Vitellogenin and Vitellogenin-Like Genes in the Brown Planthopper

Abstract

Vitellogenin (Vg) is precursor of vitellin. Here, we identified a <i>Vg</i> (<i>NlVg</i>) and two <i>Vg</i>-likes (<i>NlVg</i>-like1 and <i>NlVg</i>-like2) in the brown planthopper, <i>Nilaparvata lugens</i>. Phylogenetic analyses showed that NlVg-like1 and NlVg-like2 are not clustered with the conventional insect Vgs associated with vitellogenesis. Temporo-spatial expression analyses showed that the <i>NlVg</i> and <i>NlVg</i>-like2 transcript levels increased significantly 24 h after emergence and were primarily expressed in female adults. However, <i>NlVg</i>-like1 was expressed during all stages, and in both genders. Tissue-specific analyses showed that all three genes were most highly expressed in the fat body. The injection of double-stranded RNA targeting <i>NlVg</i> showed that <i>NlVg</i> is essential not only for oocyte development but also for nymph development. The knockdown of <i>NlVg</i>-like1 in female adults resulted in failure to hatch or death before eggshell emergence in 18% of offspring embryos, suggesting that <i>NlVg</i>-like1 plays an important role during late embryogenesis. Approximately 65% of eggs laid by females that were treated with double-stranded RNA targeting <i>NlVg</i>-like2 failed to hatch, indicating that <i>NlVg</i>-like2 plays a role in nutrition absorption during oocyte, or embryonic development. Our results illustrate the structural and functional differences among the <i>Vg</i> and <i>Vg</i>-like genes and provide potential targets for RNA-interference-based insect pest management strategies.