Non-Specific Phospholipase C1 Affects Silicon Distribution and Mechanical Strength in Stem Nodes of Rice

<div class="line" id="line-15"> 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&hyphen;specific phospholipase C1, NPC1, alters silicon content in nodes and husks of rice (Oryza sativa). Silicon content in NPC1&hyphen;overexpressing (OE) plants was decreased in nodes but increased in husks compared to wild&hyphen;type, whereas RNAi suppression of NPC1 resulted in the opposite changes to those of NPC1&hyphen;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&hyphen;OE plants have lower contents of cellulose and hemicellulose, and thinner sclerenchyma and vascular bundle fibre cells than wild&hyphen;type plants; whereas NPC1&hyphen;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.</div>