Mechanism for the partitioning of glycerolipid biosynthetic pathways in leaves and seeds

在许多生物体中，膜脂和储存脂都主要由甘油脂组成，甘油骨架上通常含有两个或三个脂肪酸部分。在高等植物中，所有的脂肪酸都是在叶绿体中合成的，而膜和储存脂生物合成的主要部位在一个细胞中是空间分离的。由于每个植物器官含有不同比例的两种甘油脂，而这一比例本身是每个器官特性的主要特征之一，因此植物如何控制膜和储存甘油脂两种不同生物合成途径的分配是人们感兴趣的问题。在本项目中，我们研究了植物各器官膜生物合成和贮藏甘油脂生物合成两条不同途径的严格控制系统。在本研究过程中，我们发现了几种营养缺乏条件强烈促进了Tag的合成，并阐明了磷脂酸盐磷酸水解酶(PAH1/2)在叶片Tag合成中的重要性。此外，我们还发现了新的突变体，这些突变体缺乏对根中叶绿体膜生物发生的抑制。

Both membrane and storage lipids are mainly composed of glycerolipids in many living organisms, which commonly contain two or three fatty acid moieties attached to a glycerol backbone. In case of higher plants, all of the fatty acids are synthesized in plastids, whereas the major sites for the membrane and storage lipid biosyntheses are spatially separated in a cell. Since each plant organ contain different ratio of the two types of the glycerolipids and the ratio itself is one of a major feature of each organ identity, it is of interest how plants control the partitioning of the two different biosynthetic pathways for the membrane and storage glycerolipids. In this project, we studied on the strict control system for the partitioning of two different pathways of membrane and storage glycerolipid biosyntheses in each plant organ. In the course of this study, we found several nutrient deficient conditions strongly enhanced TAG synthesis even in leaves, and clarified the importance of phosphatidate phosphohydrolase (PAH1/2) in the leaf TAG synthesis. Moreover, we identified novel mutants which lack suppression of chloroplast membrane biogenesis in roots.