关键词: 茶小绿叶蝉, 粘样蛋白, 基因克隆, 表达模式, RNA干扰

Abstract: 【Aim】This study aims to investigate the molecular characteristics, expression patterns, and biological functions of the mucin-like protein EfMLP genes of Empoasca flavescens. 【Methods】Based on the transcriptome data of E. flavescens, the full-length cDNA sequences of four EfMLP genes were cloned by PCR and analyzed by bioinformatics. qRT-PCR was used to detect the expression levels of EfMLP genes across different developmental stages (egg, 1st-5th instar nymphs, and newly emerged female and male adults), and in different tissues (integument, fat body, salivary gland, gut, ovary, and testis) of the newly emerged adults. EfMLP2 and EfMLP4 in the 5th instar nymph were silenced by RNAi through feeding method, and the survival rates of E. flavescens after silencing the EfMLP genes by RNAi were determined by bioassay. 【Results】 The full-length cDNA sequences of four EfMLP genes of E. flavescens were obtained, and named EfMLP1, EfMLP2, EfMLP3 and EfMLP4 with the GenBank accession numbers of OR504428, OR504429, OR504430 and OR504431, respectively. The obtained four EfMLPs all contain highly repetitive tandem repeat sequences, which are rich in O-linked glycosylation sites, forming the mucin domain (MD). Among them, both EfMLP3 and EfMLP4 contain a conserved type-2 chitin binding domain (CBD). Phylogenetic analysis result revealed that EfMLPs were divided into two different branches belonging to two different MLP types, which showed no correlation with insect taxonomy, but might be considered to be related to their functions. EfMLP1 and EfMLP2 exhibited specifically high expression in the newly emerged female and male adults and the salivary glands of the newly emerged adults. In contrast, the expression of EfMLP3 and EfMLP4 was identified in various developmental stages, including egg, nymphal and adult stages, as well as in diverse tissues such as the fat body of the newly emerged adult. Inhibition of the expression of EfMLP2 and EfMLP4 in E. flavescens by feeding dsEfMLP2 and dsEfMLP4 significantly reduced the survival rate of E. flavescens compared with the control group fed with dsGFP. 【Conclusion】 EfMLPs play an important role in the feeding of E. flavescens and can be used as a potential target in control of this pest insect based on RNAi strategies.

Key words: Empoasca flavescens, mucin-like protein, gene cloning, expression pattern, RNA interference