The Arabidopsis (Arabidopsis thaliana) fatty acid biosynthesis1 (fab1) mutant has increased levels of the saturated fatty acid 16:0, resulting from decreased activity of 3-ketoacyl-ACP synthase II. In fab1 leaves, phosphatidylglycerol, the major chloroplast phospholipid, contains >40% high-melting-point molecular species (HMP-PG; molecules that contain only 16:0, 16:1-trans, and 18:0 fatty acids)—a trait associated with chilling-sensitive plants—compared with <10% in wild-type Arabidopsis. Although they do not exhibit short-term chilling sensitivity when exposed to low temperatures (2°C to 6°C) for long periods, fab1 plants do suffer collapse of photosynthesis, degradation of chloroplasts, and eventually death. To test the relevance of HMP-PG to the fab1 phenotype, we used transgenic 16:0 desaturases targeted to the endoplasmic reticulum and the chloroplast to lower 16:0 in leaf lipids of fab1 plants. We produced two lines that had very similar lipid compositions except that one, ER-FAT5, contained high HMP-PG, similar to the fab1 parent, while the second, TP-DES9*, contained <10% HMP-PG, similar to the wild type. TP-DES9* plants, but not ER-FAT5 plants, showed strong recovery and growth following 75 d at 2°C, demonstrating the role of HMP-PG in low-temperature damage and death in fab1, and in chilling-sensitive plants more broadly.

拟南芥（Arabidopsis thaliana）脂肪酸生物合成1（fab1）突变体具有较高的饱和脂肪酸16：0水平，这是由于3-酮酰基-ACP合酶II的活性降低所致。在fab1叶片中，主要的叶绿体磷脂磷脂酰甘油包含40％以上的高熔点分子种类（HMP-PG；仅包含16：0、16：1反式和18：0脂肪酸的分子）-a与低温敏感植物相关的性状-与野生型拟南芥中不足10％的植物相比。尽管它们长时间暴露在低温（2摄氏度至6摄氏度）下并没有表现出短期的低温敏感性，但fab1植物确实遭受了光合作用的崩溃，叶绿体的降解并最终死亡。为了测试HMP-PG与fab1表型的相关性，我们使用了转基因16：在fab1植物的叶脂中，针对内质网和叶绿体的0种去饱和酶降低了16：0。我们生产了两类脂质组成非常相似的品系，除了其中一类的ER-FAT5含有与fab1亲本相似的高HMP-PG，而另一类的TP-DES9 *含有与野生型相似的HMP-PG不到10％ 。TP-DES9 *植物（而非ER-FAT5植物）在2摄氏度下经过75天后显示出强劲的恢复和生长，证明了HMP-PG在fab1和低温敏感植物中的低温损伤和死亡中的作用。 。含有少于10％的HMP-PG（与野生型相似）。TP-DES9 *植物（而非ER-FAT5植物）在2摄氏度下经过75天后显示出强劲的恢复和生长，证明了HMP-PG在fab1和低温敏感植物中的低温损伤和死亡中的作用。 。含有少于10％的HMP-PG（与野生型相似）。TP-DES9 *植物（而非ER-FAT5植物）在2摄氏度下经过75天后显示出强劲的恢复和生长，证明了HMP-PG在fab1和低温敏感植物中的低温损伤和死亡中的作用。 。