Defining the lipidome of Arabidopsis leaf mitochondria: Specific lipid complement and lipid biosynthesis capacity

Mitochondria are considered as power stations of the cell, playing critical roles in various biological processes such as energy conversion, stress responses and programmed cell death. To maintain the structural and functional integrities of mitochondria, it is crucial to achieve a defined membrane lipid composition between different lipid classes wherein specific proportions of individual lipid species are present. Although mitochondria are capable of self-synthesizing a few lipid classes, many phospholipids are synthesized in the endoplasmic reticulum and transferred to mitochondria via membrane contact sites, as mitochondria are excluded from the vesicular transportation pathway. However, knowledge on the capability of lipid biosynthesis in mitochondria and the precise mechanism of maintaining the homeostasis of mitochondrial lipids is still scarce. Here we describe the lipidome of mitochondria isolated from Arabidopsis leaves, including the molecular species of glycerolipids, sphingolipids and sterols to depict the lipid landscape of mitochondrial membranes. In addition, we define proteins involved in lipid metabolism by proteomic analysis. Proteins putatively localized to the membrane contact sites are proposed based on the proteomic results and online databases. Collectively, our results suggest that leaf mitochondria are capable, with the assistant of membrane contact site-localized proteins, in generating several lipid classes including phosphatidylethanolamines, cardiolipins, diacylgalactosylglycerols and free sterols. We anticipate our work to be a foundation to further investigate the functional roles of lipids and their involvement in biochemical reactions in plant mitochondria. One sentence summary The lipid landscape of plant mitochondria suggests that they are capable in generating several phospholipid classes with the assistant of membrane contact site-localized proteins. ### Competing Interest Statement The authors have declared no competing interest.