The orange colour of carrots, pumpkins, sweet potatoes, oranges, and many other fruits and vegetables comes from carotenes, a type of photosynthetic pigment. These pigments convert the light energy that the plants absorb from the sun into chemical energy for the plants' growth. Similarly the hues of autumn leaves are from the same pigment after chlorophyll is removed.
The orange is a hybrid between pomelo (Citrus maxima) and mandarin (Citrus reticulata). It has genes that are ~25% pomelo and ~75% mandarin however, it is not a simple backcrossed BC1 hybrid, but hybridized over multiple generations
