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Abstract• A discriminant study based on samples taken from high and low yielding oleoresin trees of two Greek populations, Chalkidiki and Euboia, was carried out. Oleoresin of Pinus halepensis Mill. was characterised by GC/MS analysis.• The objectives of this study were: (i) to identify in detail the composition of the oleoresin of P. halepensis and in particular of high yielding trees (plus trees) (ii) to investigate a potential relationship between the oleoresin compounds and the oleoresin yield and (iii) to investigate any correlations among the compounds.• About forty monoterpenes, sesquiterpenes and diterpenes were identified as main compounds representing 97.40% of the analyzed oleoresin. α-Pinene, methyl abietate, abietic acid, palustric acid, isopimaric acid and neoabietic acid were the major compounds. Efficient discrimination was achieved between the two populations and between the two groups of trees (high and low yielding). In both cases, the differentiation was due to the quantitative variability of certain compounds. High positive correlations were found among certain compounds.• The results suggest that the oleoresin profile is a useful tool for the discrimination of trees according to their provenance or their oleoresin yield.

A combination of Murashige and Skoog's medium and N 6 -benzyladenine (BA) at various concentrations (0, 0.1, 0.25, 0.5, 0.75, 1.0, 1.25 and 1.5 mg l )1 ) was supplied to shoot tips from root cuttings of a 50-yearold wild-cherry tree (Prunus avium). The concentration of BA in the growing medium was a determining factor with respect to the number of proliferated shoots per explant in vitro. Normal and fasciated shoots were generated when BA was present at 0.5, 0.75, 1.0 and 1.25 mg l )1 in the medium and the mean numbers of normal shoots per explant were 3.63, 5.37, 8.93 and 7.30 respectively, and those of the fasciated shoots per explant were 0.03, 0.1, 0.47 and 0.4 respectively. Anatomical analysis by confocal microscopy of sections of paraffin-embedded specimens revealed that the cell structure and organization of the cortex and vascular cylinder in the fasciated shoots was similar to that in normal shoots. However, the cross-sectional area of stem of the fasciations was apparently greater than that of the normal shoots. In particular, the volume of vascular tissues, of pith and of some individual parenchyma cells in the cortex and pith was apparently greater in fasciated shoots than in normal shoots. Increases in cytokinesis and morphogenetic activity, such as the development of callus-like regions and the formation of adventitious shoots, were observed in the cortex and pith throughout the fasciations. The fasciated shoots had numerous buds and initiating new shoots at their apices while normal shoots had a single dominant axial bud.

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Summary — Fascicle shoots proved to be an ideal plant material for micropropagation of the pine hybrid P brutia (Ten) x P halepensis (Mill). This could be possibly attributed to their morphological and physiological state. Induced fascicle shoots of 4-yr-old seedlings were used as explants. Their induction was achieved by spraying once with the new herbicide Arsenal (1 000 mg I -1 ). First, explants were elongated in vitro on LP medium and then transferred to the multiplication stage. Multiplication was accomplished by decapitating, quick-dipping in 0.22 mM BA and inoculating the explants on BIMI medium. On the induced first-generation shoots the same procedure was applied, in order to obtain second-generation shoots and then these were proceeded to the rooting and acclimatization stages. In particular, when microcuttings were pretreated with 2.46 μM IBA + 2.7 μM NAA + 0.65% agar w/v + 1.5% sucrose w/v for 7 d and then transferred to greenhouse conditions, a good root system was developed within an 8-12-week period. A large variation in rootability was noted between clones. The above method may be proved to be efficient for clones that exhibit high rooting ability.