Identification and quantification of phenolic compounds in fresh and processed table olives of cv. ‘Kalamata’

Mediterranean diet is almost synonymous to the healthy lifestyle and diet nowadays. Some of the major components of the diet are the products of the olive tree, fruits and olive oil, which are classified as medical foods, due to their nutraceutical benefits and their protective properties against cancer, cardiovascular diseases, age-related diseases, neurodegenerative disorders and other diseases. The key contributors to these properties are the phenolic compounds such as hydroxytyrosol, tyrosol and oleuropein. Table olives are being processed with several methods in order to reduce the bitterness of the olive fruit and the impact of the processing on phenolic compounds has not been studied extensively. In the present study, changes in the concentration of the most important phenolic compounds were quantified in fresh, Greek-style and Spanish-style processed olive fruits of cv. ‘Kalamata’, using two different analytical methods for identification and quantification: high-performance liquid chromatography diode array detector (HPLC-DAD) and ultrahigh-performance liquid chromatography tandem mass spectrometry (LC-(ESI)-MS/MS). The phenolic compounds that were identified and quantified were hydroxytyrosol, tyrosol, verbascocide, rutin, oleuropein and luteolin. Both processing methods used altered the phenolic compounds concentration in ‘Kalamata’ olive fruits compared to untreated fruits. In both analytical methods, a statistically significant increase in verbascoside and hydroxytyrosol concentration and a statistically significant decrease in rutin concentration was observed in both, Greek-style and Spanish-style, processed olive fruits

The Role of DNA Methylation in Perennial Plants

DNA methylation is an important epigenetic modification of the genome in all organisms. This review presents the effect of DNA methylation in perennial fruit trees such as chestnut, apple, peach etc. In particular, DNA methylation has been shown to affect bud dormancy, the changes of developmental stages such as: flowering, the synthesis of anthocyanins, among other flavonoid compounds; it also affects the fertilization and perpetuation of many fruit trees. Finally, DNA methylation can be used as a tool for investigating the epigenetic diversity of a species

In vitro Propagation and Assessment of Genetic Relationships of Citrus Rootstocks Using ISSR Molecular Markers

The behavior of six citrus rootstocks, Volkameriana, Citrumelo ‘Swingle’, Citrange ‘Carrizo’, Poncirus trifoliata ‘Serra’, Poncirus trifoliata ‘Rubidoux’ and Poncirus trifoliata ‘Flying Dragon’, in in vitro propagation was studied and compared for shoot proliferation and rooting. In addition, the genetic relationships among the rootstocks studied and other Citrus species, using the Inter-Simple Sequence Repeats (ISSR) molecular markers, were investigated. Nodal explants of three months old shoots were used in Murashige and Skoog medium supplemented with N6-benzyladenine (BA) for shoot proliferation and with naphthaleneacetic acid (NAA) for rooting. The rootstock Volkameriana showed a statistically significant higher number of shoots (1.81), shoot length (15.14 mm) and number of leaves per explant (5.81), while all three Poncirus trifoliata rootstocks showed the lowest numbers. The number of roots and root length per explant were evaluated at the end of the rooting phase. The rootstock ‘Swingle’ showed a higher number of roots per explant (4.2) followed by ‘Flying Dragon’ (3.93) and ‘Carrizo’ (3.23) rootstocks. The rootstocks ‘Swingle’ (140.8 mm), Volkameriana (148 mm) and ‘Flying Dragon’ (131.12 mm) had significantly higher root length per explant compared to ‘Carrizo’ (31 mm) and ‘Rubidoux’ (34.5 mm). The ISSR molecular marker technique used in the present study grouped successfully the different species, varieties and rootstocks studied, revealing their genetic variability. The genetic variability observed among the rootstocks ranged between 0.29 (Poncirus trifoliata ‘Serra’ and Citrumelo ‘Swingle’) and 0.60 (Volkameriana and Citrumelo ‘Swingle’). The response of the rootstocks studied in in vitro propagation however is not related to their genetic affinity

Genetic relatedness among cultivars of the greek plum germplasm

Genetic diversity of the Greek plum germplasm collection was investigated using a combined RAPD and ISSR molecular markers approach. Twenty-six genotypes held at NAGREF-Naoussa were analyzed, producing in total 150 loci, of which 116 were polymorphic. Both techniques were highly informative and had a discrimination power greater than 0.9. RAPD and ISSR dendrograms were fairly correlated. The accessions were clustered according to ploidy and species. All Prunus domestica genotypes were grouped together and showed greater similarity to P. insititia and P. cerasifera genotypes compared to P. salicina, which was found genetically diverged. Bayesian structural analysis revealed significant admixture among genotypes. Greek varieties P. domestica 'Goulina' and 'Asvestochoriou' exhibited a distinctive genetic background, differentiating them from foreign varieties. This feature could make them attractive for breeding programs, since they can increase genetic diversity

Total Phenolic Content and Antioxidant Activity in Leaves and Drupes of Ten Olive Varieties

Leaves and drupes of the olive varieties "Koroneiki", "Lianolia Kerkyras", "Mastoidis", "Arbequina", "Adramytini", "Megaritiki", "Gaidourelia", "Kalamata", "Konservolia" and "Chalkidiki", were collected at different seasons during the years 2008 & 2009 and investigated for their total phenolic content and antioxidant activity. Total phenolic content and antioxidant activity were determined according to Folin-Ciocalteau and DPPH assays, respectively. Different varieties presented differences in the total phenolic content and total antioxidant activity per tissue. For both years, most varieties showed higher total phenolic content in new season leaves than in green and black drupes. New season leaves on April showed the highest total phenolic content than the leaves of September and December of the same year, with a few exceptions. There was a positive correlation between the antioxidant activity and the total phenolic content. Highest phenolic content was accompanied by a lower IC50 value and as a result higher antioxidant activity

Genomic and chromosomal organization of Ty1- copia-like sequences in Olea europaea and evolutionary relationships of Olea retroelements

The Ty1- copia-like retrotransposon is one of the commonest class of transposable elements in the plant kingdom, often comprising several percent of the total DNA content. We aimed to study the evolutionary relationships of Olea retroelements, using part of the reverse transcriptase domain, as well as the genomic and chromosomal organization of these sequences in Olea europaea chromosomes and their transcription activity and copy number. Fourteen clones, that were isolated from four different species, were sequenced and a phylogenetic tree was constructed based on their predicted amino acids. Five clones derived from O. europaea were clustered together with a 87% nucleotide sequence homology and two Olea oleaster clones showed 98% sequence homology. The rest of the clones showed heterogeneity among them, leading to a common ancestral transposon that existed before the genus arose. The Ty1- copia-like sequences have a dispersed genomic organization, physically distributed on all chromosomes, showing minor clustering in some cases and low copy numbers in the smallest chromosome pair. The total copy number in the O. europaea genome was estimated by dot blotting to be 40,000 in a haploid nucleus, but a number of these are non-functional since the sequenced clones contained stop codons and frame-shifts. Some Ty1- copia-like copies, present in O. europaea, were found to be methylated, while no differences in methylation were observed between DNA isolated from young leaves and callus-suspension cultures

Genetic relatedness among cultivars of the greek plum germplasm

Genetic diversity of the Greek plum germplasm collection was investigated using a combined RAPD and ISSR molecular markers approach. Twenty-six genotypes held at NAGREF-Naoussa were analyzed, producing in total 150 loci, of which 116 were polymorphic. Both techniques were highly informative and had a discrimination power greater than 0.9. RAPD and ISSR dendrograms were fairly correlated. The accessions were clustered according to ploidy and species. All Prunus domestica genotypes were grouped together and showed greater similarity to P. insititia and P. cerasifera genotypes compared to P. salicina, which was found genetically diverged. Bayesian structural analysis revealed significant admixture among genotypes. Greek varieties P. domestica 'Goulina' and 'Asvestochoriou' exhibited a distinctive genetic background, differentiating them from foreign varieties. This feature could make them attractive for breeding programs, since they can increase genetic diversity

Genomic organization, sequence interrelationship, and physical localization using in situ hybridization of two tandemly repeated DNA sequences in the genus Olea

Two tandemly repeated DNA sequences, the 81-bp family and pOS218, have been isolated from a Sau3AI Olea europaea ssp. sativa partial genomic library. Sequencing of the 81-bp element showed the monomer to be between 78 and 84 bases long and to contain 51-58% adenine and thymidine residues. Comparison between the monomers revealed heterogeneity of the sequence primary structure. The clone pOS218 is 218 bases long, and sequence comparison between the two elements revealed that an internal region of the pOS218 repeated DNA sequence had 79% homology to the 81 bp repeat sequence. A breakage-reunion mechanism, involving the CAAAA sequence, could be responsible for the derivation of pOS218 from the 81 bp family element. By using double target in situ hybridization, co-localization of the two sequences on Olea chromosomes was observed. The sequences were present at DAPI stained heterochromatic regions, as major or minor sites having a subtelomeric or interstitial location. Methylation studies using two sets of isoschizomers, Sau3AI-MboI and MspI-HpaII, demonstrated that most cytosine residues in the GATC sites and the internal cytosine in the CCGG sites of both elements were methylated in O. europaea ssp. sativa. No major difference in methylation was apparent between DNA extracted from young leaves or from callus of O. europaea ssp. sativa. Both elements are also present in Olea chrysophylla, Olea oleaster, and Olea africana, but are absent from other Oleaceae genera, including Phillyrea, Forsythia, Ligustrum, Parasyringa, and Jasminum

Phenolic Profile of Leaves and Drupes of Ten Olive Varieties

Leaves and drupes of the olive varieties "Koroneiki", "Lianolia Kerkyras", "Mastoidis", "Arbequina", "Adramytini", "Megaritiki", "Gaidourelia", "Kalamata", "Konservolia" and "Chalkidiki" were collected at different seasons during 2008 and 2009 and investigated by HPLC for their phenolic profile and the concentration of the phenolic compounds present. The phenolic compounds identified in 2008 new season leaves were, in declining concentration order, oleuropein, 7-O-glucoside of luteolin and rutin whereas for those collected in 2009 the main phenolic compounds were oleuropein, rutin, 4-O-glucoside of luteolin and 7-O-glucoside of apigenin. In September - December 2009 collected leaves, oleuropein presented the higher concentration followed by 7-O-glucoside of luteolin, 4-O-glucoside of luteolin and rutin. Regarding green and black drupes for both years, the main phenolic compounds were oleuropein, verbascoside and rutin. Verbascoside was only found in drupes whereas the 7-O-glucoside of apigenin only in leaves. Εach tissue, for both years, had a similar phenolic profile in all varieties

Genetic structure of the Greek olive germplasm revealed by RAPD, ISSR and SSR markers

The olive is globally considered as one of the most significant crops, with more than 1200 distinctive cultivars and an abundant number of wild forms. Greece, the third largest producer worldwide, has been considered a secondary centre of domestication and its genetic recourses are potentially valuable for olive breeding. In the current study, the genetic diversity of an extended Greek olive germplasm collection (101 accessions) was revealed using RAPD, ISSR and SSR markers in an attempt to explore the genetic relationships among them, and comprehend how genetic variability is partitioned between the Greek germplasm. A Bayesian model-based clustering method was employed and allocation of genotypes into defined gene pools according to genetic and geographic criteria was detected. Genealogies detected by Median-Joining coalescent simulations, classified all genotypes into a complex network. Both linear and reticulate ties among the Greek olive cultivars were revealed. Hence, data suggested that both sexual and vegetative propagation have contributed to the evolution of the Greek olive germplasm. Furthermore, clustering of olive cultivars was correlated to their primarily usage (table or oil producing) and fruit size. Finally, Greek olive cultivars are characterized providing a useful clarification on synonyms and homonyms, facilitating the identification of duplicates