Monika Persson

Relative amounts and enantiomeric compositions of monoterpene hydrocarbons in xylem and needles of Picea abies

Abstract The relative amounts of 23 monoterpene hydrocarbons, including enantiomers, present in extracts of branch xylem and needles from 41 Picea abies plus-trees of widely different origins, were determined. A two-dimensional gas chromatographic system was used for the determination of the enantiomeric compositions of the seven major chiral monoterpenes. Data were evaluated by multivariate data analysis. Large variations were found in the enantiomeric compositions, as well as in the relative amounts of the monoterpenes, both within and among the trees. Trees from the same geographic area did not show a greater similarity in their composition of volatiles than trees from different geographic areas. In the xylem, (−)-β-pinene and (−)-β-phellandrene, and in the needle samples, (−)-α-pinene, (−)-limonene and (−)-camphene, dominated over their (+)-enantiomers. Among-tree variation in enantiomeric composition was higher in xylem samples than in needle samples, except for β-pinene and β-phellandrene.

Enantiomeric Composition of Monoterpene Hydrocarbons in Some Conifers and Receptor Neuron Discrimination of α-Pinene and Limonene Enantiomers in the Pine Weevil, Hylobius abietis

The enantiomeric composition of seven monoterpene hydrocarbons in headspace volatiles of spruce sawdust and seedlings (Picea abies), pine seedlings (Pinus sylvestris), and branches of juniper (Juniperus communis) was determined by gas chromatographic separation on a β-Cyclodextrin column. For the six monoterpenes, α-pinene, camphene, β-pinene, sabinene, limonene, and β-phellandrene, both enantiomers were present, whereas for 3-carene only the (+)-configuration was found. The amount of each enantiomer varied considerably both in relation to total amount of all of them, and for the six pairs also in relation to the opposite enantiomer. One olfactory receptor neuron in the pine weevil (Hylobius abietis) showed a strong response to α-pinene when stimulated with all four headspace materials via a GC equipped with a DB-WAX column. The same neuron was subsequently tested with repeated stimulations via the GC effluent containing the (+)- or (–)-enantiomer. A marked better response to (+)- than to (–)-α-pinene was elicited. Another olfactory receptor neuron that responded strongly to limonene when stimulated with the spruce volatiles was tested for enantiomers of limonene. This neuron responded more strongly to (–)- than to (+)-limonene, when stimulated alternately with each of the limonene enantiomers. Discrimination between enantiomers by plant olfactory receptor neurons suggests that the enantiomeric ratios of volatile compounds may be important in host location by the pine weevil.

Enantiomeric compositions of monoterpene hydrocarbons in different tissues of four individuals of Pinus sylvestris

Abstract The relative amounts of volatiles, mainly monoterpene hydrocarbons, were determined in eight different tissues of each of four individuals of Pinus sylvestris . The four trees represented widely different monoterpene compositions. Two-dimensional gas chromatography, using columns with stationary phases containing functionalized cyclodextrins, allowed the determination of the enantiomeric compositions of seven major chiral monoterpene hydrocarbons. Large differences in the relative amounts of the monoterpene hydrocarbons as well as in their enantiomeric compositions were found both within and between individuals. The extremely large relative amounts of (+)-3-carene or (−)-limonene found in the samples of 1-year-old phloem and bark of branches and in the shoots of some of the trees were not found in the xylem of the trunk or root or in the needles of the same trees. Only the (+)-enantiomer of 3-carene was detected. The (−)-enantiomers of β-pinene, sabinene and β-phellandrene dominated over the corresponding (+)-enantiomers in all samples.

Occurrence and correlations of monoterpene hydrocarbon enantiomers in Pinus sylvestris and Picea abies.

The relative amounts and enantiomeric compositions of monoterpene hydrocarbons in branch and trunk xylem, in needles, and in resin from apical buds in 18 Pinus sylvestris trees have been determined and compared with the terpene content in branch xylem and needles of Picea abies. Besides the high amount of (+)-3-carene, an excess of (+)-α-pinene has been found in P. sylvestris, whereas in P. abies (−)-α-pinene dominates over (+)-α-pinene. In P. sylvestris, clear positive correlations were found between (+)-α-pinene and (+)-camphene in the four tissues analyzed. Good positive correlations were also observed between (−)-α-pinene and (−)-camphene in the two types of xylem, between (+)-α-pinene and (+)-β-pinene in the resin, and between tricyclene and (−)-camphene in resin and needles. In P. abies, positive correlations were found between (+)-α-pinene and (+)-camphene in the branch xylem and between tricyclene and (−)-camphene as well as between (−)-α-pinene and (−)-camphene in the needles. Complex relationships between (−)-α-pinene and (−)-β-pinene were found both in the P. abies and in the P. sylvestris tissues. The importance of the enantiomeric composition of α-pinene for the host selection of Ips typographus, Tomicus piniperda, and Hylobius abietis is discussed.

Enantiomeric composition of six chiral monoterpene hydrocarbons in different tissues of Picea abies

Abstract The enantiomeric compositions of α-pinene, camphene, β-pinene, sabinene, limonene and β-phellandrene were determined in 10 different tissues of Norway spruce, Picea abies . The xylem of root, trunk, branch and twig as well as the phloem of root and twig, oleoresin, needles of different age and male and female flowers were analysed by multidimensional GC. Large differences in enantiomeric composition of the chiral monoterpene hydrocarbons were found between the tissues. The relative amount and enantiomeric composition of limonene in branches changed during storage.

Correlations between selected monoterpene hydrocarbons in the xylem of six Pinus (pinaceae) species

Summary. The compositions of 23 monoterpene hydrocarbons of six pine species (Pinus sylvestris,P. yunnanensis, P. armandii, P. tropicalis, P. cubensis and P. caribaea) were compared, using multivariate data analysis. Four of the six species were clearly different from the other species in a Principal Components Analysis (PCA) model, based on the relative amounts (selective normalization) of the monoterpenes. The correlation coefficients between constituents were determined separately for each species and the strongest correlations were found between (+)-α-pinene and (+)-camphene and between the corresponding (—)-enantiomers, in all species. This pattern, i.e. a good correlation in all species, was neither shown by the correlation of the structurally more similar (+)-α/β-pinenes, nor by the (—)-α/β-pinenes or within the enantiomeric pairs of α-pinene and β-pinene. For these pairs of monoterpenes, good correlations were found in some species. None of the species showed good correlations in all the investigated monoterpene pairs presented here. Correlations between monoterpenes in insect-attacked trees (P. cubensis and P. caribaea, attacked by Dioryctria horneana, and P. yunnanensis, attacked by Tomicus piniperda) were also determined. The results are discussed from chemotaxonomic and biosynthetic points of view.

Enantiomeric compositions of monoterpene hydrocarbons in the wood of healthy and top-cut Pinus sylvestris

Abstract The enantiomeric compositions of seven monoterpene hydrocarbons occurring in Pinus sylvestris L. wood (including bark) before and after top-cutting were determined. The investigation included trees of two chemotypes characterized by high and low 3-carene content, respectively. Top-cutting of the trees caused a weak disturbance in the enantiomeric composition of β-pinene in trees of the low 3-carene chemotype. The (−)-enantiomer of 3-carene was not detected in any of the specimens investigated. The results and their relation to the biosynthetic pathways proposed for the formation of monoterpene hydrocarbons in higher plants are discussed.