MATURATION IN NORWAY SPRUCE - ALTERATIONS IN LIPID-COMPOSITION

The cell membrane lipid composition was determined in newly developed shoots from Norway spruce (Picea abies L., Karst.) of different stages of maturity. Total acyl lipids of the shoots showed a marked constanc y during maturation as determined from the level of fatty acids. Howev er, major phospholipids and free sterols increased with maturation to a maximum at age 20-50 years and then decreased. The maturation stage, 20-50 years, was also reflected in the total fatty acid composition w ith higher proportion of octadeca-9,12-dienoic acid and lower proporti on of hexadecanoic acid. Further, the spruce shoots contained some les s usual fatty acids with octadeca-5,9,12-trienoic acid dominating. The molecular species of the major phospholipids, phosphatidyl choline an d phosphatidyl ethanolamine, was determined by gas chromatography-mass spectrometry. Microsomal membranes were prepared from newly developed shoots of mature trees, 50-100 years. In addition, microsomes were al so isolated from spruce seedlings. Membranes from mature trees showed a higher proportion of octadeca-9,12-dienoic acid and a lower proporti on of octadeca-5,9,12-trienoic acid and octadeca-9,12,15-trienoic acid , also reflected in the major phospholipid, phosphatidyl choline. The relative distribution of phospholipids changed with maturation leading to an altered ratio phosphatidyl choline/phosphatidyl ethanolamine. T he importance of the Lipid changes during maturation for the membrane properties is discussed.