Cytidinediphosphate‐diacylglycerol synthase 5 is required for phospholipid homeostasis and is negatively involved in hyperosmotic stress tolerance

Summary Cytidinediphosphate diacylglycerol synthase ( CDS ) uses phosphatidic acid ( PA ) and cytidinetriphosphate to produce cytidinediphosphate‐diacylglycerol, an intermediate for phosphatidylglycerol ( PG ) and phosphatidylinositol ( PI ) synthesis. This study shows that CDS 5, one of the five CDS s of the Oryza sativa (rice) genome, has multifaceted effects on plant growth and stress responses. The loss of CDS 5 resulted in a decrease in PG and PI levels, defective thylakoid membranes, pale leaves in seedlings and growth retardation. In addition, the loss of CDS 5 led to an elevated PA level and enhanced hyperosmotic tolerance. The inhibition of phospholipase D ( PLD )‐derived PA formation in cds5 restored the hyperosmotic stress tolerance of the mutant phenotype to that of the wild type, suggesting that CDS 5 functions as a suppressor in PLD ‐derived PA signaling and negatively affects hyperosmotic stress tolerance.