The Theobroma cacao tree, used to make chocolate, struggles with diseases: a problem that could be alleviated through breeding for new varieties. As a tropical tree crop, its long time to maturity and limited geographic range restrict breeding efforts. Genetic engineering could be a faster approach, although current protocols using the Agrobacterium-mediated transformation method have low efficiencies. This project aims to optimize the existing protocol by comparing ptxD and SulR to nptII as selectable marker genes for transformed cells.