Vigna unguiculata L. Walp. Leaves as a Source of Phytochemicals of Dietary Interest: Optimization of Ultrasound-Assisted Extraction and Assessment of Traditional Consumer Habits

Vigna unguiculata L. Walp. is an African crop spread worldwide mainly for pulses production. Despite being a neglected and under-utilized food, cowpea leaves are a rich source of phytochemicals and micronutrients. The aim of the work is to characterize the phytochemical composition of cowpea leaves by an optimized ultrasound-assisted extraction (USAE) and to compare raw and boiled leaves. A three-level factorial design (Box-Behnken) was employed for the optimization of the USAE considering three different parameters (% ethanol, drug-to-solvent ratio, and number of cycles). The optimized extracts were characterized by LC/MS/MS. Finally, leaves were boiled at 100 °C for 30 min to simulate traditional cooking procedures and compared to raw leaves. The best extraction condition was EtOH/H2 O 1 : 2 v/v, drug to solvent ratio 1 : 47 w/v, and 3 extraction cycles. The phytochemicals identified mainly belong to the family of phenolic acids, flavonoids, terpenoids, and alkaloids. Boiled leaves revealed a significant loss of most phytochemicals and a net decrease of their antioxidant activity compared to the raw ones. The results highlight the potential nutraceutical value of cowpea leaves whilst the impoverishment triggered by traditional consumer habits pushes the need to evaluate alternative cooking procedures helpful in the maintenance of their phytochemical properties.

The problem of misidentification between edible and poisonous wild plants: Reports from the Mediterranean area

Today, in many European countries, people are looking for wild edible plants to experience new tastes and flavors, by following the new trend of being green and environmentally friendly. Young borage and spinach leaves can be easily confused by inexpert pickers with those of other plants, including poisonous ones, such as Mandragora autumnalis Bertol. (mandrake) or Digitalis purpurea L. (foxglove), common in southern and northern Italy respectively. In the last twenty years, several cases of intoxication by accidental ingestion of mandrake and foxglove have been reported. The purpose of this work was to perform a pharmacognostic characterization of young leaves from borage, mandrake, foxglove and spinach, by micro-morphological, molecular and phytochemical techniques. The results showed that each of the three techniques investigated could be sufficient alone to provide useful information for the identification of poisonous species helping the medical staff to manage quickly the poisoned patients. However, the multi-disciplinary approach proposed could be very useful to asses the presence of poisonous plants in complex matrices, to build a database containing morphological, molecular and phytochemical data for the identification of poisonous species or in forensic toxicology, given their increasingly frequent use due to their low cost and relatively common availability.

Evaluating the efficacy of restoration plantings through DNA barcoding of frugivorous bird diets

Frugivores are critical components of restoration programs because they are seed dispersers. Thus, knowledge about bird-plant trophic relationships is essential in the evaluation of the efficacy of restoration processes. Traditionally, the diet of frugivores is characterized by microscopically identifying plant residues in droppings, which is time-consuming, requires botanical knowledge, and cannot be used for fragments lacking detectable morphological characteristics (e.g., fragmented seeds and skins). We examined whether DNA barcoding can be used as a universal tool to rapidly characterize the diet of a frugivorous bird, Eurasian blackcap (Sylvia atricapilla). We used the DNA barcoding results to assess restoration efforts and monitor the diversity of potentially dispersed plants in a protected area in northern Italy. We collected 642 Eurasian Blackcap droppings at the restored site during the autumn migration over 3 years. Intact seeds and fragmented plant material were analyzed at 2 plastidial barcode loci (rbcL and trnH-psbA), and the resulting plant identifications were validated by comparison with a reference molecular data set of local flora. At least 17 plant species, including 7 of the 11 newly transplanted taxa, were found. Our results demonstrate the potential for DNA barcoding to be used to monitor the effectiveness of restoration plantings and to obtain information about fruit consumption and dispersal of invasive or unexpected plant species. Such an approach provides valuable information that could be used to study local plant biodiversity and to survey its evolution over time.

Evaluation of the probiotic properties of new Lactobacillus and Bifidobacterium strains and their in vitro effect

Probiotic ingestion is recommended as a preventive approach to maintain the balance of the intestinal microbiota and to enhance the human well-being. During the whole life of each individual, the gut microbiota composition could be altered by lifestyle, diet, antibiotic therapies and other stress conditions, which may lead to acute and chronic disorders. Hence, probiotics can be administered for the prevention or treatment of some disorders, including lactose malabsorption, acute diarrhoea, irritable bowel syndrome, necrotizing enterocolitis and mild forms of inflammatory bowel disease. The probiotic-mediated effect is an important issue that needs to be addressed in relation to strain-specific probiotic properties. In this work, the probiotic properties of new Lactobacillus and Bifidobacterium strains were screened, and their effects in vitro were evaluated. They were screened for probiotic properties by determining their tolerance to low pH and to bile salts, antibiotic sensitivity, antimicrobial activity and vitamin B8, B9 and B12 production, and by considering their ability to increase the antioxidant potential and to modulate the inflammatory status of systemic-miming cell lines in vitro. Three out of the examined strains presenting the most performant probiotic properties, as Lactobacillus plantarum PBS067, Lactobacillus rhamnosus PBS070 and Bifidobacterium animalis subsp. lactis PBSO75, were evaluated for their effects also on human intestinal HT-29 cell line. The obtained results support the possibility to move to another level of study, that is, the oral administration of these probiotical strains to patients with acute and chronic gut disorders, by in vivo experiments.

A DNA barcoding approach to identify plant species in multiflower honey

The purpose of this study was to test the ability of DNA barcoding to identify the plant origins of processed honey. Four multifloral honeys produced at different sites in a floristically rich area in the northern Italian Alps were examined by using the rbcL and trnH-psbA plastid regions as barcode markers. An extensive reference database of barcode sequences was generated for the local flora to determine the taxonomic composition of honey. Thirty-nine plant species were identified in the four honey samples, each of which originated from a mix of common plants belonging to Castanea, Quercus, Fagus and several herbaceous taxa. Interestingly, at least one endemic plant was found in all four honey samples, providing a clear signature for the geographic identity of these products. DNA of the toxic plant Atropa belladonna was detected in one sample, illustrating the usefulness of DNA barcoding for evaluating the safety of honey.

Wild grapevine: silvestris, hybrids or cultivars that escaped from vineyards? Molecular evidence in Sardinia

Vitis vinifera ssp. silvestris, the spontaneous subspecies of V. vinifera L., is believed to be the ancestor of present grapevine cultivars. In this work, polymorphism at 13 SSR loci was investigated to answer the following key question: are wild plants (i) true silvestris, (ii) hybrids between wild and cultivated plants or (iii) or 'escapes' from vineyards? In particular, the objective of the present study was to identify truly wild individuals and to search for possible hybridization events. The study was performed in Sardinia, the second largest island in the Mediterranean Sea, which is characterized by a large and well-described number of both grape cultivars and wild populations. This region was ideal for the study because of its spatial isolation and, consequently, limited contamination from outside material. The results of this study show that domesticated and wild grapevine germplasms are genetically divergent and thus are real silvestris. Pure lineages (both domesticated and wild) show very high average posterior probabilities of assignment to their own clusters, with a low level of introgression.

Haplotype richness in refugial areas: phylogeographical structure of Saxifraga callosa

This paper illustrates the phylogeographical structure of Saxifraga callosa in order to describe its genetic richness in refugial areas and to reconstruct its glacial history. S. callosa is a species spread throughout south-east France and Italy with a high distribution in the Maritime Alps. Four chloroplast microsatellite and AFLP markers were analyzed in populations of S. callosa. The size variants of all tested loci amount to 11 different haplotypes. Intrapopulational haplotype variation was found in two of the populations analyzed: on the Mt. Toraggio in the Maritime Alps, and in the Apuan Alps. On the other hand, no intrapopulational variation was found in 25 populations, most of which were sampled from isolated areas. Analysis of the haplotype distribution showed that population subdivision across all populations was high (G (ST) = 0.899). Moreover, its genetic structure was studied using AMOVA and STRUCTURE analysis. The study legitimated inferred conclusions about the phylogeographical structure of the species and identified centers of diversity. Considerations concerning genetic structure and divergence among three major clades (Maritime Alps, Apuan Alps and Apennines), the patchy distribution of haplotypes, and the high number of private haplotypes support the proposal that S. callosa survived in some refugia within the Italian Peninsula refugium, and that mainly northern populations of refugia were involved in postglacial recolonization.

Chloroplast microsatellites markers to assess genetic diversity in wild and cultivated grapevines of Iran

To assess the haplotype diversity and genetic relationship between them, A set of 69 Iranian cultivated accessions, six European cultivars and an accession of Vitis labrusca along with 63 wild grapevine individuals were studied using chloroplast microsatellite markers. Results showed that among analyzed cpssr loci only ccmp 3 and ccmp10 were polymorphic within cultivars and only ccmp3 was polymorphic in wild grape individuals. The size variants of both loci combine in a total of 4 different haplotypes. All the 4 haplotype are displayed in the cultivars while only 2 are presented in wild grapes. Sultani or keshmeshi Bidane cultivar has the haplotype III that there is not this haplotype among the wild grapes of studied regions. Concerning to existence of both haplotypes I and II in the number of Iranian cultivated and wild grapes, it is possible to consider that the wild grapes are ancestor of some of our native cultivars.

Natural hybridization in Saxifraga callosa Sm

Saxifraga callosa Sm. is an evergreen perennial species distributed from Eastern Spain, through the Western Alps and the Apennines, to southern Italy. The existence of high morphological variation within different subspecies indicates that phenotypic characters are useful but not sufficient taxonomic tools. Indeed, available morphological data already suggested that S. callosa subentity lantoscana may be an outcross between S. callosa and S. cochlearis. In this work, by analyzing ITS (Internal Transcribed Sequences), AFLP (Amplified Fragment Length Polymorphisms), and cpDNA (chloroplast DNA) markers, a comprehensive study of the genomic relationships among S. callosa and related species has been carried out. The sequence of the ITS region of S. callosa subentity lantoscana gave no conclusive results on the taxonomy status of S. callosa subentity lantoscana. On the other hand, the use of the "NewHybrids" software to analyze an AFLP data-set (208 polymorphic amplified fragments) supported a significant posterior probability that S. callosa subentity lantoscana individuals are natural hybrids between S. callosa and S. cochlearis. The level of introgression of genes from alien genomes was confirmed by a simpler and quick methodology that analyze length variation in cpDNA sequences.

Zea mays L. protein changes in response to potassium dichromate treatments

The plant metabolic response to heavy metal stress is largely unknown. The present investigation was undertaken to examine the influence of different concentrations of potassium dichromate on the Zea mays L. plantlets. A clear effect of chromium on maize plantlets growth and seed germination was observed strating from 100-300 ppm up to 1500 ppm. In this concentration range, chromium uptake was dependent on the concentration in the medium. Metallothioneins, involved in heavy metal binding, were measured by capillary electrophoresis (CE), and showed a dose-response induction. Protein profile analyzed by two-dimensional gel electrophoresis showed differential expression of several proteins. Identification of spots of upregulated proteins was performed by MALDI mass spectrometry. Results showed that proteins induced by heavy metal exposure are principally involved in oxidative stress tolerance or in other stress pathways. Induction of proteins implicated in sugar metabolism was also observed. Identification of factors involved in plant response may lead to a better understanding of the mechanisms involved in cell protection and tolerance. This information could be used to improve agricultural production and environmental quality.

Genomic stability in Arabidopsis thaliana transgenic plants obtained by floral dip

The occurrence of DNA modification is an undesired phenomenon accompanying plant cell transformation. The event has been correlated with the stress imposed by the presently utilised transformation procedures, all depending on plant differentiation from in vitro cell culture, but other causes have not been excluded. In this work, transgenic Arabidopsis thaliana plants have been produced by an approach that does not require cell dedifferentiation, being based on in planta Agrobacterium-mediated gene transfer by flower infiltration, which is followed by recovery and selection of transgenic progeny. Genomic DNA changes in transgenic and control plants have been investigated by AFLP and RAMP analysis. Results show no statistically relevant genomic modifications in transgenic plants, as compared with control untreated plants. Variations were observed in callus-derived A. thaliana plants, thus supporting the conclusion that somaclonal variation is essentially correlated with the stress imposed by the in vitro cell culture, rather than with the integration of a foreign gene.

A survey of genetic diversity and reproductive biology of Puya raimondii (Bromeliaceae), the endangered queen of the Andes

Puya raimondii Harms is an outstanding giant rosette bromeliad found solely around 4000 m above sea level in the Andes. It flowers at the end of an 80 - 100-year or even longer life cycle and yields an enormous (4 - 6 m tall) spike composed of from 15,000 to 20,000 flowers. It is endemic and currently endangered, with populations distributed from Peru to the north of Bolivia. A genomic DNA marker-based analysis of the genetic structure of eight populations representative of the whole distribution of P. raimondii in Peru is reported in this paper. As few as 14 genotypes out of 160 plants were detected. Only 5 and 18 of the 217 AFLP marker loci screened were polymorphic within and among these populations, respectively. Four populations were completely monomorphic, each of the others displayed only one to three polymorphic loci. Less than 4 % of the total genomic variation was within populations and genetic similarity among populations was as high as 98.3 %. Results for seven cpSSR marker loci were in agreement with the existence of a single progenitor. Flow cytometry of seed nuclear DNA content and RAPD marker segregation analysis of progeny plantlets demonstrated that the extremely uniform genome of P. raimondii populations is not compatible with agamospermy (apomixis), but consistent with an inbreeding reproductive strategy. There is an urgent need for a protection programme to save not only this precious, isolated species, but also the unique ecosystem depending on it.

Evidence of a secondary grapevine domestication centre detected by SSR analysis

The origin of the grapevine was investigated with archaeobotanical, cultural and historical data. A primary domestication centre was located in the Near East region but there is no agreement on the existence or role of secondary domestication centres. In this work, PCR-based microsatellite analysis has been applied to study the origin of some Italian cultivated grapevines from in situ direct domestication of the wild autoctonous grapevine. Three different Italian locations in Grosseto, Cosenza and Nuoro were identified for this study, and domesticated grapevine as well as wild local accessions growing in these location, were analysed by SSR markers. Cluster analysis performed on Cosenza and Grosseto samples showed a high value of genetic distance between domesticated and wild accessions. On the contrary two cultivars (Bovale Murru and Bovale Muristellu) recovered in Nuoro (in the Sardinia island) were very close to some wild varieties. This suggests that the latter two cultivars may have originated from wild grapevines and consequently that in this location a secondary grapevine domestication event occurred. Six Lambrusco varieties were also included in this analysis as ancient putative ancestors of the cultivated grapevines. The molecular analysis excluded this hypothesis and suggest Lambrusco as an independent Vitis taxon.

AFLP analysis as biomarker of exposure to organic and inorganic genotoxic substances in plants

In recent years several plant species have been in use as bioindicators and several tests have been developed to evaluate the toxicity of environmental pollutants in vegetal organisms. In the present paper Arabidopsis thaliana (L.) Heynh. (ecotype Wassilewskija) was used as bioindicators of two genotoxic substances: potassium dichromate and dihydrophenanthrene. Inhibition of seed germination was observed with both pollutants. AFLP analysis (i) indicated that both substances are genotoxic, (ii) showed that dihydrophenanthrene induces DNA changes in different target sequences than potassium dichromate, (iii) quantified the genotoxic effect using cluster analysis by comparing DNA from treated plants with that of control plants. On the basis of these considerations we suggest that AFLP method is a powerful tool for measuring qualitative and quantitative genotoxic activity due to environmental pollutants. AFLP method can be applied to a wide range of bioindicator organisms and may become a universal methodology to identify target genes for specific genotoxic agents. This could open up possibilities for designing specifically targeted assays and new approaches to risk assessment.

Resolution of viable and membrane-compromised bacteria in freshwater and marine waters based on analytical flow cytometry and nucleic acid double staining

The membrane integrity of a cell is a well-accepted criterion for characterizing viable (active or inactive) cells and distinguishing them from damaged and membrane-compromised cells. This information is of major importance in studies of the function of microbial assemblages in natural environments, in order to assign bulk activities measured by various methods to the very active cells that are effectively responsible for the observations. To achieve this task for bacteria in freshwater and marine waters, we propose a nucleic acid double-staining assay based on analytical flow cytometry, which allows us to distinguish viable from damaged and membrane-compromised bacteria and to sort out noise and detritus. This method is derived from the work of S. Barbesti et al. (Cytometry 40:214-218, 2000) which was conducted on cultured bacteria. The principle of this approach is to use simultaneously a permeant (SYBR Green; Molecular Probes) and an impermeant (propidium iodide) probe and to take advantage of the energy transfer which occurs between them when both probes are staining nucleic acids. A full quenching of the permeant probe fluorescence by the impermeant probe will point to cells with a compromised membrane, a partial quenching will indicate cells with a slightly damaged membrane, and a lack of quenching will characterize intact membrane cells identified as viable. In the present study, this approach has been adapted to bacteria in freshwater and marine waters of the Mediterranean region. It is fast and easy to use and shows that a large fraction of bacteria with low DNA content can be composed of viable cells. Admittedly, limitations stem from the unknown behavior of unidentified species present in natural environments which may depart from the established permeability properties with respect to the fluorescing dyes.

Two and three-color fluorescence flow cytometric analysis of immunoidentified viable bacteria

BACKGROUND

Traditional culture methods well established in the past and still in use are not able to detect the environmental microorganisms that exist in a viable but not culturable state. A number of different fluorescence-based assays have been developed over the past decade to detect and identify viable bacteria in the environment.

METHODS

We have developed a simple and rapid method for measuring the number and viability of immunolabeled bacteria by means of a two/three color fluorescence flow cytometric analysis. After washing, cultured bacteria in suspension were labeled with a rabbit polyclonal antibody recognizing the wall lipopolysaccharide complex. A secondary biotinylated anti-rabbit polyclonal antibody was added allowing the cells to be labeled with the streptavidin R-phycoerythrin-Cyanine 5 (RPE-Cy5) fluorochrome. Before flow cytometric analysis, bacterial suspensions were stained with SYBR Green I and propidium iodide which stain all of the cells and the non viable ones, respectively.

RESULTS AND CONCLUSIONS

With the appropriate filter sets of both Bryte-HS (Bio-Rad, Hercules, CA) and FACScan (Becton Dickinson, San Jose, CA) flow cytometers, the measurement of separated green (SYBR Green I), orange-red (propidium iodide), and far red (RPE-Cy5) fluorescence was possible, allowing the enumeration of viable immunodetected bacteria. The entire protocol is completed in less than 3 h, offering numerous possibilities for rapid and precise analyses in sanitary, industrial, and environmental microbiology.