耐冷性に関する形質転換植物の作製

1.目的：低温是制约农业生产的重要环境之一。如果热带起源的对冷敏感的植物能够转化为更耐寒的植物，世界上的净粮食产量可以大大提高。已有研究表明，植物对冷害的敏感性与叶绿体膜脂之一的磷脂酰甘油(PG)的脂肪酸饱和程度密切相关。提示PG的饱和程度受酰基载体蛋白：甘油-3-磷酸酰基转移酶(ATase)的控制。本研究的目的是通过基因导入技术，将冷敏植物转化为抗寒植物。结果：(1)用Ti质粒双载体法将抗寒植物拟南芥的ATase基因导入烟草。Southern印迹、Northern印迹和Western印迹分析表明，导入的基因已整合到基因组中并得到表达，基因产物被转运到叶绿体并加工成成熟蛋白。(2)转基因烟草植株的脂类分析表明，PG中的脂肪酸饱和度发生了变化，而其他脂类中的含量没有变化。(3)通过转基因植株与对照植株的比较，表明转基因植株具有更强的抗冷性。(4)将冷敏感型植物南瓜的ATase基因导入烟草后，其PG饱和水平和冷敏性均有所提高。结论：通过基因导入改变植物膜脂饱和度和冷敏性是可能的。

1. Purpose: Low temperature is one of the important environments which limit the agricultural production. If chilling-sensitive plants of tropical origin can be converted to be more chilling-resistant, the net food production in the world can be much improved. It has been demonstrated that chilling sensitivity of plants is highly correlated with the level of saturation of fatty acids of phosphatidylglycerol (PG), one of the chloroplastic membrane lipids. It is suggested that the level of saturation of PG is under the control of the enzyme, acyl-(acyl-carrier-protein): glycerol-3-phosphate acyltransferase (ATase). The purpose of this research is to convert a chilling-sensitive plant into a chilling-resistant plant, by technique of gene introduction.2. Results: (1) cDNA for ATase from a chilling resistant plant, Arabidopsis, was introduced into tobacco by Ti plasmid binary vector method. Analyses by southern blot, northern blot and Western blot demonstrated that the introduced gene was incorporated into the genome, and expressed, and that the gene product was transported into the chloroplast and processed to become the mature protein. (2) The analysis of the lipids of the tobacco transgenic plant indicated that the level of saturation of fatty acids was changed in PG, but in no other lipids. (3) By comparing the transgenic plants with control plants, it appeared that the transgenic plants were more resistant to chilling. (4) When the cDNA for ATase from a chilling sensitive plant, squash, was introduced to tobacco, the level of saturation of PG and the chilling sensitivity were both increased.3. Conclusion: It is now possible that the saturation of membrane lipids and also chilling sensitivity of plant can be modified by gene introduction.