Inheritance of seedcoat color in derivatives of Pinto beans

A number of seedcoat color variants were found in the Pinto variety of beans. These derivatives have been subjected to a genetic analysis for seedcoat color. Most of the variations can be explained by assuming interactions of three genes, M, Rk, and Br, which are all present in the dorminant form in normal Pinto beans. M, a gene for mottling, has two allels, Mst for striped distribution of the mottling and m for self-colored beans. Br is a color modifier of the mottling. In the presence of m, the Br gene has no effect, in beans of the constitution M Br the mottling is brown, while in M br the mottling is green or pink in color. Rk is a color gene, affecting the ground color of mottled beans or the seed coat color of self colored beans. Rk produces buff color, while the recessive rk produces pink color. Beans of the constitution M Rk Br are brown/buff; M Rk br, green/buff, M rk Br brown/pink and M rk br pink/pink. There is some linkage between the Rk and Br loci, the value calculated from all the available material being .6%. There is a striking similarity between some of the Pinto derivative and other commercial varieties of western dry beans. These similarities of seedcoat color have been studied genetically. At least four commercial varieties could have arisen by a few mutations from the Pinto prototype. These may be represented by the following slight differences in genetic constitution: Pinto, P M Rk Br Striped Pinto, P Mg Rk Br Pink, P m rk Br or P m rk br Bayo, P M Rk br Red Kidney, P m rk Br or P m rk br Great Northern, p M Rk Br Other color biotypes found in the Pinto derivatives and tested genetically were: Green/buff, M Rk br, similar to Bayo Pink/pink, M rk br Brown/pink, M rk Br. Buff, m Rk Pink, m rk, similar to Pink.