Is the Strawberry Tree, Arbutus unedo (Ericaceae), native to Ireland, or was it brought by the first copper miners?

The Strawberry Tree (Arbutus unedo L.) is often referred to as one of Ireland’s ‘Lusitanian’ species to describe its disjunct distribution, since it is absent from Britain and is mainly found around the Mediterranean Sea and on the Iberian Peninsula. In Ireland, it is regarded as native in the south-west and in Co. Sligo. However, a recent genetic study suggests that it could have been introduced to Ireland directly from northern Spain. This possibility was previously dismissed, since palynological and archaeological evidence showed it to be present in south-west Ireland 4,000 years ago. Here, we examine how an introduction might have occurred prior to this date, by first reviewing what is known of its distribution, ecology and history in Ireland along with archaeological information. Then, combining an updated distribution of A. unedo where it is regarded as native in Ireland with historical accounts, palynological and archaeological records and other information from the literature, we present two online maps, designed to be an ongoing accessible resource. The information has enabled us to propose a means by which A. unedo might have arrived in Ireland with miners who came to work the first known copper mine in north-west Europe, in the Chalcolithic phase of the Late Neolithic, which was at Ross Island on Lough Leane in Co. Kerry. The species’ distribution today suggests that it then spread with subsequent Bronze Age copper mining activity in south-west Ireland, though this is unlikely to account for its arrival in Co. Sligo. Previous suggestions that A. unedo was once much more widely distributed in Ireland and subsequently contracted due to preferential cutting for smelting, are shown to be unfounded.

MOROCCAN STRAWBERRY TREE (Arbutus Unedo L.) LEAVES: COMPARATIVE STUDY OF THE NUTRITIONAL VALUE AND MINERAL COMPOSITION

Strawberry tree (Arbutus Unedo L.) is one of the evergreen trees that grow spontaneously in Moroccan forests. This tall shrub is traditionally used in grazing zones of some Moroccan areas, especially during the dry season, but its value in Morocco has still been underestimated. In this paper, the nutritional composition of A. unedo leaves sample collected from seven Moroccan regions has been assessed. For this, the leaves were dried, crushed, and chemically analyzed for their proximate composition, energetic value, total and reducing sugar, and mineral composition. Results of this study suggested that samples from BniAarouse (BA) region showed the highest contents of essential nutrients such as proteins, dietary fiber, ashes, and fat with average values of 7.53, 17.89, 4.14, and 8.05 g/ 100 g of dry weight, respectively, which positively influences its consumption by small ruminants. Cluster analysis based on surveyed parameters separated the strawberries individuals into four distinct groups, providing a high variability among and within studied locations. That could be related to the diversity of the edaphoclimatic conditions between regions and to the genetic effect. The results of the present study highlighted the potential use of leaves as livestock feed, with intermediate quality, and promotes their optimal cultivation and subsequent domestication in Morocco.

Comparative Study on the Phenolic Fingerprint and Antioxidant Activity of Strawberry Tree (Arbutus unedo L.) Leaves and Fruits

The strawberry tree (Arbutus unedo L., Ericaceae family) is an evergreen Mediterranean shrub whose leaves and fruits are used in traditional medicine due to their antioxidant, antimicrobial, antidiabetic, diuretic, and antiproliferative properties. The health benefits are mainly attributed to the presence of phenolic compounds. The aim of this study was to compare the phenolic profiles, total phenolic content (TPC), and radical scavenging activity (RSA) of A. unedo leaves and fruits collected at two locations in Croatia. Phenolic profiles were identified using an ultra-high-performance liquid chromatograph (UHPLC) coupled with a hybrid mass spectrometer (LTQ Orbitrap MS). TPC was determined by Folin–Ciocalteu’s assay, while RSA was investigated using DPPH reagent. A total of 64 phenolics (60 and 42 compounds in leaves and fruits, respectively) were identified. Hyperoside and flavan-3-ols were predominant compounds in leaves, while gallocatechin and catechin were the major compounds found in fruits. To the authors’ knowledge, 16 and 5 phenolics in leaves and fruits, respectively, were reported for the first time. Principal component analysis (PCA) showed that UHPLC-LTQ Orbitrap MS could be used to identify which phenolics were able to discriminate samples regarding plant tissue and geographical origin. TPC in leaves and fruits were in the ranges of 67.07–104.74 and 16.78–25.86 mg gallic acid equivalents (GAE)/g dried weight (dw), respectively. RSA for leaves and fruits were in the ranges of 408.92–430.98 and 74.30–104.04 μmol Trolox equivalents (TE)/g dw, respectively. The number of identified phenolics was lower in fruits compared to leaves. Such a large number of bioactive phenolics identified and the strong antioxidant activity pointed to A. unedo as a promising health-promoting plant and natural food preservative.

Moroccan Strawberry Tree (Arbutus unedo L.) Fruits: Nutritional Value and Mineral Composition

The strawberry tree (Arbutus unedo L.), grown throughout the Mediterranean, produces edible fruit; as it is easily bruised, the sweet, reddish fruit is used mostly to prepare jams, marmalades and alcoholic beverages. As the genus is paraphyletic, phytochemical analysis can assist in defining the fruit composition with the species Arbutus unedo L. (A. unedo). Here we report on the carbohydrate, total sugar, protein, fat, fiber, ash, and mineral content of wild fruit, harvested from 45 specimens from five locations. The dominant nutrients were carbohydrates (78.2–84.8 g/100 g), total sugars (52.1–67.2 g/100 g) and dietary fiber (11.0–20.1 g/100 g). Other important nutrients supplied by A. unedo fruit include P, K, and Fe. The fruit was observed to contain health-promoting components providing 42 and 36%, of recommended daily allowance (RDA) for fiber and zinc, respectively, as well as iron and manganese, at levels exceeding minimum RDA. The free-sugar profile revealed high glucose followed by fructose content with minor amounts of sucrose (14, 11, and 6 g/100 g, respectively). Significant differences both between regions and within individuals were observed for several traits. The richness of fruit nutrients in A. unedo confers nutritional value and as such, a promising alternative fruit source.

Identification and Characterization of Arbutus unedo L. Endophytic Bacteria Isolated from Wild and Cultivated Trees for the Biological Control of Phytophthora cinnamomi

Arbutus unedo L. is a resilient tree with a circum-Mediterranean distribution. Besides its ecological relevance, it is vital for local economies as a fruit tree. Several microorganisms are responsible for strawberry tree diseases, leading to production constrictions. Thus, the development of alternative plant protection strategies is necessary, such as bacterial endophytes, which may increase their host’s overall fitness and productivity. As agricultural practices are a driving factor of microbiota, this paper aimed to isolate, identify and characterize endophytic bacteria from strawberry tree leaves from plants growing spontaneously in a natural environment as well as from plants growing in orchards. A total of 62 endophytes were isolated from leaves and identified as Bacillus, Paenibacillus, Pseudomonas, Sphingomonas and Staphylococcus. Although a slightly higher number of species was found in wild plants, no differences in terms of diversity indexes were found. Sixteen isolates were tested in vitro for their antagonistic effect against A. unedo mycopathogens. B. cereus was the most effective antagonist causing a growth reduction of 20% in Glomerella cingulata and 40% in Phytophthora cinnamomi and Mycosphaerella aurantia. Several endophytic isolates also exhibited plant growth-promoting potential. This study provides insights into the diversity of endophytic bacteria in A. unedo leaves and their potential role as growth promoters and pathogen antagonists.

Identification and Characterization of Arbutus Unedo L. Endophytic Bacteria Isolated From Wild and Cultivated Trees for the Biological Control of Phytophthora

Arbutus unedo L. is a resilient tree with a circum-Mediterranean distribution. Besides its ecological relevance, it is vital for local economies as a fruit tree. Several microorganisms are responsible for strawberry tree diseases leading to production constrictions. Thus, the development of alternative plant protection strategies is necessary and bacteria endophytes may increase their host overall fitness and productivity. As agricultural practices are a driving factor of microbiota, this paper aimed to isolate, identify and characterize endophytic bacteria from strawberry tree leaves from plants growing spontaneously in a natural environment as well as from plants growing on orchards. 62 endophytes were isolated from leaves and identified as Bacillus, Paenibacillus, Pseudomonas, Sphingomonas and Staphylococcus. Although a slightly higher number of species was found in wild plants, no differences in terms of diversity indexes were found. Sixteen isolates were tested in vitro for their antagonistic effect against A. unedo mycopathogens. B. cereus was the most effective antagonist causing a growth reduction of 20% in Glomerella cingulata and 40% in Phytophthora cinnamomi and Mycosphaerella aurantia. Also, several endophytic isolates exhibited plant growth-promoting potential. This study provides insights into the diversity of endophytic bacteria in A. unedo leaves and their potential role as growth-promoters and pathogen antagonists.

LC-ESI/LTQ-Orbitrap-MS Based Metabolomics in Evaluation of Bitter Taste of Arbutus unedo Honey

Strawberry tree honey is a high-value honey from the Mediterranean area and it is characterised by a typical bitter taste. To possibly identify the secondary metabolites responsible for the bitter taste, the honey was fractionated on a C18 column and the individual fractions were subjected to sensory analysis and then analysed by liquid chromatography coupled with high-resolution tandem mass spectrometry in negative ion mode, using a mass spectrometer with an electrospray source coupled to a hybrid high resolution mass analyser (LC-ESI/LTQ-Orbitrap-MS). A chemometric model obtained by preliminary principal component analysis (PCA) of LC-ESI/LTQ-Orbitrap-MS data allowed the identification of the fractions that caused the perception of bitterness. Subsequently, a partial least squares (PLS) regression model was built. The studies carried out with multivariate analysis showed that unedone (2-(1,2-dihydroxypropyl)-4,4,8-trimethyl-1-oxaspiro [2.5] oct-7-en-6-one) can be considered responsible for the bitter taste of strawberry tree honey. Confirmation of the bitter taste of unedone was obtained by sensory evaluation of a pure standard, allowing it to be added to the list of natural compounds responsible for giving the sensation of bitterness to humans.