The colors of peppers are determined by the interaction of several genes. An allele Y promotes the early elimination of chlorophyll (a green pigment), whereas y does not. Allele R determines red and r determines yellow carotenoid pigments. Alleles c1 and c2 of two different genes down-regulate the amounts of carotenoids, causing the lighter shades. Orange is down-regulated red. Brown is green plus red. Pale yellow is down-regulated yellow.

[Anthony Griffiths.]