the Main valley. Similar relations have been observed in stressed field-grown maize plants. The physiological significance of this excess ABA is not yet understood. Elevated CO2 is an important environmental factor causing stomatal closure, and in laboratory experiments CO2 has been shown to enhance guard cell sensitivity to ABA and vice versa. We injected ABA into the veins of cotton leaves grown in open-top chambers at high CO2 concentration (650 μl 1-1) under highly stressed field conditions in Arizona and measured the stomatal conductance of the treated leaves. The results confirmed the earlier observations from laboratory experiments with excised leaves and epidermal strips of interactions between CO2 and ABA. The importance of varying guard cell sensitivity to ABA under field conditions has also been reported for Arbutus grown in a natural Portuguese macchia, nutrient deficient cotton and stressed field-grown maize plants. Our investigations indicate that ABA also has an important stress-physiological role as a root-to-shoot signal influencing stomatal responses to environmental perturbations under natural conditions.

Anatomy and ultrastructure of the arbutoid mycorrhiza of Arbutus unedo-Laccaria amethystea from axenic culture are described. In comparison to non-inoculated roots, the rhizodermal cells of mycorrhizas are of greater volume, their nuclei are enlarged and show an irregular shape, plasmalemma and cytoplasm with mitochondria, plastids, endoplasmic reticulum and dictyosomes are increased. Several ontogenetical states are documented. The arbutoid mycorrhiza as a connecting link between ectomycorrhiza and ericoid mycorrhiza is discussed.

Midday depression of net photosynthesis and transpiration in the Mediterranean sclerophylls Arbutus unedo L. and Quercus suber L. occurs with a depression of mesophyll photosynthetic activity as indicated by calculated carboxylation efficiency (CE) and constant diurnal calculated leaf intercellular partial pressure of CO2 (Ci). This work examines the hypothesis that this midday depression can be explained by the distribution of patches of either wide-open or closed stomata on the leaf surface, independent of a coupling mechanism between stomata and mesophyll that results in a midday depression of photosynthetic activity of the mesophyll. Pressure infiltration of four liquids differing in their surface tension was used as a method to show the occurrence of stomatal patchiness and to determine the status of stomatal aperture within the patches. Liquids were selected such that the threshold leaf conductance necessary for infiltration through the stomatal pores covered the expected diurnal range of calculated leaf conductance (g) for these species. Infiltration experiments were carried out with leaves of potted plants under simulated Mediterranean summer conditions in a growth chamber. For all four liquids, leaves of both species were found to be fully infiltratable in the morning and in the late afternoon while during the periods leading up to and away from midday the leaves showed a pronounced patchy distribution of infiltratable and non-infiltratable areas. Similar linear relationships between the amount of liquid infiltrated and g (measured by porometry prior to detachment and infiltration) for all liquids clearly revealed the existence of pneumatically isolated patches containing only wide-open or closed stomata. The good correspondence between the midday depression of CE, calculated under the assumption of no stomatal patchiness, and the diurnal changes in non-infiltratable leaf area strongly indicates that the apparent reduction in mesophyll activity results from assuming no stomatal patchiness. It is suggested that simultaneous responses of stomata and mesophyll activity reported for other species may also be attributed to the occurrence of stomatal patchiness. In Quercus coccifera L., where the lack of constant diurnal calculated Ci and major depression of measured CE at noontime indicates different stomatal behavior, non-linear and dissimilar relationships between g and the infiltratable quantities of the four liquids were found. This indicates a wide distribution of stomatal aperture on the leaf surface rather than only wide-open or closed stomata.

Mature flowering Arbutus texana trees were successfully micropropagated from shoot tips. Optimum shoot proliferation was achieved on a basal medium consisting of WPM salts, MS vitamins, and sucrose supplemented with 11.1 or 22.2 μm BA and no auxin. Microcuttings rooted readily when pulsed with 6.1 μm IBA for 1 week and transferred to auxin-free medium. The addition of charcoal to the rooting medium improved root branching and elongation but suppressed root formation. Chemical names used: N-(phenylmethyl)-1H-purin-6-amine (BA); indole-3-butyric acid (IBA).

were dominated by Pseudotsuga menziesii (Pinaceae), Lithocarpus densiflorus (Fagaceae) and Arbutus menziesii (Ericaceae), and contained nine additional tree species. During the 14 yr interval, Lithocarpus accounted for 98% of recruitment of new stems, and had greater recruitment into taller height classes and a much lower mortality rate in the understory than did Arbutus or Pseudotsuga. Lithocarpus was also the only species filling canopy gaps. However, its relative basal area increased only 3% because death of canopy trees partially offset growth. There was no recruitment of Arbutus or Pseudotsuga. Arbutus suffered mortality and extensive crown die-back, and its density and relative basal area dropped. Mortality of small stems reduced Pseudotsuga's density, but no canopy stems died and growth increased Pseudotsuga's relative basal area 4%. These results indicate that in the absence of fire, Arbutus decreases and Lithocarpus increases in importance, and due to Pseudotsuga's great potential longevity and size, these forests remain co-dominated by Lithocarpus and Pseudotsuga.