The transcription factor E93 modulates Mmp1 expression to regulate testicular fusion during the prepupal stage in...

The cotton bollworm (Helicoverpa armigera) is a major globally distributed agricultural pest. A notable aspect of its male gonad development is testicular fusion during the larval-pupal transition, though the underlying regulatory mechanisms are poorly understood. In this study, we determined that the critical period for testicular fusion occurs at the pre-pupal stage in Helicoverpa armigera. RNAi-mediated knockdown of HaE93 in last-instar larvae disrupted this process. Comparative transcriptomic analysis revealed that HaE93 knockdown disrupts juvenile hormone (JH) and 20-hydroxyecdysone (20E) signaling and significantly alters the expression of genes encoding extracellular matrix (ECM) components, remodeling enzymes, cadherins, and integrins. RT-qPCR analysis showed that the expression peaks of matrix metalloproteinases (Mmps) in testes coincided with the period of testicular fusion, with HaMmp1 being particularly highly expressed in the testicular sheath. Furthermore, knockdown of HaMmp1 recapitulated the testicular fusion failure phenotype. Mating trials and egg hatchability assays demonstrated that dsHaMmp1-treated males had significantly reduced mating success and offspring survival. The observed significant downregulation of spermatogenesis-related genes in these males suggests that complete testicular fusion is crucial for male reproduction. In summary, our findings demonstrate that HaE93 regulates testicular fusion by modulating HaMmp1 expression, thus identifying HaMmp1 as a potential target for genetic pest management strategies aimed at inducing male sterility.