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

在许多生物体中，膜脂和储存脂主要由甘油脂组成，甘油脂通常含有两个或三个脂肪酸基团，它们附着在一个甘油主链上。在高等植物中，所有的脂肪酸都是在质体中合成的，而膜和储存脂质生物合成的主要位点在细胞中是空间分离的。由于每个植物器官含有两种类型的甘油脂的不同比例，而比例本身是每个器官身份的主要特征之一，植物如何控制膜和储存甘油脂的两种不同生物合成途径的分配是一个有趣的问题。在本项目中，我们研究了植物各器官中膜和储存甘油脂生物合成两种不同途径的严格控制系统。在本研究过程中，我们发现几种营养缺乏条件甚至在叶片中也能强烈地促进TAG的合成，并阐明了磷脂酸磷酸水解酶（PAH1/2）在叶片TAG合成中的重要性。此外，我们还发现了对根系叶绿体膜生物发生缺乏抑制的新突变体。

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.