Characteristic and Functional Study of Intersex, a Gene Related to Female Fertility in Bemisia tabaci

Abstract

The intersex (ix) gene acts in concert with doublesex (dsx) at the end of the sex determination hierarchy to control somatic sexual differentiation in Drosophila melanogaster. Here, we report the Drosophila ix homolog in Bemisia tabaci (Btix) with differential splicing events. Four isoforms were found in B. tabaci adults, including two sex-specific transcripts (Btix F and Btix M). Knockdown of Btix had no measurable effects on female morphological phenotypes but reduced the expression of the vitellogenin gene and resulted in the production of significantly fewer eggs, a lower eclosion rate, and a shorter body size of female progeny in comparison with control females. These results increase our understanding of the genes underlying sex determination in B. tabaci and reveal a potential target for RNA interference-based pest management.

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

“…Nevertheless, the Dmix is transcribed non-sex specifically and contains only one exon in D. melanogaster [ 1 ]. Despite discoveries of sex-specific splicing transcripts of ix in many insects, e.g., a testis-specific isoform of ix founded in B. mori [ 20 ], female pupae stage-specific ix isoform described in M. vitrata [ 3 ] and two sex-specific variants of ix reported in B. tabaci [ 5 ], the underlying functions of these sex-specific isoforms remain largely unknown. In BPH, the Nlix produces two isoforms by alternative splicing, both of which are expressed non-sex specifically.…”

“…Intersex ( ix ) is a gene involved in the sex-determining cascade of insects. It was first well-characterized in Drosophila melanogaster [ 1 ] and showed apparently deep conservation in insect species, as Bombyx mori [ 2 ], Maruca vitrata [ 3 ], Cyclommatus metallifer [ 4 ], Bemisia tabaci [ 5 ] and Oncopeltus fasciatus [ 6 ]. In D. melanogaster , the DmIX protein forms a complex with the female-specific product of Dmdsx (DmDSX F ) at the bottom of the sex-determining cascade, thereby implementing the sex-specific differentiation of sexually dimorphic characters among female individuals [ 1 , 7 , 8 ].…”

“…RNAi knockdown of ix led to reduced genitalia size in O. fasciatus males, while exerting indistinct effects in C. metallifer males [ 4 , 6 ]. Besides, the ix homolog of B. tabaci has been confirmed to produce four isoforms by alternative splicing, including one female splice variant, one male splice variant and two non-sex-specific unspliced variants in contrast to ix of D. melanogaster [ 5 ]. In the RNAi experiments of whitefly adults, no distinction in the morphological structure of genitalia was detected between wildtype and RNAi-treated groups, despite somewhat reduced fecundity and eclosion rate of progeny in females.…”

Intersex Plays a Role in Microbial Homeostasis in the Brown Planthopper

“…Extraordinary experimental efforts have been conducted to elucidate the role of Nlix in biological processes of insects, such as growth and development, sex differentiation, and reproduction [ 29 , 30 , 31 , 32 ]. The function of Nlix in regulating microbial community composition was first discovered.…”

“…The intersex ( ix ) gene is well conserved in insects, nevertheless, it has a multiplicity of functions in different species. For instance, it participates in sex differentiation, regulates external genital development, and female fecundity [ 29 , 30 , 31 , 32 ]. In our previous studies, we found that knocking out Nlix in nymphs led to the arrest of reproductive system development and failure of molting in BPHs.…”