The transformer-2 gene is essential for female and male development in Gryllus bimaculatus

As an alternative splicing co-factor in most insect sex determination systems, transformer-2 (tra-2) plays an essential role in regulating sexual development. Although the functions of tra-2 have been well clarified in holometabolous insects, research in hemimetabolous insects is still very limited. In the present study, we identified the tra-2 homologue in Gryllus bimaculatus (Orthoptera: Gryllidae) and cloned two isoforms. Silencing of Gbtra-2 in nymphs led to abnormal development of forewings and a lethal phenotype. In addition, silencing Gbtra-2 impaired reproductive ability in both male and female adults, manifested as inhibiting ovarian development and leading to abnormal development of spermatozoa. Moreover, maternal RNAi of Gbtra-2 in adult females resulted in embryonic lethality. These findings suggested the crucial role of Gbtra-2 in the development of forewings, embryos, and nymphs as well as fertility in both sexes.