Identification and characterization of doublesex in Bemisia tabaci

Abstract

Bemisia tabaci (Gennadius) is an important agricultural pest with a worldwide distribution. Although B. tabaci is known to have a unique haplodiploid reproductive strategy, its sex determination mechanism is largely unknown. In this study, we cloned the full-length sequence of B. tabaci doublesex (Btdsx) and found that Btdsx has 28 splicing isoforms. We found two new splicing isoforms of transformer 2 (Bttra2), which encode two proteins. We also confirmed that both genes lack sex-specific splicing isoforms. Real-time quantitative PCR analysis showed that the expression of Btdsx and Bttra2 is higher in males than in females. RNA interference of Bttra2 affected the expression of Btdsx and vice versa. Furthermore, silencing of Bttra2 or Btdsx caused malformation of the male genitalia (anal style). It did not affect the female phenotype, but reduced the expression of vitellogenin gene in females. These results indicate that Btdsx is associated with sex determination in B. tabaci and that Btdsx and Bttra2 affect each other and are important for male genitalia formation. In addition to increasing our understanding of the roles of dsx and tra2 in the sex determination of B. tabaci, the results will be useful for studies of sex determination in other haplodiploid species.

Hemimetabolous insects elucidate the origin of sexual development via alternative splicing

“…In P. humanus (Phthiraptera), the alternative splicing of dsx follows the usual pattern, with a common N-terminal domain and alternative C-termini, but we found that both dsx isoforms are present in both sexes. Previous work in the hemipteran Bemisia tabaci also failed to detect sex-specific dsx isoforms (95), suggesting that some insects may have secondarily lost sex-specific dsx splicing.…”

Genome‐wide dissection of sex determination genes in the highly invasive whitefly species Bemisia tabaci Q/MED

“…S2; Table ). Among these genes, PSI , tra2 and dsx have been documented previously (Xie et al ., ; Liu et al ., ; Guo et al ., ), whereas the other 23 (88.5%), including tra and fru , were identified for the first time in this study.…”

“…Second, 20 SDGs with incomplete sequences or the same predicted amino acids between the female and male transcriptomic datasets were filtered (Table S5). The remaining six SDGs were verified by RT‐PCR [ dsx , tra2 and PSI verified previously (Liu et al ., ; Guo et al ., ) and da , mle and Imp verified in this paper]. PCR validation in this paper was conducted using designed sex‐specific primers (Table S7) with newly emerged female or male samples.…”

“…After screening, six SDGs with putative sex‐specific splicing remained (Tables S5 and S6). Among these SDGs, PSI , dsx and tra2 have been previously studied (Liu et al ., ; Guo et al ., ), whereas the remaining three genes were validated by PCR in this study. The results showed that da and mle undergo sex‐specific splicing in B. tabaci , whereas Imp does not (Figs A, B and S4; Table S8).…”

“…As a globally invasive polyphagous pest with a haplodiploid reproduction system (males that develop from unfertilized eggs are haploid and females that develop from fertilized eggs are diploid) (Blackman and Cahill, ), the sweetpotato whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae), is an emerging model for the study of signalling cascades and gene expression networks that govern sex determination. To date, only three SDGs ( PSI , tra2 and dsx ) have been identified (Xie et al ., ; Liu et al ., ; Guo et al ., ). The mechanism underlying sex determination in whiteflies is poorly understood.…”