Investigating a role for phospholipids in plastid pleomorphy

Abstract

Plastids, a defining feature of plants, produce stroma-filled extensions or tubules known as stromules. Although stromules are reliably induced upon exogenous sucrose treatment and inhibited upon silver nitrate treatment, a clear mechanism and function behind this phenomenon remains to be elucidated. The lack of inorganic phosphate appears to affect stromule levels as well as simultaneously cause a conversion of extraplastidic membrane lipids from phospholipids to galactolipids, suggesting a lipid-based mechanism for their formation. Non-specific phospholipase C 4 and non-specific phospholipase C 5, while responsible for this conversion, do not affect stromule formation. The origin of plastidial phosphatidylcholine upstream of phospholipid to galactolipid conversion is likely due to the presence of plastid associated membranes and does not play a role in stromule formation. The observations from my microscopy based studies demonstrate the organelle pleomorphy influencing ability of lysophosphatidylcholine, implicating acyl-editing, better known as the Lands cycle, in stromule formation.