耐冷性に関する形質転換植物の作製

1.目的：低温是限制农业生产的重要环境之一。如果能够将热带原产的对寒冷敏感的植物转化为更耐寒冷的植物，世界粮食净产量就可以大大提高。植物对低温的敏感性与叶绿体膜脂磷脂酰甘油（PG）的饱和度密切相关。表明PG的饱和水平受酰基-（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感植物转化为抗冷植物.结果：（1）利用Ti质粒双元载体法将拟南芥ATase基因导入烟草。Southern、北方和Western印迹分析表明，外源基因已整合到基因组中并表达，基因产物被转运到叶绿体中并加工成成熟蛋白。(2)对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，而其他脂类中的脂肪酸饱和度没有变化。(3)通过与对照植株的比较，表明转基因植株具有更强的抗冷性。(4)将冷敏感植物南瓜的ATase基因导入烟草后，烟草PG饱和度和冷敏感性均得到提高.结论：通过基因导入可以改变植物的膜脂饱和度，进而改变植物的冷敏感性。

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.