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The Effect of Methyl Jasmonate on Fatty Acid and Sterol Content in Tulip Stems
J. Plant Physiol.
Vol. 140. pp. 399-401 {1992}
The Effect of Methyl Jasmonate on Fatty Acid and Sterol Content in Tulip Stems MARIAN SANIEWSKI, MARCIN HORBOWICZ*,
and JANUSZ
CZAPSKI'~
Research Institute of Pomology and Floriculture, 96-100 Skierniewice, Poland * Research Institute of Vegetable Crops, 96-100 Skierniewice, Poland Received October 24, 1991 . Accepted March 26, 1992
Summary
The effect of methyl jasmonate GA-Me) on fatty acid and sterol concentrations in the first internode of tulip stem during JA-Me induction of gum production (gummosis) was investigated. JA-Me greatly increased the concentrations of free and bound oleic and linoleic acids, and did not affect the concentrations of free and bound palmitic, stearic and linolenic acids. Methyl jasmonate approximately doubled the concentration of stigmasterol and did not influence the concentrations of campesterol and j3-sitosterol. The changes in fatty acid and sterol concentrations induced by methyl jasmonate in tulip stem may be caused by increased senescence and possibly may be associated with induction of gum formation.
Key words: Tulipa, methyl jasmonate, fatty acids, sterols. Abbreviation: JA-Me = methyl jasmonate. Introduction
Jasmonic acid and methyl jasmonate GA-Me) are known to be widespread native plant compounds (Meyer et al., 1984; Sembdner and Gross, 1986). These compounds have been shown to be physiologically active in various plant processes (Sembdner and Gross, 1986; Parthier, 1990; Ueda and Kato, 1980; Saniewski and Czapski, 1985). Recently, Koda et al. (1991) found that jasmonic acid and methyl jasmonate show strong tuber-inducing activity in potato grown in vitro. It has been shown previously (Puchalski et al., 1985) that methyl jasmonate applied on the bottom surface of all leaves causes a rapid and intense senescence of the leaves of intact tulips. Saniewski and Puchalski (1988) showed that methyl jasmonate induces gum formation in the bulb, stem and basal part of leaf in tulips. The gums consist mainly of pentose sugars, xylose and arabinose, after hydrolysis (Saniewski and Puchalski, 1988). The biosynthetic pathway(s) of gum polysaccharides induced by JA-Me are unknown. It is well known that fructosans, starch and sucrose are the main storage carbohydrates in the bulb scales of tulips (Moe and Wickstf0m, 1973; Thompson and Rutherford, 1977); in the tulip leaves, fructose, glucose, sucrose, myo-inositol, © 1992 by Gustav Fischer Verlag, Stuttgart
stachyose, tuliposides A and B, and traces of arabinose and xylose occur (Rutter et al., 1977). Sucrose is the main mobile leaf assimilate in tulips (Ho and Rees, 1975) and possibly is the substrate for gum formation in stems. Methyl jasmonate stimulates stem ethylene production and ethylene-forming enzyme activity in tulips, but silver thiosulphate (STS), an inhibitor of ethylene action and synthesis, inhibits gummosis and ethylene production caused by JA-Me (Saniewski, 1989). The mechanism of physiological action of methyl jasmonate in induction of gummosis in tulip stem is unknown. The biosynthesis of jasmonic acid and methyl jasmonate originates from linolenic acid, and the first step of the reaction is catalyzed by lipoxygenase (Vick and Zimmerman, 1984). It was recently shown that methyl jasmonate applied to mature green tomato fruits greatly increases the concentration of free linolenic acid and to a lesser degree decreases the amount of free linoleic acid, but does not affect the level of free lauric, myristic, palmitic, stearic, palmitoleic and oleic acids in ripened fruits. The ratio of linolenic acid to linoleic acid content increases 4.5 -7.7 times in methyl jasmonate treated samples (Czapski et al., 1992, in press).
400
MARIAN SANIEWSKI, MARCIN HORBOWICZ, and JANUSZ CZAPSKI
The aim of this work was to study the effect of methyl jasmonate on fatty acid and sterol contents in the stem of tulips during the induction of gummosis by the compound.
Materials and Methods
Plant material The experiments were performed with tulips cv. Gudoshnik from commercial stocks. After lifting, bulbs with a circumference of 12cm were stored at 17 -20°C until the end of October, and were then cooled to 5 °C as unrooted bulbs for at least 12 weeks. After the cooling period the dry scales were removed and bulbs were individually planted in pots and cultured at IS-20°C in natural light. Three to 4 days before flowering, the first (basal) internode of intact plants was treated with methyl jasmonate at a concentration of 1.0% w/w in lanolin paste (prepared by mixing the lanolin with X part of distilled water). Control plants were treated with lanolin paste only. At least 20 plants were used per treatment and the experiment was repeated three times. Four days after treatment with JA-Me when tissue infiltration was visible about 2 em above the place of application, this part of the stem was cut off and frozen at -20°C. The same procedure was used for pieces of the first internode from control plants treated with lanolin only. A mixed sample of stem tissue from 15 plants was prepared from the control and JA-Me treated material. These frozen samples were lyophilized and used for analysis.
Determination offree and total fatty acids Lyophilized samples were weighed and blended with 40 mL 0.05N NaOH and a few drops of silicon antifoam solution in an Ultra-Turax tissue grinder at 13,500 rpm. The slurry was filtered with 1 g Celite-545 as a filter aid through Whatman No.1 paper under reduced pressure. The filtrate was acidified with 1 mL 6 N HCI. After adding 50 J-lg internal standard (margarinic acid), free fatty acids were extracted twice with 50 mL hexane. Combined hexane extracts were dried by passing through a 5 g anhydrous sulphate layer, and then evaporated to dryness on a rotary evaporator. Methyl esters of fatty acids were prepared with boron trifluoridemethanol reagent (Metcalfe et al., 1966). Quantitative and qualitative determinations of fatty acid methyl esters were performed by GLC using a Pye Unicam 204 gas chromatograph equipped with a 200xO.2cm column (packed with 10% Silar 10C on Chromosorb W, SO/100mesh) and a flame ionization detector. The column temperature was programmed to increase from 121°C to 210 °C at 6°C min -1. The amounts of individual fatty acids were calculated from standard curves of appropriate acid esters. The total amounts of individual fatty acids were determined after lipid hydrolysis (3 h at SO 0C) using 2 mL 5 % KOH in methanol. After cooling and adding 2 mL 10 % NaCl solution, the mixture was extracted twice with 2 mL isooctane. The water fraction contained fatty acid potassium salts while the isooctane layer contained sterols. The total amounts of individual fatty acids were then analyzed (after acidification of the water fraction with 6N HCI to pH = 1) according to the procedure for free fatty acids, as described above. Bound fatty acid content was calculated from the total and free fatty acid content by subtraction.
Determination ofsterols The isooctane fraction containing sterols was dried using 100 mg anhydrous sodium sulphate; after filtration, it was evaporated to
Fig. 1: Induction of gums in the middle of the first internode of tulip stem, 7 days after treatment with methyl jasmonate. Left = control, lanolin was applied only: no gums; Right = JA-Me: gummosis can be observed and gums are extruded onto the surface of stem (arrow). Table 1: The effect of methyl jasmonate, applied to the first (basal) internode of tulip stem, on the contents of some free and bound fatty acids (in mglg of dry matter), measured 4 days after treatment. Results are given as mean ± standard deviation. Fatty acids Free fatty acids Bound fatty acids Control JA-Me Control JA-Me Palmitic acid (C 16:0) 1.1 ±0.42 1.4±O.13 3.HO.52 3.8±0.20 Stearic acid (C 18:0) 0.l±0.05 0.l±0.01 0.5±0.01 0.5±0.06 Oleic acid (C 18: 1) 0.HO.10 1.0±0.08 1.1±0.09 2.4±0.10 Linoleic acid (C 18:2) 7.2±0.64 13.l±0.56 10.6± 1.52 26.H2.76 Linolenic acid (C 18: 3) 3.2±0.23 3.l±0.36 5.2±0.79 6.0± 1.01
dryness at room temperature using a stream of nitrogen. Sterols were silylated Oohansson and Appelqvist, 1975) and analyzed by GLC using a Pye Unicam 204 gas chromatograph equipped with a 200 x 0.4 column (packed with 3 % OV-l on Gas-Chrom Q 100-120 mesh) and a flame ionization detector. The column temperature was maintained at 261°C. The amounts of individual sterols were calculated from standard curves of appropriate sterolsilyl derivatives.
Results and Discussion
Infiltration of stem tissues was observed about 2 cm above the point of application of methyl jasmonate four days after treatment. The infiltration was associated with the appearance of liquid gums, which in the next 2 or 3 days extruded onto the surface of the stem and solidified (Fig. 1). The main free and bound fatty acid of the first internode tissues of tulip stem, in decreasing order of abundance, were linoleic, linolenic, palmitic, oleic and stearic acids (Table 1).
Effect of methyl jasmonate on fatty acids and sterols Table 2: The effect of methyl jasmonate, applied to the first (basal) internode of tulip stem, on the contents of sterols (in J.Lg/ g of dry matter), measured 4 days after treatment. Results are given as mean ± standard deviation. Sterols
Control
JA-Me
Campesterol Stigmasterol i1-sitosterol
247±17.1 122±17.0 616±42.6
285±20.8 234± 11.9 552±38.2
401
membrane lipids are associated with changes in membrane permeability (Beutelmann and Kende, 1977; Simon, 1974). Acknowledgements
We wish to thank Dr. E. Demole, Firmenich SA, Geneva, Switzerland, for the gift of authentic (± )-methyl jasmonate. References
Four days after treatment of the first internode with methyl jasmonate the contents of both free and bound oleic and linoleic acids greatly increased as compared with the control internode (Table 1). Methyl jasmonate did not significantly affect free and bound forms of palmitic, stearic and linolenic acids (Table 1). Campesterol, stigmasterol and (j-sitosterol (highest concentration) were identified in the first internode of tulip stem (Table 2). These sterols commonly occur in plants (Goad, 1977). Methyl jasmonate approximately doubled the concentration of stigmasterol and did not affect the concentrations of campesterol and (j-sitosterol in comparison to the control internode (Table 2). Whether the increase in stigmasterol concentration in tulip stem treated with methyl jasmonate is due to stimulation of synthesis from (j-sitosterol or to inhibition of its degradation has not been studied. The changes in the fatty acid and sterol concentrations induced by methyl jasmonate in tulip stem may be caused by increased senescence and possibly may be associated with induction of gum formation. The stimulatory effect of methyl jasmonate on senescence of leaves of many plants, including tulip, is well documented (Ueda and Kato, 1980; Puchalski et al., 1985). Linoleic and linolenic acids have been identified as senescence-promoting substances in plants but the mechanism of their action in the process is not clear (Ueda and Kato, 1982; Thomas, 1986; Ueda et aI., 1991). Oxidative breakdown of membrane lipids appears to be a characteristic feature of senescence for a number of plant tissues (Beutelmann and Kende, 1977; McKersie et aI., 1978). It is suggested that the increase in concentrations of oleic and linoleic acids (and stigmasterol in tulip stem) under the influence of methyl jasmonate induced changes in membrane fluidity and permeability. It is well known that changes in
BEUTELMANN, P. and H. KENDE: Plant Physiol. 59, 888-893 (1977). CZAPSKI, J., M. HORBOWlCZ, and M. SANIEWSKI: BioI. Plant. (1992), in press. GOAD, 1. J.: In: TEVINI, M. and H. K. LICHTENTHALER (eds.): Lipids and Lipid Polymers in Higher Plants, 146-168. Springer-Verlag, Berlin-Heidelberg-New York (1977). JOHANSSON, A. and 1.-A. ApPELQVIST: Lipids 13, 658-662 (1978). Ho,1. C. and A. R. REES: New Phytol. 74,421-428 (1975). KODA, Y., Y. KIKUTA, H. TAZAKI, Y. TsuJINo, S. SAKAMURA, and T. YOSHIHARA: Phytochemistry 30, 1435-1438 (1991). McKERSIE, B. D., J. R. LEPocK, J. KRUUV, and J. E. THOMPSON: Biochim. Biophys. Acta 508, 197 -212 (1978). METCALFE, 1. D., A. A. SCHMITZ, and J. R. PELKA: Anal. Chern. 38, 514-517 (1966).
MEYER, A., O. MIERSCH, C. BUTTNER, W. DATHE, and G. SEMBDNER: J. Plant Growth Regul. 3, 1-8 (1984). MOE, R. and A. WICKSTR0M: Physiol. Plant. 28, 81-87 (1973). PARTHIER, B.: J. Plant Growth Regul. 9, 57 -63 (1990). PUCHALSKI, J., M. SANIEWSKI, and P. KLIM: Acta Hortic. 167, 247 -257 (1985).
RUTTER, J.
c., W. R. JOHNSTON, and C. W. WILLMER: J. Exper. Bot.
28, 1019-1028 (1977).
SANIEWSKI, M.: Bull. Pol. Ac.: BioI. 37, 41-48 (1989). SANIEWSKI, M. and J. CZAPSKI: Experientia 41,256-257 (1985). SANIEWSKI, M. and J. PUCHALSKI: Bull. Pol. Ac.: BioI. 35 - 38 (1988). SEMBDNER, G. and D. GROSS: In: Bopp, M. (ed.): Plant Growth Substances 1985, 139-147. Springer-Verlag, Berlin-HeidelbergNew York- Tokyo (1986). SIMON, E. W.: New Phytol. 73, 377 -420 (1974). THOMAS, H.: J. Plant Physiol. 123, 97 -105 (1986). THOMPSON, T. and P. P. RUTHERFORD: J. Hort. Sci. 52, 9-17 (1977). UEDA, J. and J. KATO: Plant Physiol. 66, 246-249 (1980). - - J. Plant Growth Regul. 1, 195-203 (1982). UEDA, J., T. MIZUMOTO, and J. KATO: Biochem. Physiol. Pflanzen 187, 203-210 (1991).
VICK, B. A. and D. C. ZIMMERMAN: Plant Physiol. 75, 458-461 (1984).
Vol. 140. pp. 399-401 {1992}
The Effect of Methyl Jasmonate on Fatty Acid and Sterol Content in Tulip Stems MARIAN SANIEWSKI, MARCIN HORBOWICZ*,
and JANUSZ
CZAPSKI'~
Research Institute of Pomology and Floriculture, 96-100 Skierniewice, Poland * Research Institute of Vegetable Crops, 96-100 Skierniewice, Poland Received October 24, 1991 . Accepted March 26, 1992
Summary
The effect of methyl jasmonate GA-Me) on fatty acid and sterol concentrations in the first internode of tulip stem during JA-Me induction of gum production (gummosis) was investigated. JA-Me greatly increased the concentrations of free and bound oleic and linoleic acids, and did not affect the concentrations of free and bound palmitic, stearic and linolenic acids. Methyl jasmonate approximately doubled the concentration of stigmasterol and did not influence the concentrations of campesterol and j3-sitosterol. The changes in fatty acid and sterol concentrations induced by methyl jasmonate in tulip stem may be caused by increased senescence and possibly may be associated with induction of gum formation.
Key words: Tulipa, methyl jasmonate, fatty acids, sterols. Abbreviation: JA-Me = methyl jasmonate. Introduction
Jasmonic acid and methyl jasmonate GA-Me) are known to be widespread native plant compounds (Meyer et al., 1984; Sembdner and Gross, 1986). These compounds have been shown to be physiologically active in various plant processes (Sembdner and Gross, 1986; Parthier, 1990; Ueda and Kato, 1980; Saniewski and Czapski, 1985). Recently, Koda et al. (1991) found that jasmonic acid and methyl jasmonate show strong tuber-inducing activity in potato grown in vitro. It has been shown previously (Puchalski et al., 1985) that methyl jasmonate applied on the bottom surface of all leaves causes a rapid and intense senescence of the leaves of intact tulips. Saniewski and Puchalski (1988) showed that methyl jasmonate induces gum formation in the bulb, stem and basal part of leaf in tulips. The gums consist mainly of pentose sugars, xylose and arabinose, after hydrolysis (Saniewski and Puchalski, 1988). The biosynthetic pathway(s) of gum polysaccharides induced by JA-Me are unknown. It is well known that fructosans, starch and sucrose are the main storage carbohydrates in the bulb scales of tulips (Moe and Wickstf0m, 1973; Thompson and Rutherford, 1977); in the tulip leaves, fructose, glucose, sucrose, myo-inositol, © 1992 by Gustav Fischer Verlag, Stuttgart
stachyose, tuliposides A and B, and traces of arabinose and xylose occur (Rutter et al., 1977). Sucrose is the main mobile leaf assimilate in tulips (Ho and Rees, 1975) and possibly is the substrate for gum formation in stems. Methyl jasmonate stimulates stem ethylene production and ethylene-forming enzyme activity in tulips, but silver thiosulphate (STS), an inhibitor of ethylene action and synthesis, inhibits gummosis and ethylene production caused by JA-Me (Saniewski, 1989). The mechanism of physiological action of methyl jasmonate in induction of gummosis in tulip stem is unknown. The biosynthesis of jasmonic acid and methyl jasmonate originates from linolenic acid, and the first step of the reaction is catalyzed by lipoxygenase (Vick and Zimmerman, 1984). It was recently shown that methyl jasmonate applied to mature green tomato fruits greatly increases the concentration of free linolenic acid and to a lesser degree decreases the amount of free linoleic acid, but does not affect the level of free lauric, myristic, palmitic, stearic, palmitoleic and oleic acids in ripened fruits. The ratio of linolenic acid to linoleic acid content increases 4.5 -7.7 times in methyl jasmonate treated samples (Czapski et al., 1992, in press).
400
MARIAN SANIEWSKI, MARCIN HORBOWICZ, and JANUSZ CZAPSKI
The aim of this work was to study the effect of methyl jasmonate on fatty acid and sterol contents in the stem of tulips during the induction of gummosis by the compound.
Materials and Methods
Plant material The experiments were performed with tulips cv. Gudoshnik from commercial stocks. After lifting, bulbs with a circumference of 12cm were stored at 17 -20°C until the end of October, and were then cooled to 5 °C as unrooted bulbs for at least 12 weeks. After the cooling period the dry scales were removed and bulbs were individually planted in pots and cultured at IS-20°C in natural light. Three to 4 days before flowering, the first (basal) internode of intact plants was treated with methyl jasmonate at a concentration of 1.0% w/w in lanolin paste (prepared by mixing the lanolin with X part of distilled water). Control plants were treated with lanolin paste only. At least 20 plants were used per treatment and the experiment was repeated three times. Four days after treatment with JA-Me when tissue infiltration was visible about 2 em above the place of application, this part of the stem was cut off and frozen at -20°C. The same procedure was used for pieces of the first internode from control plants treated with lanolin only. A mixed sample of stem tissue from 15 plants was prepared from the control and JA-Me treated material. These frozen samples were lyophilized and used for analysis.
Determination offree and total fatty acids Lyophilized samples were weighed and blended with 40 mL 0.05N NaOH and a few drops of silicon antifoam solution in an Ultra-Turax tissue grinder at 13,500 rpm. The slurry was filtered with 1 g Celite-545 as a filter aid through Whatman No.1 paper under reduced pressure. The filtrate was acidified with 1 mL 6 N HCI. After adding 50 J-lg internal standard (margarinic acid), free fatty acids were extracted twice with 50 mL hexane. Combined hexane extracts were dried by passing through a 5 g anhydrous sulphate layer, and then evaporated to dryness on a rotary evaporator. Methyl esters of fatty acids were prepared with boron trifluoridemethanol reagent (Metcalfe et al., 1966). Quantitative and qualitative determinations of fatty acid methyl esters were performed by GLC using a Pye Unicam 204 gas chromatograph equipped with a 200xO.2cm column (packed with 10% Silar 10C on Chromosorb W, SO/100mesh) and a flame ionization detector. The column temperature was programmed to increase from 121°C to 210 °C at 6°C min -1. The amounts of individual fatty acids were calculated from standard curves of appropriate acid esters. The total amounts of individual fatty acids were determined after lipid hydrolysis (3 h at SO 0C) using 2 mL 5 % KOH in methanol. After cooling and adding 2 mL 10 % NaCl solution, the mixture was extracted twice with 2 mL isooctane. The water fraction contained fatty acid potassium salts while the isooctane layer contained sterols. The total amounts of individual fatty acids were then analyzed (after acidification of the water fraction with 6N HCI to pH = 1) according to the procedure for free fatty acids, as described above. Bound fatty acid content was calculated from the total and free fatty acid content by subtraction.
Determination ofsterols The isooctane fraction containing sterols was dried using 100 mg anhydrous sodium sulphate; after filtration, it was evaporated to
Fig. 1: Induction of gums in the middle of the first internode of tulip stem, 7 days after treatment with methyl jasmonate. Left = control, lanolin was applied only: no gums; Right = JA-Me: gummosis can be observed and gums are extruded onto the surface of stem (arrow). Table 1: The effect of methyl jasmonate, applied to the first (basal) internode of tulip stem, on the contents of some free and bound fatty acids (in mglg of dry matter), measured 4 days after treatment. Results are given as mean ± standard deviation. Fatty acids Free fatty acids Bound fatty acids Control JA-Me Control JA-Me Palmitic acid (C 16:0) 1.1 ±0.42 1.4±O.13 3.HO.52 3.8±0.20 Stearic acid (C 18:0) 0.l±0.05 0.l±0.01 0.5±0.01 0.5±0.06 Oleic acid (C 18: 1) 0.HO.10 1.0±0.08 1.1±0.09 2.4±0.10 Linoleic acid (C 18:2) 7.2±0.64 13.l±0.56 10.6± 1.52 26.H2.76 Linolenic acid (C 18: 3) 3.2±0.23 3.l±0.36 5.2±0.79 6.0± 1.01
dryness at room temperature using a stream of nitrogen. Sterols were silylated Oohansson and Appelqvist, 1975) and analyzed by GLC using a Pye Unicam 204 gas chromatograph equipped with a 200 x 0.4 column (packed with 3 % OV-l on Gas-Chrom Q 100-120 mesh) and a flame ionization detector. The column temperature was maintained at 261°C. The amounts of individual sterols were calculated from standard curves of appropriate sterolsilyl derivatives.
Results and Discussion
Infiltration of stem tissues was observed about 2 cm above the point of application of methyl jasmonate four days after treatment. The infiltration was associated with the appearance of liquid gums, which in the next 2 or 3 days extruded onto the surface of the stem and solidified (Fig. 1). The main free and bound fatty acid of the first internode tissues of tulip stem, in decreasing order of abundance, were linoleic, linolenic, palmitic, oleic and stearic acids (Table 1).
Effect of methyl jasmonate on fatty acids and sterols Table 2: The effect of methyl jasmonate, applied to the first (basal) internode of tulip stem, on the contents of sterols (in J.Lg/ g of dry matter), measured 4 days after treatment. Results are given as mean ± standard deviation. Sterols
Control
JA-Me
Campesterol Stigmasterol i1-sitosterol
247±17.1 122±17.0 616±42.6
285±20.8 234± 11.9 552±38.2
401
membrane lipids are associated with changes in membrane permeability (Beutelmann and Kende, 1977; Simon, 1974). Acknowledgements
We wish to thank Dr. E. Demole, Firmenich SA, Geneva, Switzerland, for the gift of authentic (± )-methyl jasmonate. References
Four days after treatment of the first internode with methyl jasmonate the contents of both free and bound oleic and linoleic acids greatly increased as compared with the control internode (Table 1). Methyl jasmonate did not significantly affect free and bound forms of palmitic, stearic and linolenic acids (Table 1). Campesterol, stigmasterol and (j-sitosterol (highest concentration) were identified in the first internode of tulip stem (Table 2). These sterols commonly occur in plants (Goad, 1977). Methyl jasmonate approximately doubled the concentration of stigmasterol and did not affect the concentrations of campesterol and (j-sitosterol in comparison to the control internode (Table 2). Whether the increase in stigmasterol concentration in tulip stem treated with methyl jasmonate is due to stimulation of synthesis from (j-sitosterol or to inhibition of its degradation has not been studied. The changes in the fatty acid and sterol concentrations induced by methyl jasmonate in tulip stem may be caused by increased senescence and possibly may be associated with induction of gum formation. The stimulatory effect of methyl jasmonate on senescence of leaves of many plants, including tulip, is well documented (Ueda and Kato, 1980; Puchalski et al., 1985). Linoleic and linolenic acids have been identified as senescence-promoting substances in plants but the mechanism of their action in the process is not clear (Ueda and Kato, 1982; Thomas, 1986; Ueda et aI., 1991). Oxidative breakdown of membrane lipids appears to be a characteristic feature of senescence for a number of plant tissues (Beutelmann and Kende, 1977; McKersie et aI., 1978). It is suggested that the increase in concentrations of oleic and linoleic acids (and stigmasterol in tulip stem) under the influence of methyl jasmonate induced changes in membrane fluidity and permeability. It is well known that changes in
BEUTELMANN, P. and H. KENDE: Plant Physiol. 59, 888-893 (1977). CZAPSKI, J., M. HORBOWlCZ, and M. SANIEWSKI: BioI. Plant. (1992), in press. GOAD, 1. J.: In: TEVINI, M. and H. K. LICHTENTHALER (eds.): Lipids and Lipid Polymers in Higher Plants, 146-168. Springer-Verlag, Berlin-Heidelberg-New York (1977). JOHANSSON, A. and 1.-A. ApPELQVIST: Lipids 13, 658-662 (1978). Ho,1. C. and A. R. REES: New Phytol. 74,421-428 (1975). KODA, Y., Y. KIKUTA, H. TAZAKI, Y. TsuJINo, S. SAKAMURA, and T. YOSHIHARA: Phytochemistry 30, 1435-1438 (1991). McKERSIE, B. D., J. R. LEPocK, J. KRUUV, and J. E. THOMPSON: Biochim. Biophys. Acta 508, 197 -212 (1978). METCALFE, 1. D., A. A. SCHMITZ, and J. R. PELKA: Anal. Chern. 38, 514-517 (1966).
MEYER, A., O. MIERSCH, C. BUTTNER, W. DATHE, and G. SEMBDNER: J. Plant Growth Regul. 3, 1-8 (1984). MOE, R. and A. WICKSTR0M: Physiol. Plant. 28, 81-87 (1973). PARTHIER, B.: J. Plant Growth Regul. 9, 57 -63 (1990). PUCHALSKI, J., M. SANIEWSKI, and P. KLIM: Acta Hortic. 167, 247 -257 (1985).
RUTTER, J.
c., W. R. JOHNSTON, and C. W. WILLMER: J. Exper. Bot.
28, 1019-1028 (1977).
SANIEWSKI, M.: Bull. Pol. Ac.: BioI. 37, 41-48 (1989). SANIEWSKI, M. and J. CZAPSKI: Experientia 41,256-257 (1985). SANIEWSKI, M. and J. PUCHALSKI: Bull. Pol. Ac.: BioI. 35 - 38 (1988). SEMBDNER, G. and D. GROSS: In: Bopp, M. (ed.): Plant Growth Substances 1985, 139-147. Springer-Verlag, Berlin-HeidelbergNew York- Tokyo (1986). SIMON, E. W.: New Phytol. 73, 377 -420 (1974). THOMAS, H.: J. Plant Physiol. 123, 97 -105 (1986). THOMPSON, T. and P. P. RUTHERFORD: J. Hort. Sci. 52, 9-17 (1977). UEDA, J. and J. KATO: Plant Physiol. 66, 246-249 (1980). - - J. Plant Growth Regul. 1, 195-203 (1982). UEDA, J., T. MIZUMOTO, and J. KATO: Biochem. Physiol. Pflanzen 187, 203-210 (1991).
VICK, B. A. and D. C. ZIMMERMAN: Plant Physiol. 75, 458-461 (1984).