Lipidomic profiling analysis reveals the dynamics of phospholipid molecules in Arabidopsis thaliana seedling growth

High-throughput lipidomic profiling provides a sensitive approach for discovering minor lipid species. By using an advance in electrospray ionization tandem mass spectrome- try, a large set of phospholipid molecular species （126 species） with high resolution were identified from Arabidopsis seedling; of them 31 species are newly identified （16 are unique in plants）, including 13 species of phosphatidic acid （PA）, nine phosphati- dylcholine, six phosphatidylinositol and three phosphatidylser- ine. Further analysis of the lipidomic profile reveals dynamics of phospholipids and distinct species alterations during seedling development. PA molecules are found at the lowest levels in imbibition and follow an increasing trend during seedling growth, while phosphatidylethanolamine （PE） molecules show the opposite pattern with highest levels at imbibition and a general decreasing trend at later stages. Of PA molecular species, 34：2-, 34：3-, 36：4, 36：5-, 38：3- and 38：4-PA increase during radicle emergence, and 34：2- and 34：3-PA reach highest levels during hypocotyl and cotyledon emergence from the seed coat. Conversely, molecular species of PE show higher levels in imbibition and decrease in later stages. These results suggest the crucial roles of specific molecular species and homeostasis of phospholipid molecules in seedling growth and provide insights into the mechanisms of how phospholipid molecules are involved in regulating plant development.