Greenaway, W.

May, J.

Scaysbrook, T.

Whatley, F.R.

Bud and leaf exudates from Populus alba, P. balsam ifera, P. nigra and P. tremuloides were analyzed by gas chromatography/mass spectrometry and their components were identified. For three of the four species, P. alba, P. balsam ifera and P. nigra, the bud and leaf exudates were similar within each species, though there were marked differences between species. Bud and leaf exudates of P. alba contained only hydrocarbons, those of P. balsam ifera contained primarily dihydrochalcones and those of P. nigra contained primarily caffeic acid esters. Bud and leaf exudates of P. tremuloides were different both from each other and from those of the other three species. Bud exudate of P. tremuloides contained a range of phenolic compounds which were largely lacking from the leaf exudate

DigitalCommons@USU

Utah State University DigitalCommons@USU Aspen Bibliography Aspen Research 1992 Compositions of bud and leaf exudates of some Populus species W. Greenaway J. May T. Scaysbrook F.R. Whatley Follow this and additional works at: https://digitalcommons.usu.edu/aspen_bib  Part of the Forest Sciences Commons Recommended Citation Greenaway, W. et al. 1992. Compositions of bud and leaf exudates of some Populus species. Zeitschrift fur Naturforschung. Section-C, Biosciences. 47 (5-6): 329-334. This Article is brought to you for free and open access by the Aspen Research at DigitalCommons@USU. It has been accepted for inclusion in Aspen Bibliography by an authorized administrator of DigitalCommons@USU. For more information, please contact digitalcommons@usu.edu. Compositions of Bud and Leaf Exudates of Some Populus Species ComparedW. Greenaway, J. May, T. Scaysbrook, and F. R. WhatleyDepartment o f Plant Sciences, University o f Oxford, South Parks Road, Oxford, OX 1 3RB, U.K.Z. Naturforsch. 47c, 329-334  (1992); received February 19, 1992Poplar Bud Exudate, Poplar Leaf Exudate, GC-MSBud and leaf exudates from Populus alba, P. balsamifera, P. nigra and P. tremuloides were analyzed by gas chromatography/mass spectrometry and their components were identified. For three o f the four species, P. alba, P. balsamifera and P. nigra, the bud and leaf exudates were similar within each species, though there were marked differences between species. Bud and leaf exudates o f P. alba contained only hydrocarbons, those o f P. balsamifera contained primarily dihydrochalcones and those o f P. nigra contained primarily caffeic acid esters. Bud and leaf exudates o f P. tremuloides were different both from each other and from those o f the other three species. Bud exudate o f  P. tremuloides contained a range o f phenolic compounds which were largely lacking from the leaf exudate.IntroductionMost poplar species exude onto the surface of their buds phenolic compounds, especially flavon­oid aglycones. The complexity of this exudate var­ies with the species and appears to correlate with the taxonomy of the genus [1].Poplars of Section Leuce produce the simplest bud exudate. Those of subsection Albidae, e.g. P. alba L., exude only hydrocarbons [2] whereas those of subsection Trepidae, e.g. P. tremuloides Michx., secrete a phenolic exudate which includes only the flavanones produced by the first steps of flavonoid metabolism, such as naringenin (5,7,4'-trihydroxyflavonone) and its methyl ethers [2, 3], By contrast poplars of Section Aigeiros, such as P. deltoides Marsh [4] and P. nigra L. [5], and of Section Tacamahaca, such as P. balsami­fera  L. [6], produce a more complex bud exudate which contains primarily flavonoids resulting from the further metabolism of naringenin.Phenolic compounds are also exuded onto the leaf surfaces of some poplars, such as P. deltoides[7] and P. nigra [8], but we are not aware of any de­tailed reports of the composition of these leaf exu­dates or of any attempts to relate the compositions of bud and leaf exudates. We here report a com­parison of leaf and bud exudates of specimens of P. alba, P. balsamifera, P. nigra and P. tremu-Reprint requests to W. Greenaway.Verlag der Zeitschrift für Naturforschung,D-W-7400 Tübingen0939-5075/92/0500-0329 $01.30/0loides, four poplars with bud exudates of very dif­ferent compositions.Materials and MethodsReagentsBis-(trimethylsilyl)trifluoroacetamide (BSTFA) containing 1 % trimethylchlorosilane (TMCS) was obtained from Sigma (Poole, U.K.). Pyridine (Aristar) and ethyl acetate (Analar) were obtained from BDH Chemicals Ltd. (Poole, U.K.).Plant materialBud and leaf exudates were collected from speci­mens of P. alba ref. I, P. balsamifera ref. 349, P. nigra ref. N, and P. tremuloides ref. H and ref. T 1, grown at clone bed locations N 19, B 16, D8, 110 and K l l  respectively at Alice Holt Lodge, Forestry Commission, Farnham, U.K.Sample preparationBud exudate was collected by washing 5 buds of each of P. balsamifera and P. nigra and 20 buds of each of P. alba and P. tremuloides with ethyl ace­tate, as previously described [9]. Leaf exudate was collected from the 3rd and 4th leaves below the ap­ical buds of four shoots of each specimen. A 3 ml sample of ethyl acetate was pipetted over the sur­face of a leaf and collected in a 50 ml beaker. This ethyl acetate sample was again pipetted over all 8 leaves of a particular specimen.The ethyl acetate washes from the buds or the leaves were evaporated to dryness and derivatized330 W. Greenaway et al. • Composition o f Bud and Leaf Exudates o f Populus Specieswith BSTFA containing 1 % TMCS to produce tri- methylsilyl (TMS) derivatives for gas chromato­graphy as previously described [9].Gas chromatography -  mass spectrometryWas as previously described [9].Identification o f  compoundsWas as previously described [10]. Flavonoid standards were either purchased from Apin Chem­icals (Abingdon, U.K.) or from Plantech U.K. (Reading, U.K.) or were provided as a gift by Pro­fessor E. Wollenweber (Darmstadt, Germany). Further reference compounds were synthesized as previously described [11].Results and DiscussionCompounds which occurred at levels of > 5 %  TIC in any one or more of the bud or leaf exu­dates, are listed in Table I.For P. alba, ref. I, little material was removed from either bud or leaf. The major constituents, common to both bud and leaf exudates, were the hydrocarbons heptacosane23 (80% and 65% TIC respectively) and nonacosane29 (16 and 23% TIC respectively). In addition leaf washings contained minor amounts of pentacosane16, hexacosene19 and sucrose25 (Fig. 1 a, b; Table I).For P. balsamifera, ref. 349, the components of bud and leaf exudate were similar to each other but quite different from exudates of P. alba (Fig. lc , d; Table I). The major components common to both bud and leaf were three dihydro- chalcones, viz 2',6'-dihydroxy-4'-methoxydihydro- chalcone9 (10% and 11% TIC respectively), 2,,4\6'-trihydroxydihydrochalcone11 (33% and 25% TIC respectively) and 2',4',6'-trihydroxy-4-methoxydihydrochalcone20 (11% and 8% TIC respectively). Other components were common to both exudates, although the hydrocarbons16’23’29 were present in greater quantity in the leaf exudate than in the bud exudate (Fig. lc , d; Table I). The latter observation may be due to the removal of wax constituents from the leaf surface.For P. nigra, ref. N, bud and leaf exudates are similar to each other in composition although dif­ferent from those of P. alba and P. balsamifera. Leaf exudate of P. nigra contained higher amounts of the hydrocarbons pentacosane16, heptacosane23and nonacosane29 (4%, 15% and 12% TIC respec­tively) than did the bud exudate (1%, 4% and 2% TIC respectively). In both bud and leaf exudate the major phenolic components were 3-methyl- 3-butenyl-caffeate4’8, 3-methyl-2-butenyl-caf- feate510 and pinostrobin chalcone12 (Fig. 2 a, b; Table I). One difference noted is that the bud exu­date contained 8% of octadecenoic acid6, though it is not present in the leaf exudate.Bud and leaf exudates of P. tremuloides ref. T 1, were on the contrary not similar (Fig. 2 c, d; Ta­ble I) although both were again different from those of the other poplars. Bud exudate contained, as major phenolic components, coumaric acid3 (6% TIC), benzyl coum arate713 (14% TIC, benzyl caffeate14-21 (17% TIC) and salicin17 (13% TIC). Except for salicin17 (9% TIC) these phenolic com­ponents are virtually absent from leaf exudate which contains primarily hydrocarbons16’19,23 (20% TIC), sucrose25 (20% TIC), octacosanol28 (8% TIC) and hexacosanal31 (7% TIC). Of the ten phenolics which comprise 68% TIC of bud exu­date only three, coumaric acid3, salicin17 and cate- chin30, together comprising 15% TIC, are present in leaf exudate.Comparison of bud and leaf exudates of a sec­ond specimen of P. tremuloides, ref. H, confirmed the absence from the leaf exudate of many of the phenolic components characteristic of the bud exudate.For three of the four poplars analyzed, P. alba, P. balsamifera and P. nigra, the leaf exudate re­flects the characteristic phenolic composition of the bud exudate, but this is not the case for the fourth species, P. tremuloides.We are currently developing a chemotaxonomy of Populus based on the analysis of bud exudates. From our limited sample it appears that the com­position of the leaf exudate could also be used, but it is much less convenient than the bud exudate and has the disadvantage of including a propor­tion of the leaf waxes.AcknowledgementsWe thank P. Howard, Forestry Commission, U.K. for permission to collect plant material from the Forestry Commission clonal collection and Professor E. Wollenweber, Institut für Botanik der Technischen Hochschule, Darmstadt, Germany for the generous gift of flavonoid compounds.W. Greenaway et al. ■ Composition o f Bud and Leaf Exudates o f  Populus Species 331Table I. Major constituents (>  5%) o f bud and leaf exudates o f Populus alba, P. balsamifera, P. nigra and P. tremuloides.Total ion current [%]*Peak2 Compound3 TMS M U 4 P. alba P. balsamifera P. nigra P. tremuloidesNo. groups Bud Leaf Bud Leaf Bud Leaf Bud Leafphenolics3 /rarts-Coumaric acid 2 19.32 — _ 1 T5 T _ 6 14 3-Methyl-3-butenyl-m-caffeate6 2 21.74 - - - - 2 3 - -5 3-Methyl-2-butenyl-cw-caffeate6 2 22.11 - - - - 16 13 - -7 Benzyl-cis-4-coumarate6 1 22.68 - - - - - - 2 -8 3-Methyl-3-butenyl-/ra«5-caffeate6 2 23.47 - - - - 9 4 - -9 2',6'-Dihydroxy-4'-methoxydihydrochalcone 2 23.74 - - 10 11 T 2 - -10 3-Methyl-2-butenyl-/rarts-caffeate6 2 23.93 - - - - 11 9 - -II 2',4',6'-Trihydroxydihydrochalcone 3 24.23 - - 33 25 T 1 - -12 2',6'-Dihydroxy-4-methoxycalcone (pinostrobin chalcone)2 24.49 — — 2 2 4 9 — —13 Benzyl-rranj,-4-coumarate6 1 24.63 - - 4 1 T T 12 -14 Benzyl-ds-caffeate6 2 24.68 - - - - - - 10 -15 5,7-Dihydroxyflavanone (pinocembrin) 2 24.97 - - 2 5 T 1 - -17 Salicin ? 25.74 - - - - - 1 13 918 Coniferyl benzoate 1 25.83 - - - - - - 6 -20 2',4',6'-Trihydroxy-4-methoxydihydrochalcone 3 26.61 - - 11 8 - - - -2! Benzyl-rrarts-caffeate6 2 26.98 - - - - - T 7 -22 3,5,7-Trihydroxyflavone7 (galangin) 2 26.99 - - 2 4 - - - -24 5,4'-Dihydroxy-7-methoxyflavanone7(sakuranetin)1 27.07 - — ~ — - 4 -26 3,5,7-Trihydroxyflavone7 3 27.52 - - 4 6 - - - -27 5,4'-Dihydroxy-7-methoxyflavanone7 2 28.18 - - - - - - 5 -30 ?ra/7.s-3,5,7,3',4'-Flavanpentol (catechin) non-phenolics5 29.15 3 51 Succinic acid 2 13.09 - — — — 5 2 — —2 Bisabolol 1 17.46 - - 6 2 — - - -6 Octadecenoic acid 1 22.13 - - - - 8 T - -16 Pentacosane (C25 hydrocarbon) - 25.00 - 4 T 3 1 4 1 519 Hexacosene - 25.94 - T - - T T - 723 Heptacosane (C27 hydrocarbon) - 27.00 80 65 T 6 4 15 4 825 Sucrose 8? 27.37 - 2 - - - 1 — 2028 Octacosanol8 - 28.20 - - - - - - - 8>9 Nonacosane (C29 hydrocarbon) - 29.00 16 23 T 4 2 12 T 151 Hexacosanal8 - 30.38 - - - - - - - 732 Hexacosanoic acid 1 30.54 - - - - - - - 633 Henecontane (C 31 hydrocarbon) - 31.00 - - - T - 5 - -The ion current generated depends on the characteristics o f the compound concerned and is not a true quantitation (see [11]).Peak numbers correspond to those given in the chromatograms shown in Fig. 1 and 2.The name given does not include the TMS substituents.Methylene units (M U ) as defined by Dalgliesh et al. [12]) are given to two decimal places to indicate the elution sequence of peaks which chromatograph closely. Factors such as concentration o f  the compound concerned and/or the characteristics o f  a particular GC column are liable to affect the chromatography, and for general purposes the M U figures are probably reliable to a single decimal place only [13],‘T’ indicates an amount between 0.1% and 0.5%.Both cis and trans isomers o f this compound are present which between them total > 5%  o f TIC. We note that the cis isomer occurs in some cases at higher levels than in our previous analyses.This compound is present as two TMS derivatives which between them total >  5% o f TIC.Identified by library searches only. We have no chemical standards o f  these compounds.332 W. Greenaway et al. ■ Composition o f  Bud and Leaf Exudates o f Populus Species(a)budP.alba■ A2 329P.balsamiferaFig. 1. Total ion chromatograms (TIC) between scans 2000-4000  (M U 18-31) o f  Populus alba (a) bud exudate (b) leaf exudate and P. balsamifera (c) bud exudate (d) leaf exudate. Within a species bud and leaf exudates are similar, al­though the two species produce very different exudates. Identifications o f numbered peaks are given in Table I.W. Greenaway et al. ■ Composition o f Bud and Leaf Exudates o f Populus Species 333P.tremuloidesFig. 2. Total ion chromatograms between scans 2000-4000  (M U  18-31) o f  Populus nigra (a) bud exudate (b) leaf exudate and P. tremuloides (c) bud exudate (d) leaf exudate. Bud and leaf exudate o f P. nigra contain a similar range of compounds whereas those o f P. tremuloides are different. Identifications o f  numbered peaks are given in Table I.334 W. Greenaway et al. ■ Composition o f  Bud and Leaf Exudates o f Populus Species[1] E. Wollenweber, Biochem. Syst. Ecol. 3, 3 5 -4 5  (1975).[2] W. Greenaway, S. English, J. May, and F. R. What­ley, Biochem. Syst. Ecol. 19, 507-518 (1991).[3] S. English, W. Greenaway, and F. R. Whatley, Can. J. Bot. 69, 2291-2295 (1991).[4] W. Greenaway, S. English, and F. R. Whatley, Z. Naturforsch. 45c, 587-593  (1990).[5] W. Greenaway, S. English, and F. R. Whatley, Z. Naturforsch. 45c, 931-936  (1990).[6] W. Greenaway, J. May, and F. R. Whatley, J. Chromatogr. 472, 393-400  (1989).[7] L. Shain and J. B. Miller, Phytopathology 72, 8 7 7 -  880(1982).[8] Y. Charriere-Ladreix, J. Microscopie 17, 299-316(1973).[9] T. Scaysbrook, W. Greenaway, and F. R. Whatley, Z. Naturforsch. 47 c, 197-200 (1992).[10] W. Greenaway, T. Scaysbrook, and F. R. Whatley, Z. Naturforsch. 43c, 301-305  (1988).[11] W. Greenaway, T. Scaysbrook, and F. R. Whatley, Proc. R. Soc. Lond. B. 232, 249-272  (1987).[12] C. E. Dalgliesh, E. C. Horning, M. G. Horning, K. L. Knox, and K. Yarger, Biochem. J. 101, 7 9 2 -  810(1966).[13] W. Greenaway and F. R. Whatley, J. Chromatogr. 519,145-158(1990).

Compositions of bud and leaf exudates of some Populus species

Abstract

Similar works

Full text

Available Versions

DigitalCommons@USU