What past discoveries about genetics did scientists make that now allow them to add genes from one organism to another or engineered genes into an organism?

Scientists have made significant advancements in genetics, particularly with the discovery of recombinant DNA technology in the 1970s, which allows for the manipulation and insertion of genes from one organism into another. Techniques such as CRISPR-Cas9 have further revolutionized this field by enabling precise editing of genes within an organism's genome. Additionally, the understanding of plasmids and the role of vectors in gene transfer has facilitated the development of genetically modified organisms (GMOs) for various applications in agriculture and medicine. These foundational discoveries have paved the way for biotechnological innovations that enhance traits or introduce new functions in organisms.