LAUSR

BACKGROUND Laodelphax striatellus transmits rice stripe virus (RSV) during sap feeding of the rice plant. The insect saliva proteins play direct and indirect roles in mediating RSV transmission; however, the function of most saliva proteins remained unclear. RESULTS In this study, we sequenced the L. striatellus saliva proteins by shotgun LC-ESI-MS/MS. We identified 41 secreted saliva proteins, among which, a saliva mucin-like protein, designated LssaMP, was the most abundant. In silico analysis revealed the sequence conservation among planthoppers. We revealed that the LssaMP gene is specifically expressed in the salivary glands and the protein is secreted as a component of gel saliva. Using LssaMP-specific dsRNA to silence the gene expression, we revealed that LssaMP is required for formation of the salivary sheath, which is an important structure for sap feeding. Disrupting LssaMP expression resulted in inefficient formation of the feeding structure, thereby stopping insects from secreting watery saliva and acquiring sufficient nutrients from the phloem sap. We confirmed that RSV is mainly released via the watery saliva, which passes through the salivary sheathes into the plant phloem. An insufficient feeding structure results in decreased release of watery saliva, as well as the arboviruses. CONCLUSION This study clarified the function of an insect saliva protein in mediating insect feeding, as well as arbovirus transmission. This article is protected by copyright. All rights reserved.