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Masculinizer gene controls male sex determination in the codling moth, Cydia pomonella
Kristýna Pospíšilová1, Arjen E Van't Hof2, Atsuo Yoshido2
1Biology Centre of the Czech Academy of Sciences, Institute of Entomology, 370 05, České Budějovice, Czech Republic; Faculty of Science, University of South Bohemia, 370 05, České Budějovice, Czech Republic.
Abstract:
The molecular mechanisms of sex determination in moths and butterflies (Lepidoptera) with female heterogamety (WZ/ZZ) are poorly understood, except in the silkworm Bombyx mori. However, the Masculinizer (Masc) gene that controls male development and dosage compensation in B. mori, appears to be conserved in Lepidoptera, as its masculinizing function was recently confirmed in several moth species. In this work, we investigated the role of the Masc gene in sex determination of the codling moth Cydia pomonella (Tortricidae), a globally important pest of pome fruits and walnuts. The gene structure of the C. pomonella Masc ortholog, CpMasc, is similar to B. mori Masc. However, unlike B. mori, we identified 14 splice variants of CpMasc in the available transcriptomes. Subsequent screening for sex specificity and genetic variation using publicly available data and RT-PCR revealed three male-specific splice variants. Then qPCR analysis of these variants revealed sex-biased expression showing a peak only in early male embryos. Knockdown of CpMasc by RNAi during early embryogenesis resulted in a shift from male-to female-specific splicing of the C. pomonella doublesex (Cpdsx) gene, its downstream effector, in ZZ embryos, leading to a strongly female-biased sex ratio. These data clearly demonstrate that CpMasc functions as a masculinizing gene in the sex-determining cascade of C. pomonella. Our study also showed that CpMasc transcripts are provided maternally, as they were detected in unfertilized eggs after oviposition and in mature eggs dissected from virgin females. This finding is unique, as maternal provision of mRNA has rarely been studied in Lepidoptera.
Insights
The Masculinizer (Masc) gene controls male development in the codling moth. Knocking down CpMasc in ZZ embryos shifted sex determination to female, demonstrating its crucial role in male development.
Area of Science:
- * Molecular biology
- * Entomology
- * Genetics
Background:
- * Sex determination in Lepidoptera (moths and butterflies) with female heterogamety (WZ/ZZ) is largely unknown, except in Bombyx mori.
- * The Masculinizer (Masc) gene is vital for male development and dosage compensation in B. mori.
- * Masc's masculinizing function is conserved across several moth species.
Purpose of the Study:
- * To investigate the role of the Masc gene in the sex determination of the codling moth, Cydia pomonella.
- * To analyze the gene structure and splice variants of the C. pomonella Masc ortholog (CpMasc).
- * To determine the sex-specific expression and function of CpMasc in C. pomonella.
Main Methods:
- * Gene structure analysis of CpMasc.
- * Identification and screening of CpMasc splice variants using transcriptomic data and RT-PCR.
- * Quantitative PCR (qPCR) to analyze sex-biased expression of CpMasc variants.
- * RNA interference (RNAi) to knock down CpMasc expression during embryogenesis.
- * Analysis of the downstream effector gene, C. pomonella doublesex (Cpdsx), splicing patterns.
Main Results:
- * CpMasc shares structural similarity with B. mori Masc but exhibits 14 splice variants.
- * Three male-specific CpMasc splice variants were identified with sex-biased expression peaking in early male embryos.
- * RNAi-mediated knockdown of CpMasc in ZZ embryos caused a shift to female-specific splicing of Cpdsx.
- * Knockdown resulted in a strongly female-biased sex ratio in the offspring.
- * CpMasc transcripts were detected in unfertilized and mature eggs, indicating maternal provision.
Conclusions:
- * CpMasc functions as a masculinizing gene in the sex-determining cascade of C. pomonella.
- * The identified splice variants and their sex-specific expression are critical for male development.
- * Maternal provision of CpMasc mRNA is a unique feature in Lepidoptera sex determination.
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