Researchers developed an optimized transgenesis system for Drosophila using the phiC31 integrase, which allows precise and efficient insertion of transgenes into specific genomic locations. This system uses germ-line-specific integrase sources, eliminating the need for coinjection of integrase mRNA and improving transformation efficiency. The system includes attP landing sites that can be modified in situ, enabling versatile and high-throughput transgene analysis. The study demonstrates that the phiC31-based system outperforms traditional P-element-mediated transgenesis in terms of efficiency, ease of use, and versatility. The system allows for the generation of transgenic lines with high transformation frequencies, and the use of endogenous integrase sources enhances the reliability and efficiency of the process. The system also includes a "split-white" reconstitution system that provides an immediate visual readout for specific attP targeting. The study highlights the potential of this system for systematic screening of large cDNA sets and regulatory elements, and for advancing the understanding of gene function in Drosophila. The system is characterized by its high specificity, efficiency, and flexibility, making it a valuable tool for genetic research in Drosophila.Researchers developed an optimized transgenesis system for Drosophila using the phiC31 integrase, which allows precise and efficient insertion of transgenes into specific genomic locations. This system uses germ-line-specific integrase sources, eliminating the need for coinjection of integrase mRNA and improving transformation efficiency. The system includes attP landing sites that can be modified in situ, enabling versatile and high-throughput transgene analysis. The study demonstrates that the phiC31-based system outperforms traditional P-element-mediated transgenesis in terms of efficiency, ease of use, and versatility. The system allows for the generation of transgenic lines with high transformation frequencies, and the use of endogenous integrase sources enhances the reliability and efficiency of the process. The system also includes a "split-white" reconstitution system that provides an immediate visual readout for specific attP targeting. The study highlights the potential of this system for systematic screening of large cDNA sets and regulatory elements, and for advancing the understanding of gene function in Drosophila. The system is characterized by its high specificity, efficiency, and flexibility, making it a valuable tool for genetic research in Drosophila.