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Current year needles from 5 yr-old Norway spruce trees, which had been exposed to either episodes of atmospheric O3 or periodic mistings with stimulated 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 mistings were detected but significant decreases on the degree of unsaturation of both C16 and C18 fatty acids, the molar percentage of δ5, 9, 12, 15 18:4, and the molar ratio of δ5, 918:2 to δ9, 1218:2 in monogalactosyl diglyceride (MGDG) due to summer O3 exposures were found. Molar percentages and ratios to a significant effect of summer O3 on the δ5- and δ12-desaturases acting upon phosphatidyl choline (PC) in the endoplasmic reticulum, The replacement of the δ6-subset of C18 fatty acids by an equivalent δ5-series throughout was confirmed by gas cromatography and mass spectrometry. Molecular modelling also showed that the δ5-forms, which resembled the δ9-isomers, are very different in shape to the δ6-series and this may account, in part, for the extremely low winter temperatures from which Norway spruce needles may recover. [ABSTRACT FROM AUTHOR]

Glycolipids, neutral lipids and chlorophyll of chloroplasts of pine needles (Pinus sylvestris L) and apple bark tissue (Malus sylvestris Mill. cv Golden Delicious) were determined in a series of experiments in which growth temperature and daylength were changed. Trees were exposed to 0 and 20°C and to daylength conditions of 9 and 14 h. All 16 possible combinations were studied by transfer of the trees from the original condition to each of the other conditions. There was no direct relation between cold hardiness and glycolipid composition in apple bark and pine chloroplasts, when temperature and/or daylength were changed. Glycolipid and neutral lipid composition seemed to be strongly determined by the sequence of the imposed sets of daylength and temperature, and the effects of these factors on lipids strongly differed from that on cold hardiness. When the treatments were given in seasonal order, the corresponding changes in chloroplast glycolipids matched those reported in the literature for needles collected in the forest the year around. Glycolipid synthesis could well be under phytochrome control. [ABSTRACT FROM AUTHOR]