Abstract:  【Aim】 To identify and analyze proteins in the egg-associated secretions of the small brown planthopper, Laodelphax striatellus, so as to lay a foundation for screening effectors of L. striatellus and studying their functions. 【Methods】Intact eggs of L. striatellus were collected in the rice leaf sheath under a microscope, then were washed using phosphate buffer solution to get the egg-associated secretions. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was applied to identify the proteome of the egg-associated secretions. The functional conservation and specificity of 35 proteins from the proteome of the egg-associated secretions of L. striatellus were analyzed through comparing the 35 proteins with the salivary proteins from 10 arthropod species. The expression levels of 10 genes (LsHSP70, LsPDIA3, LsHSP90, LsPPIase, LsADPRF1, LsHSP68, LsEF1α, LsATPS, LsG3PD and RZF49036) in different developmental stages (egg, 1st-5th instar nymphs and adult), and tissues (oviduct, salivary gland, gut and fat body) of female adults of L. striatellus were determined by qPCR. 【Results】A total of 149 proteins in the egg-associated secretions of L. striatellus were finally identified, and among them, 35 proteins with two or more unique peptides were detected. Among these 35 proteins, six proteins were found to be commonly present in the saliva proteomes of at least five arthropod species, implying their similar functions in both feeding and oviposition, and other nine proteins were not found in the saliva proteomes of arthropods, implying that these nine proteins may be specifically involved in the oviposition process of L. striatellus. qPCR results showed that LsHSP90 and LsEF1α were highly expressed in female adults, but LsEF1α was not expressed in male adults. LsPDIA3 and LsHSP90 were highly expressed in the oviduct, and other genes exhibited various expression levels in different developmental stages and female adult tissues of L. striatellus. 【Conclusion】A total of 149 proteins have been identified in the egg-associated secretions of L. striatellus, some of them may have conservation or specificity compared with the salivary proteins from arthropod species, and their expression patterns in different developmental stages and tissues also show some variations.

Key words: Laodelphax striatellus, egg-associated secretions, proteome, salivary proteins, expression patterns