Common bean (Phaseolus vulgaris L.) is the most important food legume in the tropics of Latin America and East, Central, and Southern Africa. It belongs to the family Fabaceae, and it has two gene pools (Mesoamerican and Andean) based on their centers of origin from Central and South America, respectively (Gepts and Debouck, 1991). These gene pools differ in seed size and color, in the protein phaseolin, and in morphological and molecular characteristics (Beebe, 2012). The crop is grown by smallholder farmers in Latin America and East Africa, where it is often exposed to unfavorable conditions such as drought, low soil fertility, and heat (Beebe et al., 2008). It is an inexpensive source of protein and calories for small farmers in countries with endemic poverty (Rao, 2014).