Ethnobotanical, phytochemical and therapeutic effects of Myrtus communis L. berries seeds on gastrointestinal tract diseases: a review.

Medicinal plants have always had an important place in the therapeutic arsenal of humanity and particularly in the treatment of gastrointestinal tract diseases. Myrtus communis L., known as common myrtle, is native to Southern Europe, North Africa, and Western Asia. The different parts of this plant are used as antiinflammatory, antiulcer, antidiabetic, urinary antiseptic, and to treat the respiratory and digestive systems diseases. For the first time, an exhaustive bibliographic research of the seeds of myrtle berries has been carried out. As a result, it has been found that this plant is very rich in biologically active compounds such as phospholipids, polyunsaturated fatty acids, and phenolic compounds. This has made it effective in the treatment of digestive diseases. In order to emphasize the importance of myrtle berries seeds, this review has been established by discussing its botanical, morphological, phytochemical, ethnomedicinal studies as well as its effect on digestive tract diseases.

High Correlated Paternity Leads to Negative Effects on Progeny Performance in Two Mediterranean Shrub Species.

Anthropogenic habitat deterioration can promote changes in plant mating systems that subsequently may affect progeny performance, thereby conditioning plant recruitment for the next generation. However, very few studies yet tested mating system parameters other than outcrossing rates; and the direct effects of the genetic diversity of the pollen received by maternal plants (i.e. correlated paternity) has often been overlooked. In this study, we investigated the relation between correlated paternity and progeny performance in two common Mediterranean shrubs, Myrtus communis and Pistacia lentiscus. To do so, we collected open-pollinated progeny from selected maternal plants, calculated mating system parameters using microsatellite genotyping and conducted sowing experiments under greenhouse and field conditions. Our results showed that some progeny fitness components were negatively affected by the high correlated paternity of maternal plants. In Myrtus communis, high correlated paternity had a negative effect on the proportion and timing of seedling emergence in the natural field conditions and in the greenhouse sowing experiment, respectively. In Pistacia lentiscus, seedling emergence time under field conditions was also negatively influenced by high correlated paternity and a progeny survival analysis in the field experiment showed greater mortality of seedlings from maternal plants with high correlated paternity. Overall, we found effects of correlated paternity on the progeny performance of Myrtus communis, a self-compatible species. Further, we also detected effects of correlated paternity on the progeny emergence time and survival in Pistacia lentiscus, an obligate outcrossed species. This study represents one of the few existing empirical examples which highlight the influence that correlated paternity may exert on progeny performance in multiple stages during early seedling growth.

The Genus Myrtus L. in Algeria: Composition and Biological Aspects of Essential Oils from M. communis and M. nivellei: A Review.

The genus Myrtus L. (Myrtaceae family) comprises two species, Myrtus communis L. (known as common myrtle) growing wild all around the Mediterranean basin and Myrtus nivellei Batt. and Trab. (known as Saharan myrtle), found in central Sahara. Only one country, Algeria, hosts both species, M. communis in the North and M. nivellei in the South. The aim of this review was to collect, summarize, and compare the main results reported relative to the essential oils isolated from aerial parts of both species: botanical aspects, habitat, traditional use, chemical composition, new compounds, antimicrobial activity, antioxidant activity, anti-inflammatory effect, and insecticidal activity. Both essential oils have potential applications in human health.

Season-dependent and independent responses of Mediterranean scrub to light conditions.

Semi-arid plant species cope with excess of solar radiation with morphological and physiological adaptations that assure their survival when other abiotic stressors interact. At the leaf level, sun and shade plants may differ in the set of traits that regulate environmental stressors. Here, we evaluated if leaf-level physiological seasonal response of Mediterranean scrub species (Myrtus communis, Halimium halimifolium, Rosmarinus officinalis, and Cistus salvifolius) depended on light availability conditions. We aimed to determine which of these responses prevailed independently of the marked seasonality of Mediterranean climate, to define a leaf-level strategy in the scrub community. Thirty six leaf response variables - involving gas exchange, water status, photosystem II photochemical efficiency, photosynthetic pigments and leaf structure - were seasonally measured in sun exposed and shaded plants under field conditions. Physiological responses showed a common pattern throughout the year, in spite of the marked seasonality of the Mediterranean climate and of species-specific differences in the response to light intensity. Variables related to light use, CO2 assimilation, leaf pigment content, and LMA (leaf mass area) presented differences that were consistent throughout the year, although autumn was the season with greater contrast between sun and shade plants. Our data suggest that in Mediterranean scrub shade plants the lutein pool could have an important role in the photoprotection of the photosynthetic tissues. There was a negative linear correlation between the ratio lutein/total chlorophylls and the majority of leaf level variables. The combined effect of abiotic stress factors (light and drought or light and cold) was variable-specific, in some cases enhancing differences between sun and shade plants, while in others leading to unified strategies in all scrub species.

Variability of chemical composition and antioxidant activity of essential oils between Myrtus communis var. Leucocarpa DC and var. Melanocarpa DC.

Essential oils (EOs) from several individuals of Myrtus communis L. (M. communis) growing in different habitats in Sardinia have been studied. The analyses were focused on four groups of samples, namely cultivated and wild M. communis var. melanocarpa DC, characterized by red/purple berries, and cultivated and wild M. communis var. leucocarpa DC, characterized by white berries. Qualitative and quantitative analyses demonstrated different EO fingerprints among the studied samples: cultivated and wild leucocarpa variety differs mainly from the melanocarpa variety by a high amount of myrtenyl acetate (>200 mg/mL and 0.4 mg/mL in leucocarpa and melanocarpa varieties respectively). Conversely, the wild group is characterized by a higher amount, compared with the cultivated species, of linalool (about 110 mg/mL and 20 mg/mL respectively), linalyl acetate (about 24 mg/mL and about 6 mg/mL respectively) whereas EOs of the cultivated plants were rich in pinocarveol-cis compared with wild plants (about 2 mg/mL and about 0.5 mg/mL respectively). Principal component analysis applied to the chromatographic data confirm a differentiation and classification of EOs from the four groups of M. communis plants. Finally, antioxidant activity of the studied EOs shows differences between the various categories of samples.

Changes in growth, physiological parameters and the hormonal status of Myrtus communis L. plants irrigated with water with different chemical compositions.

Myrtus communis, an important Mediterranean ornamental shrub, was used to study the effect of irrigation water with different chemical compositions in the plant response. A treatment with NaCl was used to establish the plant resistance to high salinity at long term. Plants were subjected to four irrigation treatments with drainage for three months: Control (0.8 dS m(-1)); two treatments using reclaimed water (RWs): RW1 (2.0 dS m(-1)) and RW2 (5.0 dS m(-1)); and NaCl (10.0 dS m(-1)). High levels of electric conductivity of RWs not affected plant growth, while NaCl decreased leaf dry weight. Coinciding with the accumulation of Na(+) and Cl(-) in the roots, soil water potential decreased, which hinders the mobilization of water to the leaves, decreasing leaf water potential. The osmotic adjustment in the NaCl treatment was due to Na(+) and Cl(-) ions, although the proline could contribute as an Osmo compatible solute, increasing the turgor plants. Also changes in cell walls rigidity minimize the negative effects on the water balance; however, a higher lipid peroxidation was observed in these plants. Stomatal closure was associated with a decrease in K(+) and an increase in abscisic acid. NaCl produced an increase in salicylic acid and did not affect jasmonic acid contents at the end of the experiment. Similar behavior in soil and leaf water potentials, although less pronounced than in NaCl, was shown in RW2 plants. The abscisic acid increased in the RW2 with respect to the control and a decrease in stomatal conductance was observed at the end of the experiment. Plants irrigated with RW1 behaved similarly to the control.

NaCl-induced physiological and biochemical adaptative mechanisms in the ornamental Myrtus communis L. plants.

Physiological and biochemical changes in Myrtus communis L. plants after being subjected to different solutions of NaCl (44, and 88 mM) for up to 30 days (Phase I) and after recovery from the salinity period (Phase II) were studied. Myrtle plants showed salinity tolerance by displaying a series of adaptative mechanisms to cope with salt-stress, including controlled ion homeostasis, the increase in root/shoot ratio, the reduction of water potentials and stomatal conductance to limit water loss. In addition, they displayed different strategies to protect the photosynthetic machinery, including limiting toxic ion accumulation in leaves, increase in chlorophyll content, and changes in chlorophyll fluorescence parameters, leaf anatomy and increases in catalase activity. Anatomical modifications in leaves, including a decrease in spongy parenchyma and increased intercellular spaces, allow CO2 diffusion in a situation of reduced stomatal aperture. In spite of all these changes, salinity produced oxidative stress in myrtle plants as monitored by increases in oxidative stress parameter values. The post-recovery period is perceived as a new stress situation, as observed through effects on plant growth and alterations in non-photochemical quenching parameters and lipid peroxidation values.

Salts and nutrients present in regenerated waters induce changes in water relations, antioxidative metabolism, ion accumulation and restricted ion uptake in Myrtus communis L. plants.

The use of reclaimed water (RW) constitutes a valuable strategy for the efficient management of water and nutrients in landscaping. However, RW may contain levels of toxic ions, affecting plant production or quality, a very important aspect for ornamental plants. The present paper evaluates the effect of different quality RWs on physiological and biochemical parameters and the recovery capacity in Myrtus communis L. plants. M. communis plants were submitted to 3 irrigation treatments with RW from different sources (22 weeks): RW1 (1.7 dS m(-1)), RW2 (4.0 dS m(-1)) and RW3 (8.0 dS m(-1)) and one control (C, 0.8 dS m(-1)). During a recovery period of 11 weeks, all plants were irrigated with the control water. The RW treatments did not negatively affect plant growth, while RW2 even led to an increase in biomass. After recovery,only plants irrigated with RW3 showed some negative effects on growth, which was related to a decrease in the net photosynthesis rate, higher Na accumulation and a reduction in K levels. An increase in salinity was accompanied by decreases in leaf water potential, relative water content and gas exchange parameters, and increases in Na and Cl uptake. Plants accumulated Na in roots and restricted its translocation to the aerial part. The highest salinity levels produced oxidative stress, as seen from the rise in electrolyte leakage and lipid peroxidation. The use of regenerated water together with carefully managed drainage practices, which avoid the accumulation of salt by the substrate, will provide economic and environmental benefits.

Characterization of the response of in vitro cultured Myrtus communis L. plants to high concentrations of NaCl.

Effect of salt stress was examined in in vitro shoot cultures of Myrtus communis L. a species of the Mediterranean maquis. To determine the effects of high salt concentrations on myrtle plantlets and contribute toward understanding the mechanisms adopted from this species to counteract soil salinity, in vitro rooted shoots were transferred to a liquid culture medium containing 0, 125 or 250 mM NaCl for 30 days. After 15 and 30 days of in vitro culture, shoot and root growth, chlorosis and necrosis extension, chlorophylls, carotenoids, proline, arginine, cysteine and total sugars content, as well as guaiacol peroxidase (G-POD, EC 1.11.1.7) and ascorbate peroxidase (APX, EC 1.11.1.11) activities were determined. In treated plants shoot and root growth, as well as chlorophyll content, significantly decreased, while carotenoids content was not affected by the NaCl treatment. Among osmolytes, proline did not significantly increase, arginine and cysteine decreased, while total sugars were found to be higher in the treated plants than in the control. Enhancement of G-POD and APX activities was positively related to increasing salt concentrations in the culture media, regardless of the exposure time. Salt-treated plants did not show significant changes in lipid peroxidation or DNA fragmentation after 30 days salt treatment, regardless of the NaCl concentrations applied. The results represent a contribution towards understanding the mechanisms adopted by this species to high salinity.

Contrasting heterozygosity-fitness correlations between populations of a self-compatible shrub in a fragmented landscape.

The mechanisms underlying heterozygosity-fitness correlations (HFCs) are subject of intense debates, especially about how important population features such as size or degree of isolation influence HFCs. Here, we report variation in HFCs between Large and Small populations of a self-compatible shrub (Myrtus communis) occurring within an extremely fragmented landscape. In each of the five study populations, we obtained data on both heterozygosity and fitness for 9-12 maternal families (i.e. offspring from the same mother plant). Whereas heterozygosity explained most of the variance (60-86 %) in growth rate of seedling families within Large populations, this relationship was absent within Small populations. Our results suggest that inbreeding may explain the observed HFCs within Large populations, and that different genetic processes (such as genetic drift and/or selection) could have overridden HFCs within Small populations. While it is difficult to draw general conclusions from five populations, we think our results open new research perspectives on how different genetic processes underlie variation in HFCs under different population contexts. Our study also points to a need for further attention on the complex relationships between heterozygosity in self-compatible plants and their progeny in relation to mating system variation. Finally, our results provide interesting new insights into how population genetic diversity is maintained or lost in a highly fragmented landscape.

Phytostabilisation with Mediterranean shrubs and liming improved soil quality in a pot experiment with a pyrite mine soil.

Phytoremediation can be a suitable option to manage derelict mine soils. A pot experiment was carried out under semi-controlled conditions with a mine-impacted soil. A further contamination event was mimicked by applying 5% of pyritic sludge. Four species were planted in pots (Myrtus communis, Retama sphaerocarpa, Rosmarinus officinalis and Tamarix gallica), and some pots remained unplanted as a control. The substrates were moderately to highly contaminated, mainly with arsenic and zinc. The strong acidification induced by the pyritic sludge was buffered with lime and plants survived in all the pots. Liming provoked an effective immobilisation of metals and arsenic. Plant establishment decreased labile As in the substrate by 50%, mainly M. communis, although the levels of extractable metals were not affected by the plants. R. sphaerocarpa and M. communis increased the levels of C and N in the soil by 23% and 34% respectively, and also enhanced enzymatic activities and microbial respiration to the double in some cases. The low transfer of trace elements to shoots limited the phytoextraction rate. Our results support the use of phytostabilisation in Mediterranean mine soils and show how plants of R. sphaerocarpa and M. communis may increase soil health and quality during revegetation.

Among-individual variation in pollen limitation and inbreeding depression in a mixed-mating shrub.

BACKGROUND AND AIMS: Variation in inbreeding depression (δ) among individual plants is considered to play a central role in mating system evolution and population genetics. Moreover, such variation could be linked to individual susceptibility to pollen limitation (PL) because those individuals strongly affected by δ for seed production will require more outcross pollen for setting a given number of fruits or seeds. However, no study has tested explicitly for associations between PL and δ at the individual plant level. This study assesses the extent of among-individual variation in PL and δ, the consistency of δ across life stages, and the relationships between individual PL and δ in the mixed-mating shrub Myrtus communis. METHODS: Controlled hand-pollinations were performed in a natural M. communis population. Marked flowers were monitored until fruit production and a greenhouse experiment was conducted with the seeds produced. KEY RESULTS: Compared with selfing, outcross-pollination enhanced seed number per fruit, germination rate and seedling growth, but did not enhance fruit-set. Only seed number per fruit was pollen limited and, thus, cumulative pollen limitation depended more on pollen quality (outcross pollen) than on quantity. The effects of δ varied considerably across life stages and individual plants. Cumulative δ was high across individuals (mean δ = 0·65), although there were no positive correlations between δ values at different life stages. Interestingly, maternal plants showing stronger δ for seed production were more pollen limited, but they were also less affected by δ for seedling growth because of a seed size/number trade-off. CONCLUSIONS: Results show a general inconsistency in δ across life stages and individuals, suggesting that different deleterious loci are acting at different stages. The association between δ and PL at the individual level corroborates the idea that pollen limitation may be 'genotype-dependent' regardless of other factors.

In vitro propagation of ornamental myrtus (Myrtus communis).

The Myrtle (Myrtus communis L.) is an evergreen shrub typical of the Mediterranean area; it is an interesting plant with multipurpose use. The ornamental use takes into account the production of green cut branches for indoor decoration and production of pot plants for gardening. In this species, there is a great variability in the natural germplasm around the Mediterranean coasts for type and size of fruit, plant architecture, leaf size and internode length. Selected genotypes have been successfully sterilized and cultured in vitro. The shoots were multiplied on MS (16) salts and vitamins, with 0.5 mg/L BA and 0.2 mg/L IAA. Clones showed variation of multiplication rate and rooting percentage. IAA or IBA at 0.5 mg/L increased the rooting percentage and noticed differences in root number and length. The sucrose concentration can affect rooting, such as light intensity during the in vitro rooting phase can modulate biomass production and chlorophyll content. The combination of these factors enhanced the frequency rate of acclimatization.

Seed trait changes in dispersers' guts and consequences for germination and seedling growth.

The effectiveness of a frugivore as a disperser of a plant is greatly determined by how fruits and seeds are handled in its mouth and its digestive tract. Although a number of studies have investigated the effect of avian ingestion on germination, we still know very little about the modifications to seeds during ingestion and the specific consequences on plant fitness. Here we investigate for the first time the different mechanisms by which germination patterns of seeds are modified following ingestion by frugivores. Specifically, we examine changes in seed mass, water content, permeability, seed coat thickness, texture, and resistance in two common Mediterranean fleshy-fruited plants, Phillyrea angustifolia and Myrtus communis, after ingestion by Eurasian Blackbirds, Turdus merula. We found a number of differences between the plant species: Phillyrea seeds lost mass, mainly due to water loss, and had thinner coats after gut passage, but Myrtus seeds did not. Seeds of both species showed increased permeability, while Myrtus seeds in particular became less resistant to breakage. No quantifiable changes in seed coat texture were detected in either species, although this trait was partly associated with differences in germination rate in Phillyrea. High intraspecific plant variation was found for most seed traits measured. Seed passage through birds' guts sped up germination in both species, especially in Myrtus. Increased permeability in seeds of both species following ingestion resulted in a higher germination rate. Moreover, seeds with thick coats (and in the case of Phillyrea, harder coats) germinated at a slower rate and produced seedlings that also grew more slowly, indicating a cost of coat thickness and/or hardness for seedling emergence. Results obtained here contribute to explaining the great heterogeneity in germination responses among and within plant species and the large variety of factors, both intrinsic and extrinsic to the plants, that influence such responses.

Comparison of arsenic resistance in Mediterranean woody shrubs used in restoration activities.

Myrtus communis, Arbutus unedo and Retama sphaerocarpa are Mediterranean shrubs widely used in revegetation of semiarid degraded soils. The aim of this work is to study the resistance of these plants to arsenic under controlled conditions, in order to evaluate their potential use in revegetation and/or phytoremediation of As-polluted soils. R. sphaerocarpa showed higher resistance to As than M. communis or A. unedo according to its higher EC50, P status and P/As molar ratio in both, roots and shoots, and the lower increases in lipid peroxidation and decrease of chlorophyll levels in response to arsenic, while the highest arsenate sensitivity was obtained for A. unedo. Arsenic was mainly retained in roots, and, although M. communis accumulated higher arsenic amounts than the other two species, R. sphaerocarpa showed the highest root to shoot transfer. Most of the studied parameters (chlorophylls, MDA and total thiols) showed significant correlation with arsenic concentration in roots and leaves of plants, so they can be useful indexes in the diagnosis of arsenic toxicity in these species. According to our results, both M. communis and R. sphaerocarpa could be used in the revegetation of moderately arsenic contaminated sites.

Intra-specific biodiversity of Italian myrtle (Myrtus communis) through chemical markers profile and biological activities of leaf methanolic extracts.

Methanolic extracts of Myrtus communis leaves from two Italian regions (Calabria and Sardinia) were processed to determine the content of myrtenol, linalool and eucalyptol. Among the Calabrian and Sardinian myrtle samples, linalool and eucalyptol chemotypes were prevalent. The extracts were also tested for antioxidant, antibacterial and antifungal activities. Myrtle leaves samples were dried and extracted through maceration. Partition chromatography was adopted to separate myrtenol, linalool and eucalyptol fractions. Analyses were performed through GC and GC-MS. Some of the samples showed a good scavenger activity evidenced by DPPH radical scavenging assay and beta-carotene bleaching test. Antibacterial and antifungal activities were generally weak. The phytochemical and biological characterization of all the extracts were determined with an aim to characterize the intra-specific biodiversity of myrtle populations.