Abstract: 【Aim】 The dosage compensation mechanism of Helicoverpa armigera is still unclear. This study aims to clone male-specific lethal 1 gene Hamsl1 from H. armigera and to investigate whether it regulates dosage compensation of H. armigera by RNA interference technology. 【Methods】 The full-length cDNA of Hamsl1 sequence of H. armigera was cloned by RT-PCR based on homologous sequence alignment. The gene expression profiles of Hamsl1 in different developmental stages of H. armigera were detected by qPCR. After RNAi of Hamsl1 via microinjection of Hamsl1 siRNA into the 3rd instar larvae of H. armigera, the expression levels of 15 Z-linked genes were detected by qPCR to verify whether Hamsl1 regulates the dose of genes on Z chromosome. 【Results】 The full-length cDNA of Hamsl1 was successfully cloned from H. armigera, and its mRNA was identified to have two alternative splicing transcripts, which were designated as Hamsl1a (GenBank accession no.: MK564008) and Hamsl1b (GenBank accession no.: MK564009), respectively. Functional domain analysis showed that HaMSL1 contains a typical PEHE domain and a coiled-coil domain, which are the characteristics of MSL1 protein. The qPCR analysis demonstrated that Hamsl1 gene was located on the Z chromosome of H. armigera. The expression of both Hamsl1a and Hamsl1b showed the developmental stage specificity, peaking at the adult stage, and the sex specificity with significantly different expression level between female and male after pupation. Fifteen Z-linked genes were identified by homologous alignment and qPCR at the DNA level. Microinjecting Hamsl1 siRNA into the 3rd instar larvae of H. armigera for 72 h resulted in a RNA interference efficiency of 36.01%-64.27%, but no male specific lethal phenomenon was found in the tested insects. The 15 Z-linked genes in the Hamsl1 RNAi group showed significantly up-regulated expression in males as compared to those in the control group, but no significant expression change in females. 【Conclusion】 This study preliminarily proves that Hamsl1 gene is located on the Z chromosome of H. armigera and may regulate the dosage compensation by inhibiting the expression of Z-linked genes in male H. armigera. This study provides a theoretical foundation for further study of the molecular mechanism of dosage compensation and environmentally-friendly control of H. armigera.

Key words: Helicoverpa armigera, Hamsl1, sex chromosome, dosage compensation, RNAi