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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 CDS5, one of the five CDSs of the Oryza sativa (rice) genome, has multifaceted effects on plant growth and stress responses. The loss of CDS5 resulted in a decrease in PG and PI levels, defective thylakoid membranes, pale leaves in seedlings and growth retardation. In addition, the loss of CDS5 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 CDS5 functions as a suppressor in PLD‐derived PA signaling and negatively affects hyperosmotic stress tolerance. [ABSTRACT FROM AUTHOR]

Silicon, the second abundant element in the crust, is beneficial for plant growth, mechanical strength, and stress responses. Here we show that manipulation of the non-specific phospholipase C1, NPC1, alters silicon content in nodes and husks of rice ( Oryza sativa). Silicon content in NPC1-overexpressing ( OE) plants was decreased in nodes but increased in husks compared to wild-type, whereas RNAi suppression of NPC1 resulted in the opposite changes to those of NPC1- OE plants. NPC1 from rice hydrolyzed phospholipids and galactolipids to generate diacylglycerol that can be phosphorylated to phosphatidic acid. Phosphatidic acid interacts with Lsi6, a silicon transporter that is expressed at the highest level in nodes. In addition, the node cells of NPC1- OE plants have lower contents of cellulose and hemicellulose, and thinner sclerenchyma and vascular bundle fibre cells than wild-type plants; whereas NPC1- RNAi plants displayed the opposite changes. These data indicate that NPC1 modulates silicon distribution and secondary cell wall deposition in nodes and grains, affecting mechanical strength and seed shattering. [ABSTRACT FROM AUTHOR]