Transformation of a very chilling-sensitive orchid, "Phalenopusis" with Agrobacreium carrying spinach fatty acid desaturase

温度是控制野生和栽培植物物种分布的主要环境因素。许多起源于热带或亚热带的重要经济植物，如玉米、香蕉、柑橘和南瓜，暴露在略高于其组织冰点的温度下会受到伤害。Lyons和Reason提出，冷害主要是由膜脂对低温的物理反应引起的。最近，Murata提出，在高等植物叶绿体中，磷脂酰甘油(PG)可能是导致冷害的主要分子，因为它含有饱和脂肪酸的分子物种。甘油-3-磷酸酰基转移酶和硬脂酰酸性磷酸脱氢酶(SAD)这两种酶的性质在不饱和PG物种的合成中被认为是非常重要的。SAD在高等植物的C18脂肪酸中引入了第一个双键，因此，它参与了控制膜脂不饱和的程度。我们报道了一个编码菠菜抗寒植物幼叶SAD前体的cDNA克隆的分离和鉴定。然后，我们尝试了用根癌农杆菌携带插入菠菜基因克隆的pBL121/SAD对冷敏植物矮牵牛和蝴蝶兰进行转化。由此获得的矮牵牛的几个转化子已经被继续比较PG的脂肪酸组成和冷敏性。目前还没有获得蝴蝶兰的转化子。

Temperature is a major environmental factor governing the distribution of both wild and cultivated plant species. Many economically important plants having tropical or subtropical origins, for example maize, banana, citrus and squash, are injured by exposure to temperatures slightly above the freezing point of their tissues. Lyons and Raison have proposed that chilling injury is primarily caused by the physical response of membrane lipids to low temperature. Recently, Murata proposed that, in chloroplasts of higher plants, phosphatidylglycerol (PG) might be the molecule resposible for the primary event in chilling injury by virtue of its content of molecular species containing saturated fatty acids.Properties of two enzymes, Glycerol-3-phosphate acyltransferase and Stearoyl ACP desaturase (SAD), have been recognized to be very important on synthesis of unsaturated PG species. SAD introduces the first double bond into C18 fatty acids in higher plants and, threfore, it is involved in cotrolling the extent of unsaturation of membrane lipids. We have reported the isolation and characterization of a cDNA clone that encodes a precursor to SAD of spinach young leaf, chilling resistant plant. Then, we tried transformation of chilling sensitive plants, petunia and Phalenopusis, with Agrobacterium tumefaciens carrying pBl 121/SAD which was inserted the spinach cDNA clone. Several transformants of petunia obtained thus have been continued to compare the fatty acid composition of PG and the chilling sensitivity. No transformant of Phalenopusis is obtained at present time.