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 inNPC1-overexpressing (OE) plants was decreased in nodes but increased in husks compared to wild-type, whereas RNAi suppression ofNPC1resulted in the opposite changes to those ofNPC1-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 ofNPC1-OE plants have lower contents of cellulose and hemicellulose, and thinner sclerenchyma and vascular bundle fibre cells than wild-type plants; whereasNPC1-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.Significance Statement
Silicon is a main component of secondary cell walls. Here we use under- and over-expression of a non-specific phospholipase, NPC1, to show that NPC1 impacts lipid levels, cellulose content, silicon distribution, mechanical strength of rice nodes, and seed shattering; genetic alterations of NPC1 thus have consequences for rice production.