Bassett (2007) wrote a comprehensive review of the genetics of seed-coat color and pattern in common bean (Phaseolus vulgaris). The gene loci T, P, and V have multiple alleles, which express pleiotropic effects on color and pattern in flowers and seed coats. The pattern gene T is required to express totally colored seed coats with no effect on flower color, whereas t expresses white flower and is required to express seed coats with partly colored patterns (colored vs. white). The color gene P is required to express pigmented seed coats, whereas p mic expresses a white micropyle stripe (Fig. 1) on seed coats (Bassett, 1998, 2003a). The p allele expresses white seed coat and flower, and the p hbw and p stp alleles express patterned flower color and seed coat color (Bassett, 1996, 2003a).
The color-modifying gene V (with T P B) is required to express bishops violet flower and black seed coat, whereas v expresses white flower and (with T P B) mineral brown seed coat. The v lae allele expresses pale pink flowers, with the banner petal expressing much darker pink than the wing petals. Thus, v lae is a flower color pattern gene. The V wf gene was transferred from Phaseolus coccineus to P. vulgaris by interspecific crossing and expresses white flowers without any pleiotropic effect on the color of seed coat (Bassett, 1997). Thus, (with B) V wf expresses black seed coat. The flower color pattern gene wb (with V) expresses (nearly) white banner petal and slight loss of violet color in the wing petals (Bassett, 1993). The wb pattern gene was transferred from P. coccineus to common bean by interspecific crossing. Although wb was reported (Bassett, 1993) to be nonallelic with V and Blu, additional test crosses are needed to preclude the possibility that wb is a new allele at either T or P.
The P. coccineus variety ‘Painted Lady’ has bicolor flowers with a vermilion banner petal and pure white wings. The inheritance of vermilion flower color is not fully known, but the gene for salmon red flower, Sal, is certainly required, and the scarlet flower color gene, Am, is probably required (Bassett, 2003b). Lamprecht (1941) used ‘Painted Lady’ in his inheritance studies of interspecific crosses with P. coccineus, noting that ‘Painted Lady’ had “two-colored” flowers. He further noted that P. coccineus (same as his P. multiflorus) had two series of two-colored flowers, “one of them with a darker standard than the wings (‘Painted Lady’ type), the other being the reverse [the white banner (wb) type].” Subsequently, Lamprecht (1948) reported (no supporting data presented) that the two-colored flowers of P. coccineus (‘Painted Lady’ type) were inherited as a recessive trait, to which he assigned the gene symbol bic for bicolorata. The preliminary hypothesis of our research is that the bicolor flower trait may be controlled by a new allele at Wb. The objectives of this paper are 1) to describe the transfer of the bicolor trait into common bean, 2) to investigate the inheritance of bicolor, 3) to test for allelism of bicolor with known genes for flower color or pattern, and 4) to make the allelism test crosses t × wb and wb × p mic to complete the testing for allelism in all possible combinations of the genes T, P, V, and Wb.
Bassett, M.J. 1993 A new gene for flower color pattern, white banner (wb), in progeny of an interspecific hybrid between common bean and scarlet runner beans J. Amer. Soc. Hort. Sci. 118 878 880
Bassett, M.J. 1994b The griseoalbus (gray-white) seed coat color is controlled by an allele (p gri) at the P locus in common bean HortScience 29 1178 1179
Bassett, M.J. 1997 A new allele (V wf) at the V locus for flower and seed coat color in common bean J. Amer. Soc. Hort. Sci. 122 519 521
Bassett, M.J. 1998 A third recessive allele, stp mic, for seed coat pattern at the Stp locus in common bean J. Amer. Soc. Hort. Sci. 123 404 406
Bassett, M.J. 2003a Allelism between the P and Stp genes for seed coat color and pattern in common bean J. Amer. Soc. Hort. Sci. 128 548 551
Bassett, M.J. 2003b Inheritance of scarlet color and vein pattern in flowers and oxblood red seed coat color derived from the interspecific cross of common bean with scarlet runner bean (Phaseolus coccineus L.) J. Amer. Soc. Hort. Sci. 128 559 563
Bassett, M.J., Shearon, C. & McClean, P. 1999 Allelism found between two common bean genes, hilum ring color (D) and partly colored seed coat pattern (Z), formerly assumed to be independent J. Amer. Soc. Hort. Sci. 124 649 653
Lamprecht, H. 1948 On the effect and linkage of genes transmitted from Phaseolus coccineus to Ph. vulgaris Agr. Hort. Genet. 6 64 81