Monoterpenoid diversity in relation to morphology of Pinus brutia and Pinus halepensis in an east Mediterranean area (Attiki, Greece): Implications for pine evolution

Pinus halepensis and P. brutia hybridize extensively. The analysis of monoterpenoid and morphological variability of 122 pine trees at five sites showed that the within-site heterogeneity is high while the entire provenance diversity is comparable with that of a circum-Mediterranean scale. Four morphotypes and four chemotypes were recognized. The congruence between morphological and monoterpenoid classification of pines was high (coefficient of contingency 89%) while thirteen family groups of genetically closely related trees were found by means of a specifically designed sampling scheme of continuous classification - identification and re-sampling. Putative hybrids contributed substantially to the observed diversity and there is considerable heterogeneity between sites. Low-altitude sites, presumably susceptible to sea-level fluctuations, alluvial deposition and human influence, are in general more diverse at both levels of genetic complexity than inland sites. The hybrid phenotypes were not merely intermediate forms of parental taxa, and in a multivariate sense they are located on a parabola in the space of morphological properties. The arrangement of hybrids in the monoterpenoid space did not reveal any clear-cut pattern except that three major composite axes can summarize 98.9% of the entire monoterpenoid variation. The observed pattern of variation was interpreted as a result of waves of introgressive influence of eastern P. brutia population on P. halepensis, which was caused by marine transgressions in Pliocene and eustatic sea-level fluctuations in Pleistocene. The human influence on this introgression accelerated the process, and amplified the resulted pattern, although it blurred in many instances the biogeographic routes of germplasm mixing. Its bearing on the evolution of pines is discussed, and it was found that the 'Eocene refugia hypothesis' of C.I. Millar holds by analogy also in central Aegean pines

A method for detecting the biosystematic significance of the essential oil composition: The case of five Hellenic Hypericum L. species

We examined the importance of the constitutive terpenoids of five species of Hypericum native to the Greek mainland, Crete Island and the west Aegean. The species studied are Hypericum empetrifolium Willd. (sect. Coridium Spach), Hypericum rumeliacum Boiss. subsp. apollinis Robson & Strid, Hypericum perfoliatum L. (sect. Drosocarpium Spach), Hypericum triquetrifolium Turra and Hypericum perforatum L. (sect. Hypericum, subsect. Hypericum [Robson, N.K.B., 2001. Studies in the genus Hypericum L. (Guttiferae). 4 (1). Sections 7. Roscyna to 9. Hypericum sensu lato (part 1). Bull. Brit. Mus. (Nat. Hist.) Bot. 31, 37-88]). Canonical discriminant analysis (CDA) on 98 of the most abundant terpenoids was found to achieve a separation of species. The performed phylogenetic reconstruction supports the existing divisions of Hypericum in taxonomic sections. Other multivariate techniques were also investigated such as principal coordinate analysis and principal component analysis, but these were found inferior to CDA. These analyses transformed the data in such a way that they did not sufficiently account for the entire terpenoid variation, nor did they delineate species in accepted taxonomic sections. © 2005 Elsevier Ltd. All rights reserved

Composition and antimicrobial activity of the essential oil of Hypericum rumeliacum subsp. apollinis (Boiss. & Heldr.)

The composition and the antimicrobial activity of the aerial parts of Hypericum rumeliacum are reported. Analysis was carried out by GC/MS. The major constituents were α-pinene (43.80%), β-pinene (9.82%), dehydro-aromadendrene (6.81%) and α-copaene (5.41%). The essential oil showed a moderate in vitro activity against the six Gram negative and positive bacteria and a stronger one against the three-tested pathogenic activity. Copyright © 2003 John Wiley & Sons, Ltd

The interaction of pine scale with pines in Attica, Greece

The pine scale (Marchalina hellenica) has been introduced to Attica and reached unprecedented population densities. Using a randomised transect-based sampling design in eight sites, we sampled the insect in random 10 cm squares on the trunk and main branches of pine trees. The insect did not show any clumping other than a micro-site preference for fissures and cracks. Canonical discriminant analysis and generalised multinomial logit regression modelling were used to determine the most important ecological variables which were the following: the population density of the insects; crown transparency; mean distance between trees; and the quality of the habitat. The site and the distance from the line transect were insignificant. The interaction of crown transparency with the abundance of the insect, the mean distance between trees and the quality of each site were important in configuring the level of damage sustained by the pine tree. © 2010 Springer-Verlag

Iridoid glucosides with insecticidal activity from Galium melanantherum

The insecticidal activity of the endemic species Galium melanantherum was evaluated against Crematogaster scutellaris ants and Kalotermes flavicollis termites. Iridoid glucosides 1-7 were isolated for the first time as metabolites of the investigated plant, along with the coumarin scopolin. The main components of the extract were found to be the non-acetylated iridoids: geniposidic acid (1), 10-hydroxyloganin (2), deacetyldaphylloside (3), monotropein (4), deacetylasperulosidic acid (5) and scandoside (6), while asperulosidic acid (7) was present only in minute quantities. All isolated metabolites were identified on the basis of their spectral data. Laboratory bioassays revealed significant levels of toxicity for 1-4 against Kalotermes flavicollis termites and Crematogaster scutellaris ants. © 2007 Verlag der Zeitschrift für Naturforschung