Temperature regulation of oleate desaturase in sunflower (Helianthus annuus L.) seeds |
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Authors: | R Garcés C Sarmiento M Mancha |
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Institution: | (1) Instituto de la Grasa (C.S.I.C.), Apartado 1978, E-41080 Sevilla, Spain |
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Abstract: | The effect of temperature on oleate desaturation in developing sunflower (Helianthus annuus L.) seeds has been examined. When seeds from plants grown at low (20/10° C, day/night) temperature were transferred for 24 h to 10° C, an increase in the linoleate/oleate ratio in phosphatidylcholine and triacylglycerol was observed, but not when transfer was to 20 or 30° C. The same effect was observed in triacylglycerol, phosphatidylcholine and phosphatidylethanolamine in the newly synthesized lipids after in-vivo incubation with 1-14C]oleate at 10° C. The microsomal oleoyl phosphatidylcholine desaturase (ODS) activity of the seeds maintained at 10 C was also enhanced. The stimulation was observed after only 3 h in plants grown at high temperature (30/20° C). This effect was inhibited by cycloheximide, implying that the low-temperature stimulation of the ODS activity was caused by the synthesis of new enzyme. As a consequence, seeds from plants grown at low temperature had higher ODS activities and linoleate contents than those grown at high temperature. The microsomal ODS activity of seeds from plants grown at low temperature was dependent on incubation temperature and showed a maximum at 20° C. By contrast, this activity was almost temperature-insensitive in seeds from plants grown at high temperature. These results could explain how temperature regulates the fatty-acid composition in sunflower-seed lipids.Abbreviations DAF
days after flowering
- ODS
oleoyl phosphatidylcholine desaturase
- PC
phosphatidylcholine
- PE
phosphatidylethanolamine
- TAG
triacylglycerol
- 181
oleic acid
- 182
linoleic acid
To whom correspondence should be addressedThanks are due to M.C. Ruiz for skillful technical assistance. This work was supported by a grant from Junta de Andalucia, Spain. |
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Keywords: | Helianthus Oleate desaturase Fatty acid unsaturation Membrane fatty acids Seed (fatty acids) |
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