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Change in Fatty Acids Composition During Water stress in Cotton Plants. Relation With Drought Resistance Induced by Far Red Light
Change in Fatty Acids Composition During Water stress in Cotton Plants. Relation With Drought Resistance Induced by Far Red Light M. OUEDRAOGO, A. TREMOLIERES and C. HUBAC Laboratoire du Phytotron, C.N.R.S. F-91190 Gif-sur-Yvette, France Received September 13, 1983 . Accepted December 21,1983 Summary The resistance of cotton to water stress can be modified by the photoperiod: plants grown under short day conditions are resistant to water stress, and FR enhances their resistance. It has been shown that FR improves water economy. The determination of the composition of fatty acids during water stress was carried out under drought resistance induced by FR. In roots, FR treatment causes saturation of fatty acids. During water stress, there is a general decrease in the content of fatty acids, with saturation of fatty acids. This is true in 9 h light period and in 9 h light + FR. These changes can be related to variations in membrane fluidity. Without FR, water stress causes a marked decrease in the content of the fatty acids in the buds. When FR is given, water stress has no effect on fatty acids content, which, under these conditions, is always lower than in non water stressed plants without FR.
Key words: Gossypium hirsutum L., far red light, fatty acids, water stress. Introduction The resistance of cotton plants to water stress can be modified by the photoperiod under which plants are grown or stressed. Given short days, they are resistant to water stress, particularly those receiving 9 h of light plus 30 min far red radiation (FR) at the beginning of the dark period (Ouedraogo and Hubac, 1982). Given long days, either 16 h of continuous white light, or 9 h white light with intermittant red irradiations during the dark period, plants remain sensitive to water stress, but, if flashes of FR follow the red light treatment, this effect is reversed (Hubac and Lepage Degivry, 1981)_ In search of mechanisms involved in this resistance, the analysis of fatty acids content allowed us to examine whether membrane permeability is modified. This analysis was done in roots, the absorption organs, and in buds, essential organs for the survival under water stress.
Abbreviations: FR: far red light; C 16-0 = palmitic acid; C 18-0 - stearic acid; C 18-1 = oleic acid; C 18-2 = linoleic acid; C 18-3 = linolenic acid; 1/;w = water potential; 1/;, = osmotic potential; 1/;p - turgor potential. BF 3 = trifluoroborate.
Z. Pjlanzenphysiol. Ed. 114. S. 239-245. 1984.
240
M. OUEDRAOGO, A. TREMOLIERES and C. HUBAC
Material and methods Plant material and growth conditions Cotton plants, Gossypium hirsutum L. cv. Bou, were grown in vermiculite at the Phytotron
in Gif/Yvette. The plants were grown under a growth room at a constant temperature regime of 27°C and 70 % relative humidity. illumination came from a set of fluorescent tubes yielding 100W m- 2sec- 1• Plants were watered every morning with a nutrient solution (Hubac et al., 1969) and every evening with deionised water. In a first set of experiments, plants were grown for 3 weeks in the normal 9 h photoperiod as well as in 9 h photoperiod plus a 30 min exposure to FR before darkness. The FR was 12.5 W m- 2sec- 1• Only irrigated plants were analyzed. As FR induces morphological differences during plant growth (Ouedraogo and Hubac, 19821,c), a second set of experiments was carried out with plants grown in a 9h light period for 3 weeks, then water stressed in 9 h light or 9 h light + FR, by cessation of watering.
Leaf water and osmotic potentials Leaf water and osmotic potentials were measured on the 3rd or 4th leaf from the apex (when fully expanded). Leaf water potential (1/;w) was measured with a xylem pressure chamber (Scholander et al., 1965). Osmotic potential (1/;,) was determined using a psychrometer with Peltier cooling (Spanner, 1951) after freezing the material. Turgor potential (1/;p) was calculated as the difference between 1/;w and 1/;,.
Analysis offatty acids For the analysis of fatty acids, lipids in roots and buds (defined as meristems surrounded by primordial leaves) were extracted according to Bligh and Dyer (1959). Total fatty acids were extracted by direct trans esterification in methanol BF3 according to Metcalfe et al. (1966), and the different fatty acids methyl-esters were analyzed by gas-liquid chromatography on a column of diethylenglycosuccinate, 4 %, at 170°C. For measuring the amount of total fatty acids, heptodecanolc acid (C 17-0) (free acid) was added as an internal standard before the methylation.
Results Sensitivity to drought
The comparison is made between plants grown and water stressed in 9 h light or 9 h light + FR, as well as between plants grown in 9 h light, but stressed under FR conditions. Table 1 shows that there is a great difference between the three sets of plants: those which received the FR supplement before and during water stress remain viable (recover when rewatered) after 27 days of water stress, whereas plants without FR survive only 13 days of stress. The increased ability to withstand water stress is also evident (but to a lesser extent) when the plants are grown without FR, but water stressed in the presence of FR for 30 min. The analysis of the leaf potential [water (I/;w), osmotic (1/;,), and turgor (I/;p)] confirm that plants which are grown and water stressed with FR treatment remain turgid longer than the controls (Fig. 1). It can be concluded that FR induces water economy. Z. Pj/anzenphysiol. Ed. 114. S. 239-245. 1984.
Fatty acids during water stress
241
Table 1: Water-stress sensitivity of plants cultivated for 3 weeks under 9 h illumination or 9 h + 30 min FR (at the beginning of the dark period) and water-stressed under these different conditions. during growth Light Regime during water-stress
9h
9h
9h+FR
9h
9h+FR
9h+FR
Number of days of water-stress that plants could survive*)
13±2
20±4
27±2
*) The number of days under the water-stress conditions that the plants were able to recover from when rewatered. 10-5
Pa
III
····~';~•.. ,~ .. ~- .. _
'lip
'--"
o 1 2 DAYS
..• 9H
..
F.R.L.
. --..9H
3 4 5 6 7 OF WATER STRESS
III I
'II", 0
'lis
'"I" III
'","
o
()I
I
Fig. 1: Leaf water potential (1/;w), osmotic potential (1/;,) and turgor potential (1/;p) of plants grown and water stressed under 9 h light or 9 h light + FR. 9 h = thin lines - 9 h + FR = thick lines.
Changes in fatty acid pattern in relation to water stress a) Composition offatty acids in the roots ofplants with or without FR treatment
Because this water economy with FR treatment may be due to the properties of membranes we examined the composition of fatty acids in the roots which are first implicated in the absorption of water. Z. Pjlanzenphysiol. Bd. 114. S. 239-245. 1984.
242
M.
OUEDRAOGO,
A.
TREMOLIERES
and C.
HUBAC
Table 2: Percentage of fatty acids in roots of plants grown under 9 h light period or 9 h light + FR. Fatty acids
Light regime 9h
9h+FR
C C C C C
28.8 5.6 7.8 35.2 20.3
38.6 6.1 8.2 24.9 16.3
16-0 18-0 18-1 18-2 18-3
~
I-
Z
0 0 (X)
~
a..
"-
\J
~o 0
I-
'
Z
w
I-
Z
0
U
Vl
9H
0 0
9H
a
+
F.R.L.
u
>-
II-
0 0 0/
«
u.
0
0
2
3
4
5 6 7 B DAYS OF
9 10 11 12 13 WATER STRESS
Fig. 2: Total content of fatty acid in roots of plants grown under 9 h light period and water stressed under 9 h light or 9 h light + FR. 9 h = thin lines - 9 h + FR = thick lines.
When plants are grown under 9 h light period or 9 h light + FR, there are great morphological differences between the two kinds of plants. For this reason, we have only presented, the percentage of fatty acids (Tab.2); but the total content of fatty acids per root was markedly decreased in plants grown with FR treatment. The FR treatment produces an increase in palmitic acid and a decrease in linoleic and linolenic acids. When plants are grown under a 9 h light period and water stressed under 9 h light or 9 h light + FR, we observed a decrease in the content of total fatty acids (Fig. 2). This decrease is slightly more pronounced with FR treatment than without. Z. Pjlanzenphysiol. Bd. 114. S. 239-245. 1984.
Fatty acids during water stress
243
w \)
~ ~ z w
C
16:0
- ........ 7- ...... c
18: 2
U
"" w
0 '
CL Vl
Q
U
«
• ".,~-:-A Y'"---:.-<:;, ..~" v.-.""-. ...
g
>-
lI-
«
~
..
0
.
(N
lL
..
--'-
,...o
o
1
.,,~
. .
2
."-.-.......
~."
---
.......
'-!<"."-.
/--
.
___ C
. . . ~-=-~~-C
~~~
18:3 18 :1
/~-
3
4
5 6 7 8 DAYS OF
9 10 11 12 13 WATER STRESS
Fig. 3: Composition of fatty acids in roots of plants grown under 9 h light period and water stressed under 9 h light or 9 h light + FR. 9 h light = thin lines - 9 h light + FR = thick lines.
The percentage of fatty acids (Fig. 3) shows that palmitic and oleic acids increase significantly, and both linoleic and linolenic acids decrease.
b) Composition offatty acids in buds ofplants after 6 days of water stress with or without FR treatment Buds are essential organs in the survival process under water stress. Therefore the composition of fatty acids in buds was analyzed in plants subjected to water stress for six days with or without FR treatment, and compared to the composition of fatty acids in buds in irrigated plants. Table 3 shows that in non-treated plants, water stress induces a very important decrease in the content of total fatty acids as compared to the controls. In FR treated plants, no difference in the content of fatty acids between stressed and irrigated Table 3: Total content of fatty acids and percentage of different fatty acids in buds. Light regime
Total fatty acids (JLg/per bud)
9h 9h+FR
A 154.5 61.8
A
B 92.9 69.6
C 16-0 A 34.0 35.6
C 18-0 B 36.0 32.3
A 4.7 6.0
B 5.3 6.2
Percentage of C 18-1 C 18-2 A 5.0 4.7
B 6.9 6.9
A 33.1 26.7
C 18-3 B 26.9 27.0
A 23.0 27.0
B 24.9 27.6
= irrigated plants. B = water stressed plants. Z. Pjl.anzenphysiol. Bd. 114. S. 239--245. 1984.
244
M.
OUEDRAOGO,
A.
TREMOLIERES
and C. HUBAC
plants can be noticed. In all cases, with or without FR, there is no significant difference in the percentage of fatty acids. Discussion In this study, three different phenomena are examined: the first concerns the adaptation of irrigated plants treated with FR; the second is the effect of FR during water stress; the third deals with the effect of water stress and FR treatment on the composition of fatty acids in buds. 1) Irrigated plants, grown under different photoperiods (9 h light + FR or 9 h light) are only able to become drought resistant when irradiated with FR. The analysis of fatty acids in roots shows a decrease in the total content of fatty acids when FR is gIven. The FR treatment also induces a saturation of fatty acids, with an increase in palmitic acid and a decrease in linoleic and linolenic acids. These fatty acids are membrane components. Saturation can tentatively be correlated with a decrease in membrane fluidity in roots, which can explain the decrease in water absorption by the root observed with FR treatment (Hubac et al., in press). There is then adaptation to drought. Content of fatty acids in buds of FR-treated plants remains lower than in non FR treated plants irrigated normally. It may be proposed that one of the effects of FR is the inhibition or reduction of bud growth because the content of fatty acids reflects the amount of membrane lipids and membrane growth. 2) During water stress itself, we have observed in roots a decrease in the content of fatty acids and a saturation of these fatty acids. These results are only slightly more significant with FR treatment, in comparison with 9 h light. This is consistent with the hypothesis of a decrease in membrane fluidity during water stress in resistant as well as in non-resistant plants. It is in agreement with the study of Pham Thi et al. (1982) on cotton leaves, in which a decrease of total fatty acid content and an increase of saturation have also been observed. But there are no significant difference in leaf membranes between resistant and non-resistant cotton species (Pham Thi, in press). Drought resistance in the roots is not associated with the modification of membrane lipids during water stress itself. 3) In the buds, water stress induces an important decrease in the content of fatty acids in plants grown under 9 h light, yet with the FR treatment there is no difference between irrigated and stressed plants: buds of treated plants are not affected in their fatty acid content after six days under water stress. It seems possible that FR acts by rapidly stopping lipid metabolism in buds. The relationship between the modification of the lipid metabolism in buds, growth of buds and drought resistance will be further examined. Acknowledgements We thank Mrs. S. Abou-Haidar for her help in the translation of this manuscript.
Z. Pjlanzenphysiol. Bd. 114. S. 239-245. 1984.
Fatty acids during water stress
245
References BLIGH, E. C. and W. S. DYER: Can. J. Biochem. Biophys. 37, 911-919 (1959). GIDDING, T. H. Jr. and A. D. HANSON: Planta 155, 493-501 (1982). HUBAC, C. and M. T. LEPAGE DEGIVRY: Physiol. Veg. 19, 87-97 (1981). HUBAC, c., D. GUERRIER, and J. FERRAN: Oecol. Plant. 4, 325-346 (1969). HUBAC, c., M. OUEDRAOGO, D. GUERRIER, and J. FERRAN: Soc. Bot. in press. METCALFE, L. P., A. A. SMITZ, andJ. P. PELKA: Anal. Chern. 38,514-515 (1966). OUEDRAOGO, M. and C. HUBAC: Plant and Cell Physiol. 23, 1297-1303 (1982). PHAM THI, A. T.: Soc. Bot. in press. PHAM THI, A. T., C. FLOOD, and J. VIEIRA DA SILVA: In Biochemistry and Metabolism of Plant lipids. Edited by J. F. G. M. WINTERMANS and P. J. C. KUIPER 451-454. Elsevier Biochemical Press B. V., 1982. SCHOLANDER, P. F., H. T. HAMMEL, D. EDDA, F. D. BRADSTREET, and E. A. HEMMINGSEN: Science 148, 339-346 (1965). SPANNER, D. c.:J. Exp. Bot. 2,145-168 (1951). TREMOLIERES, A., J. P. DUBACQ, and D. DRAPIER: Phytochemistry 21,41-45 (1982).
Z. Pjlanzenphysiol. Ed. 114. S. 239-245. 1984.
Key words: Gossypium hirsutum L., far red light, fatty acids, water stress. Introduction The resistance of cotton plants to water stress can be modified by the photoperiod under which plants are grown or stressed. Given short days, they are resistant to water stress, particularly those receiving 9 h of light plus 30 min far red radiation (FR) at the beginning of the dark period (Ouedraogo and Hubac, 1982). Given long days, either 16 h of continuous white light, or 9 h white light with intermittant red irradiations during the dark period, plants remain sensitive to water stress, but, if flashes of FR follow the red light treatment, this effect is reversed (Hubac and Lepage Degivry, 1981)_ In search of mechanisms involved in this resistance, the analysis of fatty acids content allowed us to examine whether membrane permeability is modified. This analysis was done in roots, the absorption organs, and in buds, essential organs for the survival under water stress.
Abbreviations: FR: far red light; C 16-0 = palmitic acid; C 18-0 - stearic acid; C 18-1 = oleic acid; C 18-2 = linoleic acid; C 18-3 = linolenic acid; 1/;w = water potential; 1/;, = osmotic potential; 1/;p - turgor potential. BF 3 = trifluoroborate.
Z. Pjlanzenphysiol. Ed. 114. S. 239-245. 1984.
240
M. OUEDRAOGO, A. TREMOLIERES and C. HUBAC
Material and methods Plant material and growth conditions Cotton plants, Gossypium hirsutum L. cv. Bou, were grown in vermiculite at the Phytotron
in Gif/Yvette. The plants were grown under a growth room at a constant temperature regime of 27°C and 70 % relative humidity. illumination came from a set of fluorescent tubes yielding 100W m- 2sec- 1• Plants were watered every morning with a nutrient solution (Hubac et al., 1969) and every evening with deionised water. In a first set of experiments, plants were grown for 3 weeks in the normal 9 h photoperiod as well as in 9 h photoperiod plus a 30 min exposure to FR before darkness. The FR was 12.5 W m- 2sec- 1• Only irrigated plants were analyzed. As FR induces morphological differences during plant growth (Ouedraogo and Hubac, 19821,c), a second set of experiments was carried out with plants grown in a 9h light period for 3 weeks, then water stressed in 9 h light or 9 h light + FR, by cessation of watering.
Leaf water and osmotic potentials Leaf water and osmotic potentials were measured on the 3rd or 4th leaf from the apex (when fully expanded). Leaf water potential (1/;w) was measured with a xylem pressure chamber (Scholander et al., 1965). Osmotic potential (1/;,) was determined using a psychrometer with Peltier cooling (Spanner, 1951) after freezing the material. Turgor potential (1/;p) was calculated as the difference between 1/;w and 1/;,.
Analysis offatty acids For the analysis of fatty acids, lipids in roots and buds (defined as meristems surrounded by primordial leaves) were extracted according to Bligh and Dyer (1959). Total fatty acids were extracted by direct trans esterification in methanol BF3 according to Metcalfe et al. (1966), and the different fatty acids methyl-esters were analyzed by gas-liquid chromatography on a column of diethylenglycosuccinate, 4 %, at 170°C. For measuring the amount of total fatty acids, heptodecanolc acid (C 17-0) (free acid) was added as an internal standard before the methylation.
Results Sensitivity to drought
The comparison is made between plants grown and water stressed in 9 h light or 9 h light + FR, as well as between plants grown in 9 h light, but stressed under FR conditions. Table 1 shows that there is a great difference between the three sets of plants: those which received the FR supplement before and during water stress remain viable (recover when rewatered) after 27 days of water stress, whereas plants without FR survive only 13 days of stress. The increased ability to withstand water stress is also evident (but to a lesser extent) when the plants are grown without FR, but water stressed in the presence of FR for 30 min. The analysis of the leaf potential [water (I/;w), osmotic (1/;,), and turgor (I/;p)] confirm that plants which are grown and water stressed with FR treatment remain turgid longer than the controls (Fig. 1). It can be concluded that FR induces water economy. Z. Pj/anzenphysiol. Ed. 114. S. 239-245. 1984.
Fatty acids during water stress
241
Table 1: Water-stress sensitivity of plants cultivated for 3 weeks under 9 h illumination or 9 h + 30 min FR (at the beginning of the dark period) and water-stressed under these different conditions. during growth Light Regime during water-stress
9h
9h
9h+FR
9h
9h+FR
9h+FR
Number of days of water-stress that plants could survive*)
13±2
20±4
27±2
*) The number of days under the water-stress conditions that the plants were able to recover from when rewatered. 10-5
Pa
III
····~';~•.. ,~ .. ~- .. _
'lip
'--"
o 1 2 DAYS
..• 9H
..
F.R.L.
. --..9H
3 4 5 6 7 OF WATER STRESS
III I
'II", 0
'lis
'"I" III
'","
o
()I
I
Fig. 1: Leaf water potential (1/;w), osmotic potential (1/;,) and turgor potential (1/;p) of plants grown and water stressed under 9 h light or 9 h light + FR. 9 h = thin lines - 9 h + FR = thick lines.
Changes in fatty acid pattern in relation to water stress a) Composition offatty acids in the roots ofplants with or without FR treatment
Because this water economy with FR treatment may be due to the properties of membranes we examined the composition of fatty acids in the roots which are first implicated in the absorption of water. Z. Pjlanzenphysiol. Bd. 114. S. 239-245. 1984.
242
M.
OUEDRAOGO,
A.
TREMOLIERES
and C.
HUBAC
Table 2: Percentage of fatty acids in roots of plants grown under 9 h light period or 9 h light + FR. Fatty acids
Light regime 9h
9h+FR
C C C C C
28.8 5.6 7.8 35.2 20.3
38.6 6.1 8.2 24.9 16.3
16-0 18-0 18-1 18-2 18-3
~
I-
Z
0 0 (X)
~
a..
"-
\J
~o 0
I-
'
Z
w
I-
Z
0
U
Vl
9H
0 0
9H
a
+
F.R.L.
u
>-
II-
0 0 0/
«
u.
0
0
2
3
4
5 6 7 B DAYS OF
9 10 11 12 13 WATER STRESS
Fig. 2: Total content of fatty acid in roots of plants grown under 9 h light period and water stressed under 9 h light or 9 h light + FR. 9 h = thin lines - 9 h + FR = thick lines.
When plants are grown under 9 h light period or 9 h light + FR, there are great morphological differences between the two kinds of plants. For this reason, we have only presented, the percentage of fatty acids (Tab.2); but the total content of fatty acids per root was markedly decreased in plants grown with FR treatment. The FR treatment produces an increase in palmitic acid and a decrease in linoleic and linolenic acids. When plants are grown under a 9 h light period and water stressed under 9 h light or 9 h light + FR, we observed a decrease in the content of total fatty acids (Fig. 2). This decrease is slightly more pronounced with FR treatment than without. Z. Pjlanzenphysiol. Bd. 114. S. 239-245. 1984.
Fatty acids during water stress
243
w \)
~ ~ z w
C
16:0
- ........ 7- ...... c
18: 2
U
"" w
0 '
CL Vl
Q
U
«
• ".,~-:-A Y'"---:.-<:;, ..~" v.-.""-. ...
g
>-
lI-
«
~
..
0
.
(N
lL
..
--'-
,...o
o
1
.,,~
. .
2
."-.-.......
~."
---
.......
'-!<"."-.
/--
.
___ C
. . . ~-=-~~-C
~~~
18:3 18 :1
/~-
3
4
5 6 7 8 DAYS OF
9 10 11 12 13 WATER STRESS
Fig. 3: Composition of fatty acids in roots of plants grown under 9 h light period and water stressed under 9 h light or 9 h light + FR. 9 h light = thin lines - 9 h light + FR = thick lines.
The percentage of fatty acids (Fig. 3) shows that palmitic and oleic acids increase significantly, and both linoleic and linolenic acids decrease.
b) Composition offatty acids in buds ofplants after 6 days of water stress with or without FR treatment Buds are essential organs in the survival process under water stress. Therefore the composition of fatty acids in buds was analyzed in plants subjected to water stress for six days with or without FR treatment, and compared to the composition of fatty acids in buds in irrigated plants. Table 3 shows that in non-treated plants, water stress induces a very important decrease in the content of total fatty acids as compared to the controls. In FR treated plants, no difference in the content of fatty acids between stressed and irrigated Table 3: Total content of fatty acids and percentage of different fatty acids in buds. Light regime
Total fatty acids (JLg/per bud)
9h 9h+FR
A 154.5 61.8
A
B 92.9 69.6
C 16-0 A 34.0 35.6
C 18-0 B 36.0 32.3
A 4.7 6.0
B 5.3 6.2
Percentage of C 18-1 C 18-2 A 5.0 4.7
B 6.9 6.9
A 33.1 26.7
C 18-3 B 26.9 27.0
A 23.0 27.0
B 24.9 27.6
= irrigated plants. B = water stressed plants. Z. Pjl.anzenphysiol. Bd. 114. S. 239--245. 1984.
244
M.
OUEDRAOGO,
A.
TREMOLIERES
and C. HUBAC
plants can be noticed. In all cases, with or without FR, there is no significant difference in the percentage of fatty acids. Discussion In this study, three different phenomena are examined: the first concerns the adaptation of irrigated plants treated with FR; the second is the effect of FR during water stress; the third deals with the effect of water stress and FR treatment on the composition of fatty acids in buds. 1) Irrigated plants, grown under different photoperiods (9 h light + FR or 9 h light) are only able to become drought resistant when irradiated with FR. The analysis of fatty acids in roots shows a decrease in the total content of fatty acids when FR is gIven. The FR treatment also induces a saturation of fatty acids, with an increase in palmitic acid and a decrease in linoleic and linolenic acids. These fatty acids are membrane components. Saturation can tentatively be correlated with a decrease in membrane fluidity in roots, which can explain the decrease in water absorption by the root observed with FR treatment (Hubac et al., in press). There is then adaptation to drought. Content of fatty acids in buds of FR-treated plants remains lower than in non FR treated plants irrigated normally. It may be proposed that one of the effects of FR is the inhibition or reduction of bud growth because the content of fatty acids reflects the amount of membrane lipids and membrane growth. 2) During water stress itself, we have observed in roots a decrease in the content of fatty acids and a saturation of these fatty acids. These results are only slightly more significant with FR treatment, in comparison with 9 h light. This is consistent with the hypothesis of a decrease in membrane fluidity during water stress in resistant as well as in non-resistant plants. It is in agreement with the study of Pham Thi et al. (1982) on cotton leaves, in which a decrease of total fatty acid content and an increase of saturation have also been observed. But there are no significant difference in leaf membranes between resistant and non-resistant cotton species (Pham Thi, in press). Drought resistance in the roots is not associated with the modification of membrane lipids during water stress itself. 3) In the buds, water stress induces an important decrease in the content of fatty acids in plants grown under 9 h light, yet with the FR treatment there is no difference between irrigated and stressed plants: buds of treated plants are not affected in their fatty acid content after six days under water stress. It seems possible that FR acts by rapidly stopping lipid metabolism in buds. The relationship between the modification of the lipid metabolism in buds, growth of buds and drought resistance will be further examined. Acknowledgements We thank Mrs. S. Abou-Haidar for her help in the translation of this manuscript.
Z. Pjlanzenphysiol. Bd. 114. S. 239-245. 1984.
Fatty acids during water stress
245
References BLIGH, E. C. and W. S. DYER: Can. J. Biochem. Biophys. 37, 911-919 (1959). GIDDING, T. H. Jr. and A. D. HANSON: Planta 155, 493-501 (1982). HUBAC, C. and M. T. LEPAGE DEGIVRY: Physiol. Veg. 19, 87-97 (1981). HUBAC, c., D. GUERRIER, and J. FERRAN: Oecol. Plant. 4, 325-346 (1969). HUBAC, c., M. OUEDRAOGO, D. GUERRIER, and J. FERRAN: Soc. Bot. in press. METCALFE, L. P., A. A. SMITZ, andJ. P. PELKA: Anal. Chern. 38,514-515 (1966). OUEDRAOGO, M. and C. HUBAC: Plant and Cell Physiol. 23, 1297-1303 (1982). PHAM THI, A. T.: Soc. Bot. in press. PHAM THI, A. T., C. FLOOD, and J. VIEIRA DA SILVA: In Biochemistry and Metabolism of Plant lipids. Edited by J. F. G. M. WINTERMANS and P. J. C. KUIPER 451-454. Elsevier Biochemical Press B. V., 1982. SCHOLANDER, P. F., H. T. HAMMEL, D. EDDA, F. D. BRADSTREET, and E. A. HEMMINGSEN: Science 148, 339-346 (1965). SPANNER, D. c.:J. Exp. Bot. 2,145-168 (1951). TREMOLIERES, A., J. P. DUBACQ, and D. DRAPIER: Phytochemistry 21,41-45 (1982).
Z. Pjlanzenphysiol. Ed. 114. S. 239-245. 1984.