Identification and functional verification of Y‐chromosome‐specific gene typo‐gyf in Bactrocera dorsalis

Abstract

AbstractGenes on the Y chromosome play important roles in male sex determination and development. The identification of Y‐chromosome‐specific genes not only provides a theoretical basis for the study of male reproductive development, but also offers genetic control targets for agricultural pests. However, Y‐chromosome genes are rarely characterized due to their high repeatability and high heterochromatinization, especially in the oriental fruit fly. In this study, 1 011 Y‐chromosome‐specific candidate sequences were screened from 2 to 4 h Bactrocera dorsalis embryo datasets with the chromosome quotient method, 6 of which were identified as Y‐chromosome‐specific sequences by polymerase chain reaction, including typo‐gyf, a 19 126‐bp DNA sequence containing a 575‐amino acid open reading frame. Testicular deformation and a significant reduction in sperm number were observed after typo‐gyf knockdown with RNA interference in embryos. After typo‐gyf knockout with clustered regularly interspaced palindromic repeats (CRISPR) / CRISPR‐associated protein 9 in the embryonic stage, the sex ratio of the emergent adults was unbalanced, with far more females than males. A genotype analysis of these females with the Y‐chromosome gene MoY revealed no sex reversal. Typo‐gyf knockout led to the death of XY individuals in the embryonic stage. We conclude that typo‐gyf is an essential gene for male survival, and is also involved in testicular development and spermatogenesis. The identification of typo‐gyf and its functional verification provide insight into the roles of Y‐chromosome genes in male development.