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Carotenoid contents in leaves grown under various light intensities
BiochemicalSystemadcsand Ecology,Vol. 15, No. 5, pp. 523--527, 1987. Printed in Great Britain.
0305-1978/87 $3.00+0.00 Pergamon Journals Ltd.
Carotenoid Contents in Leaves Grown under Various Light Intensities* B. CZECZUGA Department of General Biology, Medical Academy, 15-230 Bialystok, Poland
Key Word Index--Mosses; pteridophytes; gymnosperms; angiosperms; carotenoids; t[]-carotene; lutein; light intensity. Abstract--The carotenoid content in the leaves of mosses, pteridophytes, gymnosperms and angiosperms (dicotyledons and monocotyledons) growing in the sunlight and in the shade was studied. In the leaves of plants growing in the shade the total carotenoid content and Z-carotene increases as does chlorophyll. On the other hand, in the leaves of all plants a marked increase in lutein content was observed only in the leaves exposed to sunlight. The data indicates that carotenoids play a significant role, equal to that of chlorophyll, as 'antennae' absorbing light in plants.
Introduction During our studies of the content of photosynthetically active pigments in the lower plants under various degrees of light intensity [1-8] it was found that under shade conditions the content of photosynthetically active pigments increases. This applied to chlorophylls and carotenoids in green algae [2-4] and phycobiliprotein pigments in blue-green [5] and red algae [6-8]. In lichens, however, such an unambiguous pattern as that found in the algae was not observed. In many species an increase in chlorophylls and carotenoids was noted [3] when they grew in the shade, but Xanthoria species showed a marked increase in the carotenoid content in plants growing in sunlight [4]. This seems to indicate that the carotenoids in Xanthoria may serve as a barrier to protect the photosynthetic apparatus from photodestruction, as well as perhaps functioning as additional antennae to trap light energy of a shorter wavelength than those absorbed by the chlorophylls. Bearing this in mind, we decided to analyse the carotenoid content in the leaves of plant species from several different major plant taxa (mosses, pteridophytes, gymnosperms and angiosperms) growing in various light intensities in order to find out whether the phenomenon observed in Xanthoria is of wider importance. *Part 10 in the series 'The effect of light on the content of photosynthetically active pigments in plants'. For Part 9 see Czeczuga, B. (1987) Biochem. Sys& Ecol. 15, 519. (Received 14 March 1987)
Results The results of the analysis of the content of total carotenoids, ~-carotene and lutein in the leaves of plants exposed to varying light intensity are given in Table 1. In the leaves growing in the shade, the total carotenoid content, like that of ~-carotene, increases considerably over plants exposed to sunlight. Completely different results were however obtained from the analysis of lutein. Leaves in shady places contained far less lutein than those exposed to sunlight. Discussion One of the decisive factors in the photosynthesis process is, of course, light. Where there is a deficit of light, the plant sets a series of compensatory mechanisms into motion. This involves mainly increases in pigments, which fulfil the function of 'antennae' absorbing the required light energy or to the structures in the chloroplasts in which the pigments are found. In algae, these structures (chromatophores) increase under poor light, whereas in higher plants not only do the number of chloroplasts increase but their position in the cell changes. As regards the photosynthetically active pigments, observations have been made mainly on chlorophylls. In both algae [1, 9-11] and in higher plants [12], the cellular chlorophyll content increases when the light intensity is low. This applies especially to Chl. b, as is indicated by the Chl. a-Chl, b ratio; under high light intensity this ratio is higher but where the light if low it falls. This observation
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B. CZECZUGA
TABLE 1. TOTAL CONTENT OF CAROTENOIDS, ~-CAROTENE AND LUTEIN IN LEAVES OF PLANTS Total content, [Ltg g-' dw
~-Carotene, %
Shade
Sun
Ratio Shade:Sun
Shade
Sun
Ratio Shade:Sun
Shade
Sun
Ratio Shade:Sun
196.3 175.9
101.7 144.0
1.9 1.2
44.5 44.6
3.8 32.1
11.7 1.4
35.9 50.7
78.9 62.2
0.5 0.8
89.5 261.7 94.0 101.7
79.5 87.0 43.0 41.1
1.1 3.0 2.2 2.5
50.5 40,5 36.0 55.3
30.1 31.2 28.5 22,3
1.7 1.3 1.3 2.5
20.2 30.6 43.5 36.6
52.2 39.3 66,6 61.8
0,4 0.8 0.7 0.6
57.4 97.5 186.4 179.5 153.4 84.3 132.0 102.1 37.7 172.9 76.4 88.4 106.5 110.6 124.7 131.4 101.1 83.1 68.8 52.9
41.7 61.1 61.2 131.8 105.3 53.6 92.8 62.2 14.9 93.9 29.2 41.4 50.3 46.9 75.4 59.3 64.0 76.5 48.4 47.3
1.4 1,6 3.5 1.4 1.5 1,6 1.4 1.6 2.5 1.8 2.6 2.1 2.1 2.4 1.7 2.2 1.6 1.1 1.4 1.1
33.1 41.4 39.2 47.1 42.4 39.3 46.6 32.0 3.6 40.8 25.8 46.2 41.5 38.0 33.1 42.1 41.9 51.1 38.4 49.9
21.9 38.0 25.7 24.9 20.5 26.8 35.1 27.6 1.1 30.1 15.9 40.1 3.7 30.0 29.0 32.0 33.2 43.0 28.2 40.0
1.5 1.1 1.5 1.9 2.1 1.5 1.3 1.2 3.3 1.4 1.6 1.2 11.2 1.3 1.1 1.3 1.3 1.2 1.4 1.2
25.3 32.0 47.2 41.1 40.3 39.7 23.4 47.8 50.0 36.3 45.2 35.2 31.2 36.0 48.0 45.9 31.1 32.4 43.4 34.5
36.8 42.9 55.2 67.6 58.5 44.1 33.7 54.6 67.2 56.8 57.8 46.0 40.2 52.5 56.6 55.6 39.7 41.7 59.3 39.6
0.7 0.7 0.9 0.6 0.7 0.9 0.7 0.9 0.7 0.6 0.8 0.8 0.8 0.7 0.8 0.8 0.8 0.8 0.7 0.9
118.6 234.6 248.3 277.8 118.9 262.7 294.6 267.5 207.7
87.7 170.8 137.6 173,8 111.1 200.9 210.5 161,8 146.5
1.4 1.4 1.8 1.6 1.1 1.3 1.4 1.7 1.4
9.6 42.6 11.4 8.7 12.1 7.9 10.4 14.0 27.0
8.2 36.5 10.2 5.6 11.5 4.9 2.6 4.1 13.9
1.4 1.2 1.1 1.6 1.1 1.6 4.0 3.4 1.9
54.4 27.7 56.5 70.7 42.5 62.6 64.7 57.4 39.0
66.9 46.4 71.8 76.7 63.1 82.4 84.3 80.6 52.0
0.8 0.6 0.8 0.9 0.7 0.8 0.6 0.7 0.6
134.3
121.9
1.1
17.8
9.6
1.9
57.1
67.6
0.8
125.7 205.9 215.8 178.4 142.7 262.9 294.5 320.2 150.7 170.2 314.8 223.0 225.9
101.0 143.4 151.8 96.0 134.5 149.6 112.4 257.2 89.9 65.9 168.0 139.5 144.1
1.2 1.4 1.4 1.9 1.1 1.8 2.6 1.2 1.7 2.6 1.9 1.6 1.6
36.4 13.3 47.6 33.6 37.8 35.7 63.9 5.2 39.6 11.3 8.2 12.6 9.8
25.9 3.3 25.6 10.7 22.3 27.4 23.8 2.1 31.0 2.8 5.8 3.2 6.9
1.4 4.0 1.9 3.1 1.7 1.3 2.7 2.5 1.3 4.0 1.4 3.9 1.7
34.2 57.1 35.6 38.9 38.7 38.5 24.2 48.0 38.5 63.3 65.2 65.4 69.0
54.8 77.0 62.4 71.1 62.7 60.2 64.5 62.2 54.1 89.3 82.2 81.8 82.6
0.6 0.7 0.6 0.6 0.6 0.6 0.4 0.8 0.7 0.7 0.8 0.8 0.8
Species
Lutein, %
Bryophyta
Entodon schreberi~lild.) Mnkm. Ptilium crista-castrensis (L.) De Not. Pteridophyta
Lycopodium annotinum L. Equisetum sylvaticum L. Pteridium aquilinum L. Dryopteris spinulosa (Mull.) Ktze. Gymnospermae
Taxus baccata L. Abies concolor Engelm. Larix decidua Mill. Larix leptolepis Gord. Larix sibirica Ledeb. Picea abies Karst Picea pungens Engelm. Pinus mughus Scop. Pinus nigra Arnold Pinus silves~'is L. Pinus strobus L. Pseudotsuga taxifolia Britt. Metasequoia glyptostroboides Hu et Cheng Chamaecyparis pisifera Endl. Juniperus chinensis L. Juniperus communis L. Juniperus sabina L. Juniperus virginiana L. Thuja occidentalis L. Thuja orientalis L. Angiospermae Dico~ledones Herbaceous plants Stellaria media (L.) Viii. Ficaria verna Huds. Chelidonium majus L. Trifolium repens L. Malva neglecta Wallr.
Heracleum sphondylium L. Plantago major L. Leotodon hispidus L. Taraxacum officinaleWeb. Bushes
Vaccinium my~'llus L. Trees
Populus tremula L. Salix viminalis L. Alnusglutl)7osa(L.) Gertn. Betula verrucosa Ehrh. Carpinus betulus L. Corylus avellana L. Quercuspetraea(Matt.) Liebl. Quercus robur L. Quercus rubra Du Roi Ulmus carpinifolia G. Sorbus aucuparia L. Acer platanoides L. Acer pseudo-platanus L.
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CAROTENOID CONTENTS IN LEAVES GROWN UNDER VARIOUS LIGHT INTENSITIES TABLE 1--CONTINUED
Total content, IJg g-~ dw
E-Carotene,%
Shade
Ratio Shade: Sun
Shade
Sun
Species Acer saccharinum L. Aescu/us hippocastanum L. Tilia cordata Mill. Tilia platyphyllos Scop. Tilia tomentosa Moench. Fraxinus excelsiorL. Monocotyledones Alisma plantago-aqua~ca L. SagittaHa sagittifolia L. Potamogeton pect~)~atusL. Gagea lutea (L.) Ker-Gawler Tulipa sylvestris L. Lilium martagon L. Convallaria majalis L. Polygonatum odoratum (Mill.) Druce Iris sibirica L. Juncus conglomeratus L. Dactylis glomerata L. Poa pratensis L. Lolium temulentum L. Bromus secalinus L. Agropyron repens (L.) P.B. Alopecurus pratensis L. Setaria glauca (L.) P.B. Acorus calamus L. Calla palustris L. Lemna minorL. Carex serodna Merat. Zea mays L.
Lutein, %
Sun
Ratio Shade :Sun
Shade
Sun
Ratio Shade:Sun
221.5 343.2 330.9 281.4 268.5 265.8
81.5 294.7 275.8 254.0 205.8 232.7
2.7 1.2 1.2 1.1 1.3 1.1
38.5 36.1 33.8 29.7 30.5 68.2
30.3 27.7 25.4 3.8 23.6 47.5
1.3 1.3 1.3 7.8 1.3 1.4
48.1 42.7 52.1 53.3 45.6 27.5
54.3 54.0 67.3 87.0 57.2 44.1
0.9 0.8 0.8 0.6 0.8 0.6
283.5 334.3 180.9 188.1 309.4 282.2 268.7 164.1 230.6 110.8 354.3
185.3 270.9 95.6 71.8 154.8 184.2 186.9 128.5 160.4 99.4 288.4
1.5 1.2 1.9 2.6 2.0 1.5 1.4 1.3 1.4 1.1 1.2
89.3
66.3
1.3
54.0 281.2 134.5 226.1 112.0 395.4 434.3 164.5 369.7 321.6
47.0 239.2 101.6 107.2 89.3 213.8 359.0 57.1 303.0 239.0
1.1 1.2 1.3 2.1 1.3 1.8 1.2 2.9 1.2 1.3
18.3 29.7 24.3 37.8 31.3 29.8 31.2 26.6 29.7 58.8 24.4 34.9 20.5 33.9 39.9 43.9 36.2 24.3 40.9 26.7 39.2 42.9
11.5 20.2 22.6 27.1 28.1 23.9 29.7 11.4 13.0 21.8 16.2 27.5 17.7 17.2 21.9 16.1 21.4 19.3 20.7 15.2 28.8 30.8
1.6 1.5 1.1 1.4 1.1 1.2 1.1 2.3 2.3 2.7 1.5 1.3 1.2 2.0 1.8 2.7 1.7 1.3 2.0 1.8 1,4 1.4
54.1 63.2 66.6 32.9 55.7 38.5 38.2 43.2 56.6 33.2 34.6 37.7 58.0 59.3 50.4 49.4 45.3 32.0 54.4 53.1 53.6 48.9
72.5 75.4 74.0 41.8 59.3 48.2 56.6 63.4 73.4 72.2 48.8 57.3 60.5 77.3 63.3 75.1 75.6 44.7 74.5 68.5 66.5 62.7
0.7 0.8 0.9 0.8 0.9 0.8 0.7 0.7 0.8 0.5 0.7 0.7 0.9 0.8 0.8 0.7 0.6 0.7 0.7 0.8 0.8 0.8
has been made for algae [13-15], liverworts [16], mosses [17, 18] and in seed plants [12]. The results of the present studies also indicate this (Table 2). Few studies of changes in carotenoid content under different intensities of light have been carried out so far [2, 3] and have dealt with the total carotenoid content. There are some studies of the effect of varying light intensity on the synthesis of some carotenoids in seed plants [19]. It is generally considered that in higher plants, Chl. b and carotenoids may well be part of the lighttrapping antennae, in addition to the various forms of Chl. a-protein complexes. Carotenoids are believed to also serve to protect chlorophyll pigments from photodestruction [20]. With this in view, and bearing in mind the different total carotenoid content in leaves of plants grown under varying intensities of light (the total carotenoid content increasing under dim light) one may assume that carotenoids play an important
role in plants as light-trapping antennae under low light conditions whereas, their role in high intensity light is that of protection of the chlorophyll pigments from photodestruction. A significant observation is the general tendency of p-carotene to increase in poorly lighted leaves (Table 1). A similar observation has been made in the seedlings of several species of pine [19]. It was also found that in leaves receiving less light, there was larger amounts of violaxanthin but lower quantities of zeaxanthin (Table 3). TABLE 2. RELATIVE AMOUNTS OF CHLOROPHYLLS FOUND IN SHADE AND SUN LEAVES
Ratio ChL a:Chl, b Shade
Sun
Ratio Chl. a shade: Chl. asun
2.13 1.66 2.95 2.70
3.13 4,80 3.15 3.60
0.95 0.98 1.01 1.01
Species Acer platanoides Tilia cordata Leontodon hispidus Plantago major
Ratio Chl. b shade: Chl. b sun 2.71 1.44 1.08 1.35
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B. CZECZUGA
TABLE 3. COMPARISON OF ZEAXANTHIN AND VIOLAXANTHIN CONTENT IN THE LEAVESFROM SHADE AND SUN Zeaxanthin (%)*
Violaxanthin
Species
Shade Sun
Ratio ShadeSun shade: sun
Ratio shade: sun
Entodon schreberi Lycopodium annotinum Pteridium aquilinum Taxus baccata Abies concolor Larix leptolepis Picea abies Pinus nigra Pseudotsuga taxifolia Metasequoia glyptostroboides Juniperus communis Thuja occidentalis Chelidonium majus Malva neglecta Trifolium repens Acer pseudo-platanus Quercus robur Ulmus carpinifolia Carex serotina
2.6 0.6
0.6 0.t
3.1 6.0
1.1 1.5
4.4 2.8 1.0 4.4 6.3 0.1 3.8 4.2 0.5
1.7 2.1 9.0 3.4 2.2 13.0 1.4 2.0 4.0
7.6 2.1
1.7 2.1
4.1 0.3 5.1 5.9 2.3
4.2 5.5 2.3 2.0 1.4 0.7
4.3 5.1 4.9 15.8 3.1 3.4 6.6 11.7 2.9 3.4 1.5 5.4 11.1 13.8 9.8 8.9 11.3 7.2 1.1
0.3 0.1 0.8 0.5 0.7
0.4 0.4 0.2 0.2 0.2 0.6
3.5 9.2 5.1 7.6 6.0 9.0 15.0 14.1 1.3 5.4 8.4 2.0 13.5 15.9 9.9 12.7 4.5 8.8 0.9
sunlit leaves [23]. There are a number of reports on the changes in carotenoids in leaves from spring to autumn; some of the papers deal with carotenes only [24-26], others with xanthophylls [27, 28], while others again concern carotenoids in general [29-33]. These papers show that with the ageing of the leaves, that is, as the autumn season approaches, the amount of free [23] or esterified [31, 32] xanthophylls increases and the carotene content decreases. At the end of the vegetative season, the lutein content of the leaves, especially the epoxide forms, also increase [23]. The larger amount of lutein and particularly its epoxide form in leaves exposed to higher light could be explained as being the result of more intense metabolic processes in general, including the conversion of carotenoids [23]. As a result of these changes the ageing processes of the leaves are more rapid and consequently carotenoids of the autumn group appear.
*Percentage of total carotenoids (see Table 1).
This is in agreement with data given in the literature on the 'violaxanthin cycle' [21, 22]. Furthermore, in leaves of plants under high light considerably more lutein (particularly its epoxide) occurred than in leaves under low light. Large amounts of mutatoxanthin (Table 4), one of the autumn carotenoids, also occurred in TABLE 4. COMPARISON OF MUTATOXANTHIN CONTENT IN THE LEAVES FROM SHADE AND SUN Mutatoxanthin (%)* Species
Shade
Entodon schreberi Lycopodium annotinum Taxus baccata Larix decidua Picea abies Pinus nigra Metasequoia glyptosb'oboides Juniperus chinensis Thuja orientalis Plantago major Ouercus petraea Fraxinus excelsior 8romus seca/inus Ca//a pa/ustr/s Carex serotina Zea mays
2.4 0.6 5.2 5.0 1,3 3.4 3.2 2.5 1.5 0.9
3.6 1.2 0.2 0.2
Sun 3.3 2.6 7.6 10.3 3.5 14.8 11.1 5.2 3.9 3.8 1.5 3.1 16.6 4.2 2.8 2.3
*Percentage of total carotenoids (see Table 1).
Ratio shade : sun 0.7 0.2 0.7 6.5 0.4 0.2 0.3 0.5 0.4 0.2
0.2 0.3 0.1 0.1
Experimental In the investigation, 2 species of moss, 4 species of pteridophytes, 20 species of gymnosperms and 5 species of angiosperms (dicotyledons, 28 and monocotyledons, 22) plants were studied including species of bushes, trees and herbaceous plants (Table 1). The trees were specially selected as growing either partly in sunlight or in shade, so that leaves from the same tree but growing under different light conditions could be examined. The herbaceous plants leaves, on the other hand, were collected from several plants growing in both sunny and shady places, but as far as possible from the same biotope. For the studies, only leaves of the same age, were collected because of the difference in the carotenoid content of leaves of various ages (Table 5). The intensity of sunlight in the exposed sites ranged from 6.4 to 4.8 W m -2, and in the shady sites from 3.0 to 0.72 W m -2. The carotenoids were extracted and separated according to earlier methods [34], and their identification was by CC and TLC as described earlier [16, 34]. The standard preparation (F. Hoffman and La Roche, Sigma, U.S.A.) was used to identify TABLE 5. CAROTENOID CONTENT IN TILIA CORDATA LEAVES OF VARIOUS AGES Month
Carotenoid*
Major carotenoids (%)
Total content (l~g g 1 dry wt)
May July September
1,4,6,7,8 2,3,4,5,6,7,8,9 4,6,8,9,10
6 (39.3) 6 (66.0) 6 (77.4)
65.5 206.5 191.5
*l--phytoene, 2--1ycopene, 3--(x-carotene, 4--~-carotene, 5--~cryptoxanthin, 6~lutein epoxide, 7--zeaxanthin, 8--neoxanthin, 9--violaxanthin, 10~mutatoxanthin.
CAROTENOID CONTENTS IN LEAVES GROWN UNDER VARIOUS LIGHT INTENSITIES carotenoids. Quantitative determinations of the concentrations of carotenoid solutions were made from the visible absorption spectra [35]. The contents of chlorophylls were determined by the method of ref. [36].
References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17.
Czeczuga, B. (1963) Acta Hydrobiol. 5, 137 Czeczuga, B. (1977) Bull. Acad. Pol. Sc~, Ser. Biol. 25, 507. Czeczuga, B. (1981) Nova Hedwigia 35, 371. Czeczuga, B. (1983) Biochem. Syst. Ecol. 11, 329. Czeczuga, B. (1986) Phyton Austria 26, 1. Czeczuga, B. and Taylor, F. J. (1983) Nova Hedwigia 37, 441. Czeczuga, B. (1985) Polar Biol. 4, 179. Czeczuga, B. (1985) Acta Soc. Bot Pol. 54, 137. Jeffrey, S. W. and Vesk, M. (1977) J. Phycol. 13, 271. Vesk, M. and Jeffrey, S. W. (1977) J. Phycol. 13, 280. Paerl, H. W. (1984) Oecologia Berlin 61, 143. Ida, K. (1961) Bot. Mag. Tokyo94, 181. Yokohama, Y. and Misonou, 1". (1980) Jap. J. Phycol. 28, 219. Yokohama, J. (1982) Jap. J. Phycol. 30, 311. Perez-Bermudez, P., Carcia-Carrascosa, M., Cornejo, M. J. and Segura, J. (1981) Aquat Bot 11, 373. Czeczuga, B. (1985) Phyton Austria 25, 113. Martin, C. E. (1980) Bryologist83, 84.
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18. Martin, C. E. and Churchill, S. P. (1982) J. Bryo/. 12, 297. 19. Wi~ckowski, S. and Goodwin, T. W. (1966) Phytochemistry 5, 1345. 20. Goodwin, T. W. (1976) Chemistry and Biochemistry of Plant Pigments. Academic Press, London. 21. Saakov, V. S. (1965) FizioL Rast 12, 377. 22. Yamamoto, H. Y. (1979) PureAppl. Chem. 51, 639. 23. Czeczuga, B. (1986) Biochem. Syst Ecol. 14, 203. 24. Goodwin, T. W. (1958) Biochem. J. 68, 503. 25. Leonowicz, A., Sapiecha, K. and Wierzchowski, Z. (1962) Bull. Acad. Pol. Sc~, Ser. Biol. 10, 505. 26. Sanger, J. E. (1971) Ecology52, 1075. 27. Gribanovski-Sassu, O., Pellicciari, R. and Cataldi Hiughez, C. (1969) Ann. Ist_ Super. Sanita 5, 51. 28. Britton, G. (1982) Physiol. Veg.20, 735. 29. Masarovicova, E. and Duda, M. (1976) Biologia Bratislava 31, 15. 30. Ida, K. (1981) Bot, Mag. Tokyo94, 41. 31. Cardini, F. (1982) Giorn. Bot. Ital. 116, 97. 32. Cardini, F. (1983) Giorn. Bot. Ital. 117, 75. 33. Czeczuga, B. (1985) Biochem. Syst Ecol. 13, 221. 34. Czeczuga, B. and Czerpak, R. (1968) Eur. J. Biochem. 5, 429. 35. Davies, H. S. (1976) Chemistry and Biochemistry of Plant Pigments (Goodwin, T. W., ed.). Academic Press, London. 36. Jeffrey, S. W. and Humphrey, G. F. (1975) Biochem. Physiol. Pflanz, 167, 191.
0305-1978/87 $3.00+0.00 Pergamon Journals Ltd.
Carotenoid Contents in Leaves Grown under Various Light Intensities* B. CZECZUGA Department of General Biology, Medical Academy, 15-230 Bialystok, Poland
Key Word Index--Mosses; pteridophytes; gymnosperms; angiosperms; carotenoids; t[]-carotene; lutein; light intensity. Abstract--The carotenoid content in the leaves of mosses, pteridophytes, gymnosperms and angiosperms (dicotyledons and monocotyledons) growing in the sunlight and in the shade was studied. In the leaves of plants growing in the shade the total carotenoid content and Z-carotene increases as does chlorophyll. On the other hand, in the leaves of all plants a marked increase in lutein content was observed only in the leaves exposed to sunlight. The data indicates that carotenoids play a significant role, equal to that of chlorophyll, as 'antennae' absorbing light in plants.
Introduction During our studies of the content of photosynthetically active pigments in the lower plants under various degrees of light intensity [1-8] it was found that under shade conditions the content of photosynthetically active pigments increases. This applied to chlorophylls and carotenoids in green algae [2-4] and phycobiliprotein pigments in blue-green [5] and red algae [6-8]. In lichens, however, such an unambiguous pattern as that found in the algae was not observed. In many species an increase in chlorophylls and carotenoids was noted [3] when they grew in the shade, but Xanthoria species showed a marked increase in the carotenoid content in plants growing in sunlight [4]. This seems to indicate that the carotenoids in Xanthoria may serve as a barrier to protect the photosynthetic apparatus from photodestruction, as well as perhaps functioning as additional antennae to trap light energy of a shorter wavelength than those absorbed by the chlorophylls. Bearing this in mind, we decided to analyse the carotenoid content in the leaves of plant species from several different major plant taxa (mosses, pteridophytes, gymnosperms and angiosperms) growing in various light intensities in order to find out whether the phenomenon observed in Xanthoria is of wider importance. *Part 10 in the series 'The effect of light on the content of photosynthetically active pigments in plants'. For Part 9 see Czeczuga, B. (1987) Biochem. Sys& Ecol. 15, 519. (Received 14 March 1987)
Results The results of the analysis of the content of total carotenoids, ~-carotene and lutein in the leaves of plants exposed to varying light intensity are given in Table 1. In the leaves growing in the shade, the total carotenoid content, like that of ~-carotene, increases considerably over plants exposed to sunlight. Completely different results were however obtained from the analysis of lutein. Leaves in shady places contained far less lutein than those exposed to sunlight. Discussion One of the decisive factors in the photosynthesis process is, of course, light. Where there is a deficit of light, the plant sets a series of compensatory mechanisms into motion. This involves mainly increases in pigments, which fulfil the function of 'antennae' absorbing the required light energy or to the structures in the chloroplasts in which the pigments are found. In algae, these structures (chromatophores) increase under poor light, whereas in higher plants not only do the number of chloroplasts increase but their position in the cell changes. As regards the photosynthetically active pigments, observations have been made mainly on chlorophylls. In both algae [1, 9-11] and in higher plants [12], the cellular chlorophyll content increases when the light intensity is low. This applies especially to Chl. b, as is indicated by the Chl. a-Chl, b ratio; under high light intensity this ratio is higher but where the light if low it falls. This observation
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B. CZECZUGA
TABLE 1. TOTAL CONTENT OF CAROTENOIDS, ~-CAROTENE AND LUTEIN IN LEAVES OF PLANTS Total content, [Ltg g-' dw
~-Carotene, %
Shade
Sun
Ratio Shade:Sun
Shade
Sun
Ratio Shade:Sun
Shade
Sun
Ratio Shade:Sun
196.3 175.9
101.7 144.0
1.9 1.2
44.5 44.6
3.8 32.1
11.7 1.4
35.9 50.7
78.9 62.2
0.5 0.8
89.5 261.7 94.0 101.7
79.5 87.0 43.0 41.1
1.1 3.0 2.2 2.5
50.5 40,5 36.0 55.3
30.1 31.2 28.5 22,3
1.7 1.3 1.3 2.5
20.2 30.6 43.5 36.6
52.2 39.3 66,6 61.8
0,4 0.8 0.7 0.6
57.4 97.5 186.4 179.5 153.4 84.3 132.0 102.1 37.7 172.9 76.4 88.4 106.5 110.6 124.7 131.4 101.1 83.1 68.8 52.9
41.7 61.1 61.2 131.8 105.3 53.6 92.8 62.2 14.9 93.9 29.2 41.4 50.3 46.9 75.4 59.3 64.0 76.5 48.4 47.3
1.4 1,6 3.5 1.4 1.5 1,6 1.4 1.6 2.5 1.8 2.6 2.1 2.1 2.4 1.7 2.2 1.6 1.1 1.4 1.1
33.1 41.4 39.2 47.1 42.4 39.3 46.6 32.0 3.6 40.8 25.8 46.2 41.5 38.0 33.1 42.1 41.9 51.1 38.4 49.9
21.9 38.0 25.7 24.9 20.5 26.8 35.1 27.6 1.1 30.1 15.9 40.1 3.7 30.0 29.0 32.0 33.2 43.0 28.2 40.0
1.5 1.1 1.5 1.9 2.1 1.5 1.3 1.2 3.3 1.4 1.6 1.2 11.2 1.3 1.1 1.3 1.3 1.2 1.4 1.2
25.3 32.0 47.2 41.1 40.3 39.7 23.4 47.8 50.0 36.3 45.2 35.2 31.2 36.0 48.0 45.9 31.1 32.4 43.4 34.5
36.8 42.9 55.2 67.6 58.5 44.1 33.7 54.6 67.2 56.8 57.8 46.0 40.2 52.5 56.6 55.6 39.7 41.7 59.3 39.6
0.7 0.7 0.9 0.6 0.7 0.9 0.7 0.9 0.7 0.6 0.8 0.8 0.8 0.7 0.8 0.8 0.8 0.8 0.7 0.9
118.6 234.6 248.3 277.8 118.9 262.7 294.6 267.5 207.7
87.7 170.8 137.6 173,8 111.1 200.9 210.5 161,8 146.5
1.4 1.4 1.8 1.6 1.1 1.3 1.4 1.7 1.4
9.6 42.6 11.4 8.7 12.1 7.9 10.4 14.0 27.0
8.2 36.5 10.2 5.6 11.5 4.9 2.6 4.1 13.9
1.4 1.2 1.1 1.6 1.1 1.6 4.0 3.4 1.9
54.4 27.7 56.5 70.7 42.5 62.6 64.7 57.4 39.0
66.9 46.4 71.8 76.7 63.1 82.4 84.3 80.6 52.0
0.8 0.6 0.8 0.9 0.7 0.8 0.6 0.7 0.6
134.3
121.9
1.1
17.8
9.6
1.9
57.1
67.6
0.8
125.7 205.9 215.8 178.4 142.7 262.9 294.5 320.2 150.7 170.2 314.8 223.0 225.9
101.0 143.4 151.8 96.0 134.5 149.6 112.4 257.2 89.9 65.9 168.0 139.5 144.1
1.2 1.4 1.4 1.9 1.1 1.8 2.6 1.2 1.7 2.6 1.9 1.6 1.6
36.4 13.3 47.6 33.6 37.8 35.7 63.9 5.2 39.6 11.3 8.2 12.6 9.8
25.9 3.3 25.6 10.7 22.3 27.4 23.8 2.1 31.0 2.8 5.8 3.2 6.9
1.4 4.0 1.9 3.1 1.7 1.3 2.7 2.5 1.3 4.0 1.4 3.9 1.7
34.2 57.1 35.6 38.9 38.7 38.5 24.2 48.0 38.5 63.3 65.2 65.4 69.0
54.8 77.0 62.4 71.1 62.7 60.2 64.5 62.2 54.1 89.3 82.2 81.8 82.6
0.6 0.7 0.6 0.6 0.6 0.6 0.4 0.8 0.7 0.7 0.8 0.8 0.8
Species
Lutein, %
Bryophyta
Entodon schreberi~lild.) Mnkm. Ptilium crista-castrensis (L.) De Not. Pteridophyta
Lycopodium annotinum L. Equisetum sylvaticum L. Pteridium aquilinum L. Dryopteris spinulosa (Mull.) Ktze. Gymnospermae
Taxus baccata L. Abies concolor Engelm. Larix decidua Mill. Larix leptolepis Gord. Larix sibirica Ledeb. Picea abies Karst Picea pungens Engelm. Pinus mughus Scop. Pinus nigra Arnold Pinus silves~'is L. Pinus strobus L. Pseudotsuga taxifolia Britt. Metasequoia glyptostroboides Hu et Cheng Chamaecyparis pisifera Endl. Juniperus chinensis L. Juniperus communis L. Juniperus sabina L. Juniperus virginiana L. Thuja occidentalis L. Thuja orientalis L. Angiospermae Dico~ledones Herbaceous plants Stellaria media (L.) Viii. Ficaria verna Huds. Chelidonium majus L. Trifolium repens L. Malva neglecta Wallr.
Heracleum sphondylium L. Plantago major L. Leotodon hispidus L. Taraxacum officinaleWeb. Bushes
Vaccinium my~'llus L. Trees
Populus tremula L. Salix viminalis L. Alnusglutl)7osa(L.) Gertn. Betula verrucosa Ehrh. Carpinus betulus L. Corylus avellana L. Quercuspetraea(Matt.) Liebl. Quercus robur L. Quercus rubra Du Roi Ulmus carpinifolia G. Sorbus aucuparia L. Acer platanoides L. Acer pseudo-platanus L.
525
CAROTENOID CONTENTS IN LEAVES GROWN UNDER VARIOUS LIGHT INTENSITIES TABLE 1--CONTINUED
Total content, IJg g-~ dw
E-Carotene,%
Shade
Ratio Shade: Sun
Shade
Sun
Species Acer saccharinum L. Aescu/us hippocastanum L. Tilia cordata Mill. Tilia platyphyllos Scop. Tilia tomentosa Moench. Fraxinus excelsiorL. Monocotyledones Alisma plantago-aqua~ca L. SagittaHa sagittifolia L. Potamogeton pect~)~atusL. Gagea lutea (L.) Ker-Gawler Tulipa sylvestris L. Lilium martagon L. Convallaria majalis L. Polygonatum odoratum (Mill.) Druce Iris sibirica L. Juncus conglomeratus L. Dactylis glomerata L. Poa pratensis L. Lolium temulentum L. Bromus secalinus L. Agropyron repens (L.) P.B. Alopecurus pratensis L. Setaria glauca (L.) P.B. Acorus calamus L. Calla palustris L. Lemna minorL. Carex serodna Merat. Zea mays L.
Lutein, %
Sun
Ratio Shade :Sun
Shade
Sun
Ratio Shade:Sun
221.5 343.2 330.9 281.4 268.5 265.8
81.5 294.7 275.8 254.0 205.8 232.7
2.7 1.2 1.2 1.1 1.3 1.1
38.5 36.1 33.8 29.7 30.5 68.2
30.3 27.7 25.4 3.8 23.6 47.5
1.3 1.3 1.3 7.8 1.3 1.4
48.1 42.7 52.1 53.3 45.6 27.5
54.3 54.0 67.3 87.0 57.2 44.1
0.9 0.8 0.8 0.6 0.8 0.6
283.5 334.3 180.9 188.1 309.4 282.2 268.7 164.1 230.6 110.8 354.3
185.3 270.9 95.6 71.8 154.8 184.2 186.9 128.5 160.4 99.4 288.4
1.5 1.2 1.9 2.6 2.0 1.5 1.4 1.3 1.4 1.1 1.2
89.3
66.3
1.3
54.0 281.2 134.5 226.1 112.0 395.4 434.3 164.5 369.7 321.6
47.0 239.2 101.6 107.2 89.3 213.8 359.0 57.1 303.0 239.0
1.1 1.2 1.3 2.1 1.3 1.8 1.2 2.9 1.2 1.3
18.3 29.7 24.3 37.8 31.3 29.8 31.2 26.6 29.7 58.8 24.4 34.9 20.5 33.9 39.9 43.9 36.2 24.3 40.9 26.7 39.2 42.9
11.5 20.2 22.6 27.1 28.1 23.9 29.7 11.4 13.0 21.8 16.2 27.5 17.7 17.2 21.9 16.1 21.4 19.3 20.7 15.2 28.8 30.8
1.6 1.5 1.1 1.4 1.1 1.2 1.1 2.3 2.3 2.7 1.5 1.3 1.2 2.0 1.8 2.7 1.7 1.3 2.0 1.8 1,4 1.4
54.1 63.2 66.6 32.9 55.7 38.5 38.2 43.2 56.6 33.2 34.6 37.7 58.0 59.3 50.4 49.4 45.3 32.0 54.4 53.1 53.6 48.9
72.5 75.4 74.0 41.8 59.3 48.2 56.6 63.4 73.4 72.2 48.8 57.3 60.5 77.3 63.3 75.1 75.6 44.7 74.5 68.5 66.5 62.7
0.7 0.8 0.9 0.8 0.9 0.8 0.7 0.7 0.8 0.5 0.7 0.7 0.9 0.8 0.8 0.7 0.6 0.7 0.7 0.8 0.8 0.8
has been made for algae [13-15], liverworts [16], mosses [17, 18] and in seed plants [12]. The results of the present studies also indicate this (Table 2). Few studies of changes in carotenoid content under different intensities of light have been carried out so far [2, 3] and have dealt with the total carotenoid content. There are some studies of the effect of varying light intensity on the synthesis of some carotenoids in seed plants [19]. It is generally considered that in higher plants, Chl. b and carotenoids may well be part of the lighttrapping antennae, in addition to the various forms of Chl. a-protein complexes. Carotenoids are believed to also serve to protect chlorophyll pigments from photodestruction [20]. With this in view, and bearing in mind the different total carotenoid content in leaves of plants grown under varying intensities of light (the total carotenoid content increasing under dim light) one may assume that carotenoids play an important
role in plants as light-trapping antennae under low light conditions whereas, their role in high intensity light is that of protection of the chlorophyll pigments from photodestruction. A significant observation is the general tendency of p-carotene to increase in poorly lighted leaves (Table 1). A similar observation has been made in the seedlings of several species of pine [19]. It was also found that in leaves receiving less light, there was larger amounts of violaxanthin but lower quantities of zeaxanthin (Table 3). TABLE 2. RELATIVE AMOUNTS OF CHLOROPHYLLS FOUND IN SHADE AND SUN LEAVES
Ratio ChL a:Chl, b Shade
Sun
Ratio Chl. a shade: Chl. asun
2.13 1.66 2.95 2.70
3.13 4,80 3.15 3.60
0.95 0.98 1.01 1.01
Species Acer platanoides Tilia cordata Leontodon hispidus Plantago major
Ratio Chl. b shade: Chl. b sun 2.71 1.44 1.08 1.35
526
B. CZECZUGA
TABLE 3. COMPARISON OF ZEAXANTHIN AND VIOLAXANTHIN CONTENT IN THE LEAVESFROM SHADE AND SUN Zeaxanthin (%)*
Violaxanthin
Species
Shade Sun
Ratio ShadeSun shade: sun
Ratio shade: sun
Entodon schreberi Lycopodium annotinum Pteridium aquilinum Taxus baccata Abies concolor Larix leptolepis Picea abies Pinus nigra Pseudotsuga taxifolia Metasequoia glyptostroboides Juniperus communis Thuja occidentalis Chelidonium majus Malva neglecta Trifolium repens Acer pseudo-platanus Quercus robur Ulmus carpinifolia Carex serotina
2.6 0.6
0.6 0.t
3.1 6.0
1.1 1.5
4.4 2.8 1.0 4.4 6.3 0.1 3.8 4.2 0.5
1.7 2.1 9.0 3.4 2.2 13.0 1.4 2.0 4.0
7.6 2.1
1.7 2.1
4.1 0.3 5.1 5.9 2.3
4.2 5.5 2.3 2.0 1.4 0.7
4.3 5.1 4.9 15.8 3.1 3.4 6.6 11.7 2.9 3.4 1.5 5.4 11.1 13.8 9.8 8.9 11.3 7.2 1.1
0.3 0.1 0.8 0.5 0.7
0.4 0.4 0.2 0.2 0.2 0.6
3.5 9.2 5.1 7.6 6.0 9.0 15.0 14.1 1.3 5.4 8.4 2.0 13.5 15.9 9.9 12.7 4.5 8.8 0.9
sunlit leaves [23]. There are a number of reports on the changes in carotenoids in leaves from spring to autumn; some of the papers deal with carotenes only [24-26], others with xanthophylls [27, 28], while others again concern carotenoids in general [29-33]. These papers show that with the ageing of the leaves, that is, as the autumn season approaches, the amount of free [23] or esterified [31, 32] xanthophylls increases and the carotene content decreases. At the end of the vegetative season, the lutein content of the leaves, especially the epoxide forms, also increase [23]. The larger amount of lutein and particularly its epoxide form in leaves exposed to higher light could be explained as being the result of more intense metabolic processes in general, including the conversion of carotenoids [23]. As a result of these changes the ageing processes of the leaves are more rapid and consequently carotenoids of the autumn group appear.
*Percentage of total carotenoids (see Table 1).
This is in agreement with data given in the literature on the 'violaxanthin cycle' [21, 22]. Furthermore, in leaves of plants under high light considerably more lutein (particularly its epoxide) occurred than in leaves under low light. Large amounts of mutatoxanthin (Table 4), one of the autumn carotenoids, also occurred in TABLE 4. COMPARISON OF MUTATOXANTHIN CONTENT IN THE LEAVES FROM SHADE AND SUN Mutatoxanthin (%)* Species
Shade
Entodon schreberi Lycopodium annotinum Taxus baccata Larix decidua Picea abies Pinus nigra Metasequoia glyptosb'oboides Juniperus chinensis Thuja orientalis Plantago major Ouercus petraea Fraxinus excelsior 8romus seca/inus Ca//a pa/ustr/s Carex serotina Zea mays
2.4 0.6 5.2 5.0 1,3 3.4 3.2 2.5 1.5 0.9
3.6 1.2 0.2 0.2
Sun 3.3 2.6 7.6 10.3 3.5 14.8 11.1 5.2 3.9 3.8 1.5 3.1 16.6 4.2 2.8 2.3
*Percentage of total carotenoids (see Table 1).
Ratio shade : sun 0.7 0.2 0.7 6.5 0.4 0.2 0.3 0.5 0.4 0.2
0.2 0.3 0.1 0.1
Experimental In the investigation, 2 species of moss, 4 species of pteridophytes, 20 species of gymnosperms and 5 species of angiosperms (dicotyledons, 28 and monocotyledons, 22) plants were studied including species of bushes, trees and herbaceous plants (Table 1). The trees were specially selected as growing either partly in sunlight or in shade, so that leaves from the same tree but growing under different light conditions could be examined. The herbaceous plants leaves, on the other hand, were collected from several plants growing in both sunny and shady places, but as far as possible from the same biotope. For the studies, only leaves of the same age, were collected because of the difference in the carotenoid content of leaves of various ages (Table 5). The intensity of sunlight in the exposed sites ranged from 6.4 to 4.8 W m -2, and in the shady sites from 3.0 to 0.72 W m -2. The carotenoids were extracted and separated according to earlier methods [34], and their identification was by CC and TLC as described earlier [16, 34]. The standard preparation (F. Hoffman and La Roche, Sigma, U.S.A.) was used to identify TABLE 5. CAROTENOID CONTENT IN TILIA CORDATA LEAVES OF VARIOUS AGES Month
Carotenoid*
Major carotenoids (%)
Total content (l~g g 1 dry wt)
May July September
1,4,6,7,8 2,3,4,5,6,7,8,9 4,6,8,9,10
6 (39.3) 6 (66.0) 6 (77.4)
65.5 206.5 191.5
*l--phytoene, 2--1ycopene, 3--(x-carotene, 4--~-carotene, 5--~cryptoxanthin, 6~lutein epoxide, 7--zeaxanthin, 8--neoxanthin, 9--violaxanthin, 10~mutatoxanthin.
CAROTENOID CONTENTS IN LEAVES GROWN UNDER VARIOUS LIGHT INTENSITIES carotenoids. Quantitative determinations of the concentrations of carotenoid solutions were made from the visible absorption spectra [35]. The contents of chlorophylls were determined by the method of ref. [36].
References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17.
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527
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