Functional diversity of the Osiris gene family in the brown planthopper

Osiris is a large insect-specific gene family with multiple functions. Owing to highly conserved sequences and similar expression patterns across insect species, the Osiris gene family is believed to play specific roles in the insect kingdom. However, current studies on Osiris gene functions have focused primarily on several holometabolous insects, such as Drosophila melanogaster and Bombyx mori, with few systematic studies on hemimetabolous insects. In this study, we identified 20 Osiris genes by searching the genome and transcriptome databases of the brown planthopper Nilaparvata lugens. The Nilaparvata lugens Osiris genes presented similar development- and tissue-specific expression profiles. A functional investigation using RNAi in 4th instar nymphs and newly eclosed adult females revealed that the knockdown of Osiris genes resulted in multiple phenotypes, including a lethal phenotype; morphological changes in the wing, ovary and ovipositor; and hatching and feeding failure. These observations suggested that the Osiris genes play different functional roles at the individual and tissue levels. This study expanded the knowledge of Osiris gene functions and provided a better understanding of the importance of the Osiris gene family in the development and reproduction of insects.