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Influence of episodes of summer O 3 on δ 5 and δ 9 fatty acids in autumnal lipids of Norway spruce [ Picea abies (L.) Karst]
Author(s) -
WELLBLRN ALAN R.,
ROBINSON DEBORAH C.,
THOMSON ALAN,
LEITH IAN D.
Publication year - 1994
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1994.tb04286.x
Subject(s) - degree of unsaturation , picea abies , chemistry , fatty acid , botany , phospholipid , diglyceride , polyunsaturated fatty acid , food science , chromatography , biology , biochemistry , membrane
SUMMARY Current year needles from 5 yr‐old Norway spruce trees, which had been exposed to either episodes of atmospheric O 3 , or periodic mistings with simulated acid rainwater throughout three summer periods, were‐analyzed for changes in molar percentages and ratios of fatty acids isolated from different lipids at the time of maximum winter hardening. No significant changes due to acidic misting were detected but significant decreases in the degree of unsaturation off both C 16 and C 18 , fatty acids, the molar percentage of δ 5,9,12,15 , and the molar ratio δ 5,9 18: 2 to δ 9,12 18:2 in monogalactosyl diglyceride (MGDG) due to summer 0 3 exposures were found. Molar percentages and ratios of fatty acids did not change much in other lipids bur these changes in plastidie MGDG could be traced to a significant effect of summer O 3 on the δ 4 ‐ and δ 12 ‐desaturases acting upon phosphatidyl choline (PC) in the endoplasmic reticulum. The replacement of the δ 6 ‐subset of C 18 fatty acids by an equivalent δ 5 ‐series throughout was confirmed by Gas chromatography and mass spectrometry Molecular modelling also showed that the δ 5 forms, which resembled the δ 5 ‐isomers, are very different in shape to the δ 5 ‐series and this may account, in part, for the extremely low winter temperatures from which Norway spruce needles may recover.