Does Sulfoquinovosyl Diacylglycerol Synthase OsSQD1 Affect the Composition of Lipids in Rice Phosphate-Deprived Root?

Lipids are the essential components of the cell intracellular and plasma membranes. Sulfoquinovosyldiacylglycerol (SQDG) is a glycolipid; glycolipids can replace phospholipids in maintaining phosphate (Pi) homeostasis in plants which are undergoing Pi starvation. Sulfoquinovosyl diacylglycerol synthase 1 (OsSQD1) is a critical enzyme in the first step of catalyzation in the formation of SQDG in rice. In this study, the expression pattern of different zones in roots of in response to different Pi conditions is examined, and it is found that is highly expressed in lateral roots under Pi-sufficient and -deficient conditions. The root phenotype observation of different transgenic lines suggests that the knockout/down of inhibits the formation and growth of lateral roots under different Pi conditions. Additionally, the lipid concentrations in transgenic line roots indicate that knockout/down decreases the concentration of phospholipids and glycolipids in Pi-starved roots. The mutation also changes the composition of different lipid species with different acyl chain lengths, mainly under Pi-deprived conditions. The relative transcript expression of genes relating to glycolipid synthesis and phospholipid degradation is estimated to help study the mechanism by which exerts an influence on the alteration of lipid composition and concentration in Pi-starved roots. Moreover, in Pi-starved roots, the knockout of decreases the unsaturated fatty acid content of phospholipids and glycolipids. To summarize, the present study demonstrates that plays a key role in the maintenance of phospholipid and glycolipid composition in Pi-deprived rice roots, which may influence root growth and development under Pi-deprived conditions.