Pleiotropic Roles of the Orthologue of the Drosophila melanogaster Intersex Gene in the Brown Planthopper.

Intersex(ix), a gene involved in the sex-determining cascade of Drosophila melanogaster, works in concert with the female-specific product of doublesex (dsx) at the end of the hierarchy to implement the sex-specific differentiation of sexually dimorphic characters in female individuals. In this study, the ix homolog was identified in the brown planthopper (BPH), Nilaparvata lugens, which contained two splice variants expressed in both female and male insects. We found that Nlix played a vital role in the early nymphal development of BPH, showing an accumulated effect. RNAi-mediated knockdown of Nlix at 4th instar led to the external genital defects in both sexes, consequently resulting in the loss of reproductive ability in female and male individuals. After dsRNA injection, the males were normal on testes, while the females had defective ovarian development. Nlix was also required for early embryogenesis. Notably, when the dsNlix microinjection was performed in newly emerged females, the copulatory bursas were abnormally enlarged while the other tissues of the reproductive system developed normally. Our results demonstrated the pleiotropic roles of Nlix in embryogenesis and development of the reproductive system in a hemimetabolous insect species.

间性（ix）是一个参与黑腹果蝇性别决定级联的基因，它在层级末端与双性（dsx）的雌性特异性产物协同作用，以实现雌性个体中两性异形特征的性别特异性分化。在本研究中，在褐飞虱（Nilaparvata lugens）中鉴定出了ix同源物，它包含在雌性和雄性昆虫中均有表达的两种剪接变体。我们发现Nlix在褐飞虱若虫早期发育中起着至关重要的作用，呈现出累积效应。在四龄若虫期通过RNA干扰介导的Nlix敲低导致雌雄两性的外生殖器缺陷，进而导致雌雄个体生殖能力丧失。注射dsRNA后，雄性睾丸正常，而雌性卵巢发育不良。Nlix对早期胚胎发生也是必需的。值得注意的是，当在新羽化的雌性中进行dsNlix微量注射时，交配囊异常增大，而生殖系统的其他组织发育正常。我们的研究结果证明了Nlix在一种半变态昆虫物种的胚胎发生和生殖系统发育中的多效性作用。