烟草高级脂肪酸代谢及影响因素研究进展

摘要

As one kind of important compounds in tobacco plants,fatty acids play remarkable roles in their growth and development,as well as tobacco quality and flavor. Recently,it also has been verified that fatty acids are involved in the formation of stress tolerance in tobacco plants. Tobacco seeds are rich in lipids and various kinds of fatty acids,and the contents of linoleic acid,oleic acid and palmitic acid increase gradually with the developing of tobacco seeds ;and they can be considered to be utilized as a potential biomass source. During the process of growth and development of tobacco leaves,fatty acid contents increase gradually,reach the maximum when tobacco plants are blooming,then decrease during maturing and senescing of tobacco leaves ;at the same time,the saturated fatty acids are transformed into the unsaturated ones. Moreover,the contents of fatty acids are higher in lower and middle leaves than those in upper ones of tobacco plants,and also higher in palisade tissue than in spongy tissue in tobacco leaves. In addition,genotype and environmental factors such as light irradiation,temperature, geographical factors,fertilization,flue-curing methods,mechanical injury and so on apply significant effects on composition and content of fatty acids,as well as key enzyme activities and their gene expressions in the biosynthesis and metabolism of fatty acids in tobacco leaves. Chill-hardening may enhance chilling resistance of tobacco plants by increasing the contents of the polyunsaturated fatty acids and reducing the contents of saturated fatty acids. It is also an effective method to increase the contents of unsaturated fatty acids in tobacco plants with over-expressing the genes of the acyl-ACP desaturase,ACP,fatty acids desaturase and fatty acids dehydrogenase by genetic engineering,which in turn improves the stress tolerance of tobacco plants to abiotic stresses,such as drought,high temperature and highlight stress and so on. Based on the above-mentioned works,the paper presents the future research direction,aiming at providing the theoretical and practical guidance for the study of this field.%脂肪酸作为烟草中一类重要的化合物,对烟草的生长发育及烟叶的品质风格有重要的影响.近年来,脂肪酸代谢也被证实参与了烟草抗逆性的形成.烟草种子富含油脂和各类脂肪酸,随着烟草种子发育,亚油酸、油酸和棕榈酸含量不断增加,可作为一类潜在的生物质能源加以开发利用.在烟草叶片的生长发育过程中,脂肪酸含量逐渐升高,开花时达到最大,随烟叶成熟衰老而逐渐降低,同时饱和脂肪酸逐渐转变为不饱和脂肪酸.烟叶中、下部叶片脂肪酸含量高于上部烟叶,栅栏组织中高于海绵组织中.此外,基因型以及光照、温度、地理因素、施肥、烘烤方法、机械伤害等环境因素均显著影响烟叶内脂肪酸的组成、含量及其脂肪酸生物合成和代谢关键酶活性和基因表达.低温锻炼可显著提高烟叶内多不饱和脂肪酸含量,降低饱和脂肪酸含量,提高烟叶的耐冷性.通过基因工程手段在烟草中过表达脂酰-ACP去饱和酶、酰基载体蛋白、脂肪酸去饱和酶及脂肪酸脱氢酶等基因可有效提高烟草内不饱和脂肪酸的含量,增强烟草在干旱、高温、强光等非生物胁迫环境下的抗逆性.基于以上结果,提出未来的研究方向,旨在为该领域的研究提供理论和实践指导.