Wolfenden J, Wellburn A R
Division of Biological Sciences, Institute of Environmental & Biological Sciences, Lancaster University, Lancaster, LAI 4YQ.
New Phytol. 1991 Jun;118(2):323-329. doi: 10.1111/j.1469-8137.1991.tb00984.x.
Norway spruce trees [Picea abies (L.) Karst] were exposed to ozone during the summers of three consecutive years and the fatty acid composition of the chloroplast membrane lipid, monogalactosyl diglyceride (MCDG) was analysed over the last 14 months. Significant variations in the degree of unsaturation and the percentage of linolenic acid (18:3) were not found, either on a seasonal basis or in relation to ozone treatment. The proportion of octadecatetraenoic acid (18:4) and other Δ fatty acids increased during autumn in trees grown in filtered air, but this seasonal effect was less pronounced in ozone-treated trees. The ratio of two forms of linoleate, 18:2 and 18:2 also increased significantly during the frost hardening period but not in trees previously exposed to ozone. This implies that two separate biosynthetic pathways exist, one for the Δ and one for the Δ desaturated series, which operate at different relative rates, depending on environmental conditions. It is suggested that ozone may interfere with the biosynthesis of 18:4 during frost hardening by inhibiting the Δ desaturation of oleate.
挪威云杉树[欧洲云杉（Picea abies (L.) Karst）]在连续三年的夏季暴露于臭氧环境中，并在过去14个月里对叶绿体膜脂单半乳糖基甘油二酯（MCDG）的脂肪酸组成进行了分析。无论是在季节变化方面，还是与臭氧处理相关的方面，均未发现不饱和程度和亚麻酸（18:3）百分比有显著变化。在过滤空气中生长的树木，十八碳四烯酸（18:4）和其他Δ脂肪酸的比例在秋季有所增加，但在经臭氧处理的树木中，这种季节效应不太明显。两种亚油酸形式（18:2和18:2）的比例在抗冻硬化期也显著增加，但在先前暴露于臭氧的树木中未出现这种情况。这意味着存在两条独立的生物合成途径，一条用于Δ系列，另一条用于Δ去饱和系列，它们根据环境条件以不同的相对速率运行。有人提出，臭氧可能通过抑制油酸的Δ去饱和作用，在抗冻硬化过程中干扰18:4的生物合成。
