Alkane distribution in epicuticular wax of some evergreen Ericaceae

INNO SALASOO Department of Chemistly, University of Oregon, Eugene, OR, U.S.A. 97403

and School of Chemistry, The University of New South Wales, Kensington, NSW 2033, ~us t ra l ia '

Received January 7, 1980

SALASOO, I. 1981. Alkane distribution in epicuticular wax of some evergreen Ericaceae. Can. J. Bot. 59: 1189-1 191. Patterns of alkane distribution in the epicuticular wax were determined for seven evergreen species of Ericaceae from western

Oregon. Hentriacontane was the major alkane in most species. Total wax hydrocarbons were lowest in plants collected on the coast.

SALASOO, I. 1981. Alkane distribution in epicuticular wax of some evergreen Ericaceae. Can. J. Bot. 59: 1189-1 191. La rkpartition des alcanes dans la cire Cpicuticulaire a CtC dCterminCe chez sept espkces d'EricacCes h feuilles persistantes

provenant de l'OrCgon occidental. L'hentriacontane est le principal alcane chez la plupart des espkces. Les hydrocarbures totaux dans la cire sont en concentration plus faible chez les plantes rCcoltCes le long de la c6te.

[Traduit par le journal]

Introduction from western Oregon, belonging to three subfamilies:

~ h ~ ~ ~ h the chemistry of plant waxes has been studied Arbutoideae, Rhododendroideae, and Vaccinioideae. for over 100 years, the detailed study of epicuticular waxes has gained momentum only in the past 2 decades Materials and methods with the advent of gas-chromatographic techniques, Details of plant material used in this study are given in Table either alone or coupled with mass spectrometry. The 1. Voucher specimens are deposited in the Herbarium of the taxonomic potenital of the alkane distribution pattern University of Oregon. in plants was recognized early (2 ) ; alkane chemistry Wax Was extracted by dipping leafy cuttings into light has been actually used to solve taxonomic problems petroleum (mixture of Pentane and hexane fractions) for

15-60 s at room temperature. The leaves of Rhododendron (e.g., 7 ) . macrophyllum were separated from stems and then immersed

A recent review On waxes points Out that the in light petroleum for 30- 120 s. One-half of each extract was alkane distribution in Ericaceae has been reported for evaporated and the residual wax weighed, A portion of the only a few species: cuticular wax of c r a n b e ~ (Vaccin- original extract containing approximately 200 mg of wax was ium macrocarpon var. Howes) fruit (11, stems and then chromatographed on 15g of neutral alumina (Woelm). leaves of Gaultheria antipoda Forst. f. and G . sub- Hydrocarbons were eluted by light petroleum and analyzed in a corymbosa Col. ( 3 ) , and leaves of Oxycoccus quadri- Hewlett-Packard 402 high efficiency gas chromatograph with petalus Gilib., Vaccinium myrtillus L., V . uliginosum a flame ionization detector at 150-280°C, with temperature L., and V . vitis-idaea L. (8 ) . More recently, Sorensen increasing at 2" per minute. The 120-cm glass column, 4 mm

et (7 ) have reported alkane analyses of the leaves of inside diameter, was packed with 3% OV-1 on Chromosorb W. Peak areas were taken to be proportional to the mass of three 'pecies of Arbutus' The present in the alkanes. Chain lengths were determine by gas chromatogra-

leaves of Rhododendron degronianum Carr. have been phy - mass spectrometry. reported only qualitatively (6).

Most of these analyses, however, were carried out on Results and discussion total alkanes, (extracted from macerated fresh leaves (8 ) or dried and ground material: leaves ( 7 ) or leaves and are given in

stems ( 3 ) ) , rather than on the alkanes of the epicuticular The yield of wax bore with classifica-

wax. while a case has been reported ( 3 ) where the tion, stage of development, or environmental factors.

surface wax and total wax gave similar results, other The percentage in wax was lowest in

workers (4) have demonstrated wide differences be- the (Rhododendron macrophyl1um and

tween the internal and external leaf hydrocarbons. Vaccinium ovatum) from the relatively mild coastal

This article is the first report on the composition of the 'limate.

alkane fraction of the epicuticular leaf wax of plants of The genera' pattern of is as

the family Ericaceae. It covers seven evergreen species expected (5) : odd-carbon 25-33 carbons dominating over the even-carbon chains, and no

'Permanent address. evidence having emerged of the presence of any alkenes

0008-402618 1/07 11 89-03$01 .OO/O 01981 National Research Council of Canada/Conseil national de recherches du Canada

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TABLE 1. Alkane distribution in epicuticular wax of Ericaceae"

Voucher Carbon chain length of alkanes Stage of specimen W ~ A

Species Date Location Areab development No. yieldC Hydrocarbonsd 23 24 25 26 27 28 29 30 31 32 33 34 35

Subfamily Arbutoideae Arbrrtrrs rt~otzicsii Pursh June 9 Eugene 2 Past flowering, 102213 0.118 34.2 lr - tr tr 2 1 22 1 41 1 29 tr I

new leaves fully grown

Arctoslopl~ylos colrrrttbiatra Piper April 26 Lorane 2 Late flowering 102219 0.101 62.7 - - tr tr I tr I2 1 52 2 31 tr -- Arclostaphylos r~c~~arlcrtsis Gray April 29 La Pine 3 Minute flower 102216 0.041 29.2 - tr tr 1 3 2 16 2 51 2 22 tr tr

buds Arclostaplgvlos ciscirln Parry May 6 Grants Pass 2 Late flowering 102217 0.107 48.?. tr - 1 tr 2 tr 8 1 36 1 50 tr -- Go~rltlro.io sl~nllo~r Pursh April 5 Lorane 2 Flower buds 102218 0.028 28.0 - t r l 2 4 6 3 9 4 4 1 1 2 -

Subfamily Rhododendroideae Rhorlodc~~rlrorr ttracropl~yllrotr February I0 Seven Devils I Very young 102214 0.200 16.2 - tr 2 1 7 2 19 2 50 3 14 tr -

G. Don flower buds

Subfamily Vaccinioideae Vaccirti~rrtr ocat11rt1 Pursh April 23 Bandon I Flowering 102215 0.089 14. I tr tr tr tr 3 1 15 2 45 3 30 tr tr n

> 'Percentages (by weight) are rounded off to the nearest 1Z. Trace (tr) - 0.1-0.5Z. ? bArea: I , coast; 2, between the Coast Range and the Cascades; 3, eastern slopes of the Cascades. u

CExpressed as percentage of weight o f fresh leaves. *Percentage of hydrocarbons in wax. m

0 9 <

TABLE 2. Published data on alkane distribution in Ericaceae" 0 r "I L? -

Carbon chain length of alkanes - Refer-

Species 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 ence -

Subfamily Arbutoideaeb Arbrrtrrsnri~o~rico (Gray) Sarg. A~brrrristtrcrr~ic~ii Pursh Arbrrtus tcxarrn Buckley Goulthrria n~rtiporlo Forst. f. Goultlrcriosebcoryrttbosa Col.

Subfamily Rhodendroideae Rlrorlodrrtrlro~t rlcgrorriatturr~ Carr. I - - I- ! i i I

Subfamily Vaccinioideae* OxycoccrrsqrrodripctnlrrsGilib. r tr 2 tr r tr 2 2 3 2 6 3 Vaccitrir~rtr 1t1.srli1111s L, - - tr tr Ir tr tr tr tr lr 3 I Vncci~rirrrr~ rrligir~osuttr L. - - - .. t r t r I 1 8 6 3 6 4 Vrrccit~iutrl !,itis-irlaca L. - - lr tr tr lr - tr I 1 9 2

'Data from reference 3 are mole percentages. other sources do not specify whether the figures represent mole or weight percentages. bSeveral sets o f data (5, 4, and 7, respeclivelyj were reported for the three Arbrrtus spp., with values below 19, not given. The ranges showing the lowest and highest values, approximated lo the nearest lz,

are reproduced here. <Qualitative data only. *Numerical data, kindly provided by Professor Herout (personal communication), rounded off to the nearest I%, with values 0.57, and below reported as traces (11)

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or branched alkanes. The major alkane was hentriacon- tane, except in Arctostaphylos viscida, where tritria- contane dominated. The amounts of C22 and lower alkanes were insignificant.

The distribution pattern in Gaultheria shallon dif- fered from the rest, with the C26 alkane exceeding C25, and C28 exceeding CZ7. Gaultheria shallon also had the highest amount of C29 and the lowest amount of C33 alkane. These results cannot be explained by the theory that the chain lengths increase with age or the stage of development of either leaves or the whole plant.

Published data on the alkane distribution in leaves of Ericaceae are reproduced in Table 2. The general pattern in two Gaultheria species from New Zealand (3) agrees with the above results. Similarly, there is agreement in pentatriacontane being found in significant amounts only in Arbutus spp. (A . arizonica in reference 7 and A. menziesii in this work). Differences in alkane patterns between the Czechoslovakian (8) and Oregonian Vac- cinium spp. may be attributed to the fact that V. myrtillus and V. uliginosum are deciduous, or to intercontinental climatic and other differences, or possibly to the effect of internal lipids in the work of Stransky et al. (8).

SALASOO 1191

Acknowledgements The author expresses his thanks to Mr. Peter Kadaja

of the U.S. Bureau of Land Management, Eugene, OR, for collecting Gaultheria shallon and Arctostaphylos columbiana, and to Professor David H. Wagner, Direc- tor and Curator of the Herbarium of University of Oregon, for conclusive identification of the plants.

1. CROTEAU, R., and I. S. FAGERSON. 1971. The chemical composition of the cuticular wax of cranberry. Phyto- chemistry, 10: 3239-3245.

2. EGLINTON, G., A. G. GONZALEZ, R. J . HAMILTON, and R. A. RAPHAEL. 1962. Hydrocarbon constituents of the wax coatings of plant leaves: a taxonomic survey. Phytochemistry, 1: 89- 102.

3. EGLINTON, G., R. J . HAMILTON, and M. MARTIN- SMITH. 1962. The alkane constituents of some New Zealand plants and their possible taxonomic implications. Phytochemistry, 1: 137-145.

4. HERBIN, G. A, , and P. A. ROBINS. 1969. Patterns of variation and development in leaf wax alkanes. Phyto- chemistry, 8: 1985-1998.

5. KOLATTUKUDY, P. E. 1970. Plant waxes. Lipids, 5: 259-275.

6. KURIHARA, T., M. KIKUCHI, S. SUZUKI, and E. TOYODA. 1976. Studies on the constituents of leaves of Rhododendron degronianum Carr. Yakugaku Zasshi, 96: 1407-141 1.

7. SORENSEN, P. D., C. E. TOTTEN, and D. M. PIATAK. 1978. Alkane chemotaxonomy of Arbutus. Biochem. Syst. Ecol. 6: 109-111.

8. STRANSKP, K., M. STREIBL, and V. HEROUT. 1967. On natural waxes. VI. Distribution of wax hydrocarbons in plants at different evolutionary levels. Collect. Czech. Chem. Commun. 32: 3213-3220.

9. TULLOCH, A. P. 1976. Chemistry of waxes of higher plants. In Biochemistry and chemistry of natural waxes. Edited by P. E. Kolattukudy. Elsevier, Amsterdam. pp. 235-287.

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