ALO docView - Comparative Analysis of Epicuticular Waxes from Some High Alpine Plant Species (1985)

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Comparative Analysis of Epicuticular Waxes f... (1985)

	Comparative Analysis of Epicuticular Waxes from Some High Alpine Plant Species Cornelius Lutz and Paul-Gerhardt Gülz Botanisches Institut der Universität zu Köln, Gyrhofstraße 15, D-5000 Köln 41 Z. Naturforsch. 40c, 599-605 (1985); received May 6, 1985 Epicuticular Waxes, Alpine Plants, Ecophysiology, Relation to Altitude, Ultrastructure Epicuticular waxes were extracted and analysed from leaves of 7 different high alpine plant species, with 3 species harvested at different altitudes: Salix herbacea (1950 m, 2825 m), Leucan- themopsis alpinum (1950 m, 3050 m), Loiseleuria procumbens (1950 m, 2660 m), Dryas octopeta- la (2400 m), Ranunculus glacialis (2800 m), Soldanella pusilla (2640 m), Oxyria digyna (2640m). Two main fractions obtained from waxes were investigated: hydrocarbons and wax-esters, -aldehydes plus -acetates. Individual wax compounds accumulated differently in the respective plant species. The gross composition did not indicate a strict altitude-dependent change in wax composition, though some Single components like the C-29/C-31 alkanes (Loiseleuria) or the C-22/ C-26 fatty acid methyl esters in Salix, changed significantly with increasing elevation of plant habitat. The evergreen leaves of Dryas and of Loiseleuria exhibited exceptionally high amounts of triterpenol esters. The results indicate that the formation of epicuticular wax layers is not based on a Special adaptation to altitude or high mountain habitats in general. Introduction In general, all aerial parts of higher plants possess a cuticula. This is the boundary to the environment and therefore of great interest especially under ecophysiological aspects. The cuticula proper is mostly covered by layers of epicuticular waxes. This outermost boundary layer has gained more and more interest in the last years. Briefly, it is composed mainly of long chain homologous series of hydrocar¬ bons, wax esters, aldehydes, acetates, free fatty acids and free alcohols. These constituents occur often substituted, e.g. with -COOH or with -OH groups, and they require several analytical methods for Separation into individual compounds [1—4]. The diversity in composition of epicuticular waxes could explain the great variability of the three dimensional structures, formed by the waxes and best observed under a scanning electron microscope [1, 5, 6]. There is a large body of literature presenting analytical data on epicuticular waxes. Even though it seems difficult to relate wax compositions measured to the systematic order of the investigated plants. Further, the ecological significance of wax composi¬ tion and structure achieves more consideration today. However, as far as we know, analyses of epicuticular waxes isolated from plants growing at Reprint requests to Dr. Cornelius Lutz. Verlag der Zeitschrift für Naturforschung, D-7400 Tübingen 0341-0382/85/0009-0599 $ 01.30/0 high altitudes (above timberline) has not yet been presented. Our ecophysiological and cytological studies on high alpine plants [7—9] have led us to ask after the role of the plant surface in communication with the often extreme growth conditions at high altitudes. Plants living in high mountain habitats have de- veloped several mechanisms to survive under the un- favourable conditions of freezing temperatures, snow covering for long periods, occasionally very high irradiance or strong mechanical forces origi- nated by wind [10, 12]. This study presents an investigation of the epicuticular waxes of selected high alpine species. The data obtained in the experiments are discussed in relation to different altitudes of plant habitats and to different environmental influences on these plants. Materials and Methods The following plants have been used to extract epicuticular waxes from their leaves: Dryas octo- petala (Rosaceae), Leucanthemopsis alpinum (Asteraceae), Loiseleuria procumbens (Ericaceae), Oxyria digyna (Polygonaceae), Ranunculus glacialis (Ranunculaceae), Salix herbacea (Salicaceae), Sol¬ danella pusilla (Primulaceae). The plants were col- lected in July 1984 at different altitudes ranging from 1950 m to 3050 m above sea level in the Central Alps