They did it by transferring genes from maize into rice to create so - called Golden Rice; golden because it produces the same pigments that yellow vegetables do. (irri.org)
Finally, its exterior contains melanin, the same pigment that colors human skin, which both protects it from UV radiation as well as inhibits the digestive action of macrophages. (scientificamerican.com)
Notice the brown pigment of the cell walls; this is melanin, the same pigment that darkens human skin. (scientificamerican.com)