Comparative proteomic analysis of sex-biased proteins in ovary and testis at different stages of Spodoptera litura.

Sex-biased protein is thought to be able to drive the phenotypic differences in males and females in insects. In this study, 1385 and 1727 proteins were identified as differentially accumulated proteins (DAPs) by comparing the protein abundances at pupae stage with those at adult stage in ovary and testis of S.litura, respectively. And among which, 548 DAPs were showed to be expressed in both ovary and testis, and 837 and 1179 proteins were considered as ovary-specific and testis-specific DAPs, respectively. To further identify DAPs related to gonad development and sex dimorphism, a total of 320 DAPs were selected and defined as "proteins of specific interest" based on several selecting criteria. Sex dimorphism is a complex and dynamic developmental progress, and these identified DAPs were suggested to be involved in multiple functions such as organonitrogen compound catabolic process, glycosylation, proteasome, N-Glycan biosynthesis and other reproduction-related processes. Overall, our results highlighted these sexual-biased, gonad development related and sexual dimorphism related DAPs, and their abundance variations along with development were also examined, which could provide important information for their functional analysis in reproduction and potential biomarkers for developing useful strategies against S. litura and other orthologous pests. BIOLOGICAL SIGNIFICANCE: Sex dimorphism entails the differentiation of two sexual functions, resulting in sexually phenotypic differences and leading to the development of female and male morphologies and behaviors. However, sex dimorphism related proteins remain to be identified in many non-model insects. In this study, iTRAQ-based proteomic analysis was applied to examine the variations of protein abundances at pupae stage and adult stage in ovary and testis of S.litura, respectively. Reproduction and sex dimorphism related proteins were further identified as "proteins of specific interest". These identified candidate proteins provided valuable information for their further functional analysis in reproduction and could serve as potential biomarkers for developing useful strategies against S. litura and other orthologous pests.