The role of the transformer gene in sex determination and reproduction in the tephritid fruit fly, Bactrocera dorsalis (Hendel).
Transformer (tra) is a switch gene in the somatic sex-determination hierarchy that regulates sexual dimorphism based on RNA splicing in many insects. In tephritids, a Y-linked male determining gene (M) controls sex in the sex-determination pathway. Here, homologues of Drosophila tra and transformer-2 (tra-2) genes were isolated and characterized in Bactrocera dorsalis (Hendel), one of the most destructive agricultural insect pests in many Asian countries. Two male-specific and one female-specific isoforms of B. dorsalis transformer (Bdtra) were identified. The presence of multiple TRA/TRA-2 binding sites in Bdtra suggests that the TRA/TRA-2 proteins are splicing regulators promoting and maintaining, epigenetically, female sex determination by a tra positive feedback loop in XX individuals during development. The expression patterns of female-specific Bdtra transcripts during early embryogenesis shows that a peak appears at 15 h after egg laying. Using dsRNA to knock-down Bdtra expression in the embryo and adult stages, we showed that sexual formation is determined early in the embryo stage and that parental RNAi does not lead to the production of all male progeny as in Tribolium castaneum. RNAi results from adult abdominal dsRNA injections show that Bdtra has a positive influence on female yolk protein gene (Bdyp1) expression and fecundity.
State Key Laboratory of Agricultural Microbiology, Hubei Key Laboratory of Insect Resource Application and Sustainable Pest Control and Institute of Urban and Horticultural Entomology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China.
Wei
W
Peng
State Key Laboratory of Agricultural Microbiology, Hubei Key Laboratory of Insect Resource Application and Sustainable Pest Control and Institute of Urban and Horticultural Entomology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China.
Wenping
W
Zheng
USDA/ARS, Center for Medical, Agricultural and Veterinary Entomology, 1700 SW 23rd Drive, Gainesville, FL, 32608, USA.
Alfred M
AM
Handler
State Key Laboratory of Agricultural Microbiology, Hubei Key Laboratory of Insect Resource Application and Sustainable Pest Control and Institute of Urban and Horticultural Entomology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China. hongyu.zhang@mail.hzau.edu.cn.
Hongyu
H
Zhang
D000818:Animals; D004330:Drosophila / Q000235:genetics; D029721:Drosophila Proteins / Q000235:genetics*; D044127:Epigenesis, Genetic; D015870:Gene Expression; D009687:Nuclear Proteins / Q000235:genetics*; D034622:RNA Interference; D012261:Ribonucleoproteins / Q000235:genetics*; D017385:Sequence Homology; D019849:Sex Determination Processes; D033621:Tephritidae / Q000196:embryology / Q000235:genetics*
D029721:Drosophila Proteins; D009687:Nuclear Proteins; D012261:Ribonucleoproteins; C097162:Tra protein, Drosophila; C066174:tra2 protein, Drosophila
Bactrocera dorsalis (Hendel); Bdtra RNAi; Tephritid sex determination; Transformer gene; Transformer-2 gene