| Autor: |
Wilmer, J. A., Lessire, R., Helsper, J. P. F. G., van der Plas, L. H. W. |
| Předmět: |
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| Zdroj: |
Physiologia Plantarum; Feb98, Vol. 102 Issue 2, p185-191, 7p |
| Abstrakt: |
Growth temperature and ABA both affect the level of erucic acid (22:1) in microspore-derived embryos (MDEs) of oilseed rape. We have previously shown that these stimuli act independently. In the present study we investigated the effects of growth temperature (15 vs 25°C) and ABA (0 vs 5 µM) on the characteristics and activity of the elongase complex, the enzymes synthesising 22:1. Due to inhibition by the substrate oleoyl-CoA at low concentrations (< 10 µM) it was not possible to determine values for Km and Vmax. Elongase activities from preparations extracted from MDEs grown under different conditions showed an optimum temperature higher than 30°C, with a Q10 value of about 3. We found considerable effects of temperature and exogenous ABA on total elongase activity in MDEs. Our results suggest that the accumulation of 22:1 is regulated by the amount of elongase enzyme and not by changes in the intrinsic characteristics of the enzyme. Elongase activity correlated closely with the absolute amount of 22:1 (µmol), whereas the correlation between elongase activity and the fraction of 22:1 (% of fatty acids) in oil was poorer. Including the total activity of acyltransferases did not improve the correlation. Acyltransferase activity itself correlated poorly with the total amount of oil formed. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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